Transcriptome analysis of Pinus halepensis under drought stress and during recovery.

Science.gov (United States)

Fox, Hagar; Doron-Faigenboim, Adi; Kelly, Gilor; Bourstein, Ronny; Attia, Ziv; Zhou, Jing; Moshe, Yosef; Moshelion, Menachem; David-Schwartz, Rakefet

2018-03-01

Forest trees use various strategies to cope with drought stress and these strategies involve complex molecular mechanisms. Pinus halepensis Miller (Aleppo pine) is found throughout the Mediterranean basin and is one of the most drought-tolerant pine species. In order to decipher the molecular mechanisms that P. halepensis uses to withstand drought, we performed large-scale physiological and transcriptome analyses. We selected a mature tree from a semi-arid area with suboptimal growth conditions for clonal propagation through cuttings. We then used a high-throughput experimental system to continuously monitor whole-plant transpiration rates, stomatal conductance and the vapor pressure deficit. The transcriptomes of plants were examined at six physiological stages: pre-stomatal response, partial stomatal closure, minimum transpiration, post-irrigation, partial recovery and full recovery. At each stage, data from plants exposed to the drought treatment were compared with data collected from well-irrigated control plants. A drought-stressed P. halepensis transcriptome was created using paired-end RNA-seq. In total, ~6000 differentially expressed, non-redundant transcripts were identified between drought-treated and control trees. Cluster analysis has revealed stress-induced down-regulation of transcripts related to photosynthesis, reactive oxygen species (ROS)-scavenging through the ascorbic acid (AsA)-glutathione cycle, fatty acid and cell wall biosynthesis, stomatal activity, and the biosynthesis of flavonoids and terpenoids. Up-regulated processes included chlorophyll degradation, ROS-scavenging through AsA-independent thiol-mediated pathways, abscisic acid response and accumulation of heat shock proteins, thaumatin and exordium. Recovery from drought induced strong transcription of retrotransposons, especially the retrovirus-related transposon Tnt1-94. The drought-related transcriptome illustrates this species' dynamic response to drought and recovery and unravels

Arbuscular mycorrhizal symbiosis induces strigolactone biosynthesis under drought and improves drought tolerance in lettuce and tomato.

Science.gov (United States)

Ruiz-Lozano, Juan Manuel; Aroca, Ricardo; Zamarreño, Ángel María; Molina, Sonia; Andreo-Jiménez, Beatriz; Porcel, Rosa; García-Mina, José María; Ruyter-Spira, Carolien; López-Ráez, Juan Antonio

2016-02-01

Arbuscular mycorrhizal (AM) symbiosis alleviates drought stress in plants. However, the intimate mechanisms involved, as well as its effect on the production of signalling molecules associated with the host plant-AM fungus interaction remains largely unknown. In the present work, the effects of drought on lettuce and tomato plant performance and hormone levels were investigated in non-AM and AM plants. Three different water regimes were applied, and their effects were analysed over time. AM plants showed an improved growth rate and efficiency of photosystem II than non-AM plants under drought from very early stages of plant colonization. The levels of the phytohormone abscisic acid, as well as the expression of the corresponding marker genes, were influenced by drought stress in non-AM and AM plants. The levels of strigolactones and the expression of corresponding marker genes were affected by both AM symbiosis and drought. The results suggest that AM symbiosis alleviates drought stress by altering the hormonal profiles and affecting plant physiology in the host plant. In addition, a correlation between AM root colonization, strigolactone levels and drought severity is shown, suggesting that under these unfavourable conditions, plants might increase strigolactone production in order to promote symbiosis establishment to cope with the stress. © 2015 John Wiley & Sons Ltd.

The effect of reservoir networks on drought propagation

NARCIS (Netherlands)

Oel, van P.R.; Martins, E.S.P.R.; Costa, A.C.

2017-01-01

Human interventions in response to drought can both alleviate and enhance drought. Developments of infrastructure for freshwater storage, groundwater abstraction and irrigation have proved to be effective in overcoming meteorological and agricultural drought in many locations worldwide. At the same

Carbon dynamics of Acer pseudoplatanus seedlings under drought and complete darkness.

Science.gov (United States)

Piper, Frida I; Fajardo, Alex

2016-11-01

Carbon (C) storage is considered a key component to plant survival under drought and shade, although the combined effects of these factors on survival remain poorly understood. We investigated how drought and shade alter the C dynamics and survival of tree seedlings, and whether drought limits the access to or usage of stored C. We experimentally applied two levels of soil humidity (well-watered versus drought, the latter induced by dry-down) and light availability (light versus complete darkness) on 1-year-old seedlings of Acer pseudoplatanus L. for 3 months. We quantified the survival, biomass, growth rate and non-structural carbohydrates (NSC) of seedlings at their time of death or at the end of the experiment for those that survived. We found that the soil dried out faster when drought was combined with light than when it was combined with complete darkness. Seedlings subjected to both drought and light showed reduced growth and reached 100% mortality earlier than any other treatment, with the highest NSC concentrations at the time of death. Seedlings exposed to both drought and complete darkness died significantly earlier than seedlings exposed to complete darkness only, but had similar NSC concentrations at time of their death, suggesting that drought accelerated the use of stored C under complete darkness. Complete darkness significantly reduced seedling growth and whole-plant NSC concentrations regardless of soil humidity, while root NSC concentrations were significantly more reduced when complete darkness was combined with drought conditions. Thus, the C dynamics in A. pseudoplatanus seedlings under complete darkness was not hindered by drought, i.e., the access and use of stored C was not limited by drought. The contrasting growth and C storage responses driven by drought under light versus complete darkness are consistent with a key role of the drought progression in the C dynamics of trees. © The Author 2016. Published by Oxford University Press. All

Evaluating Yield and Drought Stress Indices under End Season Drought Stress in Promising Genotypes of Barley

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H. Tajalli

2012-08-01

Full Text Available To study the effects of end season drought stress on yield, yield components and drought stress indices in barley, a split plot experiment arranged in randomized complete block design with three replications was conducted at the Agricultural Research Center of Birjand in 2008-2009 crop years. Drought stress, in 2 levels, consists of control (complete irrigation and stopping irrigation at the 50% of heading stage, and 20 promising genotypes of barley were the treatments of the experiment. Results revealed that stopping irrigation lead to declining of 14.64 and 8.12 percent of seed and forage yields against control condition, respectively. Using stress susceptibility index (SSI indicated that genotypes 2, 3, 7, 9, 10 and 15; using STI and GMP indices, genotypes 5, 8, 18 and 20 using MP, genotypes 8, 18 and 20, and TOL, genotypes 2, 3, 7, 9, and 10, were the most drought tolerant genotypes. Correlation between seed yield and stress evaluation indices showed that MP, GMP and STI are the best indices to be used in selection and introducing drought tolerant genotypes of barley. Considering all indices, and given that the best genotypes are those with high yield under normal condition and minimum yield reduction under drought stress, No. 18 and 20 could be introduced as the most tolerant barley genotypes to drought.

Novel Digital Features Discriminate Between Drought Resistant and Drought Sensitive Rice Under Controlled and Field Conditions

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Lingfeng Duan

2018-04-01

Full Text Available Dynamic quantification of drought response is a key issue both for variety selection and for functional genetic study of rice drought resistance. Traditional assessment of drought resistance traits, such as stay-green and leaf-rolling, has utilized manual measurements, that are often subjective, error-prone, poorly quantified and time consuming. To relieve this phenotyping bottleneck, we demonstrate a feasible, robust and non-destructive method that dynamically quantifies response to drought, under both controlled and field conditions. Firstly, RGB images of individual rice plants at different growth points were analyzed to derive 4 features that were influenced by imposition of drought. These include a feature related to the ability to stay green, which we termed greenness plant area ratio (GPAR and 3 shape descriptors [total plant area/bounding rectangle area ratio (TBR, perimeter area ratio (PAR and total plant area/convex hull area ratio (TCR]. Experiments showed that these 4 features were capable of discriminating reliably between drought resistant and drought sensitive accessions, and dynamically quantifying the drought response under controlled conditions across time (at either daily or half hourly time intervals. We compared the 3 shape descriptors and concluded that PAR was more robust and sensitive to leaf-rolling than the other shape descriptors. In addition, PAR and GPAR proved to be effective in quantification of drought response in the field. Moreover, the values obtained in field experiments using the collection of rice varieties were correlated with those derived from pot-based experiments. The general applicability of the algorithms is demonstrated by their ability to probe archival Miscanthus data previously collected on an independent platform. In conclusion, this image-based technology is robust providing a platform-independent tool for quantifying drought response that should be of general utility for breeding and functional

Global Changes in Drought Conditions Under Different Levels of Warming

Science.gov (United States)

Naumann, G.; Alfieri, L.; Wyser, K.; Mentaschi, L.; Betts, R. A.; Carrao, H.; Spinoni, J.; Vogt, J.; Feyen, L.

2018-04-01

Higher evaporative demands and more frequent and persistent dry spells associated with rising temperatures suggest that drought conditions could worsen in many regions of the world. In this study, we assess how drought conditions may develop across the globe for 1.5, 2, and 3°C warming compared to preindustrial temperatures. Results show that two thirds of global population will experience a progressive increase in drought conditions with warming. For drying areas, drought durations are projected to rise at rapidly increasing rates with warming, averaged globally from 2.0 month/°C below 1.5°C to 4.2 month/°C when approaching 3°C. Drought magnitudes could double for 30% of global landmass under stringent mitigation. If contemporary warming rates continue, water supply-demand deficits could become fivefold in size for most of Africa, Australia, southern Europe, southern and central states of the United States, Central America, the Caribbean, north-west China, and parts of Southern America. In approximately 20% of the global land surface, drought magnitude will halve with warming of 1.5°C and higher levels, mainly most land areas north of latitude 55°N, but also parts of South America and Eastern and South-eastern Asia. A progressive and significant increase in frequency of droughts is projected with warming in the Mediterranean basin, most of Africa, West and Southern Asia, Central America, and Oceania, where droughts are projected to happen 5 to 10 times more frequent even under ambitious mitigation targets and current 100-year events could occur every two to five years under 3°C of warming.

Gene expression analysis of Solanum lycopersicum and Solanum habrochaites under drought conditions

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Upama Mishra

2016-09-01

Full Text Available Drought is one of the limiting environmental factors that affect crop production worldwide. Understanding the molecular mechanism of drought stress is the key to developing drought tolerant crop. In this experiment we performed expression profiling of tomato plants under water deficit conditions using microarray technology. The data set we generated (available in the NCBI/GEO database under GSE22304 has been analyzed to identify genes that are involved in the regulation of tomato's responses to drought.

Screening for Osmotic Stress Responses in Rice Varieties under Drought Condition

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Simon Swapna

2017-09-01

Full Text Available Drought is the major abiotic stress factor that limits rice production worldwide. To evaluate the osmotic stress responses in rice varieties under drought condition, a total of 42 high-yielding rice varieties were collected from various research stations of Kerala Agricultural University in India. The experimental setup comprises of initial hydroponic treatments at different osmotic potentials, artificially induced by desired strengths of polyethylene glycol (PEG6000, and followed by the pot planted experiments in the rain-out-zone. The activities of antioxidant enzymes, relative water content, cell membrane stability, photosynthetic pigments, proline content, along with plant growth parameters of the varieties under drought condition were evaluated. Moreover, the standard scores of these rice varieties were assessed under stress and recovery conditions based on the scoring scale of the Standard Evaluation System for rice. Among the 42 rice varieties, we identified 2 rice varieties, Swarnaprabha and Kattamodan, with less leaf rolling, better drought recovery ability as well as relative water content, increased membrane stability index, osmolyte accumulation, and antioxidant enzyme activities pointed towards their degree of tolerance to drought stress. The positive adaptive responses of these rice varieties towards drought stress can be used in the genetic improvement of rice drought resistance breeding program.

Heterogeneity of hydrolytic enzyme activities under drought: imaging and quantitative analysis

Science.gov (United States)

Sanaullah, Muhammad; Razavi, Bahar S.; Kuzyakov, Yakov

2015-04-01

The zymography-based "snap-shoot" of enzyme activities in the rhizosphere is challenging to detect the in situ microbial response to global climate change. We developed in situ soil zymography and used it for identification and localization of hotspots of β-glucosidase activity in the rhizosphere of maize under drought stress (30% of field capacity). The zymographic signals were especially high at root tips and were much stronger for activity of β-glucosidase under drought as compared with optimal moisture (70% of field capacity). This distribution of enzyme activity was confirmed by fluorogenically labelled substrates applied directly to the root exudates. The activity of β-glucosidase in root exudates (produced by root and microorganism associated on the root surface), sampled within 1 hour after zymography was significantly higher by drought stressed plants as compared with optimal moisture. In contrast, the β-glucosidase activity in destructively sampled rhizosphere soil was lower under drought stress compared with optimal moisture. Furthermore, drought stress did not affected β-glucosidase activity in bulk soil, away from rhizosphere. Consequently, we conclude that higher release of mucilage by roots und drought stimulated β-glucosidase activity in the rhizosphere. Thus, the zymography revealed plant-mediated mechanisms accelerating β-glucosidase activity under drought at the root-soil interface. So, coupling of zymography and enzyme assays in the rhizosphere and non-rhizosphere soil enables precise mapping the changes in two-dimensional distribution of enzyme activities due to climate change within dynamic soil interfaces.

A process-based typology of hydrological drought

NARCIS (Netherlands)

Loon, van A.F.; Lanen, van H.A.J.

2012-01-01

Hydrological drought events have very different causes and effects. Classifying these events into distinct types can be useful for both science and management. We propose a hydrological drought typology that is based on governing drought propagation processes derived from catchment-scale drought

Drought and Carbon Cycling of Grassland Ecosystems under Global Change: A Review

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Tianjie Lei

2016-10-01

Full Text Available In recent years, the increased intensity and duration of droughts have dramatically altered the structure and function of grassland ecosystems, which have been forced to adapt to this change in climate. Combinations of global change drivers such as elevated atmospheric CO2 concentration, warming, nitrogen (N deposition, grazing, and land-use change have influenced the impact that droughts have on grassland C cycling. This influence, to some extent, can modify the relationship between droughts and grassland carbon (C cycling in the multi-factor world. Unfortunately, prior reviews have been primarily anecdotal from the 1930s to the 2010s. We investigated the current state of the study on the interactive impacts of multiple factors under drought scenarios in grassland C cycling and provided scientific advice for dealing with droughts and managing grassland C cycling in a multi-factor world. Currently, adequate information is not available on the interaction between droughts and global change drivers, which would advance our understanding of grassland C cycling responses. It was determined that future experiments and models should specifically test how droughts regulate grassland C cycling under global changes. Previous multi-factor experiments of current and future global change conditions have studied various drought scenarios poorly, including changes in precipitation frequency and amplitude, timing, and interactions with other global change drivers. Multi-factor experiments have contributed to quantifying these potential changes and have provided important information on how water affects ecosystem processes under global change. There is an urgent need to establish a systematic framework that can assess ecosystem dynamic responses to droughts under current and future global change and human activity, with a focus on the combined effects of droughts, global change drivers, and the corresponding hierarchical responses of an ecosystem.

On the propagation of drought : how climate and catchment characteristics influence hydrological drought development and recovery

NARCIS (Netherlands)

Loon, van A.F.

2013-01-01

Drought is a severe natural disaster resulting in high economic loss and huge ecological and societal impacts. In this thesis drought is defined as a period of below-normal water availability in precipitation (meteorological drought), soil moisture (soil moisture drought), or groundwater and

The Role of Precipitation Recycling in the Propagation and Intensification of Droughts in North America

Science.gov (United States)

Herrera-Estrada, J. E.; Sheffield, J.; Martinez-Agudelo, J. A.; Dominguez, F.; Wood, E. F.

2017-12-01

), precipitation deficits from land were as large and sometimes larger than those from the oceans. These results demonstrate a mechanism by which droughts can propagate spatially downwind, and point out to processes that need to be captured accurately by models used in operational seasonal forecasting and in climate change studies.

Organ-specific proteomics of soybean seedlings under flooding and drought stresses.

Science.gov (United States)

Wang, Xin; Khodadadi, Ehsaneh; Fakheri, Baratali; Komatsu, Setsuko

2017-06-06

Organ-specific analyses enrich the understanding of plant growth and development under abiotic stresses. To elucidate the cellular responses in soybean seedlings exposed to flooding and drought stresses, organ-specific analysis was performed using a gel-free/label-free proteomic technique. Physiological analysis indicated that enzyme activities of alcohol dehydrogenase and delta-1-pyrroline-5-carboxylate synthase were markedly increased in leaf and root of plants treated with 6days of flooding and drought stresses, respectively. Proteins related to photosynthesis, RNA, DNA, signaling, and the tricarboxylic acid cycle were predominately affected in leaf, hypocotyl, and root in response to flooding and drought. Notably, the tricarboxylic acid cycle was suppressed in leaf and root under both stresses. Moreover, 17 proteins, including beta-glucosidase 31 and beta-amylase 5, were identified in soybean seedlings under both stresses. The protein abundances of beta-glucosidase 31 and beta-amylase 5 were increased in leaf and root under both stresses. Additionally, the gene expression of beta-amylase 5 was upregulated in leaf exposed to the flooding and drought, and the expression level was highly correlated with the protein abundance. These results suggest that beta-amylase 5 may be involved in carbohydrate mobilization to provide energy to the leaf of soybean seedlings exposed to flooding and drought. This study examined the effects of flooding and drought on soybean seedlings in different organs using a gel-free/label-free proteomic approach. Physiological responses indicated that enzyme activities of alcohol dehydrogenase and delta-1-pyrroline-5-carboxylate synthase were increased in leaf and root of soybean seedlings exposed to flooding and drought for 6days. Functional analysis of acquired protein profiles exhibited that proteins related to photosynthesis, RNA, DNA, signaling, and the tricarboxylic acid cycle were predominated affected in leaf, hypocotyl, and root

Fatigue crack propagation behavior under creep conditions

International Nuclear Information System (INIS)

Ohji, Kiyotsugu; Kubo, Shiro

1991-01-01

The crack propagation behavior of the SUS 304 stainless steel under creep-fatigue conditions was reviewed. Cracks propagated either in purely time-dependent mode or in purely cycle-dependent mode, depending on loading conditions. The time-dependent crack propagation rate was correlated with modified J-integral J * and the cycle-dependent crack propagation rate was correlated with J-integral range ΔJ f . Threshold was observed in the cycle-dependent crack propagation, and below this threshold the time-dependent crack propagation appeared. The crack propagation rates were uniquely characterized by taking the effective values of J * and ΔJ f , when crack closure was observed. Change in crack propagation mode occurred reversibly and was predicted by the competitive damage model. The threshold disappeared and the cycle-dependent crack propagation continued in a subthreshold region under variable amplitude conditions, where the threshold was interposed between the maximum and minimum ΔJ f . (orig.)

On the use of Standardized Drought Indices under decadal climate variability: Critical assessment and drought policy implications

Science.gov (United States)

Núñez, J.; Rivera, D.; Oyarzún, R.; Arumí, J. L.

2014-09-01

Since the recent High Level Meeting on National Drought Policy held in Geneva in 2013, a greater concern about the creation and adaptation of national drought monitoring systems is expected. Consequently, backed by international recommendations, the use of Standardized Drought Indices (SDI), such as the Standardized Precipitation Index (SPI), as an operational basis of drought monitoring systems has been increasing in many parts of the world. Recommendations for the use of the SPI, and consequently, those indices that share its properties, do not take into account the limitations that this type of index can exhibit under the influence of multidecadal climate variability. These limitations are fundamentally related to the lack of consistency among the operational definition expressed by this type of index, the conceptual definition with which it is associated and the political definition it supports. Furthermore, the limitations found are not overcome by the recommendations for their application. This conclusion is supported by the long-term study of the Standardized Streamflow Index (SSI) in the arid north-central region of Chile, under the influence of multidecadal climate variability. The implications of the findings of the study are discussed with regard to their link to aspects of drought policy in the cases of Australia, the United States and Chile.

Characterization of proteins in soybean roots under flooding and drought stresses.

Science.gov (United States)

Oh, MyeongWon; Komatsu, Setsuko

2015-01-30

Flooding and drought affect soybean growth because soybean is a stress-sensitive crop. In 2-day-old plants exposed to 2-day flooding or drought, the fresh weight of roots was markedly suppressed, although the root morphology clearly differed between two conditions. To understand the response mechanisms of soybean to flooding and drought stresses, a gel-free proteomic technique was used. A total of 97 and 48 proteins were significantly changed in response to flooding and drought stresses, respectively. Proteins involved in protein synthesis were decreased by flooding stress and increased by drought. Glycolysis-related proteins were increased in roots by both flooding and drought stresses. Fermentation, stress, and cell wall-related proteins were increased in response to flooding stress, whereas cell organization and redox-related proteins were increased under drought stress. Among the identified proteins, three S-adenosylmethionine synthetases were commonly decreased and increased in response to flooding and drought stresses, respectively. The mRNA expression levels of S-adenosylmethionine synthetase genes displayed a similar tendency to the changes in protein abundance. These results suggest that S-adenosylmethionine synthetase is involved in the regulation of stress response because it was changed in response to flooding and drought stresses. This study reported on the response mechanisms of soybean to flooding and drought stresses using the gel-free proteomic technique. Proteins involved in protein synthesis were decreased by flooding stress and increased by drought. Glycolysis-related proteins were increased in roots by both flooding and drought stresses. Fermentation, stress, and cell wall-related proteins were increased in response to flooding stress, whereas cell organization and redox-related proteins were increased under drought stress. Among the identified proteins, three S-adenosylmethionine synthetases were commonly decreased and increased in response to

Mapping of QTLs for Germination Characteristics under Non-stress and Drought Stress in Rice

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Zahra MARDANI

2013-11-01

Full Text Available Identification of genetic factors controlling traits associated with seed germination under drought stress conditions, leads to identification and development of drought tolerant varieties. Present study by using a population of F2:4 derived from a cross between a drought tolerant variety, Gharib (indica and a drought sensitive variety, Sepidroud (indica, is to identify and compare QTLs associated with germination traits under drought stress and non-stress conditions. Through QTL analysis, using composite interval mapping, regarding traits such as germination rate (GR, germination percentage (GP, radicle length (RL, plumule length (PL, coleorhiza length (COL and coleoptile length (CL, totally 13 QTLs were detected under pole drought stress (−8 MPa poly ethylene glycol 6000 and 9 QTLs under non-stress conditions. Of the QTLs identified under non-stress conditions, QTLs associated with COL (qCOL-5 and GR (qGR-1 explained 21.28% and 19.73% of the total phenotypic variations, respectively. Under drought stress conditions, QTLs associated with COL (qCOL-3 and PL (qPL-5 explained 18.34% and 18.22% of the total phenotypic variations, respectively. A few drought-tolerance-related QTLs identified in previous studies are near the QTLs detected in this study, and several QTLs in this study are novel alleles. The major QTLs like qGR-1, qGP-4, qRL-12 and qCL-4 identified in both conditions for traits GR, GP, RL and CL, respectively, should be considered as the important and stable trait-controlling QTLs in rice seed germination. Those major or minor QTLs could be used to significantly improve drought tolerance by marker-assisted selection in rice.

Pinus sylvestris switches respiration substrates under shading but not during drought

Science.gov (United States)

Hartmann, Henrik; Fischer, Sarah; Hanf, Stefan; Frosch, Torsten; Poppp, Jürgen; Trumbore, Susan

2015-04-01

Reduced carbon assimilation during prolonged drought forces trees to rely on stored carbon to maintain vital processes like respiration. It has been shown, however, that the use of carbohydrates, a major carbon storage pool and main respiratory substrate in plants, strongly declines with deceasing plant hydration. Yet, no empirical evidence has been produced to what degree other carbon storage compounds like lipids and proteins may fuel respiration during drought. We exposed young scots pine trees to carbon limitation using either drought or shading and assessed respiratory substrate use by monitoring the respiratory quotient, δ13C of respired CO2and concentrations of the major storage compounds, i.e. carbohydrates (COH), lipids and amino acids. Generally, respiration was dominated by the most abundant substrate. Only shaded trees shifted from carbohydrate-dominated to lipid-dominated respiration and showed progressive carbohydrate depletion. In drought trees respiration was strongly reduced and fueled with carbohydrates from also strongly reduced carbon assimilation. Initial COH content was maintained during drought probably due to reduced COH mobilization and use and the maintained COH content may have prevented lipid catabolism via sugar signaling. Our results suggest that respiratory substrates other than carbohydrates are used under carbohydrate limitation but not during drought. Thus, respiratory substrate change cannot provide an efficient means to counterbalance carbon limitation under natural drought.

Evaluation of Diversity and Traits Correlation in Spring Wheat Cultivars under Drought Stress

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Mohammad Reza NAGHAVI

2015-09-01

Full Text Available In order to study of diversity and classify agro-morphological characters under normal irrigation and drought stress in spring wheat cultivars, 20 cultivars were evaluated in the research farm of University of Tabriz, Iran. According to the results, significant correlation was found between grain yield and number of spikes per plant, number of tiller per plant, number of fertile tillers, spike length, root length, root number, root volume, root diameter and root dry weight under both conditions. Moreover, 1,000 grain weight and plant dry weight had significant positive correlation with grain yield under drought stress. Factor analysis detected four and two factors which explained 96.77% and 90.59% of the total variation in normal irrigation and drought stress conditions, respectively. In drought stress condition the first factor justified 69.52% of total variation and was identified as yield factor. The second factor explained 21.07% of total variation and represented the biomass and plant height factor. Cluster analysis was based on the four and two factors obtained. According to the amount of factors for clusters obtained under drought stress, ‘Kavir’, ‘Niknejhad’, ‘Moghan 3’, ‘Darya’ and ‘Marvdasht’ were identified as the most drought tolerant cultivars. Other cluster was comprised of ‘Bahar’, ‘Pishtaz’, ‘Bam’, ‘Sepahan’, ‘Sistan’, ‘Pars’ and ‘Sivand’ and was named as the most sensitive under drought stress. Tolerant cultivars identified within the study can be used for direct culture or as genitors in breeding programs.

[Effects of Ca2+ on nitric oxide-induced adventitious rooting in cucumber under drought stress].

Science.gov (United States)

Li, Chun Lan; Niu, Li Juan; Hu, Lin Li; Liao, Wei Biao; Chen, Yue

2017-11-01

Cucumber (Cucumis sativus L. 'Xinchun 4') was used to explore the relationship between nitric oxide (NO) and calcium (Ca 2+ ) during adventitious rooting under drought stress. Rooting parameters, endogenous Ca 2+ fluorescent intensity and the antioxidant enzymes activity (SOD, CAT and APX) in cucumber explants under drought stress were investigated. The results showed that treatment with 200 μmol·L -1 CaCl 2 and 0.05% PEG significantly improved the number and length of adventitious root in cucumber explants under drought stress, while the application of Ca 2+ chelating agent (EGTA) and channel inhibitor (BAPTA/AM) significantly decreased NO-induced number and length of adventitious root under drought stress. Under drought stress, the fluorescence intensity of Ca 2+ in hypocotyls treated with NO and CaCl 2 was improved, however, the Ca 2+ fluorescence intensity in the hypocotyls treated with NO scavenger (cPTIO) was significantly lower than that in the hypocotyls treated with NO. Under drought stress, the activities of antioxidant enzymes in the cucumber explants were significantly promoted by the treatments with NO and CaCl 2 , however, Ca 2+ chelating agent and channel inhibitor significantly decreased the activity of antioxidant enzymes induced by NO. In conclusion, Ca 2+ might be involved in the process of NO-adjusted antioxidant enzymes activity during adventitious rooting under drought stress, which alleviated the negative effects of drought on the adventitious rooting and promoted the formation of adventitious roots.

Genome-wide transcriptional reprogramming under drought stress

KAUST Repository

Chen, Hao

2012-01-01

Soil water deficit is one of the major factors limiting plant productivity. Plants cope with this adverse environmental condition by coordinating the up- or downregulation of an array of stress responsive genes. Reprogramming the expression of these genes leads to rebalanced development and growth that are in concert with the reduced water availability and that ultimately confer enhanced stress tolerance. Currently, several techniques have been employed to monitor genome-wide transcriptional reprogramming under drought stress. The results from these high throughput studies indicate that drought stress-induced transcriptional reprogramming is dynamic, has temporal and spatial specificity, and is coupled with the circadian clock and phytohormone signaling pathways. © 2012 Springer-Verlag Berlin Heidelberg. All rights are reserved.

Non-linear effects of drought under shade: reconciling physiological and ecological models in plant communities.

Science.gov (United States)

Holmgren, Milena; Gómez-Aparicio, Lorena; Quero, José Luis; Valladares, Fernando

2012-06-01

The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical models about the role of shade under dry conditions: the trade-off and the facilitation hypotheses. We performed a meta-analysis of field and greenhouse studies evaluating the effects of drought at two or more irradiance levels on nine response variables describing plant physiological condition, growth, and survival. We explored differences in plant response across plant functional types, ecosystem types and methodological approaches. The data were best fit using quadratic models indicating a humped-back shape response to drought along an irradiance gradient for survival, whole plant biomass, maximum photosynthetic capacity, stomatal conductance and maximal photochemical efficiency. Drought effects were ameliorated at intermediate irradiance, becoming more severe at higher or lower light levels. This general pattern was maintained when controlling for potential variations in the strength of the drought treatment among light levels. Our quantitative meta-analysis indicates that dense shade ameliorates drought especially among drought-intolerant and shade-tolerant species. Wet tropical species showed larger negative effects of drought with increasing irradiance than semiarid and cold temperate species. Non-linear responses to irradiance were stronger under field conditions than under controlled greenhouse conditions. Non-linear responses to drought along the irradiance gradient reconciliate opposing views in plant ecology, indicating that facilitation is more likely within certain range of environmental conditions, fading under deep shade, especially for drought-tolerant species.

Root distribution pattern and their contribution in photosynthesis and biomass in Jerusalem artichoke under drought

International Nuclear Information System (INIS)

Puangbut, D.; Vorasoot, N.

2018-01-01

Root length density and rooting depth have been established as drought resistant traits and these could be used as selection criteria for drought resistant genotype in many plant species. However, information on deep rooting and the root distribution pattern of Jerusalem artichoke under drought conditions is not well documented in the literature. The objective of this study was to investigate the root distribution pattern in Jerusalem artichoke genotypes under irrigated and drought conditions. This experiment was conducted within a greenhouse using rhizoboxes. Three Jerusalem artichoke genotypes were tested under two water regimes (irrigated and drought). A 2 × 3 factorial experiment was arranged in a randomized complete block design with three replications over two years. Data were recorded for root traits, photosynthesis and biomass at 30 days after imposing drought. The drought decreased root length, root surface area and root dry weight, while increased the root: shoot ratio, root distribution in the deeper soil and the percentage of root length at deeper in the soil, when compared to the irrigated conditions JA-5 and JA-60 showed high root length in the lower soil profile under drought conditions, indicating these genotypes could be identified as drought resistant genotype. The highest positive correlation was found between root length at deeper soil layer with relative water content (RWC), net photosynthetic rate (Pn) and biomass. It is expected that selection of Jerusalem artichoke with high root length coupled with maintaining high RWC and their promotion to Pn could improve the biomass and tuber yield under drought conditions. (author)

Quercitol and osmotic adaptation of field-grown Eucalyptus under seasonal drought stress.

Science.gov (United States)

Arndt, Stefan K; Livesley, Stephen J; Merchant, Andrew; Bleby, Timothy M; Grierson, Pauline F

2008-07-01

This study investigated the role of quercitol in osmotic adjustment in field-grown Eucalyptus astringens Maiden subject to seasonal drought stress over the course of 1 year. The trees grew in a native woodland and a farm plantation in the semi-arid wheatbelt region of south Western Australia. Plantation trees allocated relatively more biomass to leaves than woodland trees, but they suffered greater drought stress over summer, as indicated by lower water potentials, CO(2)assimilation rates and stomatal conductances. In contrast, woodland trees had relatively fewer leaves and suffered less drought stress. Plantation trees under drought stress engaged in osmotic adjustment, but woodland trees did not. Quercitol made a significant contribution to osmotic adjustment in drought-stressed trees (25% of total solutes), and substantially more quercitol was measured in the leaves of plantation trees (5% dry matter) than in the leaves of woodland trees (2% dry matter). We found no evidence that quercitol was used as a carbon storage compound while starch reserves were depleted under drought stress. Differences in stomatal conductance, biomass allocation and quercitol production clearly indicate that E. astringens is both morphologically and physiologically 'plastic' in response to growth environment, and that osmotic adjustment is only one part of a complex strategy employed by this species to tolerate drought.

Demonstration of slow light propagation in an optical fiber under dual pump light with co-propagation and counter-propagation

Science.gov (United States)

Qiu, Wei; Liu, Jianjun; Wang, Yuda; Yang, Yujing; Gao, Yuan; Lv, Pin; Jiang, Qiuli

2018-04-01

In this paper, a general theory of coherent population oscillation effect in an Er3+ -doped fiber under the dual-frequency pumping laser with counter-propagation and co-propagation at room temperature is presented. Using the numerical simulation, in case of dual frequency light waves (1480 nm and 980 nm) with co-propagation and counter-propagation, we analyze the effect of the pump optical power ratio (M) on the group speed of light. The group velocity of light can be varied with the change of M. We research the time delay and fractional delay in an Er3+-doped fiber under the dual-frequency pumping laser with counter-propagation and co-propagation. Compared to the methods of the single pumping, the larger time delay can be got by using the technique of dual-frequency laser pumped fiber with co-propagation and counter-propagation.

Broader leaves result in better performance of indica rice under drought stress.

Science.gov (United States)

Farooq, M; Kobayashi, N; Ito, O; Wahid, A; Serraj, R

2010-09-01

Leaf growth is one of the first physiological processes affected by changes in plant water status under drought. A decrease in leaf expansion rate usually precedes any reduction in stomatal conductance or photosynthesis. Changes in leaf size and stomatal opening are potential adaptive mechanisms, which may help avoid drought by reducing transpiration rate, and can be used to improve rice genotypes in water-saving cultivation. The indica rice cultivar IR64 and four of its near-isogenic lines (NILs; BC(3)-derived lines) unique for leaf size traits, YTK 124 (long leaves), YTK 127 (broad leaves), YTK 205 (short leaves) and YTK 214 (narrow leaves), were compared in this study for changes in leaf growth and its water status. The plants were subjected to two soil water regimes, well-watered and progressive soil drying measured by the fraction of transpirable soil water (FTSW). Applied drought reduced leaf number, total leaf area, specific leaf area, plant biomass, tiller number, plant height, stomatal conductance, amount of water transpired, leaf relative water content, and leaf water potential more in IR64 and the NILs than in the respective controls; nonetheless, transpiration efficiency (TE) was slightly higher under drought than in the well-watered controls. NILs with broader leaves had higher biomass (and its individual components), less stomatal conductance, and higher TE under drought than NILs with narrow and shorter leaves. Under drought, leaf number was positively correlated with tiller number and plant height; nonetheless, root weight and total biomass, water transpired and TE, and plant height and TE were positively correlated with each other. However, a negative correlation was observed between stomatal conductance and the FTSW threshold at which normalized transpiration started to decline during soil drying. Overall, the IR64-derived lines with broader leaves performed better than NILs with narrow and short leaves under drought. Copyright 2010 Elsevier Gmb

Analysis of natural variation in bermudagrass (Cynodon dactylon) reveals physiological responses underlying drought tolerance.

Science.gov (United States)

Shi, Haitao; Wang, Yanping; Cheng, Zhangmin; Ye, Tiantian; Chan, Zhulong

2012-01-01

Bermudagrass (Cynodon dactylon) is a widely used warm-season turfgrass and one of the most drought tolerant species. Dissecting the natural variation in drought tolerance and physiological responses will bring us powerful basis and novel insight for plant breeding. In the present study, we evaluated the natural variation of drought tolerance among nine bermudagrass varieties by measuring physiological responses after drought stress treatment through withholding water. Three groups differing in drought tolerance were identified, including two tolerant, five moderately tolerant and two susceptible varieties. Under drought stress condition, drought sensitive variety (Yukon) showed relative higher water loss, more severe cell membrane damage (EL), and more accumulation of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), while drought tolerant variety (Tifgreen) exhibited significantly higher antioxidant enzymes activities. Further results indicated that drought induced cell injury in different varieties (Yukon, SR9554 and Tifgreen) exhibited liner correlation with leaf water content (LWC), H₂O₂ content, MDA content and antioxidant enzyme activities. Additionally, Tifgreen plants had significantly higher levels of osmolytes (proline level and soluble sugars) when compared with Yukon and SR9554 under drought stress condition. Taken together, our results indicated that natural variation of drought stress tolerance in bermudagrass varieties might be largely related to the induced changes of water status, osmolyte accumulation and antioxidant defense system.

Analysis of Natural Variation in Bermudagrass (Cynodon dactylon) Reveals Physiological Responses Underlying Drought Tolerance

Science.gov (United States)

Cheng, Zhangmin; Ye, Tiantian; Chan, Zhulong

2012-01-01

Bermudagrass (Cynodon dactylon) is a widely used warm-season turfgrass and one of the most drought tolerant species. Dissecting the natural variation in drought tolerance and physiological responses will bring us powerful basis and novel insight for plant breeding. In the present study, we evaluated the natural variation of drought tolerance among nine bermudagrass varieties by measuring physiological responses after drought stress treatment through withholding water. Three groups differing in drought tolerance were identified, including two tolerant, five moderately tolerant and two susceptible varieties. Under drought stress condition, drought sensitive variety (Yukon) showed relative higher water loss, more severe cell membrane damage (EL), and more accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA), while drought tolerant variety (Tifgreen) exhibited significantly higher antioxidant enzymes activities. Further results indicated that drought induced cell injury in different varieties (Yukon, SR9554 and Tifgreen) exhibited liner correlation with leaf water content (LWC), H2O2 content, MDA content and antioxidant enzyme activities. Additionally, Tifgreen plants had significantly higher levels of osmolytes (proline level and soluble sugars) when compared with Yukon and SR9554 under drought stress condition. Taken together, our results indicated that natural variation of drought stress tolerance in bermudagrass varieties might be largely related to the induced changes of water status, osmolyte accumulation and antioxidant defense system. PMID:23285294

The role of silicon in higher plants under salinity and drought stress

Directory of Open Access Journals (Sweden)

Devrim Coskun

2016-07-01

Full Text Available Although deemed a non-essential mineral nutrient, silicon (Si is clearly beneficial to plant growth and development, particularly under stress conditions, including salinity and drought. Here, we review recent research on the physiological, biochemical, and molecular mechanisms underlying Si-induced alleviation of osmotic and ionic stresses associated with salinity and drought. We distinguish between changes observed in the apoplast (i.e. suberization, lignification, and silicification of the extracellular matrix; transpirational bypass flow of solutes and water, and those of the symplast (i.e. transmembrane transport of solutes and water; gene expression; oxidative stress; metabolism, and discuss these features in the context of Si biogeochemistry and bioavailability in agricultural soils, evaluating the prospect of using Si fertilization to increase crop yield and stress tolerance under salinity and drought conditions.

Characterizing drought stress and trait influence on maize yield under current and future conditions.

Science.gov (United States)

Harrison, Matthew T; Tardieu, François; Dong, Zhanshan; Messina, Carlos D; Hammer, Graeme L

2014-03-01

Global climate change is predicted to increase temperatures, alter geographical patterns of rainfall and increase the frequency of extreme climatic events. Such changes are likely to alter the timing and magnitude of drought stresses experienced by crops. This study used new developments in the classification of crop water stress to first characterize the typology and frequency of drought-stress patterns experienced by European maize crops and their associated distributions of grain yield, and second determine the influence of the breeding traits anthesis-silking synchrony, maturity and kernel number on yield in different drought-stress scenarios, under current and future climates. Under historical conditions, a low-stress scenario occurred most frequently (ca. 40%), and three other stress types exposing crops to late-season stresses each occurred in ca. 20% of cases. A key revelation shown was that the four patterns will also be the most dominant stress patterns under 2050 conditions. Future frequencies of low drought stress were reduced by ca. 15%, and those of severe water deficit during grain filling increased from 18% to 25%. Despite this, effects of elevated CO2 on crop growth moderated detrimental effects of climate change on yield. Increasing anthesis-silking synchrony had the greatest effect on yield in low drought-stress seasonal patterns, whereas earlier maturity had the greatest effect in crops exposed to severe early-terminal drought stress. Segregating drought-stress patterns into key groups allowed greater insight into the effects of trait perturbation on crop yield under different weather conditions. We demonstrate that for crops exposed to the same drought-stress pattern, trait perturbation under current climates will have a similar impact on yield as that expected in future, even though the frequencies of severe drought stress will increase in future. These results have important ramifications for breeding of maize and have implications for

Comparative analysis of root transcriptome profiles of two pairs of drought-tolerant and susceptible rice near-isogenic lines under different drought stress

Directory of Open Access Journals (Sweden)

Moumeni Ali

2011-12-01

Full Text Available Abstract Background Plant roots are important organs to uptake soil water and nutrients, perceiving and transducing of soil water deficit signals to shoot. The current knowledge of drought stress transcriptomes in rice are mostly relying on comparative studies of diverse genetic background under drought. A more reliable approach is to use near-isogenic lines (NILs with a common genetic background but contrasting levels of resistance to drought stress under initial exposure to water deficit. Here, we examined two pairs of NILs in IR64 background with contrasting drought tolerance. We obtained gene expression profile in roots of rice NILs under different levels of drought stress help to identify genes and mechanisms involved in drought stress. Results Global gene expression analysis showed that about 55% of genes differentially expressed in roots of rice in response to drought stress treatments. The number of differentially expressed genes (DEGs increased in NILs as the level of water deficits, increased from mild to severe condition, suggesting that more genes were affected by increasing drought stress. Gene onthology (GO test and biological pathway analysis indicated that activated genes in the drought tolerant NILs IR77298-14-1-2-B-10 and IR77298-5-6-B-18 were mostly involved in secondary metabolism, amino acid metabolism, response to stimulus, defence response, transcription and signal transduction, and down-regulated genes were involved in photosynthesis and cell wall growth. We also observed gibberellic acid (GA and auxin crosstalk modulating lateral root formation in the tolerant NILs. Conclusions Transcriptome analysis on two pairs of NILs with a common genetic background (~97% showed distinctive differences in gene expression profiles and could be effective to unravel genes involved in drought tolerance. In comparison with the moderately tolerant NIL IR77298-5-6-B-18 and other susceptible NILs, the tolerant NIL IR77298-14-1-2-B-10 showed

Physiological and biochemical relationship under drought stress in ...

African Journals Online (AJOL)

Yomi

2012-01-24

Jan 24, 2012 ... Some statistical procedures like correlation, stepwise regression, factor analysis and cluster analysis were used to study the relationship between wheat grain yield and some physiological parameters under drought conditions. Results reveal that the ratio fv/fm of chlorophyll fluorescence is the most.

Simulation of water management for fodder beet to reduce yield losses under late season drought

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T. Noreldin

2016-12-01

Full Text Available The objectives of this study were to calibrate CropSyst model for fodder beet grown under full and late season drought and to use the simulation results to analyze the relationship between irrigation amount and yield, as well as in water management to reduce yield losses under full and late season drought. For this reason, two field experiments were implemented at El-Serw Agricultural Research Station in Demiatte governorate, during 2011/12 and 2012/13 growing seasons. Two irrigation treatments were studied: full irrigation and late season drought. The model was calibrated using the data obtained from the two seasons. Results indicated that the reduction in fodder beet yield under late season drought was 11 and 12% in 2011/12 and 2012/13 growing seasons, respectively. Calibration of CropSyst revealed that the percentage of difference between measured and predicted values were low in both growing seasons. The results also indicated that changing irrigation schedule after examining water stress index under full and late season drought led to increase in fodder beet yield, as well as water and land productivity. Thus, CropSyst model can give insight into when to apply irrigation water to minimize yield losses under late season drought.

Carbon and Nitrogen dynamics in deciduous and broad leaf trees under drought stress

Science.gov (United States)

Joseph, Jobin; Schaub, Marcus; Arend, Matthias; Saurer, Matthias; siegwolf, Rolf; Weiler, Markus; Gessler, Arthur

2017-04-01

Climate change is projected to lead to an increased frequency and duration of severe drought events in future. Already within the last twenty years, however, drought stress related forest mortality has been increasing across the globe. Tree and forest die off events have multiple adverse effects on ecosystem functioning and might convert previous carbon sinks to act as carbon sources instead and can thus intensify the effect of climate change and global warming. Current predictions of forest's functioning under drought and thus forest mortality under future climatic conditions are constrained by a still incomplete picture of the trees' physiological reactions that allows some trees to survive drought periods while others succumb. Concerning the effects of drought on the carbon balance and on tree hydraulics our picture is getting more complete, but still interactions between abiotic factors and pest and diseases as well as the interaction between carbon and nutrient balances as factors affecting drought induced mortality are not well understood. Reduced carbon allocation from shoots to roots might cause a lack of energy for root nutrient uptake and to a shortage of carbon skeletons for nitrogen assimilation and thus to an impaired nutrient status of trees. To tackle these points, we have performed a drought stress experiment with six different plant species, 3 broad leaf (maple, beech and oak) and 3 deciduous (pine, fir and spruce). Potted two-year-old seedlings were kept inside a greenhouse for 5 months and 3 levels of drought stress (no stress (control), intermediate and intensive drought stress) were applied by controlling water supply. Gas exchange measurements were performed periodically to monitor photosynthesis, transpiration, stomatal conductance. At the pinnacle of drought stress, we applied isotopic pulse labelling: On the one hand we exposed trees to 13CO2 to investigate on carbon dynamics and the allocation of new assimilates within the plant. Moreover

Bioactive compounds in potatoes: Accumulation under drought stress conditions

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Christina B. Wegener

2015-03-01

Full Text Available Background: Potato (Solanum tuberosum is a valuable source of bioactive compounds. Besides starch, crude fibre, amino acids (AAS, vitamins and minerals, the tubers contain diverse phenolic compounds. These phenolics and AAS confer anti-oxidant protection against reactiveoxygen species, tissue damage, and diseases like atherosclerosis, renal failure, diabetes mellitus,and cancer. Climate change and drought stress may become a major risk for crop production worldwide, resulting in reduced access for those who depend on the nutritional value of this staple crop. Objective: The aim of this study is to determine the effect of drought stress on water, lipid soluble antioxidants, anthocyanins (Ac, soluble phenols, proteins, free AAS, peroxidase (POD and lipid acyl hydrolase activity (LAH in tuber tissue. Methods: The study was carried out on three potato genotypes comprising one yellow-fleshed cultivar and two purple breeding clones. The plants were grown in pots (from April to September in a glasshouse with sufficient water supply and under drought stress conditions. After harvest, the tubers of both variants were analysed for antioxidants measured as ascorbic acid (ACE and Trolox equivalent (TXE using a photo-chemiluminescent method. Amounts of anthocyanins (Ac, soluble phenols, proteins, as well as POD and LAH activities were analysed using a UV photometer. Finally, free AAS were measured by HPLC. Results: The results revealed that drought stress significantly reduces tuber yield, but has no significant effect on antioxidants, Ac, soluble phenols and POD. Drought stress significantly increased the levels of soluble protein (P < 0.0001 and LAH (P < 0.001. Also, total amounts of free AAS were higher in the drought stressed tubers (+34.2%, on average than in the tubers grown with a sufficient water supply. Above all, proline was elevated due to drought stress.

Physiological and biochemical relationship under drought stress in ...

African Journals Online (AJOL)

Some statistical procedures like correlation, stepwise regression, factor analysis and cluster analysis were used to study the relationship between wheat grain yield and some physiological parameters under drought conditions. Results reveal that the ratio fv/fm of chlorophyll fluorescence is the most effective parameter to ...

Role of phytohormones under induced drought stress in wheat

International Nuclear Information System (INIS)

Bano, A.; Yasmeen, S.

2010-01-01

The performance of plants (grown in pots) was studied for drought induced at critical stages of grain filling. Furthermore, the effect of abscisic acid (ABA) and benzyladenine (BA), were also studied on the physiology of plants during grain filling. Seeds of two wheat varieties cv Margalla-99 (cv1) and cv Manthar-2003 (cv2) were sown in pots. Stress treatments were imposed immediately after anthesis. Drought stress resulted in maximum decrease in IAA and GA content but proline and ABA content of leaves showed maximum increase at hard dough stage in cv1. With decrease in soil moisture content under induced drought stress, the percentage decrease in IAA and GA and increase in proline and ABA was greater in leaves and spikes of potted plants. All parameters showed greater decrease in cv2 than in cv1. Application of both ABA and BA, each at 10-6 M applied at anthesis stage, was involved in osmoregulation by the production of proline. The adverse effect of drought started at anthesis stage reaching maximum at hard dough stage. ABA was more effective at the later stages of grain filling whereas, BA was more effective at early stages. (author)

Function of the auxin-responsive gene TaSAUR75 under salt and drought stress

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Yuan Guo

2018-04-01

Full Text Available Small auxin-upregulated RNAs (SAURs are genes regulated by auxin and environmental factors. In this study, we identified a SAUR gene in wheat, TaSAUR75. Under salt stress, TaSAUR75 is downregulated in wheat roots. Subcellular localization revealed that TaSAUR75 was localized in both the cytoplasm and nucleus. Overexpression of TaSAUR75 increased drought and salt tolerance in Arabidopsis. Transgenic lines showed higher root length and survival rate and higher expression of some stress-responsive genes than control plants under salt and drought stress. Less H2O2 accumulated in transgenic lines than in control plants under drought stress. Our findings reveal a positive regulatory role of the auxin-responsive gene TaSAUR75 in plant responses to drought and salt stress and provide a candidate gene for improvement of abiotic stress tolerance in crop breeding.

Screening for Osmotic Stress Responses in Rice Varieties under Drought Condition

OpenAIRE

Simon Swapna; Korukkanvilakath Samban Shylaraj

2017-01-01

Drought is the major abiotic stress factor that limits rice production worldwide. To evaluate the osmotic stress responses in rice varieties under drought condition, a total of 42 high-yielding rice varieties were collected from various research stations of Kerala Agricultural University in India. The experimental setup comprises of initial hydroponic treatments at different osmotic potentials, artificially induced by desired strengths of polyethylene glycol (PEG6000), and followed by the pot...

Agronomic performance of rape seed (brassica napus L.) mutant lines under drought conditions

International Nuclear Information System (INIS)

Shah, S.A.; Ali, I.; Shah, S.J.A.; Rehman, K.; Rashid, A.

1995-01-01

Oil seed forms of Brassica napus are not well adapted to drought and the warner environments of Pakistan. Induced mutations were, therefore, utilized for improving drought tolerance efficiency of two napus cultivars. Induction of genetic variability, selection of desirable mutants and stabilization of mutants in acceptable agronomic background were carried out during 1988-1991. Fourteen promising mutants each of cv. Pak-cheen and Tower were evaluated for different agronomic characters in separate yield trials, under extremely drought conditions. The results demonstrated that yield potential of some mutants was very high and 9 mutants of cv. Pak-cheen and 8 mutants of cv. Tower significantly (P<0.05) out yield the local commercial cultivar. Eleven mutants in both the trials matured significantly earlier than the check. Nevertheless, more extensive testing of the drought tolerant lines under diversified environs of the country will help confirm these findings. (author)

Gel-free/label-free proteomic analysis of root tip of soybean over time under flooding and drought stresses.

Science.gov (United States)

Wang, Xin; Oh, MyeongWon; Sakata, Katsumi; Komatsu, Setsuko

2016-01-01

Growth in the early stage of soybean is markedly inhibited under flooding and drought stresses. To explore the responsive mechanisms of soybean, temporal protein profiles of root tip under flooding and drought stresses were analyzed using gel-free/label-free proteomic technique. Root tip was analyzed because it was the most sensitive organ against flooding, and it was beneficial to root penetration under drought. UDP glucose: glycoprotein glucosyltransferase was decreased and increased in soybean root under flooding and drought, respectively. Temporal protein profiles indicated that fermentation and protein synthesis/degradation were essential in root tip under flooding and drought, respectively. In silico protein-protein interaction analysis revealed that the inductive and suppressive interactions between S-adenosylmethionine synthetase family protein and B-S glucosidase 44 under flooding and drought, respectively, which are related to carbohydrate metabolism. Furthermore, biotin/lipoyl attachment domain containing protein and Class II aminoacyl tRNA/biotin synthetases superfamily protein were repressed in the root tip during time-course stresses. These results suggest that biotin and biotinylation might be involved in energy management to cope with flooding and drought in early stage of soybean-root tip. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of drought tolerance and yield capacity of barley (hordeum vulgare) genotypes under irrigated and water-stressed conditions

International Nuclear Information System (INIS)

Khokhar, M.I.; Silva, J.A.T.D

2012-01-01

Twelve barley genotypes developed through different selection methods were evaluated under drought and irrigated conditions. The results of a correlation matrix revealed highly significant associations between Grain Yield (Yp) and Mean Productivity (MP), Stress Tolerance Index (STI), Geometric Mean Productivity (GMP) and Yield Index (Yi) under irrigated conditions while the Mean Productivity (MP), Yield Stability Index (Yi), Stress Tolerance Index (STI), Geometric Mean Productivity (GMP) and Yield Index (Yi) had a high response under stressed condition. Based on a principal component analysis, Geometric Mean Productivity (GMP), Mean Productivity (MP) and Stress Tolerance Index (STI) were considered to be the best parameters for selection of drought-tolerant genotypes. The 2-row barley genotypes B-07023 and B-07021 performed better in yield response under drought conditions and were more stable under stress conditions. Furthermore, drought stress reduced the yield of some genotypes while others were tolerant to drought, suggesting genetic variability in this material for drought tolerance. (author)

Effects of cold plasma treatment on alfalfa seed growth under simulated drought stress

Science.gov (United States)

Jinkui, FENG; Decheng, WANG; Changyong, SHAO; Lili, ZHANG; Xin, TANG

2018-03-01

The effect of different cold plasma treatments on the germination and seedling growth of alfalfa (Medicago sativa L.) seeds under simulated drought stress conditions was investigated. Polyethyleneglycol-6000 (PEG 6000)with the mass fraction of 0% (purified water), 5%, 10%, and 15% were applied to simulate the drought environment. The alfalfa seeds were treated with 15 different power levels ranged between 0-280 W for 15 s. The germination potential, germination rate, germination index, seedling root length, seedling height, and vigor index were investigated. Results indicated significant differences between treated with proper power and untreated alfalfa seeds. With the increase of treatment power, these indexes mentioned above almost presented bimodal curves. Under the different mass fractions of PEG 6000, results showed that the lower power led to increased germination, and the seedlings presented good adaptability to different drought conditions. Meanwhile, higher power levels resulted in a decreased germination rate. Seeds treated with 40 W resulted in higher germination potential, germination rate, seedling height, root length, and vigor index. Vigor indexes of the treated seeds under different PEG 6000 stresses increased by 38.68%, 43.91%, 74.34%, and 39.20% respectively compared to CK0-0, CK5-0, CK10-0, and CK15-0 (the control sample under 0%, 5%, 10%, and 15% PEG 6000). Therefore, 40 W was regarded as the best treatment in this research. Although the trend indexes of alfalfa seeds treated with the same power were statistically the same under different PEG 6000 stresses, the cold plasma treatment had a significant effect on the adaptability of alfalfa seeds in different drought environments. Thus, this kind of treatment is worth implementing to promote seed growth under drought situations.

Tolerance of Mycorrhiza infected pistachio (Pistacia vera L.) seedling to drought stress under glasshouse conditions.

Science.gov (United States)

Abbaspour, H; Saeidi-Sar, S; Afshari, H; Abdel-Wahhab, M A

2012-05-01

The influence of Glomus etunicatum colonization on plant growth and drought tolerance of 3-month-old Pistacia vera seedlings in potted culture was studied in two different water treatments. The arbuscular mycorrhiza (AM) inoculation and plant growth (including plant shoot and root weight, leaf area, and total chlorophyll) were higher for well-watered than for water-stressed plants. The growth of AM-treated seedlings was higher than non-AM-treatment regardless of water status. P, K, Zn and Cu contents in AM-treated shoots were greater than those in non-AM shoots under well-watered conditions and drought stress. N and Ca content were higher under drought stress, while AM symbiosis did not affect the Mg content. The contents of soluble sugars, proteins, flavonoid and proline were higher in mycorrhizal than non-mycorrhizal-treated plants under the whole water regime. AM colonization increased the activities of peroxidase enzyme in treatments, but did not affect the catalase activity in shoots and roots under well-watered conditions and drought stress. We conclude that AM colonization improved the drought tolerance of P. vera seedlings by increasing the accumulation of osmotic adjustment compounds, nutritional and antioxidant enzyme activity. It appears that AM formation enhanced the drought tolerance of pistachio plants, which increased host biomass and plant growth. Copyright © 2012 Elsevier GmbH. All rights reserved.

Bacterial mediated amelioration of drought stress in drought tolerant ...

African Journals Online (AJOL)

Bacterial mediated amelioration of drought stress in drought tolerant and susceptible cultivars of rice ( Oryza sativa L.) ... and IR-64 (drought sensitive) cultivars of rice (Oryza sativa L.) under different level of drought stress. ... from 32 Countries:.

EXOPOLYSACCHARIDE PRODUCTION BY DROUGHT TOLERANT BACILLUS SPP. AND EFFECT ON SOIL AGGREGATION UNDER DROUGHT STRESS

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Sandhya Vardharajula

2014-08-01

Full Text Available Exopolysaccharides (EPS of microbial origin with novel functionality, reproducible physico-chemical properties, are important class of polymeric materials. EPS are believed to protect bacterial cells from dessication, produce biofilms, thus enhancing the cells chances of bacterial colonizing special ecological niches. In rhizosphere, EPS are known to be useful to improve the moisture-holding capacity. Three Bacillus spp. strains identified by 16s rDNA sequence analysis as B. amyloliquefaciens strain HYD-B17; B. licheniformis strain HYTAPB18; B. subtilis strain RMPB44 were studied for the ability to tolerate matric stress and produce EPS under different water potentials. EPS production in all the three Bacillus spp strains increased with increasing water stress indicating correlation between drought stress tolerance and EPS production. Among the isolates, strain HYD-17 showed highest production of EPS. The exopolysaccharide composition of the three strains was further analyzed by HPLC. Drought stress influenced the ratio of sugars in EPS and glucose was found as major sugar in strains HYTAPB18 and RMPB44 whereas raffinose was major sugar found in strain HYD-B17. Inoculation of EPS producing Bacillus spp. strains in soil resulted in good soil aggregation under drought stress conditions at different incubation periods. This study shows that exposure to water stress conditions affects the composition and ratios of sugars in EPS produced by Bacillus spp. strains HYD-B17, HYTAPB18 and RMPB44 influencing abiotic stress tolerance of the microorganisms.

Comparative Physiological and Molecular Analyses of Two Contrasting Flue-Cured Tobacco Genotypes under Progressive Drought Stress

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Xinhong Su

2017-05-01

Full Text Available Drought is a major environmental factor that limits crop growth and productivity. Flue-cured tobacco (Nicotiana tabacum is one of the most important commercial crops worldwide and its productivity is vulnerable to drought. However, comparative analyses of physiological, biochemical and gene expression changes in flue-cured tobacco varieties differing in drought tolerance under long-term drought stress are scarce. In this study, drought stress responses of two flue-cured tobacco varieties, LJ851 and JX6007, were comparatively studied at the physiological and transcriptional levels. After exposing to progressive drought stress, the drought-tolerant LJ851 showed less growth inhibition and chlorophyll reduction than the drought-sensitive JX6007. Moreover, higher antioxidant enzyme activities and lower levels of H2O2, Malondialdehyde (MDA, and electrolyte leakage after drought stress were found in LJ851 when compared with JX6007. Further analysis showed that LJ851 plants had much less reductions than the JX6007 in the net photosynthesis rate and stomatal conductance during drought stress; indicating that LJ851 had better photosynthetic performance than JX6007 during drought. In addition, transcriptional expression analysis revealed that LJ851 exhibited significantly increased transcripts of several categories of drought-responsive genes in leaves and roots under drought conditions. Together, these results indicated that LJ851 was more drought-tolerant than JX6007 as evidenced by better photosynthetic performance, more powerful antioxidant system, and higher expression of stress defense genes during drought stress. This study will be valuable for the development of novel flue-cured tobacco varieties with improved drought tolerance by exploitation of natural genetic variations in the future.

Differential activity of autochthonous bacteria in controlling drought stress in native Lavandula and Salvia plants species under drought conditions in natural arid soil.

Science.gov (United States)

Armada, Elisabeth; Roldán, Antonio; Azcon, Rosario

2014-02-01

The effectiveness of autochthonous plant growth-promoting rhizobacteria was studied in Lavandula dentata and Salvia officinalis growing in a natural arid Mediterranean soil under drought conditions. These bacteria identified as Bacillus megaterium (Bm), Enterobacter sp. (E), Bacillus thuringiensis (Bt), and Bacillus sp. (Bsp). Each bacteria has different potential to meliorate water limitation and alleviating drought stress in these two plant species. B. thuringiensis promoted growth and drought avoidance in Lavandula by increasing K content, by depressing stomatal conductance, and it controlled shoot proline accumulation. This bacterial effect on increasing drought tolerance was related to the decrease of glutathione reductase (GR) and ascorbate peroxidase (APX) that resulted sensitive indexes of lower cellular oxidative damage involved in the adaptative drought response in B. thuringiensis-inoculated Lavandula plants. In contrast, in Salvia, having intrinsic lower shoot/root ratio, higher stomatal conductance and lower APX and GR activities than Lavandula, the bacterial effects on nutritional, physiological and antioxidant enzymatic systems were lower. The benefit of bacteria depended on intrinsic stress tolerance of plant involved. Lavadula demonstrated a greater benefit than Salvia to control drought stress when inoculated with B. thuringiensis. The bacterial drought tolerance assessed as survival, proline, and indolacetic acid production showed the potential of this bacteria to help plants to grow under drought conditions. B. thuringiensis may be used for Lavandula plant establishment in arid environments. Particular characteristic of the plant species as low shoot/root ratio and high stomatal conductance are important factors controlling the bacterial effectiveness improving nutritional, physiological, and metabolic plant activities.

Physiological and metabolomic analysis of Punica granatum (L.) under drought stress.

Science.gov (United States)

Catola, Stefano; Marino, Giovanni; Emiliani, Giovanni; Huseynova, Taravat; Musayev, Mirza; Akparov, Zeynal; Maserti, Bianca Elena

2016-02-01

Punica granatum has a noticeable adaptation to drought stress. The levels of the green leaf volatile trans-2-hexenal increased in response to drought stress suggesting a possible role of this compound in drought stress response in pomegranate. Punica granatum (L.) is a highly valued fruit crop for its health-promoting effects and it is mainly cultivated in semi-arid areas. Thus, understanding the response mechanisms to drought stress is of great importance. In the present research, a metabolomics analysis was performed to evaluate the effects of drought stress on volatile organic compounds extracted from the leaves of pomegranate plants grown under water shortage conditions. The time course experiment (7 days of water deprivation and 24-h recovery) consisted of three treatments (control, drought stress, and rehydration of drought-stressed plants). Plant weights were recorded and control plants were irrigated daily at pot capacity to provide the lost water. Fraction of transpirable soil water has been evaluated as indicator of soil water availability in stressed plants. The levels of proline, hydrogen peroxide and lipid peroxidation as well as of the photosynthetic parameters such as photosynthesis rate (A), stomatal conductance (g s), photosynthetic efficiency of photosystem II, and photochemical quenching were monitored after the imposition of drought stress and recovery as markers of plant stress. Constitutive carbon volatile components were analyzed in the leaf of control and drought-stressed leaves using Head Space Solid Phase Micro Extraction sampling coupled with Gas Chromatography Mass Spectrometry. A total of 12 volatile compounds were found in pomegranate leaf profiles, mainly aldehydes, alcohols, and organic acids. Among them, the trans-2-hexenal showed a significant increase in water-stressed and recovered leaves respect to the well-watered ones. These data evidence a possible role of the oxylipin pathway in the response to water stress in pomegranate

Assessment of transpiration efficiency in peanut (Arachis hypogaea L.) under drought using a lysimetric system.

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Ratnakumar, P; Vadez, V; Nigam, S N; Krishnamurthy, L

2009-11-01

Transpiration efficiency (TE) is an important trait for drought tolerance in peanut (Arachis hypogaea L.). The variation in TE was assessed gravimetrically using a long time interval in nine peanut genotypes (Chico, ICGS 44, ICGV 00350, ICGV 86015, ICGV 86031, ICGV 91114, JL 24, TAG 24 and TMV 2) grown in lysimeters under well-watered or drought conditions. Transpiration was measured by regularly weighing the lysimeters, in which the soil surface was mulched with a 2-cm layer of polythene beads. TE in the nine genotypes used varied from 1.4 to 2.9 g kg(-1) under well-watered and 1.7 to 2.9 g kg(-1) under drought conditions, showing consistent variation in TE among genotypes. A higher TE was found in ICGV 86031 in both well-watered and drought conditions and lower TE was found in TAG-24 under both water regimes. Although total water extraction differed little across genotypes, the pattern of water extraction from the soil profile varied among genotypes. High water extraction within 24 days following stress imposition was negatively related to pod yield (r(2) = 0.36), and negatively related to water extraction during a subsequent period of 32 days (r(2) = 0.73). By contrast, the latter, i.e. water extraction during a period corresponding to grain filling (24 to 56 days after flowering) was positively related to pod yield (r(2) = 0.36). TE was positively correlated with pod weight (r(2) = 0.30) under drought condition. Our data show that under an intermittent drought regime, TE and water extraction from the soil profile during a period corresponding to pod filling were the most important components.

Drought genetics have varying influence on corn water stress under differing water availability

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Irrigated corn (Zea mays L.) in the Great Plains will be increasingly grown under limited irrigation management and greater water stress. Hybrids with drought genetics may decrease the impacts of water stress on yield. The objective of this experiment was to evaluate the effect of drought genetics o...

Tipping point of a conifer forest ecosystem under severe drought

Science.gov (United States)

Huang, Kaicheng; Yi, Chuixiang; Wu, Donghai; Zhou, Tao; Zhao, Xiang; Blanford, William J.; Wei, Suhua; Wu, Hao; Ling, Du; Li, Zheng

2015-02-01

Drought-induced tree mortality has recently received considerable attention. Questions have arisen over the necessary intensity and duration thresholds of droughts that are sufficient to trigger rapid forest declines. The values of such tipping points leading to forest declines due to drought are presently unknown. In this study, we have evaluated the potential relationship between the level of tree growth and concurrent drought conditions with data of the tree growth-related ring width index (RWI) of the two dominant conifer species (Pinus edulis and Pinus ponderosa) in the Southwestern United States (SWUS) and the meteorological drought-related standardized precipitation evapotranspiration index (SPEI). In this effort, we determined the binned averages of RWI and the 11 month SPEI within the month of July within each bin of 30 of RWI in the range of 0-3000. We found a significant correlation between the binned averages of RWI and SPEI at the regional-scale under dryer conditions. The tipping point of forest declines to drought is predicted by the regression model as SPEItp = -1.64 and RWItp = 0, that is, persistence of the water deficit (11 month) with intensity of -1.64 leading to negligible growth for the conifer species. When climate conditions are wetter, the correlation between the binned averages of RWI and SPEI is weaker which we believe is most likely due to soil water and atmospheric moisture levels no longer being the dominant factor limiting tree growth. We also illustrate a potential application of the derived tipping point (SPEItp = -1.64) through an examination of the 2002 extreme drought event in the SWUS conifer forest regions. Distinguished differences in remote-sensing based NDVI anomalies were found between the two regions partitioned by the derived tipping point.

Tipping point of a conifer forest ecosystem under severe drought

International Nuclear Information System (INIS)

Huang, Kaicheng; Zhou, Tao; Wu, Hao; Ling, Du; Li, Zheng; Yi, Chuixiang; Blanford, William J; Wei, Suhua; Wu, Donghai; Zhao, Xiang

2015-01-01

Drought-induced tree mortality has recently received considerable attention. Questions have arisen over the necessary intensity and duration thresholds of droughts that are sufficient to trigger rapid forest declines. The values of such tipping points leading to forest declines due to drought are presently unknown. In this study, we have evaluated the potential relationship between the level of tree growth and concurrent drought conditions with data of the tree growth-related ring width index (RWI) of the two dominant conifer species (Pinus edulis and Pinus ponderosa) in the Southwestern United States (SWUS) and the meteorological drought-related standardized precipitation evapotranspiration index (SPEI). In this effort, we determined the binned averages of RWI and the 11 month SPEI within the month of July within each bin of 30 of RWI in the range of 0–3000. We found a significant correlation between the binned averages of RWI and SPEI at the regional-scale under dryer conditions. The tipping point of forest declines to drought is predicted by the regression model as SPEI tp  = −1.64 and RWI tp  = 0, that is, persistence of the water deficit (11 month) with intensity of −1.64 leading to negligible growth for the conifer species. When climate conditions are wetter, the correlation between the binned averages of RWI and SPEI is weaker which we believe is most likely due to soil water and atmospheric moisture levels no longer being the dominant factor limiting tree growth. We also illustrate a potential application of the derived tipping point (SPEI tp  = −1.64) through an examination of the 2002 extreme drought event in the SWUS conifer forest regions. Distinguished differences in remote-sensing based NDVI anomalies were found between the two regions partitioned by the derived tipping point. (letter)

Evaluation of the CBL family gene expression under drought stress and virus attack in two susceptible and drought tolerant tomato cultivars using semi-quantitative PCR analysis

Directory of Open Access Journals (Sweden)

Peyman Aghaie

2017-08-01

Full Text Available Eleven genes encoding Calcineurin B-Like proteins with a high degree of sequence conservation were identified using bioinformatics approaches in tomato. These proteins classified into five clusters including SlCBL1, SlCBL3, SlCBL4, SlCBL8 and SlCBL10 using orthology-based method of nomenclature. Sequence analysis showed that all five members of SlCBL1 and SlCBL4 contained a myristoylation conserved motif (MGXXXS/T at their N-terminals. Semi-quantitative RT-PCR showed that among the SlCBL1 members, SlCBL1-3 up-regulated under both drought and virus stresses, as well as the combined treatment. Although, both SlCBL3-1 and SlCBL3-2 up-regulated under both drought and virus stresses in both susceptive and resistant cultivars, the combined stress did not have any additional effect on the expression. Among SlCBL4 members, only SlCBL4-1 up-regulated under drought or virus attack. There was a diverse pattern of expression between the two SlCBL8 members under different stresses in both cultivars. SlCBL10 showed no change in expression pattern under drought or virus stresses in susceptive cultivar and this gene showed to be up-regulated under drought in resistant cultivar. Overall, it was concluded that changes in the expression pattern of CBL genes under biotic and abiotic stresses seemingly induced various CBL/CIPK patways in suseptive or resistant plants.

Spider foraging strategy affects trophic cascades under natural and drought conditions.

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Liu, Shengjie; Chen, Jin; Gan, Wenjin; Schaefer, Douglas; Gan, Jianmin; Yang, Xiaodong

2015-07-23

Spiders can cause trophic cascades affecting litter decomposition rates. However, it remains unclear how spiders with different foraging strategies influence faunal communities, or present cascading effects on decomposition. Furthermore, increased dry periods predicted in future climates will likely have important consequences for trophic interactions in detritus-based food webs. We investigated independent and interactive effects of spider predation and drought on litter decomposition in a tropical forest floor. We manipulated densities of dominant spiders with actively hunting or sit-and-wait foraging strategies in microcosms which mimicked the tropical-forest floor. We found a positive trophic cascade on litter decomposition was triggered by actively hunting spiders under ambient rainfall, but sit-and-wait spiders did not cause this. The drought treatment reversed the effect of actively hunting spiders on litter decomposition. Under drought conditions, we observed negative trophic cascade effects on litter decomposition in all three spider treatments. Thus, reduced rainfall can alter predator-induced indirect effects on lower trophic levels and ecosystem processes, and is an example of how such changes may alter trophic cascades in detritus-based webs of tropical forests.

Avoiding Drought Risks and Social Conflict Under Climate Change

Science.gov (United States)

Towler, E.; Lazrus, H.; Paimazumder, D.

2014-12-01

Traditional drought research has mainly focused on physical drought risks and less on the cultural processes that also contribute to how drought risks are perceived and managed. However, as society becomes more vulnerable to drought and climate change threatens to increase water scarcity, it is clear that drought research would benefit from a more interdisciplinary approach. To assess avoided drought impacts from reduced climate change, drought risks need to be assessed in the context of both climate prediction as well as improved understanding of socio-cultural processes. To this end, this study explores a risk-based framework to combine physical drought likelihoods with perceived risks from stakeholder interviews. Results are presented from a case study on how stakeholders in south-central Oklahoma perceive drought risks given diverse cultural beliefs, water uses, and uncertainties in future drought prediction. Stakeholder interviews (n=38) were conducted in 2012 to understand drought risks to various uses of water, as well as to measure worldviews from the cultural theory of risk - a theory that explains why people perceive risks differently, potentially leading to conflict over management decisions. For physical drought risk, drought projections are derived from a large ensemble of future climates generated from two RCPs that represent higher and lower emissions trajectories (i.e., RCP8.5 and RCP4.5). These are used to develop a Combined Drought Risk Matrix (CDRM) that characterizes drought risks for different water uses as the products of both physical likelihood (from the climate ensemble) and risk perception (from the interviews). We use the CRDM to explore the avoided drought risks posed to various water uses, as well as to investigate the potential for reduction of conflict over water management.

Abscisic Acid and Cytokinin-Induced Osmotic and Antioxidant Regulation in Two Drought-Tolerant and Drought-Sensitive Cultivars of Wheat During Grain Filling Under Water Deficit in Field Conditions

Directory of Open Access Journals (Sweden)

Mohammad-Reza SARAFRAZ-ARDAKANI

2014-09-01

Full Text Available Phytohormones play critical roles in regulating plant responses to stress. The present study investigates the effect of cytokinin, abscisic acid and cytokinin/abscisic acid interaction on some osmoprotectants and antioxidant parameters induced by drought stress in two wheat cultivars (Triticum aestivum L. of ‘Pishgam’ and ‘MV-17’ as tolerant and sensitive to drought during post-anthesis phase, respectively grown in field conditions. The most considerable effect of the treatments was exhibited 21 days after anthesis. Under drought conditions, the flag leaf soluble carbohydrate content increased in both cultivars while starch content was remarkably decreased in ‘Pishgam’ as compared to ‘MV-17’. Abscisic acid increased total soluble sugar and reduced starch more than other hormonal treatments, although it decreased studied monosaccharaides in ‘Pishgam’, especially. Drought stress induced high proportion of gylycinebetain and free proline in ‘Pishgam’ cultivar. Application of abscisic acid and cytokinin/abscisic acid interaction increased gylycinebetain and proline content in both cultivars under irrigation and drought conditions. The tolerant cultivar exhibited less accumulation of hydrogen peroxide and malondialdehyde in relation to significant increase of catalase and peroxidase activities and α-tocpherol content under drought conditions. All hormonal treatments increased the named enzyme activities under both irrigation and drought conditions, while higher accumulation of α-tocopherol was only showed in case of cytokinin application. Also, abscisic acid and cytokinin/abscisic acid could decrease drought-induced hydrogen peroxide and malondialdehyde level to some extent, although abscisic acid increased both of hydrogen peroxide andmalondialdehyde content in irrigation phase, especially.

Evaluation of groundwater droughts in Austria

Science.gov (United States)

Haas, Johannes Christoph; Birk, Steffen

2015-04-01

Droughts are abnormally dry periods that affect various aspects of human life on earth, ranging from negative impacts on agriculture or industry, to being the cause for conflict and loss of human life. The changing climate reinforces the importance of investigations into this phenomenon. Various methods to analyze and classify droughts have been developed. These include drought indices such as the Standard Precipitation Index SPI, the Palmer Drought Severity Index PDSI or the Crop Moisture Index CMI. These and other indices consider meteorological parameters and/or their effects on soil moisture. A depletion of soil moisture triggered by low precipitation and high evapotranspiration may also cause reduced groundwater recharge and thus decreasing groundwater levels and reduced groundwater flow to springs, streams, and wetlands. However, the existing indices were generally not designed to address such drought effects on groundwater. Thus, a Standardized Groundwater level Index has recently been proposed by Bloomfied and Marchant (2013). Yet, to our knowledge, this approach has only been applied to consolidated aquifers in the UK. This work analyzes time series of groundwater levels from various, mostly unconsolidated aquifers in Austria in order to characterize the effects of droughts on aquifers in different hydrogeologic and climatic settings as well as under different usage scenarios. In particular, comparisons are made between the water rich Alpine parts of Austria, and the dryer parts situated in the East. The time series of groundwater levels are compared to other data, such as meteorological time series and written weather records about generally accepted phenomena, such as the 2003 European drought and heat wave. Thus, valuable insight is gained into the propagation of meteorological droughts through the soil and the aquifer in different types of hydrogeologic and climatic settings, which provides a prerequisite for the assessment of the aquifers' drought

Study on osmoprotectant rhizobacteria to improve mung bean growth under drought stress

Science.gov (United States)

Maryani, Y.; Sudadi; Dewi, W. S.; Yunus, A.

2018-03-01

Climate change leads to irregular rainwater availability for crops and thus enhances drought stress. Furthermore, nowadays we face climate disadvantages such as long dry season, short rainy season and high air temperature caused by climate change. This research aimed at studying the ability of osmoprotectant rhizobacteria isolates to support mung bean growth under drought stress. The rhizobacteria were isolated from mung bean’s rhizosphere. The results showed that isolates of strain Al24-k and Ver5-k produced glycine betaine 9.6306 mg g‑1 cell, 1.7667 x 107 CFU g‑1 soil and 11.4870 mg g”1 cell, 1.9667 x 107 CFU g‑1 soil. The isolated rhizobacteria from mung bean’s rhizosphere under field capacity of soil moisture produced glycine betaine 6.8000 mg g‑1 cell, 1.2556 x 107 CFU g‑1 soil. Under 75% field capacity of soil moisture, isolates produced glycine betaine of 6.4059 mg g‑1 cell, 1.3111 x 107 CFU g‑1 soil, while under 50% from field capacity, the isolates produced glycine betaine of 7.4108 mg g‑1 cell, 1.6667 x 107 CFU g‑1 soil. The osmoprotectant rhizobacteria improved the resilience of mung bean to drought stress.

Drought evolution: greater and faster impacts on blue water than on green water

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Destouni, G.; Orth, R.

2017-12-01

Drought propagates through the terrestrial water cycle, affecting different interlinked geospheres which have so far been mostly investigated separately and without direct comparison. By use of comprehensive multi-decadal data from >400 near-natural catchments along a steep climate gradient across Europe we here analyze drought propagation from precipitation (deficits) through soil moisture to runoff (blue water) and evapotranspiration (green water). We show that soil-moisture droughts reduce runoff stronger and faster than evapotranspiration. While runoff responds within weeks, evapotranspiration can be unaffected for months, or even entirely as in central and northern Europe. Understanding these different drought pathways towards blue and green water resources contributes to improve food and water security and offers early warning potential to mitigate (future) drought impacts on society and ecosystems.

[Effects of exogenous salicylic acid on seed germination and physiological characteristics of Coronilla varia under drought stress.

Science.gov (United States)

Ma, Le Yuan; Chen, Nian Lai; Han, Guo Jun; Li, Liang

2017-10-01

This research investigated the effects of different concentrations (0, 0.5, 1.0, 2.0 mmol·L -1 ) of salicylic acid on the seed germination and physiological characteristics of legume forage Coronilla varia (cultivar 'Lvbaoshi') under PEG-6000 (concentration 8% and 12%) simulated drought stress. The results showed that under drought stress, 0.5-1.0 mmol·L -1 salicylic acid significantly increased germination percentage, germination vigour, germination index, vitality index and bud length of C. varia. Under the stress of 12% PEG, the dry mass of C. varia seedlings processed by 1.0 mmol·L -1 salicylic acid was significantly higher than that under drought stress. 0.5-1.0 mmol·L -1 salicylic acid processing significantly increased proline, soluble protein content, the activities of catalase, peroxidase and superoxide dismutase of C. varia seedlings under drought stress, but cell electrolyte permeability, H2O2 content and O2 - · production rate of seedlings were significantly decreased. 1.0 mmol·L -1 salicylic acid produced the best results. When the concentration of salicylic acid was beyond 2.0 mmol·L -1 , no mitigation effect was observed on the seed germination and growth of seedlings under drought stress. It was concluded that salicylic acid at appropriate concentrations could effectively improve osmotic regulation, antioxidation and mitigate the damage of drought stress so as to promote the growth of C. varia seedlings.

Studies on Screening of Maize (Zea mays L.) Hybrids under Drought Stress Conditions

OpenAIRE

Zahoor Ahmad

2015-01-01

Drought is one of the most serious problems posing a grave threat to cereals production including maize. Two experiments (lab and wire house) were conducted to screen out the most tolerant and most sensitive maize hybrids (7386, 6525, Hycorn, 9696, 32B33, 3672, MMRI and 31P41) under artificial imposing drought stress by PEG-6000 and under water stress applied after seedling emergence. In first experiment five water stress levels such as zero (control), -0.2 MPa, -0.4 MPa, -0.6 MPa, and -0.8 M...

Genotypic variability in faba bean (vicia faba L.) for seed yield and protein content under drought stress during vegetative and Reproductive Stages

International Nuclear Information System (INIS)

Abdelmula, A. A.; Gasim, S. M.; Link, W.; Mohamed, A. A.; Khalifa, J. E.

2012-01-01

Faba bean (viciafaba L.) is subjected to drought stress during different growth stages. In this study, variability in seed yield and protein content was investigated when drought occurred during the vegetative and reproductive stages. Twenty two genotypes of faba bean were field evaluated under three levels of drought stress at two locations in the Sudan. The three levels of drought were normal watering (non-stress), drought during the vegetative stage and drought during the reproductive stage. Data were collected on yield and vegetative traits and protein content. The results showed that yield, as well as other traits, were reduced by drought. The genotypes exhibited significant differences for 100 seed weight, plant height and protein content. The interaction between the genotypes and drought was significant for yield/plant. Some genotypes were more sensitive when drought occurred during the vegetative stage, some when drought occurred during the vegetative stage, and others were more stable under the three levels of drought. yield/plant showed significant covariance with pods/plant and plant height. The association between different characters varied according to trait and the time of drought incidence. The correlation of yield/plant with protein content was negative under all drought levels, and the average correlation coefficient was 0.32. It could be concluded that the specific adaptation and the wide adaptation have great implication for improving faba bean under drought. To select for high seed yield under drought, secondary characters, such as pods/plant and plant height could be of great importance. Drought could reduce protein content and affect its association with yield/plant.(Author)

Crack propagation of brittle rock under high geostress

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Liu, Ning; Chu, Weijiang; Chen, Pingzhi

2018-03-01

Based on fracture mechanics and numerical methods, the characteristics and failure criterions of wall rock cracks including initiation, propagation, and coalescence are analyzed systematically under different conditions. In order to consider the interaction among cracks, adopt the sliding model of multi-cracks to simulate the splitting failure of rock in axial compress. The reinforcement of bolts and shotcrete supporting to rock mass can control the cracks propagation well. Adopt both theory analysis and simulation method to study the mechanism of controlling the propagation. The best fixed angle of bolts is calculated. Then use ansys to simulate the crack arrest function of bolt to crack. Analyze the influence of different factors on stress intensity factor. The method offer more scientific and rational criterion to evaluate the splitting failure of underground engineering under high geostress.

Exploring the link between meteorological drought and streamflow to inform water resource management

Science.gov (United States)

Lennard, Amy; Macdonald, Neil; Hooke, Janet

2015-04-01

Drought indicators are an under-used metric in UK drought management. Standardised drought indicators offer a potential monitoring and management tool for operational water resource management. However, the use of these metrics needs further investigation. This work uses statistical analysis of the climatological drought signal based on meteorological drought indicators and observed streamflow data to explore the link between meteorological drought and hydrological drought to inform water resource management for a single water resource region. The region, covering 21,000 km2 of the English Midlands and central Wales, includes a variety of landscapes and climatological conditions. Analysis of the links between meteorological drought and hydrological drought performed using streamflow data from 'natural' catchments indicates a close positive relationship between meteorological drought indicators and streamflow, enhancing confidence in the application of drought indicators for monitoring and management. However, many of the catchments in the region are subject to modification through impoundments, abstractions and discharge. Therefore, it is beneficial to explore how climatological drought signal propagates into managed hydrological systems. Using a longitudinal study of catchments and sub-catchments that include natural and modified river reaches the relationship between meteorological and hydrological drought is explored. Initial statistical analysis of meteorological drought indicators and streamflow data from modified catchments shows a significantly weakened statistical relationship and reveals how anthropogenic activities may alter hydrological drought characteristics in modified catchments. Exploring how meteorological drought indicators link to streamflow across the water supply region helps build an understanding of their utility for operational water resource management.

Populus species from diverse habitats maintain high night-time conductance under drought.

Science.gov (United States)

Cirelli, Damián; Equiza, María Alejandra; Lieffers, Victor James; Tyree, Melvin Thomas

2016-02-01

We investigated the interspecific variability in nocturnal whole-plant stomatal conductance under well-watered and drought conditions in seedlings of four species of Populus from habitats characterized by abundant water supply (mesic and riparian) or from drier upland sites. The study was carried out to determine whether (i) nocturnal conductance varies across different species of Populus according to their natural habitat, (ii) nocturnal conductance is affected by water stress similarly to daytime conductance based on species habitat and (iii) differences in conductance among species could be explained partly by differences in stomatal traits. We measured whole-plant transpiration and conductance (G) of greenhouse-grown seedlings using an automated high-resolution gravimetric technique. No relationship was found between habitat preference and daytime G (GD), but night-time G (GN) was on average 1.5 times higher in riparian and mesic species (P. deltoides Bartr. ex Marsh. and P. trichocarpa Torr. & Gray) than in those from drier environments (P. tremuloides Michx. and P. × petrowskyana Schr.). GN was not significantly reduced under drought in riparian species. Upland species restricted GN significantly in response to drought, but it was still at least one order of magnitude greater that the cuticular conductance until leaf death was imminent. Under both well-watered and drought conditions, GN declined with increasing vapour pressure deficit (D). Also, a small increase in GN towards the end of the night period was observed in P. deltoides and P. × petrowskyana, suggesting the involvement of endogenous regulation. The anatomical analyses indicated a positive correlation between G and variable stomatal pore index among species and revealed that stomata are not likely to be leaky but instead seem capable of complete occlusion, which raises the question of the possible physiological role of the significant GN observed under drought. Further comparisons among

Exogenous application of abscisic acid may improve the growth and yield of sunflower hybrids under drought

International Nuclear Information System (INIS)

Hussain, S.; Iqbal, J.; Ibrahim, M.; Atta, S.; Ahmed, T.; Saleem, M.F.

2014-01-01

Sunflower genotypes perform differently under different water regimes. Drought stress at various growth stages drastically reduces the growth, development and yield of sunflower hybrids. However, exogenous application of abscisic acid helps in mitigating drought stress by improving growth, development and yield of sunflower. In the present study, three sunflower hybrids viz. DK-4040 (large stature), S-278 (medium stature) and SF-187 (short stature) were exposed to varied irrigation regimes and abscisic acid application schedule i.e. T1: four irrigations with schedule (25DAS, at bud, flower initiation and at achene formation) and with no ABA spray,T/sub 2/: three irrigations with schedule (25DAS, at flower initiation and at achene formation) and with no ABA spray, T/sub 3/: three irrigations with schedule (25DAS, at flower initiation and at achene formation) and with 8 mu MABA spray at bud initiation, T/sub 4/: three irrigations with schedule (25DAS, at bud initiation and at achene formation) and with no ABA spray, T/sub 5/: three irrigations with schedule (25DAS, at bud initiation and at achene formation) and with 8 mu M ABA spray at flower initiation. Experiment was laid out in Randomized Complete Design with factorial arrangement having three replications. ABA application at bud or at flower initiation under drought stress helped in mitigating the detrimental effects by improving growth and yield of sunflower hybrids. Enhancement in drought tolerance of sunflower genotypes was better when ABA was applied at bud initiation stage than that of at flower initiation stage under drought. Improvements in head diameter, achenes per head, 1000-achene weight, achene yield, oil yield, biological yield, harvest index, leaf area index and crop growth rate was recorded. Sunflower hybrid DK-4040 showed more improvement in drought tolerance byfoliar application of ABA under water deficit stress than that of the SF-187 and S-278. It is suggested that sunflower hybrid DK 4040

Untangling the primary drivers of pinyon monoterpene production and emissions under predicted drought

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Trowbridge, A. M.; Adams, H. D.; Breshears, D. D.; Monson, R. K.

2012-04-01

Climate and insect herbivory have important consequences for plant function, atmospheric composition, and the functioning of ecosystems and ecological communities. Within the last decade, pinyon-juniper woodlands throughout the southwestern U.S. have suffered large-scale mortality, especially of pinyon pine, due to drought and associated insect outbreaks. While much research has focused on the primary metabolic mechanisms underlying pinyon's sensitivity to drought, there remains a gap in our knowledge concerning how the resulting shift in carbon allocation toward plant secondary compounds, particularly monoterpenes, affects atmospheric process and ecological interactions. Monoterpenes are the principal constituents of pinyon resin. Because of their large global emission rates and effect on atmospheric chemistry, particularly ozone creation, identifying controls over emissions and sensitivities to environmental change is critical for global emission models. Furthermore, monoterpenes are known to impact insect behavior and act as defense compounds against herbivores, contributing to insect population fluctuations either directly through toxicity, or indirectly by influencing parasitism susceptibility. Pinyon mortality events are thought to be exacerbated by their susceptibility to herbivores resulting from weakened secondary chemical defenses, but the impact of current and predicted drought on the chemical defense status of pinyons and subsequent atmospheric and ecological consequences remain unknown. A field study was developed to examine the impact of seasonality and climate, particularly drought, on pinyon pine physiology and chemistry in the context of tiger moth (Lophocampa ingens) herbivory in pinyon-juniper woodlands. We demonstrate the importance of geography and seasonality, particularly mid-summer drought and late summer monsoons, in driving physiology and monoterpene concentrations and emissions. Emission rates significantly decreased throughout the summer

Control of root system architecture by DEEPER ROOTING 1 increases rice yield under drought conditions.

Science.gov (United States)

Uga, Yusaku; Sugimoto, Kazuhiko; Ogawa, Satoshi; Rane, Jagadish; Ishitani, Manabu; Hara, Naho; Kitomi, Yuka; Inukai, Yoshiaki; Ono, Kazuko; Kanno, Noriko; Inoue, Haruhiko; Takehisa, Hinako; Motoyama, Ritsuko; Nagamura, Yoshiaki; Wu, Jianzhong; Matsumoto, Takashi; Takai, Toshiyuki; Okuno, Kazutoshi; Yano, Masahiro

2013-09-01

The genetic improvement of drought resistance is essential for stable and adequate crop production in drought-prone areas. Here we demonstrate that alteration of root system architecture improves drought avoidance through the cloning and characterization of DEEPER ROOTING 1 (DRO1), a rice quantitative trait locus controlling root growth angle. DRO1 is negatively regulated by auxin and is involved in cell elongation in the root tip that causes asymmetric root growth and downward bending of the root in response to gravity. Higher expression of DRO1 increases the root growth angle, whereby roots grow in a more downward direction. Introducing DRO1 into a shallow-rooting rice cultivar by backcrossing enabled the resulting line to avoid drought by increasing deep rooting, which maintained high yield performance under drought conditions relative to the recipient cultivar. Our experiments suggest that control of root system architecture will contribute to drought avoidance in crops.

Evaluation of some chemical and technological properties of induced erect chickpea mutant lines developed under drought stressed conditions

International Nuclear Information System (INIS)

Moustafa, R.A.K.; Ali, H.G.M.

2009-01-01

Seeds of the chickpea variety Flip 99-47 C were treated with gamma rays at doses of 0, 50 and 75 Gy and sown in the winter season of 2004/2005 to raise M1 generation under ordinary (normal) irrigation conditions. Bulked seeds from each treatment were planted in the subsequent growing seasons of 2005/2006 and 2006/2007 to advance M2 and M3 generations, respectively under either ordinary (normal) irrigation or drought stress condition. In the third generation, three erect mutant lines were derived from 75 Gy mutagenic treatment under drought stress compared to semi spreading growth habit of the initiated variety Flip 99-47 C. In the winter season of 2007/2008, M4 bulked seeds from the three erect lines as well as unirradiated seeds of the original variety grown under either ordinary (normal) irrigation (2152.5 m 3 /fad.) or drought (1159.2 m 3 /fad.) conditions were analyzed for the chemical composition and nutritional values. Obtained results indicated that there were slight decreases in protein and fat contents accompanied with marginal increases in both ash and carbohydrates in seed samples of the erect mutant developed under drought stress as compared to unirradiated seeds of the original variety grown under ordinary (normal) irrigation treatment. An opposite trend was noticed between seed samples derived from the erect lines compared to seeds of the parent variety developed under drought condition. Negligible changes in levels of the minerals (iron, magnesium, calcium and phosphorus) were detected between seeds of the erect lines and the original variety that grown under either ordinary (normal) irrigation or drought conditions. Cooking time (min) and hydration coefficient values did not much differ between the three tested seed samples. Marginal differences in essential and non-essential amino acids were detected between seeds of the erect mutants and those of the initial variety grown under ordinary (normal) irrigation or drought stressed conditions

Forests growing under dry conditions have higher hydrological resilience to drought than do more humid forests.

Science.gov (United States)

Helman, David; Lensky, Itamar M; Yakir, Dan; Osem, Yagil

2017-07-01

More frequent and intense droughts are projected during the next century, potentially changing the hydrological balances in many forested catchments. Although the impacts of droughts on forest functionality have been vastly studied, little attention has been given to studying the effect of droughts on forest hydrology. Here, we use the Budyko framework and two recently introduced Budyko metrics (deviation and elasticity) to study the changes in the water yields (rainfall minus evapotranspiration) of forested catchments following a climatic drought (2006-2010) in pine forests distributed along a rainfall gradient (P = 280-820 mm yr -1 ) in the Eastern Mediterranean (aridity factor = 0.17-0.56). We use a satellite-based model and meteorological information to calculate the Budyko metrics. The relative water yield ranged from 48% to 8% (from the rainfall) in humid to dry forests and was mainly associated with rainfall amount (increasing with increased rainfall amount) and bedrock type (higher on hard bedrocks). Forest elasticity was larger in forests growing under drier conditions, implying that drier forests have more predictable responses to drought, according to the Budyko framework, compared to forests growing under more humid conditions. In this context, younger forests were shown more elastic than older forests. Dynamic deviation, which is defined as the water yield departure from the Budyko curve, was positive in all forests (i.e., less-than-expected water yields according to Budyko's curve), increasing with drought severity, suggesting lower hydrological resistance to drought in forests suffering from larger rainfall reductions. However, the dynamic deviation significantly decreased in forests that experienced relatively cooler conditions during the drought period. Our results suggest that forests growing under permanent dry conditions might develop a range of hydrological and eco-physiological adjustments to drought leading to higher hydrological

Genomewide Expression and Functional Interactions of Genes under Drought Stress in Maize

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Nepolean Thirunavukkarasu

2017-01-01

Full Text Available A genomewide transcriptome assay of two subtropical genotypes of maize was used to observe the expression of genes at seedling stage of drought stress. The number of genes expressed differentially was greater in HKI1532 (a drought tolerant genotype than in PC3 (a drought sensitive genotype, indicating primary differences at the transcriptional level in stress tolerance. The global coexpression networks of the two genotypes differed significantly with respect to the number of modules and the coexpression pattern within the modules. A total of 174 drought-responsive genes were selected from HKI1532, and their coexpression network revealed key correlations between different adaptive pathways, each cluster of the network representing a specific biological function. Transcription factors related to ABA-dependent stomatal closure, signalling, and phosphoprotein cascades work in concert to compensate for reduced photosynthesis. Under stress, water balance was maintained by coexpression of the genes involved in osmotic adjustments and transporter proteins. Metabolism was maintained by the coexpression of genes involved in cell wall modification and protein and lipid metabolism. The interaction of genes involved in crucial biological functions during stress was identified and the results will be useful in targeting important gene interactions to understand drought tolerance in greater detail.

River water quality modelling under drought situations – the Turia River case

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J. Paredes-Arquiola

2016-10-01

Full Text Available Drought and water shortage effects are normally exacerbated due to collateral impacts on water quality, since low streamflow affects water quality in rivers and water uses depend on it. One of the most common problems during drought conditions is maintaining a good water quality while securing the water supply to demands. This research analyses the case of the Turia River Water Resource System located in Eastern Spain. Its main water demand comes as urban demand from Valencia City, which intake is located in the final stretch of the river, where streamflow may become very low during droughts. As a result, during drought conditions concentrations of pathogens and other contaminants increase, compromising the water supply to Valencia City. In order to define possible solutions for the above-mentioned problem, we have developed an integrated model for simulating water management and water quality in the Turia River Basin to propose solutions for water quality problems under water scarcity. For this purpose, the Decision Support System Shell AQUATOOL has been used. The results demonstrate the importance of applying environmental flows as a measure of reducing pollutant's concentration depending on the evolution of a drought event and the state of the water resources system.

Interannual variations in needle and sapwood traits of Pinus edulis branches under an experimental drought

OpenAIRE

Guérin, Marceau; Martin‐Benito, Dario; von Arx, Georg; Andreu‐Hayles, Laia; Griffin, Kevin L.; Hamdan, Rayann; McDowell, Nate G.; Muscarella, Robert; Pockman, William; Gentine, Pierre

2018-01-01

Abstract In the southwestern USA, recent large‐scale die‐offs of conifers raise the question of their resilience and mortality under droughts. To date, little is known about the interannual structural response to droughts. We hypothesized that piñon pines (Pinus edulis) respond to drought by reducing the drop of leaf water potential in branches from year to year through needle morphological adjustments. We tested our hypothesis using a 7‐year experiment in central New Mexico with three wateri...

Expression of the Aeluropus littoralis AlSAP Gene Enhances Rice Yield under Field Drought at the Reproductive Stage

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Thaura Ghneim-Herrera

2017-06-01

Full Text Available We evaluated the yields of Oryza sativa L. ‘Nipponbare’ rice lines expressing a gene encoding an A20/AN1 domain stress-associated protein, AlSAP, from the halophyte grass Aeluropus littoralis under the control of different promoters. Three independent field trials were conducted, with drought imposed at the reproductive stage. In all trials, the two transgenic lines, RN5 and RN6, consistently out-performed non-transgenic (NT and wild-type (WT controls, providing 50–90% increases in grain yield (GY. Enhancement of tillering and panicle fertility contributed to this improved GY under drought. In contrast with physiological records collected during previous greenhouse dry-down experiments, where drought was imposed at the early tillering stage, we did not observe significant differences in photosynthetic parameters, leaf water potential, or accumulation of antioxidants in flag leaves of AlSAP-lines subjected to drought at flowering. However, AlSAP expression alleviated leaf rolling and leaf drying induced by drought, resulting in increased accumulation of green biomass. Therefore, the observed enhanced performance of the AlSAP-lines subjected to drought at the reproductive stage can be tentatively ascribed to a primed status of the transgenic plants, resulting from a higher accumulation of biomass during vegetative growth, allowing reserve remobilization and maintenance of productive tillering and grain filling. Under irrigated conditions, the overall performance of AlSAP-lines was comparable with, or even significantly better than, the NT and WT controls. Thus, AlSAP expression inflicted no penalty on rice yields under optimal growth conditions. Our results support the use of AlSAP transgenics to reduce rice GY losses under drought conditions.

Stochastic reservoir operation under drought with fuzzy objectives

International Nuclear Information System (INIS)

Parent, E.; Duckstein, L.

1993-01-01

Biojective reservoir operation under drought conditions is investigated using stochastic dynamic programming. As both objectives (irrigation water supply, water quality) can only be defined imprecisely, a fuzzy set approach is used to encode the decision maker (DM)'s preferences. The nature driven components are modeled by means of classical stage-state system analysis. The state is three dimensional (inflow memory, drought irrigation index, reservoir level); the decision vector elements are release and irrigation allocation. Stochasticity stems from the random nature of inflows and irrigation demands. The transition function includes a lag one inflow Markov model and mass balance equations. The human driven component is designed as a confluence of fuzzy objectives and constraints after Bellman and Zadeh. Fuzzy numbers are assessed to represent the DM's objectives by two different techniques, the direct one and indirect pairwise comparison. The real case study of the Neste river system in southwestern France is used to illustrate the approach; the result are compared to a classical sequential decision theoretical model derived earlier from the viewpoints of ease of modeling, computational efforts, plausibility and robustness of results

Influence of priming on the physiological traits of corn seed germination under drought stress

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Seyyedeh Roghayyeh KHATAMI

2015-06-01

Full Text Available This study was performed to investigate the effect of drought stress and priming on germination of corn seeds (cultivar SC704 as a factorial experiment based on completely randomized design with three replications. Treatments were drought stress in four levels including 0,-3,-6 and -9 bar and priming as control, hydro, osmo, vitamin and hormone priming. Results showed that interaction of two factors was significant on radicle and plumule dry weight, seedling vigor and germination rate. Osmo-priming remained the radicle dry weight and seedling vigor index same to control but germination rate decreased in this treatment about 38% to control. Drought stress at any severity caused seed reservoirs were not use inefficiently. In conclusion, osmo and hormone primings were the best treatments for seed invigoration under severe drought stress.

Using plant growth modeling to analyse C source-sink relations under drought: inter and intra specific comparison

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Benoit ePallas

2013-11-01

Full Text Available The ability to assimilate C and allocate NSC (non structural carbohydrates to the most appropriate organs is crucial to maximize plant ecological or agronomic performance. Such C source and sink activities are differentially affected by environmental constraints. Under drought, plant growth is generally more sink than source limited as organ expansion or appearance rate is earlier and stronger affected than C assimilation. This favors plant survival and recovery but not always agronomic performance as NSC are stored rather than used for growth due to a modified metabolism in source and sink leaves. Such interactions between plant C and water balance are complex and plant modeling can help analyzing their impact on plant phenotype. This paper addresses the impact of trade-offs between C sink and source activities and plant production under drought, combining experimental and modeling approaches. Two contrasted monocotyledonous species (rice, oil palm were studied. Experimentally, the sink limitation of plant growth under moderate drought was confirmed as well as the modifications in NSC metabolism in source and sink organs. Under severe stress, when C source became limiting, plant NSC concentration decreased. Two plant models dedicated to oil palm and rice morphogenesis were used to perform a sensitivity analysis and further explore how to optimize C sink and source drought sensitivity to maximize plant growth. Modeling results highlighted that optimal drought sensitivity depends both on drought type and species and that modeling is a great opportunity to analyse such complex processes. Further modeling needs and more generally the challenge of using models to support complex trait breeding are discussed.

Genetic studies on leaf rolling and some root traits under drought ...

African Journals Online (AJOL)

Crossing was made between three resistant and two susceptible parents to determine the genetic characteristics under drought conditions during 2002 and 2003 rice growing seasons. The resistant varieties were IET 1444, Moroberekan and Gaori, while the susceptible varieties were Sakha 101 and Sakha 102.

High-resolution multimodel projections of soil moisture drought in Europe under 1.5, 2 and 3 degree global warming

Science.gov (United States)

Samaniego, L. E.; Kumar, R.; Zink, M.; Pan, M.; Wanders, N.; Marx, A.; Sheffield, J.; Wood, E. F.; Thober, S.

2017-12-01

Droughts are creeping hydro-meteorological events that may bring societies and natural systems to their limits by inducing significant environmental changes and large socio-economic losses. Little is know about the effects of varios degrees of warming (i.e., 1.5 , 2 and 3 K) and their respective uncertainties on extreme characteristics such as drought duration and area under drought in general, and in Europe in particular. In this study we investigate the evolution of droughts characteristics under three levels of warming using an unprecedented high-resolution multi-model hydrologic ensemble over the Pan-EU domain at a scale of 5x5 km2 from 1950 until 2100. This multi-model ensemble comprises four hydrologic models (HMs: mHM, Noah-MP, PCR-GLOBWB, VIC) which are forced by five CMIP-5 Global Climate Models (GFDL-ESM2M, HadGEM2-ES, IPSL-CM5A-LR, MIROC-ESM-CHEM, NorESM1-M) under three RCP scenarios 2.6, 6.0, and 8.5. This results in a 60-member ensemble. The contribution GCM/HM uncertainties were analyzed based on a sequential sampling algorithm proposed by Samaniego et al. 2016. This study is carried out within the EDgE project funded by the Copernicus Climate Change Service (edge.climate.copernicus.eu) and the HOKLIM project funded by the German Ministry of Education (BMBF)(www.ufz.de/hoklim). The changes under three levels of warming indicate significant increase (more than 10%) of the number of droughts and area under drought with respect to 30-year climatological means obtained with E-OBS observations. Furthermore, we found that: 1) the number of drought events exhibit significant regional changes. Largest changes are observed in the Mediterrinian where frequency of droughts increases from 25% under 1.5 K to 33% under 2 K, and to more than 50% under 3 K warming. Minor changes are seen in Central-Europe and the British Isles. 2) The GCMs/HMs uncertainties have marked regional differences too, with GCM uncertainty appear to be larger everywhere. The uncertainty of

Drought responses of two gymnosperm species with contrasting stomatal regulation strategies under elevated [CO2] and temperature.

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Duan, Honglang; O'Grady, Anthony P; Duursma, Remko A; Choat, Brendan; Huang, Guomin; Smith, Renee A; Jiang, Yanan; Tissue, David T

2015-07-01

Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in stomatal regulation strategies. Water relations and carbon dynamics were examined in two species with contrasting stomatal regulation strategies: Pinus radiata D. Don (relatively isohydric gymnosperm; regulating stomata to maintain leaf water potential above critical thresholds) and Callitris rhomboidea R. Br (relatively anisohydric gymnosperm; allowing leaf water potential to decline as the soil dries), to assess response to drought as a function of [CO2] and temperature. Both species were grown in two [CO2] (C(a) (ambient, 400 μl l(-1)) and C(e) (elevated, 640 μl l(-1))) and two temperature (T(a) (ambient) and T(e) (ambient +4 °C)) treatments in a sun-lit glasshouse under well-watered conditions. Drought plants were then exposed to a progressive drought until mortality. Prior to mortality, extensive xylem cavitation occurred in both species, but significant depletion of non-structural carbohydrates was not observed in either species. Te resulted in faster mortality in P. radiata, but it did not modify the time-to-mortality in C. rhomboidea. C(e) did not delay the time-to-mortality in either species under drought or T(e) treatments. In summary, elevated temperature (+4 °C) had greater influence than elevated [CO2] (+240 μl l(-1)) on drought responses of the two studied gymnosperm species, while stomatal regulation strategies did not generally affect the relative contributions of hydraulic failure and carbohydrate depletion to mortality under severe drought. �

The evolution of the monthly hydrograph under hot drought conditions in the Southwest US

Science.gov (United States)

Solander, K.; Bennett, K. E.; Middleton, R. S.

2017-12-01

Hydrology will undergo unprecedented changes in the 21st century. In particular, the emergence of the hot drought—an extraordinary combination of recurring droughts coupled with warmer temperatures—will lead to more frequent and widespread droughts of longer duration. This will transform the natural and engineered landscape, with millions of dollars in critical infrastructure and investments in agriculture, municipalities, and energy-water supplies at stake. Here, we investigate how the monthly hydrograph will evolve under hot drought conditions by examining the response of streamflow under historic droughts overlaid with expected temperature increases in the coming decades. We use a suite of Global Climate Models and two emission scenarios coupled to the Variable Infiltration Capacity hydrology model to evaluate these changes under different levels of warming using various sub-basins within the Colorado River Basin as a test case. Results indicate a substantial change in both magnitude (up to 40% decrease) and timing (greater than one-month earlier) in peak flows with spatial differences strongly influenced by elevation. Findings indicate these shifts are being driven by changing snow and snowmelt patterns. Such changes are anticipated to have a substantial impact on food, energy, and water resources within the basin and are important to understand in advance given that they represent the extreme range of conditions likely to occur so we can improve the management of this resource and adapt to these changes during critical periods.

Screening of Bread Wheat Genotypes for Stem Reserves Remobilization, Relative Water Content and Osmotic Adjustment under Drought Stress

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Z Soleimani

2015-05-01

Full Text Available Drought one of the most important global threats against bread wheat production. In order to identify physiological traits associated with drought tolerance, 52 bread wheat varieties were cultured under two normal and drought stress condition in a randomized complete block desigen with three replications. RWC (in three independent times, leaf rolling, leaf silvering, days to flowering, days to maturity and stem reserve remobilization were investigeted. Also in a pot experiment osmotic adjustment of the varieties were measured at seedling stage. varieties Star and Bezostaya had the highest RWC (0.79 and 0.78, respectively. Osmotic adjustment in Rasol and Unknown11 were highest (0.58 and 0.56, respectively. Varieties Tipik, Unknown11 and Azar2 showed the least decrease in thousand grain weight after spraying with KI (4.8, 5.5 and 5.5, respectively. Also varieties Dez, Gaspard and MV-17 have the highest degree of leaf silvering and varieties Niknejad, Star and Kohdasht under drought stress were able than the other varieties bring their leaves to form a rolling and cope with water deficit. Under drought stress, Varieties Alborz, Zagros and Inia were observed premature than the other varieties and Gaspard and Kaslojen varieties were observed late mature than the other varieties. Altogetehr varieties Kohdasht, Star and Bezostaya can be used as genetic resources for leaf water retention under drought stress condition for imjproving other varieties. Also as Azar2 and Unknown11 had highest amount of thousand grain weight under normal condition and simoultanously showed high ability in stem reserves remobilization they can be selected as parents in crosses for improving these traits.

Evaluation of sorghum genotypes under drought stress conditions ...

African Journals Online (AJOL)

Seven genotypes of sorghum (Sorghum bicolour (L.) Moench) were studied in both drought and normal conditions. In each condition, the genotypes were evaluated using a split plot based randomized complete block design with three replications. Drought tolerance indices including stability tolerance index (STI), mean ...

Can gas exchange dynamics predict non-structural carbohydrate use under drought stress?

Science.gov (United States)

Kannenberg, S.; Phillips, R.

2016-12-01

A recent conceptual framework for understanding tree drought responses characterizes species along a continuum from isohydry to anisohydry, with theory predicting that isohydric and anisohydric trees should display different carbon (C) allocation patterns under drought conditions. We tested the hypothesis that the trade-offs inherent in the isohydry-anisohydry framework (i.e., C starvation vs. hydraulic failure) necessitate different allocation patterns to non-structural carbohydrates (NSCs), growth, and respiration. Specifically, we hypothesized that isohydric trees would decrease NSC stores and growth in the face of reduced incoming photoassimilate, whereas anisohydric trees would maintain assimilation, growth, and NSC pools due to decreased demand for stored metabolic C and enhanced osmoregulatory needs. To test this, we subjected saplings of Liriodendron tulipifera (an isohydric tree) and Quercus alba (an anisohydric tree) to a six week drought in the greenhouse, and measured assimilation, leaf water potential (midday and predawn), growth, leaf dark respiration and NSCs (both sugars and starch in aboveground and belowground tissues) in control and droughted plants. Overall, we confirmed that the isohydric and anisohydric species used NSCs differently during drought. In most tissues, both species had similar responses of NSCs to drought: starch NSCs were maintained or decreased while sugar NSCs tended to increase. Stem NSCs were a notable exception, as L. tulipifera decreased total NSC to almost zero while NSCs in Q. alba remained constant. This depletion of stem NSC in L. tulipifera was offset by increases in other tissues, however, resulting in no net change to total NSC during the drought. In contrast, Q. alba increased total NSC. Interestingly, Q. alba also decreased assimilation and growth, indicating a potential trade-off between NSC and biomass allocation. Our results show that NSCs in different tissues may have contrasting uses as storage or

Title: Potassium application regulates nitrogen metabolism and osmotic adjustment in cotton (Gossypium hirsutum L.) functional leaf under drought stress.

Science.gov (United States)

Zahoor, Rizwan; Zhao, Wenqing; Abid, Muhammad; Dong, Haoran; Zhou, Zhiguo

2017-08-01

To evaluate the role of potassium (K) in maintaining nitrogen metabolism and osmotic adjustment development of cotton functional leaves to sustain growth under soil drought and rewatering conditions, the plants of two cotton cultivars Siza 3 (low-K sensitive) and Simian 3 (low-K tolerant), were grown under three different K rates (K0, K1, and K2; 0, 150, and 300kgK 2 Oha -1 , respectively) and exposed to drought stress with 40±5% soil relative water content (SRWC). The drought stress was applied at flowering stage by withholding water for eight days followed by rewatering to a well-watered level (75±5% SRWC). The results showed that drought-stressed plants of both cultivars showed a decrease in leaf relative water content (RWC) and osmotic potential in the functional leaves and developed osmotic adjustment with an increase in the contents of free amino acids, soluble sugars, inorganic K, and nitrate as compared to well-watered plants. In drought-stressed plants, nitrogen-metabolizing enzyme activities of nitrogen reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT) were diminished significantly (P≤0.05) along with decreased chlorophyll content and soluble proteins. However, drought-stressed plants under K application not only exhibited higher osmotic adjustment with greater accumulation of osmolytes but also regulated nitrogen metabolism by maintaining higher enzyme activities, soluble proteins, and chlorophyll content in functional leaves as compared to the plants without K application. Siza 3 showed better stability in enzyme activities and resulted in 89% higher seed cotton yield under K2 as compared to K0 in drought-stressed plants, whereas this increase was 53% in the case of Simian 3. The results of the study suggested that K application enhances cotton plants' potential for sustaining high nitrogen-metabolizing enzyme activities and related components to supplement osmotic adjustment under soil drought conditions. Copyright © 2017

Post-fire environments are favourable for plant functioning of seeder and resprouter Mediterranean shrubs, even under drought.

Science.gov (United States)

Parra, Antonio; Moreno, José M

2017-05-01

Understanding how drought affects seeder and resprouter plants during post-fire regeneration is important for the anticipation of Mediterranean vegetation vulnerability in a context of increasing drought and fire caused by climate change. A Mediterranean shrubland was subjected to various drought treatments (including 45% rainfall reduction, 7 months drought yr -1 ), before and after experimental burning, by means of a rainout-shelter system with an irrigation facility. Predawn shoot water potential (Ψ pd ), relative growth rate (RGR), specific leaf area (SLA) and bulk leaf carbon isotopic composition (δ 13 C) were monitored in the main woody species during the first 3 yr after fire. Cistus ladanifer seedlings showed higher Ψ pd , RGR and SLA, and lower δ 13 C, than unburned plants during the first two post-fire years. Seedlings under drought maintained relatively high Ψ pd , but suffered a decrease in Ψ pd and RGR, and an increase in δ 13 C, relative to control treatments. Erica arborea, E. scoparia and Phillyrea angustifolia resprouts had higher Ψ pd and RGR than unburned plants during the first post-fire year. Resprouters were largely unaffected by drought. Overall, despite marked differences between the two functional groups, post-fire environments were favourable for plant functioning of both seeder and resprouter shrubs, even under the most severe drought conditions implemented. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

The propagation of a soil H218O labeling through the atmosphere-plant-soil system under drought using H218O and C18OO as two independent proxies

Science.gov (United States)

Barthel, Matthias; Sturm, Patrick; Hammerle, Albin; Siegwolf, Rolf; Gentsch, Lydia; Buchmann, Nina; Knohl, Alexander

2013-04-01

Above- and belowground processes in plants are tightly coupled via carbon and water flows through the atmosphere-plant-soil system. While recent studies elucidated the influence of drought on the carbon flow through plant and soil using 13C, much less is known about the propagation of 18O. Therefore, this study aimed to examine the timing and intensity of 18O enrichment in soil and shoot CO2 and H2O vapor fluxes of European beech saplings (Fagus sylvatica L.) after applying 18O-labeled water to the soil. A custom-made chamber system, separating shoot from soil compartments, allowed independent measurements of shoot and soil related processes in a controlled climate chamber environment. Gas-exchange of oxygen stable isotopes in CO2 and H2O-vapor served as the main tool for investigation and was monitored in real-time using laser spectroscopy. This is the first study measuring concurrently and continuously the enrichment of 18O in CO2 and H2O in shoot- and soil gas-exchange after applying 18O-labeled water to the soil. Photosynthesis (A) and stomatal conductance (gs) of drought-stressed plants showed an immediate coinciding small increase to the H218O irrigation event after only ~30 min. This rapid information transfer, however, was not accompanied by the arrival of 18O labeled water molecules within the shoot. The actual label induced 18O enrichment in transpired water and CO2 occurred not until ~4h after labeling. Further, the timing of the enrichment of 18O in the transpirational flux was similar in both treatments, thus pointing to similar transport rates. However, drought reduced the 18O exchange rate between H2O and CO2at the shoot level, likely caused by a smaller leaf CO2retroflux. Moreover, 18O exchange between H2O and CO2 occurred also in the soil. However, the there was no difference observed between the treatments.

Abscisic acid, a stress hormone helps in improving water relations and yield of sunflower (helianthus annuus l.) hybrids under drought

International Nuclear Information System (INIS)

Hussain, S.; Saleem, M.F.; Cheema, M.A.; Ashraf, M.Y.; Haq, M.A.

2010-01-01

Genotypic variation in water relations under drought is an important index of studying drought tolerance of crops. Abscisic acid (ABA) application helped in mitigating drought stress by improving water relations and yield. Three sunflower hybrids viz., DK-4040 (tall stature), S-278 (medium stature) and SF-187 (short stature) were subjected to different irrigation and ABA application regimes i.e., four irrigations (25 days after sowing (DAS), at bud initiation, at flower initiation and at achene formation) and with no ABA spray, three irrigations (25 days after sowing, at flower initiation and at achene formation) and with no ABA spray, three irrigations (25 days after sowing, at flower initiation and at achene formation) and with ABA spray at bud initiation, three irrigations (25 days after sowing), at bud initiation and at achene formation) and with no ABA spray, three irrigations (25 days after sowing), at bud initiation and at achene formation) and with ABA spray at flower initiation. The experiment was laid out in randomized complete block design with split plot arrangement and had three replications. Exogenous application of ABA under drought at either stage (bud or flower initiation) was helpful in ameliorating drought stress by improving water relations and yield of sunflower hybrids; however response was better when ABA was applied under drought at bud initiation than at flower initiation stage. Sunflower hybrid DK- 4040 showed better enhancement of drought tolerance by exogenous application of ABA under drought than SF-187 and S-278 because it showed more improvement in water potential, osmotic potential, turgor pressure, relative leaf water contents and achene yield. (author)

Potential impacts of agricultural drought on crop yield variability under a changing climate in Texas

Science.gov (United States)

Lee, K.; Leng, G.; Huang, M.; Sheffield, J.; Zhao, G.; Gao, H.

2017-12-01

Texas has the largest farm area in the U.S, and its revenue from crop production ranks third overall. With the changing climate, hydrological extremes such as droughts are becoming more frequent and intensified, causing significant yield reduction in rainfed agricultural systems. The objective of this study is to investigate the potential impacts of agricultural drought on crop yields (corn, sorghum, and wheat) under a changing climate in Texas. The Variable Infiltration Capacity (VIC) model, which is calibrated and validated over 10 major Texas river basins during the historical period, is employed in this study.The model is forced by a set of statistically downscaled climate projections from Coupled Model Intercomparison Project Phase 5 (CMIP5) model ensembles at a spatial resolution of 1/8°. The CMIP5 projections contain four Representative Concentration Pathways (RCP) that represent different greenhouse gas concentration (4.5 and 8.5 w/m2 are selected in this study). To carry out the analysis, VIC simulations from 1950 to 2099 are first analyzed to investigate how the frequency and severity of agricultural droughts will be altered in Texas (under a changing climate). Second, future crop yields are projected using a statistical crop model. Third, the effects of agricultural drought on crop yields are quantitatively analyzed. The results are expected to contribute to future water resources planning, with a goal of mitigating the negative impacts of future droughts on agricultural production in Texas.

[Physiological responses of mycorrhizal Pinus massoniana seedlings to drought stress and drought resistance evaluation].

Science.gov (United States)

Wang, Yi; Ding, Gui-jie

2013-03-01

A greenhouse pot experiment was conducted to study the effects of inoculating Pisolithus tinctorius, Cenococcum geophilum, Cantharellus cibarius, and Suillus luteus on the physiological characteristics of Pinus massoniana seedlings under the conditions of drought stress and re-watering, with the drought resistance of the mycorrhizal seedlings evaluated. Under drought stress, the MDA content and membrane' s relative permeability of P. massoniana seedlings increased, but these two indices in the inoculated (mycorrhizal) seedlings were significantly lower than these in the un-inoculated (control) seedlings. After re-watering, the MDA content and membrane's relative permeability of mycorrhizal seedlings had a rapid decrease, as compared with the control. In the first 21 days of drought stress, the production rate of superoxide radical of the seedlings increased, and the SOD, POD and NR activities of mycorrhizal seedlings increased significantly. With the extending of drought stress, the seedlings after re-watering had different recovery ability. Under the re-watering after 14 days drought stress, the SOD, POD and NR activities recovered. The drought resistance of the mycorrhizal seedlings was in the order of Suillus luteus 1 > Suillus luteus 7 > Cantharellus cibarius > Cenococcum geophilum > Pisolithus tinctorius. The SOD and MDA activities had a greater correlation with the mycorrhizal seedlings drought resistance, being able to be used as the indicators to evaluate the drought resistance of mycorrhizal seedlings.

Mesophyll conductance decreases in the wild type but not in an ABA-deficient mutant (aba1) of Nicotiana plumbaginifolia under drought conditions.

Science.gov (United States)

Mizokami, Yusuke; Noguchi, Ko; Kojima, Mikiko; Sakakibara, Hitoshi; Terashima, Ichiro

2015-03-01

Under drought conditions, leaf photosynthesis is limited by the supply of CO2 . Drought induces production of abscisic acid (ABA), and ABA decreases stomatal conductance (gs ). Previous papers reported that the drought stress also causes the decrease in mesophyll conductance (gm ). However, the relationships between ABA content and gm are unclear. We investigated the responses of gm to the leaf ABA content [(ABA)L ] using an ABA-deficient mutant, aba1, and the wild type (WT) of Nicotiana plumbaginifolia. We also measured leaf water potential (ΨL ) because leaf hydraulics may be related to gm . Under drought conditions, gm decreased with the increase in (ABA)L in WT, whereas both (ABA)L and gm were unchanged by the drought treatment in aba1. Exogenously applied ABA decreased gm in both WT and aba1 in a dose-dependent manner. ΨL in WT was decreased by the drought treatment to -0.7 MPa, whereas ΨL in aba1 was around -0.8 MPa even under the well-watered conditions and unchanged by the drought treatment. From these results, we conclude that the increase in (ABA)L is crucial for the decrease in gm under drought conditions. We discuss possible relationships between the decrease in gm and changes in the leaf hydraulics. © 2014 John Wiley & Sons Ltd.

[Characteristics and adaptation of seasonal drought in southern China under the background of climate change. V. Seasonal drought characteristics division and assessment in southern China].

Science.gov (United States)

Huang, Wan-Hua; Sui, Yue; Yang, Xiao-Guang; Dai, Shu-Wei; Li, Mao-Song

2013-10-01

Zoning seasonal drought based on the study of drought characteristics can provide theoretical basis for formulating drought mitigation plans and improving disaster reduction technologies in different arid zones under global climate change. Based on the National standard of meteorological drought indices and agricultural drought indices and the 1959-2008 meteorological data from 268 meteorological stations in southern China, this paper analyzed the climatic background and distribution characteristics of seasonal drought in southern China, and made a three-level division of seasonal drought in this region by the methods of combining comprehensive factors and main factors, stepwise screening indices, comprehensive disaster analysis, and clustering analysis. The first-level division was with the annual aridity index and seasonal aridity index as the main indices and with the precipitation during entire year and main crop growing season as the auxiliary indices, dividing the southern China into four primary zones, including semi-arid zone, sub-humid zone, humid zone, and super-humid zone. On this basis, the four primary zones were subdivided into nine second-level zones, including one semi-arid area-temperate-cold semi-arid hilly area in Sichuan-Yunnan Plateau, three sub-humid areas of warm sub-humid area in the north of the Yangtze River, warm-tropical sub-humid area in South China, and temperate-cold sub-humid plateau area in Southwest China, three humid areas of temperate-tropical humid area in the Yangtze River Basin, warm-tropical humid area in South China, and warm humid hilly area in Southwest China, and two super-humid areas of warm-tropical super-humid area in South China and temperate-cold super-humid hilly area in the south of the Yangtze River and Southwest China. According to the frequency and intensity of multiple drought indices, the second-level zones were further divided into 29 third-level zones. The distribution of each seasonal drought zone was

Increased Ratio of Electron Transport to Net Assimilation Rate Supports Elevated Isoprenoid Emission Rate in Eucalypts under Drought1[W][OPEN

Science.gov (United States)

Dani, Kaidala Ganesha Srikanta; Jamie, Ian McLeod; Prentice, Iain Colin; Atwell, Brian James

2014-01-01

Plants undergoing heat and low-CO2 stresses emit large amounts of volatile isoprenoids compared with those in stress-free conditions. One hypothesis posits that the balance between reducing power availability and its use in carbon assimilation determines constitutive isoprenoid emission rates in plants and potentially even their maximum emission capacity under brief periods of stress. To test this, we used abiotic stresses to manipulate the availability of reducing power. Specifically, we examined the effects of mild to severe drought on photosynthetic electron transport rate (ETR) and net carbon assimilation rate (NAR) and the relationship between estimated energy pools and constitutive volatile isoprenoid emission rates in two species of eucalypts: Eucalyptus occidentalis (drought tolerant) and Eucalyptus camaldulensis (drought sensitive). Isoprenoid emission rates were insensitive to mild drought, and the rates increased when the decline in NAR reached a certain species-specific threshold. ETR was sustained under drought and the ETR-NAR ratio increased, driving constitutive isoprenoid emission until severe drought caused carbon limitation of the methylerythritol phosphate pathway. The estimated residual reducing power unused for carbon assimilation, based on the energetic status model, significantly correlated with constitutive isoprenoid emission rates across gradients of drought (r2 > 0.8) and photorespiratory stress (r2 > 0.9). Carbon availability could critically limit emission rates under severe drought and photorespiratory stresses. Under most instances of moderate abiotic stress levels, increased isoprenoid emission rates compete with photorespiration for the residual reducing power not invested in carbon assimilation. A similar mechanism also explains the individual positive effects of low-CO2, heat, and drought stresses on isoprenoid emission. PMID:25139160

Diurnal regulation of photosynthesis in Jatropha curcas under drought during summer in a semi-arid region

International Nuclear Information System (INIS)

Tominaga, Jun; Inafuku, Sayuri; Coetzee, Tidimalo; Kawamitsu, Yoshinobu

2014-01-01

The diurnal photosynthetic responses to drought in Jatropha curcas have not been well assessed under field conditions in harsh semi-arid habitats. To illustrate this, diurnal changes in chlorophyll fluorescence and gas exchange rates were measured in field-grown Jatropha with or without a short (13 days) water recovery treatment under drought conditions during hot summer in a semi-arid. Sensitive stomatal closure coordinated with a drying atmosphere strictly limited a net CO 2 assimilation rate with a predominant morning peak, eventually turning negative during the day. Even though the risk of excess excitation energy which potentially causes photodamage increased with the extremely low capacity for CO 2 fixation, Jatropha preserved the integrity of PSII. Quantitative analysis of quenching partitioning revealed that regulated thermal energy dissipation accounted a large fraction of both instantaneous and daily absorbed energy by up to 80 and 72%, respectively, under the drought condition. Water recovery treatment more than doubled daily CO 2 uptake via mitigating diurnal stomatal closure. The regulated thermal dissipation flexibly adjusted PSII quantum efficiency to capacity of CO 2 fixation. In addition, downregulation of PSII quantum efficiency via sustained regulated thermal dissipation was observed and thought to be an additional photoprotective function. It is clear that Jatropha strongly rely upon the regulated thermal dissipation under drought condition, which must be critically important for this strict water conserving species, especially under a climate with high solar radiation loads as is seen in semi-arid regions. - Highlights: • Diurnal gas exchange and the fate of absorbed energy were assessed in Jatropha. • The dynamic stomatal closure was the predominant restriction under water stress. • The PSII integrity was preserved even under severe water stress. • The regulated thermal dissipation accounted by up to 72% of daily absorbed energy. �

Drought and groundwater management

DEFF Research Database (Denmark)

Amundsen, Eirik S; Jensen, Frank

This paper considers the problem of a water management authority faced with the threat of a drought that hits at an uncertain date. Three management policies are investigated: i) a laissez-faire (open-access) policy of automatic adjustment through a zero marginal private net benefit condition, ii......-drought steady-state equilibrium stock size of water under policy iii) is smaller than under policy ii) and, hence, a precautionary stock size should not be built up prior to the drought....

Favorable Alleles for Stem Water-Soluble Carbohydrates Identified by Association Analysis Contribute to Grain Weight under Drought Stress Conditions in Wheat

Science.gov (United States)

Li, Runzhi; Chang, Xiaoping; Jing, Ruilian

2015-01-01

Drought is a major environmental constraint to crop distribution and productivity. Stem water-soluble carbohydrates (WSC) buffer wheat grain yield against conditions unfavorable for photosynthesis during the grain filling stage. In this study, 262 winter wheat accessions and 209 genome-wide SSR markers were collected and used to undertake association analysis based on a mixed linear model (MLM). The WSC in different internodes at three growth stages and 1000-grain weight (TGW) were investigated under four environmental regimes (well-watered, drought stress during the whole growth period, and two levels of terminal drought stress imposed by chemical desiccation under the well-watered and drought stress during the whole growth period conditions). Under diverse drought stress conditions, WSC in lower internodes showed significant positive correlations with TGW, especially at the flowering stage under well-watered conditions and at grain filling under drought stress. Sixteen novel WSC-favorable alleles were identified, and five of them contributed to significantly higher TGW. In addition, pyramiding WSC favorable alleles was not only effective for obtaining accessions with higher WSC, but also for enhancing TGW under different water regimes. During the past fifty years of wheat breeding, WSC was selected incidentally. The average number of favorable WSC alleles increased from 1.13 in the pre-1960 period to 4.41 in the post-2000 period. The results indicate a high potential for using marker-assisted selection to pyramid WSC favorable alleles in improving WSC and TGW in wheat. PMID:25768726

Transcriptome-Wide Profiling and Expression Analysis of Diploid and Autotetraploid Paulownia tomentosa × Paulownia fortunei under Drought Stress

Science.gov (United States)

Xu, Enkai; Fan, Guoqiang; Niu, Suyan; Zhao, Zhenli; Deng, Minjie; Dong, Yanpeng

2014-01-01

Paulownia is a fast-growing deciduous hardwood species native to China, which has high ecological and economic value. In an earlier study, we reported ploidy-dependent differences in Paulownia drought tolerance by the microscopic observations of the leaves. Autotetraploid Paulownia has a higher resistance to drought stress than their diploid relatives. In order to obtain genetic information on molecular mechanisms responses of Paulownia plants to drought, Illumina/Solexa Genome sequencing platform was used to de novo assemble the transcriptomes of leaves from diploid and autotetraploid Paulownia tomentosa × Paulownia fortunei seedlings (PTF2 and PTF4 respectively) grown under control conditions and under drought stress and obtained 98,671 nonredundant unigenes. A comparative transcriptome analysis revealed that hundreds of unigenes were predicted to be involved mainly in ROS-scavenging system, amino acid and carbohydrate metabolism, plant hormone biosynthesis and signal transduction, while these unigenes exhibited differential transcript alteration of the two accessions. This study provides a comprehensive map of how P. tomentosa × P. fortunei responds to drought stress at physiological and molecular levels, which may help in understanding the mechanisms involve in water-deficit response and will be useful for further study of drought tolerance in woody plants. PMID:25405758

Applying a Dynamic Stomatal Optimization to Predict Shifts in the Functional Composition of Tropical Forests Under Increased Drought And CO2

Science.gov (United States)

Bartlett, M. K.; Detto, M.; Pacala, S. W.

2017-12-01

The accurate prediction of tropical forest carbon fluxes is key to forecasting global climate, but forest responses to projected increases in CO2 and drought are highly uncertain. Here we present a dynamic optimization that derives the trajectory of stomatal conductance (gs) during drought, a key source of model uncertainty, from plant and soil water relations and the carbon economy of the plant hydraulic system. This optimization scheme is novel in two ways. First, by accounting for the ability of capacitance (i.e., the release of water from plant storage tissue; C) to buffer evaporative water loss and maintain gs during drought, this optimization captures both drought tolerant and avoidant hydraulic strategies. Second, by determining the optimal trajectory of plant and soil water potentials, this optimization quantifies species' impacts on the water available to competing plants. These advances allowed us to apply this optimization across the range of physiology trait values observed in tropical species to evaluate shifts in the competitively optimal trait values, or evolutionarily stable hydraulic strategy (ESS), under increased drought and CO2. Increasing the length of the dry season shifted the ESS towards more drought tolerant, rather than avoidant, trait values, and these shifts were larger for longer individual drought periods (i.e., more consecutive days without rainfall), even if the total time spent in drought was the same. Concurrently doubling the CO2 level reduced the magnitude of these shifts and slightly favored drought avoidant strategies under wet conditions. Overall, these analyses predicted that short, frequent droughts would allow elevated CO2 to shift the functional composition in tropical forests towards more drought avoidant species, while infrequent but long drought periods would shift the ESS to more drought tolerant trait values, despite increased CO2. Overall, these analyses quantified the impact of physiology traits on plant performance

Coordinate changes in photosynthesis, sugar accumulation and antioxidative enzymes improve the performance of Jatropha curcas plants under drought stress

International Nuclear Information System (INIS)

Silva, Evandro N.; Ribeiro, Rafael V.; Ferreira-Silva, Sérgio L.; Vieira, Suyanne A.; Ponte, Luiz F.A.; Silveira, Joaquim A.G.

2012-01-01

The aim of this study was to assess the relationships between photosynthesis, sugars and photo-oxidative protection mechanisms in Jatropha curcas under drought stress. Leaf CO 2 assimilation rate (P N ) and instantaneous carboxylation efficiency decreased progressively as the water deficit increased. The sucrose and reducing sugar concentrations were negatively and highly correlated with photosynthesis indicating a modulation by negative feedback mechanism. The alternative electron sinks (ETR s '/P N ), relative excess of light energy (EXC) and non-photochemical quenching were strongly increased by drought, indicating effective mechanisms of energy excess dissipation. The photochemistry data indicate partial preservation of photosystem II integrity and function even under severe drought. EXC was positively correlated with superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities evidencing an effective role of these enzymes in the oxidative protection against excess of reactive oxygen species in chloroplasts. Leaf H 2 O 2 content and lipid peroxidation were inversely and highly correlated with catalase (CAT) activity indicating that drought-induced inhibition of this enzyme might have allowed oxidative damage. Our data suggest that drought triggers a coordinate down-regulation in photosynthesis through sucrose and reducing sugar accumulation and an energy excess dissipation at PSII level by non-photochemical mechanisms associate with enhancement in photorespiration, restricting photo-damages. In parallel, drought up-regulates SOD and APX activities avoiding accumulation of reactive oxygen species, while CAT activity is not able to avoid H 2 O 2 accumulation in drought-stressed J. curcas leaves. -- Highlights: ► Drought triggers a down-regulation in photosynthesis by sucrose and reducing sugar. ► Drought induces energy dissipation at PSII level and increase in photorespiration. ► Drought up-regulates SOD and APX activities avoiding accumulation of

Non-enzymatic antioxidant accumulations in BR-deficient and BR-insensitive barley mutants under control and drought conditions.

Science.gov (United States)

Gruszka, Damian; Janeczko, Anna; Dziurka, Michal; Pociecha, Ewa; Fodor, Jozsef

2017-12-07

Drought is one of the most adverse stresses that affect plant growth and yield. Disturbances in metabolic activity resulting from drought cause overproduction of reactive oxygen species. It is postulated that brassinosteroids (BRs) regulate plant tolerance to the stress conditions, but the underlying mechanisms remain largely unknown. An involvement of endogenous BRs in regulation of the antioxidant homeostasis is not fully clarified either. Therefore, the aim of this study was to elucidate the role of endogenous BRs in regulation of non-enzymatic antioxidants in barley (Hordeum vulgare) under control and drought conditions. The plant material included the 'Bowman' cultivar and a group of semi-dwarf near-isogenic lines (NILs), representing mutants deficient in BR biosynthesis or signaling. In general, accumulations of 11 compounds representing various types of non-enzymatic antioxidants were analyzed under both conditions. The analyses of accumulations of reduced and oxidized forms of ascorbate indicated that the BR mutants contain significantly higher contents of dehydroascorbic acid under drought conditions when compared with the 'Bowman' cultivar. The analysis of glutathione accumulation indicated that under the control conditions the BR-insensitive NILs contained significantly lower concentrations of this antioxidant when compared with the rest of genotypes. Therefore, we postulate that BR sensitivity is required for normal accumulation of glutathione. A complete accumulation profile of various tocopherols indicated that functional BR biosynthesis and signaling are required for their normal accumulation under both conditions. Results of this study provided an insight into the role of endogenous BRs in regulation of the non-enzymatic antioxidant homeostasis. © 2017 Scandinavian Plant Physiology Society.

Effects of Chitosan Spraying on Physiological Characteristics of Ferula flabelliloba (Apiaceae Under Drought Stress

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Gh. Taheri

2016-02-01

Full Text Available Introduction Ferula flabelliloba Rech. F. & Aell., (Apiaceae, a perennial plant with medicinal value, is one of important soil protective grown in Binalood mountains. Decreased precipitation in the previous years caused plants subjected to drought stress condition. Drought stress limits the growth and productivity of plants more than any other environmental factors. Drought stress can alter plant light absorption and consumption processes and increases production of reactive oxygen species (ROS. ROS is responsible for lipid peroxidation and associated injury to membranes, nucleic acids, proteins and enzymes. To detoxify ROS, plants develop different types of antioxidants to reduce oxidative damage and confer drought tolerance. ROS scavengers are either non- enzymatic (ascorbate, glutathione, flavonoids, alkaloids, carotenoids and phenolic compound or enzymatic containing superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase. The activity of these antioxidants and enzymes allows short-term acclimation to temporary water deficit, but these biochemicals cannot overcome the effects of extreme or prolonged drought. Chitosan is a natural biopolymer formed by low alkaline deacetylation of chitin, an important component of the exoskeletons of crustaceans such as crab, crawfish and shrimp. Chitosan can affect plant physiology and gene expression, hence these materials can increase the plant resistant to many unfavorable environmental condition. The biological properties of chitosan have led to use it for various purposes. Chitosan has been used as plant protectant against fungi, bacteria and viruses, to improve soil fertility and to stimulate plant defense system. Thus, it seems that chitosan is a promising material for improving plant growth, especially under drought stress conditions where water deficit limits plant growth and establishment. In the present study, the effects of chitosan as foliar spraying of F. flabelliloba

Photosynthesis, photoprotection and antioxidant activity of purging nut under drought deficit and recovery

Energy Technology Data Exchange (ETDEWEB)

Pompelli, Marcelo F.; Santos, Mauro G.; Almeida-Cortez, Jarcilene S. [Federal University of Pernambuco, Department of Botany, Plant Physiology Laboratory, Prof. Moraes Rego Av. s/n, Cidade Universitaria 50670901, Recife, PE (Brazil); Barata-Luis, Ricardo [Superior Institute of Agronomy, Technical University of Lisbon, Lisbon (Portugal); Vitorino, Hermerson S.; Goncalves, Eduardo R.; Rolim, Eduardo V.; Ferreira, Vilma M.; Lemos, Eurico E.; Endres, Lauricio [Plant Physiology Laboratory, Federal University of Alagoas, Maceio, Alagoas (Brazil)

2010-08-15

Biodiesel is an alternative to petroleum diesel fuel. It is a renewable, a biodegradable, and also a non-toxic fuel. The general interest to produce biodiesel from Jatropha (Jatropha curcas L.) seeds oil has increased but its ability to grow on drought-prone areas has barely been investigated. The objective of this work was to identify some physiological processes that allow the Jatropha to produce in severe arid conditions by studying its leaf gas exchange and antioxidant systems under drought stress and recovering. It measured the activity of antioxidant enzymes involved in the scavenge of reactive oxygen species (ROS), as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutamine synthetase (GS), as well as malondialdehyde (MDA) content. It was also analyzed the chlorophyll (CHL), carotenoids, amino acids and soluble proteins contents. Net photosynthesis (A) and stomata conductance (g{sub s}) decreased associate with drought stress and dropped to zero in soil water beneath 5%. Drought induced decrease in stomatal and non-stomatal photosynthetic activity. The activities of SOD, CAT, APX and GS and MDA content in leaves were significantly higher in the water-stressed plants compared to well-watered plants and decreased when the plants were rewatered. These observations suggest that oxidative stress resulting from drought deficit in Jatropha could result in the production of antioxidative enzymes to counteract the oxidative damage, and the enzymes may contribute to its ability to survive in the adverse arid environment. (author)

Serpentine endophytic bacterium Pseudomonas azotoformans ASS1 accelerates phytoremediation of soil metals under drought stress.

Science.gov (United States)

Ma, Ying; Rajkumar, Mani; Moreno, António; Zhang, Chang; Freitas, Helena

2017-10-01

This study evaluates the potential of serpentine endophytic bacterium to foster phytoremediation efficiency of Trifolium arvense grown on multi-metal (Cu, Zn and Ni) contaminated soils under drought stress. A drought resistant endophytic bacterial strain ASS1 isolated from the leaves of Alyssum serpyllifolium grown in serpentine soils was identified as Pseudomonas azotoformans based on biochemical tests and partial 16S rRNA gene sequencing. P. azotoformans ASS1 possessed abiotic stress resistance (heavy metals, drought, salinity, antibiotics and extreme temperature) and plant growth promoting (PGP) properties (phosphate solubilization, nitrogen fixation, production of 1-aminocyclopropane-1-carboxylate deaminase, siderophore and ammonia). Inoculation of T. arvense with ASS1 considerably increased the plant biomass and leaf relative water content in both roll towel assay and pot experiments in the absence and presence of drought stress (DS). In the pot experiments, ASS1 greatly enhanced chlorophyll content, catalase, peroxidase, superoxide dismutase activities, and proline content (only in the absence of drought) in plant leaves, whereas they decreased the concentrations of malondialdehyde. Irrespective of water stress, ASS1 significantly improved accumulation, total removal, bio-concentration factor and biological accumulation coefficient of metals (Cu, Zn and Ni), while decreased translocation factors of Cu. The effective colonization and survival in the rhizosphere and tissue interior assured improved plant growth and successful metal phytoremediation under DS. These results demonstrate the potential of serpentine endophytic bacterium ASS1 for protecting plants against abiotic stresses and helping plants to thrive in semiarid ecosystems and accelerate phytoremediation process in metal polluted soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Drought, flood and rainfall analysis under climate change in Crete, Greece

Science.gov (United States)

Tapoglou, Evdokia; Vozinaki, Anthi-Eirini; Tsanis, Ioannis; Nerantzaki, Sofia; Nikolaidis, Nikolaos

2017-04-01

In this study an analysis on the drought frequency and magnitude under climate change in Crete, Greece is performed. The analysis was performed for the time period from 1983-2100, divided into three sub-periods (1983-1999, 2000-2049 and 2050-2099) for inter-comparison. Two climate models were studied MPI-ESM-LR-r1-CSC-REMO and EC-EARTH-r12-SMHI-RCA4, following three possible representative concentration pathways (+2.6, +4.5 and +8.5 W/m2). In order to perform the analysis the results of a SWAT simulation which covered the entity of Crete using 352 subbasins, was used. Drought events are recognized by using the Standardized Precipitation Index (SPI) to identify the meteorological drought events and Standardized Runoff Index (SRI) for hydrological droughts. SPI and SRI drought indices, were used in order to identify the number of drought events for each climate model and scenario. In all cases, an increase in both severity and number of drought events was calculated for the future periods, compared to the baseline period 1983-1999. This increase was smaller for the +2.6 W/m2 scenario and largest for the +8.5 W/m2. The magnitude of events with 10 and 100 years return period was calculated for the subbasins of Crete and the most vulnerable were identified, both in terms of severity and the change throughout the years in index magnitude. Next a flood frequency analysis was performed for the entity of Crete Island in order to calculate the magnitude of events with 10 and 100 years return period. In order to perform the flood frequency analysis, the results of the SWAT simulation in terms of runoff in each subbasin are used. By calculating the magnitude of flood events with 10 and 100 years return period and the change in the magnitude throughout the time periods the most vulnerable subbasins are identified. The same frequency analysis was performed for the precipitation at each subbasin, and the magnitude of extreme precipitation events with 10 and 100 years return

A drought resistance-promoting microbiome is selected by root system under desert farming.

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Ramona Marasco

Full Text Available BACKGROUND: Traditional agro-systems in arid areas are a bulwark for preserving soil stability and fertility, in the sight of "reverse desertification". Nevertheless, the impact of desert farming practices on the diversity and abundance of the plant associated microbiome is poorly characterized, including its functional role in supporting plant development under drought stress. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the structure of the microbiome associated to the drought-sensitive pepper plant (Capsicum annuum L. cultivated in a traditional Egyptian farm, focusing on microbe contribution to a crucial ecosystem service, i.e. plant growth under water deficit. The root system was dissected by sampling root/soil with a different degree of association to the plant: the endosphere, the rhizosphere and the root surrounding soil that were compared to the uncultivated soil. Bacterial community structure and diversity, determined by using Denaturing Gradient Gel Electrophoresis, differed according to the microhabitat, indicating a selective pressure determined by the plant activity. Similarly, culturable bacteria genera showed different distribution in the three root system fractions. Bacillus spp. (68% of the isolates were mainly recovered from the endosphere, while rhizosphere and the root surrounding soil fractions were dominated by Klebsiella spp. (61% and 44% respectively. Most of the isolates (95% presented in vitro multiple plant growth promoting (PGP activities and stress resistance capabilities, but their distribution was different among the root system fractions analyzed, with enhanced abilities for Bacillus and the rhizobacteria strains. We show that the C. annuum rhizosphere under desert farming enriched populations of PGP bacteria capable of enhancing plant photosynthetic activity and biomass synthesis (up to 40% under drought stress. CONCLUSIONS/SIGNIFICANCE: Crop cultivation provides critical ecosystem services in arid lands with the

Enriching Genomic Resources and Transcriptional Profile Analysis of Miscanthus sinensis under Drought Stress Based on RNA Sequencing

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Gang Nie

2017-01-01

Full Text Available Miscanthus × giganteus is wildly cultivated as a potential biofuel feedstock around the world; however, the narrow genetic basis and sterile characteristics have become a limitation for its utilization. As a progenitor of M. × giganteus, M. sinensis is widely distributed around East Asia providing well abiotic stress tolerance. To enrich the M. sinensis genomic databases and resources, we sequenced and annotated the transcriptome of M. sinensis by using an Illumina HiSeq 2000 platform. Approximately 316 million high-quality trimmed reads were generated from 349 million raw reads, and a total of 114,747 unigenes were obtained after de novo assembly. Furthermore, 95,897 (83.57% unigenes were annotated to at least one database including NR, Swiss-Prot, KEGG, COG, GO, and NT, supporting that the sequences obtained were annotated properly. Differentially expressed gene analysis indicates that drought stress 15 days could be a critical period for M. sinensis response to drought stress. The high-throughput transcriptome sequencing of M. sinensis under drought stress has greatly enriched the current genomic available resources. The comparison of DEGs under different periods of drought stress identified a wealth of candidate genes involved in drought tolerance regulatory networks, which will facilitate further genetic improvement and molecular studies of the M. sinensis.

Modeling the Propagation of Mobile Phone Virus under Complex Network

Science.gov (United States)

Yang, Wei; Wei, Xi-liang; Guo, Hao; An, Gang; Guo, Lei

2014-01-01

Mobile phone virus is a rogue program written to propagate from one phone to another, which can take control of a mobile device by exploiting its vulnerabilities. In this paper the propagation model of mobile phone virus is tackled to understand how particular factors can affect its propagation and design effective containment strategies to suppress mobile phone virus. Two different propagation models of mobile phone viruses under the complex network are proposed in this paper. One is intended to describe the propagation of user-tricking virus, and the other is to describe the propagation of the vulnerability-exploiting virus. Based on the traditional epidemic models, the characteristics of mobile phone viruses and the network topology structure are incorporated into our models. A detailed analysis is conducted to analyze the propagation models. Through analysis, the stable infection-free equilibrium point and the stability condition are derived. Finally, considering the network topology, the numerical and simulation experiments are carried out. Results indicate that both models are correct and suitable for describing the spread of two different mobile phone viruses, respectively. PMID:25133209

Using stable isotopes and functional wood anatomy to identify underlying mechanisms of drought tolerance in different provenances of lodgepole pine

Science.gov (United States)

Isaac-Renton, Miriam; Montwé, David; Hamann, Andreas; Spiecker, Heinrich; Cherubini, Paolo; Treydte, Kerstin

2016-04-01

Choosing drought-tolerant seed sources for reforestation may help adapt forests to climate change. By combining dendroecological growth analysis with a long-term provenance trial, we assessed growth and drought tolerance of different populations of a wide-ranging conifer, lodgepole pine (Pinus contorta). This experimental design simulated a climate warming scenario through southward seed transfer, and an exceptional drought also occurred in 2002. We felled over 500 trees, representing 23 seed sources, which were grown for 32 years at three warm, dry sites in southern British Columbia, Canada. Northern populations showed poor growth and drought tolerance. These seed sources therefore appear to be especially at risk under climate change. Before recommending assisted migration of southern seeds towards the north, however, it is important to understand the physiological mechanisms underlying these responses. We combine functional wood anatomy with a dual-isotope approach to evaluate these mechanisms to drought response.

Individual traits as determinants of time to death under extreme drought in Pinus sylvestris L.

Science.gov (United States)

Garcia-Forner, Núria; Sala, Anna; Biel, Carme; Savé, Robert; Martínez-Vilalta, Jordi

2016-10-01

Plants exhibit a variety of drought responses involving multiple interacting traits and processes, which makes predictions of drought survival challenging. Careful evaluation of responses within species, where individuals share broadly similar drought resistance strategies, can provide insight into the relative importance of different traits and processes. We subjected Pinus sylvestris L. saplings to extreme drought (no watering) leading to death in a greenhouse to (i) determine the relative effect of predisposing factors and responses to drought on survival time, (ii) identify and rank the importance of key predictors of time to death and (iii) compare individual characteristics of dead and surviving trees sampled concurrently. Time until death varied over 3 months among individual trees (from 29 to 147 days). Survival time was best predicted (higher explained variance and impact on the median survival time) by variables related to carbon uptake and carbon/water economy before and during drought. Trees with higher concentrations of monosaccharides before the beginning of the drought treatment and with higher assimilation rates prior to and during the treatment survived longer (median survival time increased 25-70 days), even at the expense of higher water loss. Dead trees exhibited less than half the amount of nonstructural carbohydrates (NSCs) in branches, stem and relative to surviving trees sampled concurrently. Overall, our results indicate that the maintenance of carbon assimilation to prevent acute depletion of NSC content above some critical level appears to be the main factor explaining survival time of P. sylvestris trees under extreme drought. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Cysteine proteases and wheat (Triticum aestivum L) under drought: A still greatly unexplored association.

Science.gov (United States)

Botha, Anna-Maria; Kunert, Karl J; Cullis, Christopher A

2017-09-01

Bread wheat (Triticum aestivum L.) provides about 19% of global dietary energy. Environmental stress, such as drought, affects wheat growth causing premature plant senescence and ultimately plant death. A plant response to drought is an increase in protease-mediated proteolysis with rapid degradation of proteins required for metabolic processes. Among the plant proteases that are increased in their activity following stress, cysteine proteases are the best characterized. Very little is known about particular wheat cysteine protease sequences, their expression and also localization. The current knowledge on wheat cysteine proteases belonging to the five clans (CA, CD, CE, CF and CP) is outlined, in particular their expression and possible function under drought. The first successes in establishing an annotated wheat genome database are further highlighted which has allowed more detailed mining of cysteine proteases. We also share our thoughts on future research directions considering the growing availability of genomic resources of this very important food crop. Finally, we also outline future application of developed knowledge in transgenic wheat plants for environmental stress protection and also as senescence markers to monitor wheat growth under environmental stress conditions. © 2017 John Wiley & Sons Ltd.

Evaluation of Grain Quality in Bread Wheat Recombinant Inbred Lines Under Drought Stress Conditions

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H. Shahbazi

2014-04-01

Full Text Available To study drought stress effect on grain quality properties of wheat, an experiment was conductedusing 169 recombinant inbreed lines (RILS under water stress and non-stress condition and with two separated lattice designs. Grain yield, protein yield, protein content, volume of Zeleny sediment, grain hardness, water absorption, grain moisture content and grain dry matter were evaluated. Analysis of variance showed that there were significant differences among the lines for all traits. Moreover, comparison between two lines in two environmental conditions showed, the quality in bread wheat under drought stress conditions due to increment of protein yield is improved. Protein yield in both irrigation regimes has a significant and negative correlation with grain moisture and in the other hand, significant and positive correlation with the grain hardiness dry matter, Zeleny sedimentation and water intake in both conditions. The results showed that the identification of favorable quality characteristics in optimum and stressed conditions were possible and the lines with high grain quality can be used in breeding programs for improving of baking quality. Although some drought sensitive genotypes possessed a favorable baking quality but their grain yield was low.

A new index for identifying socioeconomic drought events under climate change over the East River basin in China

Science.gov (United States)

Shi, H.; Chen, J.; Wang, K.; Niu, J.

2017-12-01

Drought, which means severe water deficiencies, is a complex natural hazard that may have destructive damages on societal properties and lives. Generally, socioeconomic drought occurs when the water resources systems cannot meet the water demands due to a weather-related shortfall in water supply to societies. This paper aims to propose a new index (i.e., socioeconomic drought index (SEDI)) for identifying socioeconomic drought events on different levels (i.e., slight, moderate, severe and extreme) under climate change through considering the gap between water supply and demand. First, the minimum in-stream water requirement (MWR) is determined through comprehensively considering the requirements of water quality, ecology, navigation and water supply. Second, according to the monthly water deficit calculated as the monthly streamflow data minus the MWR, drought month can be identified. Third, according to the cumulative water deficit derived from the monthly water deficit, drought duration (i.e., the number of continuous drought months) can be detected. Fourth, the SEDI of each socioeconomic drought event can be calculated through integrating the impacts of the cumulative water deficit and drought duration. The study area is the East River basin in South China, and the impact of a multi-year reservoir (i.e., the Xinfengjiang Reservoir) on drought is also analyzed. For historical and future drought analysis, it is concluded that the proposed SEDI is feasible to identify socioeconomic drought events. The results show that a number of socioeconomic drought events (including some extreme ones) may occur during 2020-2099, and the appropriate reservoir operation can significantly ease such situation.

Nitrogen Deifciency Limited the Improvement of Photosynthesis in Maize by Elevated CO2 Under Drought

Institute of Scientific and Technical Information of China (English)

ZONG Yu-zheng; SHANGGUAN Zhou-ping

2014-01-01

Global environmental change affects plant physiological and ecosystem processes. The interaction of elevated CO2, drought and nitrogen (N) deficiency result in complex responses of C4 species photosynthetic process that challenge our current understanding. An experiment of maize (Zea mays L.) involving CO2 concentrations (380 or 750 µmol mol-1, climate chamber), osmotic stresses (10% PEG-6000, -0.32 MPa) and nitrogen constraints (N deficiency treated since the 144th drought hour) was carried out to investigate its photosynthesis capacity and leaf nitrogen use efficiency. Elevated CO2 could alleviate drought-induced photosynthetic limitation through increasing capacity of PEPC carboxylation (Vpmax) and decreasing stomatal limitations (SL). The N deifciency exacerbated drought-induced photosynthesis limitations in ambient CO2. Elevated CO2 partially alleviated the limitation induced by drought and N deifciency through improving the capacity of Rubisco carboxylation (Vmax) and decreasing SL. Plants with N deifciency transported more N to their leaves at elevated CO2, leading to a high photosynthetic nitrogen-use efifciency but low whole-plant nitrogen-use efifciency. The stress mitigation by elevated CO2 under N deifciency conditions was not enough to improving plant N use efifciency and biomass accumulation. The study demonstrated that elevated CO2 could alleviate drought-induced photosynthesis limitation, but the alleviation varied with N supplies.

MtCAS31 Aids Symbiotic Nitrogen Fixation by Protecting the Leghemoglobin MtLb120-1 Under Drought Stress in Medicago truncatula

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Xin Li

2018-05-01

Full Text Available Symbiotic nitrogen fixation (SNF in legume root nodules injects millions of tons of nitrogen into agricultural lands and provides ammonia to non-legume crops under N-deficient conditions. During plant growth and development, environmental stresses, such as drought, salt, cold, and heat stress are unavoidable. This raises an interesting question as to how the legumes cope with the environmental stress along with SNF. Under drought stress, dehydrin proteins are accumulated, which function as protein protector and osmotic substances. In this study, we found that the dehydrin MtCAS31 (cold-acclimation-specific 31 functions in SNF in Medicago truncatula during drought stress. We found that MtCAS31 is expressed in nodules and interacts with leghemoglobin MtLb120-1. The interaction between the two proteins protects MtLb120-1 from denaturation under thermal stress in vivo. Compared to wild type, cas31 mutants display a lower nitrogenase activity, a lower ATP/ADP ratio, higher expression of nodule senescence genes and higher accumulation of amyloplasts under dehydration conditions. The results suggested that MtCAS31 protects MtLb120-1 from the damage of drought stress. We identified a new function for dehydrins in SNF under drought stress, which enriches the understanding of the molecular mechanism of dehydrins.

The Effect of Mycorrhizal Inoculation of Fenugreek (Trigonella foenum-graecum L. on its Yield and Some Physiological Characteristics Under Drought Conditions

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Madineh Bijhani

2015-11-01

Full Text Available To study the effects of mycorrhizal inoculation of fenugreek (Trigonella foenum-graecum L. plants and on its growth and yield under drought stress conditions a greenhouse experiment was carried out in split plot using a randomized complete block design at Zabol University green house in 2013. Treatments were three drought stresses: control, mild stress and severe stress (70, 50 and 30% FC assigned to main plots, and three species of mycorrhizal treatments (Glomus intraradices, G. versiform, G. mosseae and non-inoculation as control to sub-plots. The effects of drought on all traits under study were significant, and reduced number of leaves per plant, plant height, root length, chlorophyll b and total chlorophyll by 15.6, 7.6, 10.7, 2.5 and 8.4 % and increased proline and carbohydrates by 38.6 and 17.7 % as compared with the control. Mycorrhizal treatments did not affect the amount of carbohydrates and proline content significantly. Interaction of mycorrhiza and drought stress was significant on grain yield, chlorophyll a and total chlorophyll. Among the mycorrhizal strains G. mosseae affected the traits significantly under drought conditions. The results suggested that mycorrhizal treatments of plants at different drought stresses could improve grain yield of fenugreek and reduce the negative effects of drought by increasing photosynthetic pigments and other quantitative and qualitative traits.

Enhanced poleward propagation of storms under climate change

Science.gov (United States)

Tamarin-Brodsky, Talia; Kaspi, Yohai

2017-12-01

Earth's midlatitudes are dominated by regions of large atmospheric weather variability—often referred to as storm tracks— which influence the distribution of temperature, precipitation and wind in the extratropics. Comprehensive climate models forced by increased greenhouse gas emissions suggest that under global warming the storm tracks shift poleward. While the poleward shift is a robust response across most models, there is currently no consensus on what the underlying dynamical mechanism is. Here we present a new perspective on the poleward shift, which is based on a Lagrangian view of the storm tracks. We show that in addition to a poleward shift in the genesis latitude of the storms, associated with the shift in baroclinicity, the latitudinal displacement of cyclonic storms increases under global warming. This is achieved by applying a storm-tracking algorithm to an ensemble of CMIP5 models. The increased latitudinal propagation in a warmer climate is shown to be a result of stronger upper-level winds and increased atmospheric water vapour. These changes in the propagation characteristics of the storms can have a significant impact on midlatitude climate.

Spatio-temporal dynamics and synoptic characteristics of wet and drought extremes in Northern Eurasia

Science.gov (United States)

Utkuzova, Dilyara; Khan, Valentina

2015-04-01

Synoptical-statistical analysis has been conducted using SPI index calculated for 478 stations with records from 1966 through 2013. Different parameters of SPI frequency distribution and long-term tendencies were calculated as well as spatial characteristics indicating drought and wetness propagation. Results of analysis demonstrate that during last years there is a tendency of increasing of the intensity of draught and wetness extremes over Russia. There are fewer droughts in the northern regions. The drought propagation for the European territory of Russia is decreasing in June and August, and increasing in July. The situation is opposite for the wetness tendencies. For the Asian territory of Russia, the drought propagation is significantly increasing in July along with decreasing wetness trend. Synoptic conditions favorable for the formation of wet and drought extremes were identified by comparing synoptic charts with the spatial patterns of SPI. For synoptic analysis, episodes of extremely wet (6 episodes for the APR and 7 episodes for the EPR) and drought (6 episodes for the APR and 6 for the EPR) events were classified using A. Katz' typology of weather regimes. For European part of Russia, extreme DROUGHT events are linked to the weather type named "MIXED", for Asian part of Russia - the type "CENTRAL". For European part of Russia, extreme WET events associated with "CENTRAL" type. There is a displacement of the planetary frontal zone into southward direction approximately for 5-25 degrees relatively to normal climatological position during WET extreme events linked to «EASTERN» classification type. Intercomparison of SPI calculated on the base of NOAA NCEP CPC CAMS for the same period and with the resolution 0,5 degree, month precipitation data, Era-Interim Daily fields archive for the period 1979-2014 with the resolution 0,5 degree reanalysis and observational precipitation data was done. The results of comparative analysis has been discussed.

Biochemical basis of drought tolerance in hybrid Populus grown under field production conditions. CRADA final report

Energy Technology Data Exchange (ETDEWEB)

Tschaplinski, T.J.; Tuskan, G.A. [Oak Ridge National Lab., TN (United States); Wierman, C. [Boise Cascade Corp., Wallula, WA (United States)

1997-04-01

The purpose of this cooperative effort was to assess the use of osmotically active compounds as molecular selection criteria for drought tolerance in Populus in a large-scale field trial. It is known that some plant species, and individuals within a plant species, can tolerate increasing stress associated with reduced moisture availability by accumulating solutes. The biochemical matrix of such metabolites varies among species and among individuals. The ability of Populus clones to tolerate drought has equal value to other fiber producers, i.e., the wood products industry, where irrigation is used in combination with other cultural treatments to obtain high dry weight yields. The research initially involved an assessment of drought stress under field conditions and characterization of changes in osmotic constitution among the seven clones across the six moisture levels. The near-term goal was to provide a mechanistic basis for clonal differences in productivity under various irrigation treatments over time.

Fatigue crack propagation under elastic plastic medium at elevated temperature

International Nuclear Information System (INIS)

Asada, Y.; Yuuki, R.; Sakon, T.; Sunamoto, D.; Tokimasa, K.; Makino, Y.; Kitagawa, M; Shingai, K.

1980-01-01

The purposes of the present study are to establish the testing method to obtain compatible data on the low cycle fatigue crack propagation at elevated temperature, and to investigate the parameter controlling the crack propagation rate. In the present study, the preliminary experiments have been carried out on low cycle fatigue crack propagation behaviour in type 304 stainless steel in air at 550 0 C, using two types of specimen with a through thickness notch. Both strain controlled and stress controlled fatigue tests have been done under a fully reversed strain or stress cycling. The data obtained are correlated with some fracture mechanics parameters and are discussed with the appropriate parameter for evaluating the low cycle fatigue crack propagation behaviour at elevated temperature. (author)

Circumvention of over-excitation of PSII by maintaining electron transport rate in leaves of four cotton genotypes developed under long-term drought.

Science.gov (United States)

Kitao, M; Lei, T T

2007-01-01

We investigated the patterns of response to a long-term drought in the field in cotton cultivars (genotypes) with known differences in their drought tolerance. Four cotton genotypes with varying physiological and morphological traits, suited to different cropping conditions, were grown in the field and subjected to a long-term moderate drought. In general, cotton leaves developed under drought had significantly higher area-based leaf nitrogen content (N (area)) than those under well irrigation. Droughted plants showed a lower light-saturated net photosynthetic rate (A (sat)) with lower stomatal conductance (g (s)) and intercellular CO (2) concentration (C (i)) than irrigated ones. Based on the responses of A (sat) to g (s) and C (i), there was no decreasing trend in A (sat) at a given g (s) and C (i) in droughted leaves, suggesting that the decline in A (sat) in field-grown cotton plants under a long-term drought can be attributed mainly to stomatal closure, but not to nonstomatal limitations. There was little evidence of an increase in thermal energy dissipation as indicated by the lack of a decrease in the photochemical efficiency of open PSII (F (v)'/F (m)') in droughted plants. On the basis of electron transport (ETR) and photochemical quenching (q (P)), however, we found evidence indicating that droughted cotton plants can circumvent the risk of excessive excitation energy in photosystem (PS) II by maintaining higher electron transport rates associated with higher N (area), even while photosynthetic rates were reduced by stomatal closure.

Screening Pakistani cotton for drought tolerance

International Nuclear Information System (INIS)

Soomro, M.H.; Markhand, G.S.

2011-01-01

The drought is one of the biggest abiotic stresses for crop production in arid and semi-arid agriculture. Thus it is a challenge for plant scientists to screen and develop the drought tolerant cotton lines. In this study, 31 cotton genotypes/cultivars were evaluated under two irrigation regimes i. e., seven irrigations (Control) and two irrigations (Stress), using split plot design with four replications. The crop growth, yield and some physiological parameters were studied. There were high inter-varietal differences for all the parameters under control as well as drought stress. Although all the varieties for all parameters were significantly affected by drought but however, CRIS-9, MARVI, CRIS-134, CRIS-126, CRIS-337, CRIS-355 and CRIS-377 maintained highest performance for all the parameters studied under high drought conditions. (author)

Evidence-based modelling of diverse plant water use strategies on stomatal and non-stomatal components under drought

Science.gov (United States)

zhou, S.; Prentice, C.; Medlyn, B. E.; Sabaté, S.

2013-12-01

Models disagree on how to represent effects of drought stress on plant gas exchange. Some models assume drought stress affects the marginal water use efficiency of plants (marginal WUE; i.e. the change in photosynthesis per unit of change in transpiration) whereas others assume drought stress acts directly on photosynthetic capacity. It is not clear whether either of these approaches is sufficient to capture the drought response, or whether the effect of drought varies among species and functional types. A collection of Eucalyptus and Quercus species derived from different hydro-climate habitats, in together with two European riparian species, were conducted with drought treatments respectively in Australia and Spain for three months. Measurements included net CO2 assimilation rate versus substomatal CO2 concentration (A-Ci) curves, fluorescence, and predawn leaf water potential at increasing levels of water stress. The correlations with quantitative plant traits of leaf, stomata, vessel, and wood density, leaf nitrogen content and 13C discrimination were also explored. We analysed the effect of drought effect on leaf gas exchange with a recently developed stomatal model that reconciles the empirical and optimal approaches on predicting optimal stomatal conductance. The model's single parameter g1 is a decreasing function of marginal WUE. The two genera showed consistence on the contrasting response patterns between species derived from mesic and arid habitats, which differed greatly in their estimated g1 values under moist conditions, and in the rate at which g1 declined with water stress. They also differed greatly in the predawn water potential at which apparent carboxylation capacity (apparent Vcmax) and mesophyll conductance (gm) declined most steeply, and in the steepness of this decline. Principal components analysis revealed a gradient in water relation strategies from sclerophyll species to malacophyll species. Malacophylls had higher g1, apparent Vcmax

Ectomycorrhizal fungi enhance nitrogen and phosphorus nutrition of Nothofagus dombeyi under drought conditions by regulating assimilative enzyme activities.

Science.gov (United States)

Alvarez, Maricel; Huygens, Dries; Olivares, Erick; Saavedra, Isabel; Alberdi, Miren; Valenzuela, Eduardo

2009-08-01

Drought stress conditions (DC) reduce plant growth and nutrition, restraining the sustainable reestablishment of Nothofagus dombeyi in temperate south Chilean forest ecosystems. Ectomycorrhizal symbioses have been documented to enhance plant nitrogen (N) and phosphorus (P) uptake under drought, but the regulation of involved assimilative enzymes remains unclear. We studied 1-year-old N. dombeyi (Mirb.) Oerst. plants in association with the ectomycorrhizal fungi Pisolithus tinctorius (Pers.) Coker & Couch. and Descolea antartica Sing. In greenhouse experiments, shoot and root dry weights, mycorrhizal colonization, foliar N and P concentrations, and root enzyme activities [glutamate synthase (glutamine oxoglutarate aminotransferase (GOGAT), EC 1.4.1.13-14), glutamine synthetase (GS, EC 6.3.1.2), glutamate dehydrogenase (GDH, EC 1.4.1.2-4), nitrate reductase (NR, EC 1.6.6.1), and acid phosphomonoesterase (PME, EC 3.1.3.1-2)] were determined as a function of soil-water content. Inoculation of N. dombeyi with P. tinctorius and D. antartica significantly stimulated plant growth and increased plant foliar N and P concentrations, especially under DC. Ectomycorrhizal inoculation increased the activity of all studied enzymes relative to non-mycorrhizal plants under drought. We speculate that GDH is a key enzyme involved in the enhancement of ectomycorrhizal carbon (C) availability by fuelling the tricarboxylic acid (TCA) cycle under conditions of drought-induced carbon deficit. All studied assimilative enzymes of the ectomycorrhizal associations, involved in C, N, and P transfers, are closely interlinked and interdependent. The up-regulation of assimilative enzyme activities by ectomycorrhizal fungal root colonizers acts as a functional mechanism to increase seedling endurance to drought. We insist upon incorporating ectomycorrhizal inoculation in existing Chilean afforestation programs.

Effect of cycocel on photosynthetic activity and essential oil of fennel (Foeniculum vulgare Mill. under drought stress

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Fatemeh Nouri

2014-12-01

Full Text Available Drought stress is one of the most important and most common environmental stresses that limit plant growth. Photosynthesis is the main determinant of plant growth and its retention ability under environmental stress condition is important for preservation of growth stability. To study the effect of spraying CCC on photosynthesis activity and essential oil content on 'Foeniculum vulgare', an experiment was done in split plot design based on complete block with four replications in research field of University of Zanjan in 2011. Levels of drought stress included, control, soft stress (when 30% of available water was out of soil, severe stress (when 90% of available water was out of soil, and three concentration of CCC 0, 1500 and 3000 mg/L. The results showed that between rates foliar application on physiologic characteristics as photosynthesis rate, transpiration severity, RWC and TΔ intercellular (Ci, stomata conductivity, mesophyll conductivity and essential oil content was significant. By spraying 3000 mg/L CCC, balanced the plant position against drought stress and could reduce negative effect. Foliar application of CCC caused significant increase in photosynthesis rate, mesophyll conductivity and significant decrease stomata conductivity, transpiration severity under drought stress and could increase essential oil content under soft stress. In this study, foliar application of CCC to content 3000 mg/L had the highest effect on this characters.

Regulation of Plant Growth, Photosynthesis, Antioxidation and Osmosis by an Arbuscular Mycorrhizal Fungus in Watermelon Seedlings under Well-Watered and Drought Conditions.

Science.gov (United States)

Mo, Yanling; Wang, Yongqi; Yang, Ruiping; Zheng, Junxian; Liu, Changming; Li, Hao; Ma, Jianxiang; Zhang, Yong; Wei, Chunhua; Zhang, Xian

2016-01-01

Drought stress has become an increasingly serious environmental issue that influences the growth and production of watermelon. Previous studies found that arbuscular mycorrhizal (AM) colonization improved the fruit yield and water use efficiency (WUE) of watermelon grown under water stress; however, the exact mechanisms remain unknown. In this study, the effects of Glomus versiforme symbiosis on the growth, physio-biochemical attributes, and stress-responsive gene expressions of watermelon seedlings grown under well-watered and drought conditions were investigated. The results showed that AM colonization did not significantly influence the shoot growth of watermelon seedlings under well-watered conditions but did promote root development irrespective of water treatment. Drought stress decreased the leaf relative water content and chlorophyll concentration, but to a lesser extent in the AM plants. Compared with the non-mycorrhizal seedlings, mycorrhizal plants had higher non-photochemical quenching values, which reduced the chloroplast ultrastructural damage in the mesophyll cells and thus maintained higher photosynthetic efficiency. Moreover, AM inoculation led to significant enhancements in the enzyme activities and gene expressions of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and monodehydroascorbate reductase in watermelon leaves upon drought imposition. Consequently, AM plants exhibited lower accumulation of MDA, H2O2 and [Formula: see text] compared with non-mycorrhizal plants. Under drought stress, the soluble sugar and proline contents were significantly increased, and further enhancements were observed by pre-treating the drought-stressed plants with AM. Taken together, our findings indicate that mycorrhizal colonization enhances watermelon drought tolerance through a stronger root system, greater protection of photosynthetic apparatus, a more efficient antioxidant system and improved osmoregulation. This study contributes

Proteomic responses of drought-tolerant and drought-sensitive cotton varieties to drought stress.

Science.gov (United States)

Zhang, Haiyan; Ni, Zhiyong; Chen, Quanjia; Guo, Zhongjun; Gao, Wenwei; Su, Xiujuan; Qu, Yanying

2016-06-01

Drought, one of the most widespread factors reducing agricultural crop productivity, affects biological processes such as development, architecture, flowering and senescence. Although protein analysis techniques and genome sequencing have made facilitated the proteomic study of cotton, information on genetic differences associated with proteomic changes in response to drought between different cotton genotypes is lacking. To determine the effects of drought stress on cotton seedlings, we used two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry to comparatively analyze proteome of drought-responsive proteins during the seedling stage in two cotton (Gossypium hirsutum L.) cultivars, drought-tolerant KK1543 and drought-sensitive Xinluzao26. A total of 110 protein spots were detected on 2-DE maps, of which 56 were identified by MALDI-TOF and MALDI-TOF/TOF mass spectrometry. The identified proteins were mainly associated with metabolism (46.4 %), antioxidants (14.2 %), and transport and cellular structure (23.2 %). Some key proteins had significantly different expression patterns between the two genotypes. In particular, 5-methyltetrahydropteroyltriglutamate-homocysteine methyltransferase, UDP-D-glucose pyrophosphorylase and ascorbate peroxidase were up-regulated in KK1543 compared with Xinluzao26. Under drought stress conditions, the vacuolar H(+)-ATPase catalytic subunit, a 14-3-3g protein, translation initiation factor 5A and pathogenesis-related protein 10 were up-regulated in KK1543, whereas ribosomal protein S12, actin, cytosolic copper/zinc superoxide dismutase, protein disulfide isomerase, S-adenosylmethionine synthase and cysteine synthase were down-regulated in Xinluzao26. This work represents the first characterization of proteomic changes that occur in response to drought in roots of cotton plants. These differentially expressed proteins may be related to

The influence of nitric oxide and mercury chloride on leaf mesophyll structure under natural drought conditions

Directory of Open Access Journals (Sweden)

Mykola M. Musiyenko

2012-03-01

Full Text Available It is established that under natural drought conditions starch was accumulated in the central part of chloroplasts of mesophyll cells and chloroplasts were localized on the periphery of cells at plasmalemma. After treatment wheat plants by nitric oxide donor the decreasing of starch deposits number and close contacts between chloroplasts were indicated, elongated nucleus was localized in the centre of cells. After treatment wheat plant by mercury chloride chloroplasts in the cells lost their oval shape and contacts, increased eventually deposition of starch, indicating the acceleration of aging tissues. Thus, nitric oxide in drought conditions reduced the destructive effect of drought on mesophyll cells, and mercury chloride caused deformation of the membrane cell.

Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO2] and temperature

Science.gov (United States)

Gauthier, Paul P. G.; Crous, Kristine Y.; Ayub, Gohar; Duan, Honglang; Weerasinghe, Lasantha K.; Ellsworth, David S.; Tjoelker, Mark G.; Evans, John R.; Tissue, David T.; Atkin, Owen K.

2014-01-01

Climate change is resulting in increasing atmospheric [CO2], rising growth temperature (T), and greater frequency/severity of drought, with each factor having the potential to alter the respiratory metabolism of leaves. Here, the effects of elevated atmospheric [CO2], sustained warming, and drought on leaf dark respiration (R dark), and the short-term T response of R dark were examined in Eucalyptus globulus. Comparisons were made using seedlings grown under different [CO2], T, and drought treatments. Using high resolution T–response curves of R dark measured over the 15–65 °C range, it was found that elevated [CO2], elevated growth T, and drought had little effect on rates of R dark measured at T CO2], growth T, and drought on T response of R dark. However, drought increased R dark at high leaf T typical of heatwave events (35–45 °C), and increased the measuring T at which maximal rates of R dark occurred (T max) by 8 °C (from 52 °C in well-watered plants to 60 °C in drought-treated plants). Leaf starch and soluble sugars decreased under drought and elevated growth T, respectively, but no effect was found under elevated [CO2]. Elevated [CO2] increased the Q 10 of R dark (i.e. proportional rise in R dark per 10 °C) over the 15–35 °C range, while drought increased Q 10 values between 35 °C and 45 °C. Collectively, the study highlights the dynamic nature of the T dependence of R dark in plants experiencing future climate change scenarios, particularly with respect to drought and elevated [CO2]. PMID:25205579

Human influences on streamflow drought characteristics in England and Wales

Science.gov (United States)

Tijdeman, Erik; Hannaford, Jamie; Stahl, Kerstin

2018-02-01

Human influences can affect streamflow drought characteristics and propagation. The question is where, when and why? To answer these questions, the impact of different human influences on streamflow droughts were assessed in England and Wales, across a broad range of climate and catchments conditions. We used a dataset consisting of catchments with near-natural flow as well as catchments for which different human influences have been indicated in the metadata (Factors Affecting Runoff) of the UK National River Flow Archive (NRFA). A screening approach was applied on the streamflow records to identify human-influenced records with drought characteristics that deviated from those found for catchments with near-natural flow. Three different deviations were considered, specifically deviations in (1) the relationship between streamflow drought duration and the base flow index, BFI (specifically, BFIHOST, the BFI predicted from the hydrological properties of soils), (2) the correlation between streamflow and precipitation and (3) the temporal occurrence of streamflow droughts compared to precipitation droughts, i.e. an increase or decrease in streamflow drought months relative to precipitation drought months over the period of record. The identified deviations were then related to the indicated human influences. Results showed that the majority of catchments for which human influences were indicated did not show streamflow drought characteristics that deviated from those expected under near-natural conditions. For the catchments that did show deviating streamflow drought characteristics, prolonged streamflow drought durations were found in some of the catchments affected by groundwater abstractions. Weaker correlations between streamflow and precipitation were found for some of the catchments with reservoirs, water transfers or groundwater augmentation schemes. An increase in streamflow drought occurrence towards the end of their records was found for some of the

Human influences on streamflow drought characteristics in England and Wales

Directory of Open Access Journals (Sweden)

E. Tijdeman

2018-02-01

Full Text Available Human influences can affect streamflow drought characteristics and propagation. The question is where, when and why? To answer these questions, the impact of different human influences on streamflow droughts were assessed in England and Wales, across a broad range of climate and catchments conditions. We used a dataset consisting of catchments with near-natural flow as well as catchments for which different human influences have been indicated in the metadata (Factors Affecting Runoff of the UK National River Flow Archive (NRFA. A screening approach was applied on the streamflow records to identify human-influenced records with drought characteristics that deviated from those found for catchments with near-natural flow. Three different deviations were considered, specifically deviations in (1 the relationship between streamflow drought duration and the base flow index, BFI (specifically, BFIHOST, the BFI predicted from the hydrological properties of soils, (2 the correlation between streamflow and precipitation and (3 the temporal occurrence of streamflow droughts compared to precipitation droughts, i.e. an increase or decrease in streamflow drought months relative to precipitation drought months over the period of record. The identified deviations were then related to the indicated human influences. Results showed that the majority of catchments for which human influences were indicated did not show streamflow drought characteristics that deviated from those expected under near-natural conditions. For the catchments that did show deviating streamflow drought characteristics, prolonged streamflow drought durations were found in some of the catchments affected by groundwater abstractions. Weaker correlations between streamflow and precipitation were found for some of the catchments with reservoirs, water transfers or groundwater augmentation schemes. An increase in streamflow drought occurrence towards the end of their records was found for

Quantitative trait loci and candidate genes underlying genotype by environment interaction in the response of Arabidopsis thaliana to drought

NARCIS (Netherlands)

El-Soda, M.; Kruijer, Willem; Malosetti, M.; Koornneef, M.; Aarts, M.G.M.

2015-01-01

Drought stress was imposed on two sets of Arabidopsis thaliana genotypes grown in sand under short-day conditions and analysed for several shoot and root growth traits. The response to drought was assessed for quantitative trait locus (QTL) mapping in a genetically diverse set of Arabidopsis

Groundwater Withdrawals under Drought: Reconciling GRACE and Models in the United States High Plains Aquifer

Science.gov (United States)

Nie, W.; Zaitchik, B. F.; Kumar, S.; Rodell, M.

2017-12-01

Advanced Land Surface Models (LSM) offer a powerful tool for studying and monitoring hydrological variability. Highly managed systems, however, present a challenge for these models, which typically have simplified or incomplete representations of human water use, if the process is represented at all. GRACE, meanwhile, detects the total change in water storage, including change due to human activities, but does not resolve the source of these changes. Here we examine recent groundwater declines in the US High Plains Aquifer (HPA), a region that is heavily utilized for irrigation and that is also affected by episodic drought. To understand observed decline in groundwater (well observation) and terrestrial water storage (GRACE) during a recent multi-year drought, we modify the Noah-MP LSM to include a groundwater pumping irrigation scheme. To account for seasonal and interannual variability in active irrigated area we apply a monthly time-varying greenness vegetation fraction (GVF) dataset to the model. A set of five experiments were performed to study the impact of irrigation with groundwater withdrawal on the simulated hydrological cycle of the HPA and to assess the importance of time-varying GVF when simulating drought conditions. The results show that including the groundwater pumping irrigation scheme in Noah-MP improves model agreement with GRACE mascon solutions for TWS and well observations of groundwater anomaly in the southern HPA, including Texas and Kansas, and that accounting for time-varying GVF is important for model realism under drought. Results for the HPA in Nebraska are mixed, likely due to misrepresentation of the recharge process. This presentation will highlight the value of the GRACE constraint for model development, present estimates of the relative contribution of climate variability and irrigation to declining TWS in the HPA under drought, and identify opportunities to integrate GRACE-FO with models for water resource monitoring in heavily

Temperature sensitivity of drought-induced tree mortality portends increased regional die-off under global-change-type drought

Science.gov (United States)

Adams, Henry D.; Guardiola-Claramonte, Maite; Barron-Gafford, Greg A.; Villegas, Juan Camilo; Breshears, David D.; Zou, Chris B.; Troch, Peter A.; Huxman, Travis E.

2009-01-01

Large-scale biogeographical shifts in vegetation are predicted in response to the altered precipitation and temperature regimes associated with global climate change. Vegetation shifts have profound ecological impacts and are an important climate-ecosystem feedback through their alteration of carbon, water, and energy exchanges of the land surface. Of particular concern is the potential for warmer temperatures to compound the effects of increasingly severe droughts by triggering widespread vegetation shifts via woody plant mortality. The sensitivity of tree mortality to temperature is dependent on which of 2 non-mutually-exclusive mechanisms predominates—temperature-sensitive carbon starvation in response to a period of protracted water stress or temperature-insensitive sudden hydraulic failure under extreme water stress (cavitation). Here we show that experimentally induced warmer temperatures (≈4 °C) shortened the time to drought-induced mortality in Pinus edulis (piñon shortened pine) trees by nearly a third, with temperature-dependent differences in cumulative respiration costs implicating carbon starvation as the primary mechanism of mortality. Extrapolating this temperature effect to the historic frequency of water deficit in the southwestern United States predicts a 5-fold increase in the frequency of regional-scale tree die-off events for this species due to temperature alone. Projected increases in drought frequency due to changes in precipitation and increases in stress from biotic agents (e.g., bark beetles) would further exacerbate mortality. Our results demonstrate the mechanism by which warmer temperatures have exacerbated recent regional die-off events and background mortality rates. Because of pervasive projected increases in temperature, our results portend widespread increases in the extent and frequency of vegetation die-off. PMID:19365070

Expression of an Arabidopsis molybdenum cofactor sulphurase gene in soybean enhances drought tolerance and increases yield under field conditions.

Science.gov (United States)

Li, Yajun; Zhang, Jiachang; Zhang, Juan; Hao, Ling; Hua, Jinping; Duan, Liusheng; Zhang, Mingcai; Li, Zhaohu

2013-08-01

LOS5/ABA3 gene encoding molybdenum cofactor sulphurase is involved in aldehyde oxidase (AO) activity in Arabidopsis, which indirectly regulates ABA biosynthesis and increased stress tolerance. Here, we used a constitutive super promoter to drive LOS5/ABA3 overexpression in soybean (Glycine max L.) to enhance drought tolerance in growth chamber and field conditions. Expression of LOS5/ABA3 was up-regulated by drought stress, which led to increasing AO activity and then a notable increase in ABA accumulation. Transgenic soybean under drought stress had reduced water loss by decreased stomatal aperture size and transpiration rate, which alleviated leaf wilting and maintained higher relative water content. Exposed to drought stress, transgenic soybean exhibited reduced cell membrane damage by reducing electrolyte leakage and production of malondialdehyde and promoting proline accumulation and antioxidant enzyme activities. Also, overexpression of LOS5/ABA3 enhanced expression of stress-up-regulated genes. Furthermore, the seed yield of transgenic plants is at least 21% higher than that of wide-type plants under drought stress conditions in the field. These data suggest that overexpression of LOS5/ABA3 could improve drought tolerance in transgenic soybean via enhanced ABA accumulation, which could activate expression of stress-up-regulated genes and cause a series of physiological and biochemical resistant responses. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

High-resolution spatio-temporal analyses of drought episodes in the western Mediterranean basin (Spanish mainland, Iberian Peninsula)

Science.gov (United States)

González-Hidalgo, J. C.; Vicente-Serrano, S. M.; Peña-Angulo, D.; Salinas, C.; Tomas-Burguera, M.; Beguería, S.

2018-04-01

The purpose of this research was to identify major drought events on the Spanish mainland between 1961 and 2014 by means of two drought indices, and analyze the spatial propagation of drought conditions. The indices applied were the standardized precipitation index (SPI) and the standardized evaporation precipitation index (SPEI). The first was calculated as standardized anomalies of precipitation at various temporal intervals, while the second examined the climatic balance normalized at monthly scale, incorporating the relationship between precipitation and the atmospheric water demand. The daily meteorological data from Spanish Meteorological Archives (AEMet) were used in performing the analyses. Within the framework of the DESEMON project, original data were converted into a high spatial resolution grid (1.1 km2) following exhaustive quality control. Values of both indices were calculated on a weekly scale and different timescales (12, 24 and 36 months). The results show that during the first half of the study period, the SPI usually returned a higher identification of drought areas, while the reverse was true from the 1990s, suggesting that the effect from atmospheric evaporative demand could have increased. The temporal propagation from 12- to 24-month and 36-month timescales analyzed in the paper seems to be a far from straightforward phenomenon that does not follow a simple rule of time lag, because events at different temporal scales can overlap in time and space. Spatially, the propagation of drought events affecting more than 25% of the total land indicates the existence of various spatial gradients of drought propagation, mostly east-west or west-east, but also north-south have been found. No generalized episodes were found with a radial pattern, i.e., from inland to the coast.

Recent advances in the dissection of drought-stress regulatory networks and strategies for development of drought-tolerant transgenic rice plants.

Science.gov (United States)

Todaka, Daisuke; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

2015-01-01

Advances have been made in the development of drought-tolerant transgenic plants, including cereals. Rice, one of the most important cereals, is considered to be a critical target for improving drought tolerance, as present-day rice cultivation requires large quantities of water and as drought-tolerant rice plants should be able to grow in small amounts of water. Numerous transgenic rice plants showing enhanced drought tolerance have been developed to date. Such genetically engineered plants have generally been developed using genes encoding proteins that control drought regulatory networks. These proteins include transcription factors, protein kinases, receptor-like kinases, enzymes related to osmoprotectant or plant hormone synthesis, and other regulatory or functional proteins. Of the drought-tolerant transgenic rice plants described in this review, approximately one-third show decreased plant height under non-stressed conditions or in response to abscisic acid treatment. In cereal crops, plant height is a very important agronomic trait directly affecting yield, although the improvement of lodging resistance should also be taken into consideration. Understanding the regulatory mechanisms of plant growth reduction under drought stress conditions holds promise for developing transgenic plants that produce high yields under drought stress conditions. Plant growth rates are reduced more rapidly than photosynthetic activity under drought conditions, implying that plants actively reduce growth in response to drought stress. In this review, we summarize studies on molecular regulatory networks involved in response to drought stress. In a separate section, we highlight progress in the development of transgenic drought-tolerant rice plants, with special attention paid to field trial investigations.

Regulation of Plant Growth, Photosynthesis, Antioxidation and Osmosis by an Arbuscular Mycorrhizal Fungus in Watermelon Seedlings under Well-Watered and Drought Conditions

Science.gov (United States)

Mo, Yanling; Wang, Yongqi; Yang, Ruiping; Zheng, Junxian; Liu, Changming; Li, Hao; Ma, Jianxiang; Zhang, Yong; Wei, Chunhua; Zhang, Xian

2016-01-01

Drought stress has become an increasingly serious environmental issue that influences the growth and production of watermelon. Previous studies found that arbuscular mycorrhizal (AM) colonization improved the fruit yield and water use efficiency (WUE) of watermelon grown under water stress; however, the exact mechanisms remain unknown. In this study, the effects of Glomus versiforme symbiosis on the growth, physio-biochemical attributes, and stress-responsive gene expressions of watermelon seedlings grown under well-watered and drought conditions were investigated. The results showed that AM colonization did not significantly influence the shoot growth of watermelon seedlings under well-watered conditions but did promote root development irrespective of water treatment. Drought stress decreased the leaf relative water content and chlorophyll concentration, but to a lesser extent in the AM plants. Compared with the non-mycorrhizal seedlings, mycorrhizal plants had higher non-photochemical quenching values, which reduced the chloroplast ultrastructural damage in the mesophyll cells and thus maintained higher photosynthetic efficiency. Moreover, AM inoculation led to significant enhancements in the enzyme activities and gene expressions of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and monodehydroascorbate reductase in watermelon leaves upon drought imposition. Consequently, AM plants exhibited lower accumulation of MDA, H2O2 and O2− compared with non-mycorrhizal plants. Under drought stress, the soluble sugar and proline contents were significantly increased, and further enhancements were observed by pre-treating the drought-stressed plants with AM. Taken together, our findings indicate that mycorrhizal colonization enhances watermelon drought tolerance through a stronger root system, greater protection of photosynthetic apparatus, a more efficient antioxidant system and improved osmoregulation. This study contributes to advances

The dtudy of physiological and biochemical responses of Agrostis stolonifera and Festuca arundinacea Schreb. under drought stress

Directory of Open Access Journals (Sweden)

Mohammad Hassan Alibiglouei

2014-12-01

Full Text Available Drought stress is a main limiting factor of turfgrass growth in arid and semi-arid regions. Therefore, in this study, the physiological and biochemical changes in two turfgrass species Agrostis stolonifera and Festuca arundinacea schreb during drought stress (70-75 centibar in a 40-day period and recovery were investigated. Control plants during drought stress were regularly irrigated at soil field capacity (20-25 centibar. The results showed that leaf relative water content and leaf chlorophyll content with long-term stress decreased. Electrolyte leakage and proline during drought stress significantly increased and in recovery stage, the level of electrolyte leakage and proline reached to the control. The activity of peroxidase and superoxide dismutase in two turfgrass significantly increased after 30 days and then significantly reduced. In F. arundinacea schreb the activity of ascorbat peroxidase after 20 days significantly increased and then significantly reduced. Also, in F. arundinacea schreb species the activity of catalase increased during drought stress and in recovery stage the activity of catalase reduced. In studied species during drought stress and recovery stage, the activity of ascorbat peroxidase and catalase significantly increased compared to the control. These results suggested that the resistant species F. arundinacea schreb, under drought stress had a low level of electrolyte leakage, higher level of relative water content and chlorophyll destruction was less than A. stolonifera.

Transcriptomic studies reveal a key metabolic pathway contributing to a well-maintained photosynthetic system under drought stress in foxtail millet (Setaria italica L.

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Weiping Shi

2018-05-01

Full Text Available Drought stress is one of the most important abiotic factors limiting crop productivity. A better understanding of the effects of drought on millet (Setaria italica L. production, a model crop for studying drought tolerance, and the underlying molecular mechanisms responsible for drought stress responses is vital to improvement of agricultural production. In this study, we exposed the drought resistant F1 hybrid, M79, and its parental lines E1 and H1 to drought stress. Subsequent physiological analysis demonstrated that M79 showed higher photosynthetic energy conversion efficiency and drought tolerance than its parents. A transcriptomic study using leaves collected six days after drought treatment, when the soil water content was about ∼20%, identified 3066, 1895, and 2148 differentially expressed genes (DEGs in M79, E1 and H1 compared to the respective untreated controls, respectively. Further analysis revealed 17 Gene Ontology (GO enrichments and 14 Kyoto Encyclopedia of Genes and Genomes (KEGG pathways in M79, including photosystem II (PSII oxygen-evolving complex, peroxidase (POD activity, plant hormone signal transduction, and chlorophyll biosynthesis. Co-regulation analysis suggested that these DEGs in M79 contributed to the formation of a regulatory network involving multiple biological processes and pathways including photosynthesis, signal transduction, transcriptional regulation, redox regulation, hormonal signaling, and osmotic regulation. RNA-seq analysis also showed that some photosynthesis-related DEGs were highly expressed in M79 compared to its parental lines under drought stress. These results indicate that various molecular pathways, including photosynthesis, respond to drought stress in M79, and provide abundant molecular information for further analysis of the underlying mechanism responding to this stress.

Transcriptomic studies reveal a key metabolic pathway contributing to a well-maintained photosynthetic system under drought stress in foxtail millet (Setaria italica L.).

Science.gov (United States)

Shi, Weiping; Cheng, Jingye; Wen, Xiaojie; Wang, Jixiang; Shi, Guanyan; Yao, Jiayan; Hou, Liyuan; Sun, Qian; Xiang, Peng; Yuan, Xiangyang; Dong, Shuqi; Guo, Pingyi; Guo, Jie

2018-01-01

Drought stress is one of the most important abiotic factors limiting crop productivity. A better understanding of the effects of drought on millet ( Setaria italica L.) production, a model crop for studying drought tolerance, and the underlying molecular mechanisms responsible for drought stress responses is vital to improvement of agricultural production. In this study, we exposed the drought resistant F 1 hybrid, M79, and its parental lines E1 and H1 to drought stress. Subsequent physiological analysis demonstrated that M79 showed higher photosynthetic energy conversion efficiency and drought tolerance than its parents. A transcriptomic study using leaves collected six days after drought treatment, when the soil water content was about ∼20%, identified 3066, 1895, and 2148 differentially expressed genes (DEGs) in M79, E1 and H1 compared to the respective untreated controls, respectively. Further analysis revealed 17 Gene Ontology (GO) enrichments and 14 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in M79, including photosystem II (PSII) oxygen-evolving complex, peroxidase (POD) activity, plant hormone signal transduction, and chlorophyll biosynthesis. Co-regulation analysis suggested that these DEGs in M79 contributed to the formation of a regulatory network involving multiple biological processes and pathways including photosynthesis, signal transduction, transcriptional regulation, redox regulation, hormonal signaling, and osmotic regulation. RNA-seq analysis also showed that some photosynthesis-related DEGs were highly expressed in M79 compared to its parental lines under drought stress. These results indicate that various molecular pathways, including photosynthesis, respond to drought stress in M79, and provide abundant molecular information for further analysis of the underlying mechanism responding to this stress.

Field Phenotyping of Soybean Roots for Drought Stress Tolerance

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Berhanu A. Fenta

2014-08-01

Full Text Available Root architecture was determined together with shoot parameters under well watered and drought conditions in the field in three soybean cultivars (A5409RG, Jackson and Prima 2000. Morphology parameters were used to classify the cultivars into different root phenotypes that could be important in conferring drought tolerance traits. A5409RG is a drought-sensitive cultivar with a shallow root phenotype and a root angle of <40°. In contrast, Jackson is a drought-escaping cultivar. It has a deep rooting phenotype with a root angle of >60°. Prima 2000 is an intermediate drought-tolerant cultivar with a root angle of 40°–60°. It has an intermediate root phenotype. Prima 2000 was the best performing cultivar under drought stress, having the greatest shoot biomass and grain yield under limited water availability. It had abundant root nodules even under drought conditions. A positive correlation was observed between nodule size, above-ground biomass and seed yield under well-watered and drought conditions. These findings demonstrate that root system phenotyping using markers that are easy-to-apply under field conditions can be used to determine genotypic differences in drought tolerance in soybean. The strong association between root and nodule parameters and whole plant productivity demonstrates the potential application of simple root phenotypic markers in screening for drought tolerance in soybean.

The complex influence of ENSO on droughts in Ecuador

KAUST Repository

Vicente-Serrano, S. M.

2016-03-26

In this study, we analyzed the influence of El Niño–Southern Oscillation (ENSO) on the spatio-temporal variability of droughts in Ecuador for a 48-year period (1965–2012). Droughts were quantified from 22 high-quality and homogenized time series of precipitation and air temperature by means of the Standardized Precipitation Evapotranspiration Index. In addition, the propagation of two different ENSO indices (El Niño 3.4 and El Niño 1 + 2 indices) and other atmospheric circulation processes (e.g., vertical velocity) on different time-scales of drought severity were investigated. The results showed a very complex influence of ENSO on drought behavior across Ecuador, with two regional patterns in the evolution of droughts: (1) the Andean chain with no changes in drought severity, and (2) the Western plains with less severe and frequent droughts. We also detected that drought variability in the Andes mountains is explained by the El Niño 3.4 index [sea surface temperature (SST) anomalies in the central Pacific], whereas the Western plains are much more driven by El Niño 1 + 2 index (SST anomalies in the eastern Pacific). Moreover, it was also observed that El Niño and La Niña phases enhance droughts in the Andes and Western plains regions, respectively. The results of this work could be crucial for predicting and monitoring drought variability and intensity in Ecuador. © 2016 Springer-Verlag Berlin Heidelberg

Deciphering acoustic emission signals in drought stressed branches: the missing link between source and sensor

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Lidewei L Vergeynst

2015-07-01

Full Text Available When drought occurs in plants, acoustic emission signals can be detected, but the actual causes of these signals are still unknown. By analyzing the waveforms of the measured signals, it should however be possible to trace the characteristics of the acoustic emission source and get information about the underlying physiological processes. A problem encountered during this analysis is that the waveform changes significantly from source to sensor and lack of knowledge on wave propagation impedes research progress made in this field. We used finite element modeling and the well-known pencil lead break source to investigate wave propagation in a branch. A cylindrical rod of polyvinyl chloride was first used to identify the theoretical propagation modes. Two wave propagation modes could be distinguished and we used the finite element model to interpret their behavior in terms of source position for both the PVC rod and a wooden rod. Both wave propagation modes were also identified in drying-induced signals from woody branches, and we used the obtained insights to provide recommendations for further acoustic emission research in plant science.

On-farm yield potential of local seed watermelon landraces under heat- and drought-prone conditions in Mali

DEFF Research Database (Denmark)

Nantoume, Aminata Dolo; Christiansen, Jørgen Lindskrog; Andersen, Sven Bode

2012-01-01

On-farm yield experiments were carried out in the Tombouctou region of Mali in 2009/10 under heat- and drought-prone desert conditions with three local landraces of seed-type watermelons. The landraces, named Fombou, Kaneye and Musa Musa by the farmers, exhibited distinct characteristics for fruit...... responsive. The yields obtained suggest that these local landraces of watermelon are valuable plant genetic resources for securing food supply in arid, heat- and drought-prone areas....

Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

Science.gov (United States)

Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

2016-02-01

The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

Pattern of Water Use and Seed Yield under Terminal Drought in Chickpea Genotypes

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Jiayin Pang

2017-08-01

Full Text Available Drought, particularly terminal drought, reduces the yield of chickpea (Cicer arietinum L.. Terminal drought tolerance and water use patterns were evaluated under controlled conditions in 10 genotypes of desi chickpea. Withholding water from early podding reduced vegetative growth, reproductive growth, seed yield, and water use efficiency for seed yield in all genotypes. The genotype Neelam, which produced the highest seed yield when water was withheld, used the least water when well-watered; however, its aboveground biomass at maturity did not differ significantly from six of the nine other genotypes. Indeed, the water-stressed Neelam had the lowest daily transpiration rate during the early stages of water stress and the highest during the later stages, thereby maintaining the highest soil water content in the first 16 days after water was withheld, which enabled higher pod production, lower pod abortion, and better seed filling. Genotypes differed in the threshold value of the fraction of transpirable soil water when flowering and seed set ceased in the water-stress treatment. We conclude that a conservative water use strategy benefits seed yield of chickpea exposed to water shortage during early podding.

The transcriptional regulatory network in the drought response and its crosstalk in abiotic stress responses including drought, cold, and heat

OpenAIRE

Nakashima, Kazuo; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

2014-01-01

Drought negatively impacts plant growth and the productivity of crops around the world. Understanding the molecular mechanisms in the drought response is important for improvement of drought tolerance using molecular techniques. In plants, abscisic acid (ABA) is accumulated under osmotic stress conditions caused by drought, and has a key role in stress responses and tolerance. Comprehensive molecular analyses have shown that ABA regulates the expression of many genes under osmotic stress cond...

Stomata character and chlorophyll content of tomato in response to Zn application under drought condition

Science.gov (United States)

Sakya, A. T.; Sulistyaningsih, E.; Indradewa, D.; Purwanto, B. H.

2018-03-01

This experiment was performed in order to evaluate the effects of Zn application under drought condition on tomato, especially its chlorophyll content and stomata character. This experiment was arranged in factorial using randomized complete block design with three replications. The treatment consisted of the Zn application method, namely: soil and foliar, the Zn dosage, namely: 0, 40 and 60 mg ZnSO4 kg-1 soil and two cultivars of tomato, namely: ‘Tyrana’ F1 and ‘Permata’ F1. The stress condition was induced by watering every 12 days of 3 weeks after transplanting until harvesting. The results showed that the soil with a Zn application under drought conditions increased the aperture stomata, chlorophyll b and chlorophyll a/b ratio. The response of stomata character, chlorophyll a and total chlorophyll in both cultivars was similar.

Genetic dissection of drought tolerance in potato

NARCIS (Netherlands)

Anithakumari, A.M.

2011-01-01

Drought is the most important cause of crop and yield loss around the world. Breeding for

drought tolerance is not straightforward, as drought is a complex trait. A better understanding

of the expression of drought traits, the genes underlying the traits and the way these

Effect of silicon application on physiological characteristics and growth of wheat (Triticum aestivum L. under drought stress condition

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A. Karmollachaab

2016-05-01

Full Text Available In order to investigate the effect of silicon application on some physiological characteristics and growth of Wheat (Triticum aestivum L. under late drought stress condition, an experiment was conducted at the Agriculture and Natural Resources University of Ramin, Khuzestan during year 2012. The experiment was conducted in the open environment as factorial randomized complete block design with three levels of drought stress (irrigation after 25, 50 and 75% depletion of available water content as the first factor and four levels of silicon (0, 10, 20 and 30 mg Si.kg-1 soil as the second factor with three replications. The results showed that drought stress imposed a negative significant effect on all traits. The drought stress led to increased electrolyte leakage and proline content, cuticular wax, leaf silicon concentration, superoxide dismutase activity (SOD and grain potassium were decreased. The severe drought stress has most effect on electrolyte leakage (up to 53%. The application of silicon except the shoot/root parameter, on all characters have been affected so that application of 30 mg Si.kg-1 soil led to decrease electrolyte leakage up to 22.5% and increased SOD activity, proline content, cuticular wax grain K and flag leaf Si concentration, 25, 12.8, 21, 17 and 30% compared to control, respectively. In general, the results showed a positive effect of silicon on wheat plant under stress conditions that were higher than no stress condition.

European drought under climate change and an assessment of the uncertainties in projections

Science.gov (United States)

Yu, R. M. S.; Osborn, T.; Conway, D.; Warren, R.; Hankin, R.

2012-04-01

Extreme weather/climate events have significant environmental and societal impacts, and anthropogenic climate change has and will continue to alter their characteristics (IPCC, 2011). Drought is one of the most damaging natural hazards through its effects on agricultural, hydrological, ecological and socio-economic systems. Climate change is stimulating demand, from public and private sector decision-makers and also other stakeholders, for better understanding of potential future drought patterns which could facilitate disaster risk management. There remain considerable levels of uncertainty in climate change projections, particularly in relation to extreme events. Our incomplete understanding of the behaviour of the climate system has led to the development of various emission scenarios, carbon cycle models and global climate models (GCMs). Uncertainties arise also from the different types and definitions of drought. This study examines climate change-induced changes in European drought characteristics, and illustrates the robustness of these projections by quantifying the effects of using different emission scenarios, carbon cycle models and GCMs. This is achieved by using the multi-institutional modular "Community Integrated Assessment System (CIAS)" (Warren et al., 2008), a flexible integrated assessment system for modelling climate change. Simulations generated by the simple climate model MAGICC6.0 are assessed. These include ten C4MIP carbon cycle models and eighteen CMIP3 GCMs under five IPCC SRES emission scenarios, four Representative Concentration Pathway (RCP) scenarios, and three mitigation scenarios with CO2-equivalent levels stabilising at 550 ppm, 500 ppm and 450 ppm. Using an ensemble of 2160 future precipitation scenarios, we present an analysis on both short (3-month) and long (12-month) meteorological droughts based on the Standardised Precipitation Index (SPI) for the baseline period (1951-2000) and two future periods of 2001-2050 and 2051

Study of Germination Characteristics of Fenugreek (Trigonella foenum-graecum L. population under Salinity and Drought Stress

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hassan Farhadi

2017-10-01

Full Text Available Introduction: Fenugreek (Trigonalla foenum-graecum L., an annual herbaceous plant belonging to the Coleoidea (Fabaceae family, has numerous medicinal properties such as decreasing blood glucose, laxative, appetizer, mucus, antipyretic and increasing the amount of milk during lactation . Among the most important problems in arid and semi-arid regions, drought stress or water shortage will have negative effects on plant growth. Drought stress occurs mostly because of reducing water availability in the soil. This may be due to excessive water loss or absorption problems, or both of them. One of the major factors limiting germination, which occurs in more arid and semi-arid regions, is salt stress. The study was done to evaluate germination of four Iranian population of fenugreek (Amol, Tabriz, Sari and Mashhad under drought and salinity stresses. Materials and methods: To investigate the effect of salinity and drought stresses on germination and seedling growth characteristics of native landrace fenugreek, two separate experiments were conducted in a Completely Randomized Design with three replications in Seed Laboratory of University of Mashhad in 2014. The experiment treatments consisted of four levels of salinity (0, 60, 120, 180 mM that was induced by different concentrations of sodium chloride and drought stress induced by polyethylene glycol 6000 (PEG 6000 at four levels (0, -3, -6 and -9 Bar with three replications. The drought stress levels were simulation by polyethylene glycol 6000 and using the Michel and Kaufmann formula. Distilled water was applied as control. Iranian seed population of fenugreek were purchased from the city of Amol, Tabriz, Sari and Mashhad then the seeds were washed with sodium hypochlorite (3 % v/v for two minutes for disinfestation and washed three times with distilled water. On the twelfth day of experiment, seedling traits such as plumule and root length and weight in Petri dishes were measured. Results and

The diel imprint of leaf metabolism on the δ13 C signal of soil respiration under control and drought conditions.

Science.gov (United States)

Barthel, Matthias; Hammerle, Albin; Sturm, Patrick; Baur, Thomas; Gentsch, Lydia; Knohl, Alexander

2011-12-01

Recent (13) CO(2) canopy pulse chase labeling studies revealed that photosynthesis influences the carbon isotopic composition of soil respired CO(2) (δ(13) C(SR)) even on a diel timescale. However, the driving mechanisms underlying these short-term responses remain unclear, in particular under drought conditions. The gas exchange of CO(2) isotopes of canopy and soil was monitored in drought/nondrought-stressed beech (Fagus sylvatica) saplings after (13) CO(2) canopy pulse labeling. A combined canopy/soil chamber system with gas-tight separated soil and canopy compartments was coupled to a laser spectrometer measuring mixing ratios and isotopic composition of CO(2) in air at high temporal resolution. The measured δ(13) C(SR) signal was then explained and substantiated by a mechanistic carbon allocation model. Leaf metabolism had a strong imprint on diel cycles in control plants, as a result of an alternating substrate supply switching between sugar and transient starch. By contrast, diel cycles in drought-stressed plants were determined by the relative contributions of autotrophic and heterotrophic respiration throughout the day. Drought reduced the speed of the link between photosynthesis and soil respiration by a factor of c. 2.5, depending on the photosynthetic rate. Drought slows the coupling between photosynthesis and soil respiration and alters the underlying mechanism causing diel variations of δ(13) C(SR). © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Linking meteorological drivers of spring-summer drought regimes to agricultural drought risk in China

Science.gov (United States)

Dai, L.; Wright, J. S.; Yu, C.; Huang, W. Y.

2017-12-01

As a drought prone country, China has experienced frequent severe droughts in recent decades. Drought frequency and severity are projected to increase in China under climate change. An understanding of the physical processes that contribute to extreme droughts is essential for seasonal forecasting, but the dominant physical mechanisms responsible for droughts in most parts of China are still unclear. Moreover, despite numerous studies on droughts in China, there are few clear connections between the meteorological and climatological drivers of extreme droughts and the associated agricultural consequences. This knowledge gap limits the capacity for decision-making support in drought management. The objectives of this study are (1) to identify robust spring-summer drought regimes over China, (2) to investigate the physical mechanisms associated with each regime, and (3) to better clarify connections between meteorological drought regimes and agricultural drought risk. First, we identify six drought regimes over China by applying an area-weighted k-means clustering technique to spatial patterns of spring-summer Standardized Precipitation Index (SPI) obtained from the ten-member ERA-20CM ensemble for 1900-2010. Second, we project these drought regimes onto agricultural drought risk maps for the three major cereal crops (rice, maize, and wheat) in China. Taking into account historical harvest areas for these crops, we then evaluate the potential impact of each drought regime on agricultural production. Third, the physical mechanisms and meteorological context behind each drought regimes are investigated based on monthly outputs from ERA20CM. We analyze the preceding and concurrent atmospheric circulation anomalies associated with each regime, and propose mechanistic explanations for drought development. This work provides a new perspective on diagnosing the physical mechanisms behind seasonal droughts, and lays a foundation for improving seasonal drought prediction and

Changes in Whole-Plant Metabolism during the Grain-Filling Stage in Sorghum Grown under Elevated CO2 and Drought.

Science.gov (United States)

De Souza, Amanda P; Cocuron, Jean-Christophe; Garcia, Ana Carolina; Alonso, Ana Paula; Buckeridge, Marcos S

2015-11-01

Projections indicate an elevation of the atmospheric CO2 concentration ([CO2]) concomitant with an intensification of drought for this century, increasing the challenges to food security. On the one hand, drought is a main environmental factor responsible for decreasing crop productivity and grain quality, especially when occurring during the grain-filling stage. On the other hand, elevated [CO2] is predicted to mitigate some of the negative effects of drought. Sorghum (Sorghum bicolor) is a C4 grass that has important economical and nutritional values in many parts of the world. Although the impact of elevated [CO2] and drought in photosynthesis and growth has been well documented for sorghum, the effects of the combination of these two environmental factors on plant metabolism have yet to be determined. To address this question, sorghum plants (cv BRS 330) were grown and monitored at ambient (400 µmol mol(-1)) or elevated (800 µmol mol(-1)) [CO2] for 120 d and subjected to drought during the grain-filling stage. Leaf photosynthesis, respiration, and stomatal conductance were measured at 90 and 120 d after planting, and plant organs (leaves, culm, roots, prop roots, and grains) were harvested. Finally, biochemical composition and intracellular metabolites were assessed for each organ. As expected, elevated [CO2] reduced the stomatal conductance, which preserved soil moisture and plant fitness under drought. Interestingly, the whole-plant metabolism was adjusted and protein content in grains was improved by 60% in sorghum grown under elevated [CO2]. © 2015 American Society of Plant Biologists. All Rights Reserved.

Evaluation of Relationship Between Auxin and Cytokinine Hormones on Yield and Yield Components of Maize under Drought Stress Condition

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A Mahrokh

2016-10-01

Full Text Available Introduction Drought is one of the major environmental conditions that adversely affects plant growth and crop yield. In the face of a global scarcity of water resources, water stress has already become a primary factor in limiting crop production worldwide. Drought is the major restriction in maize production. The plant growth reduction under drought stress conditions could be an outcome of altered hormonal balance and hence the exogenous application of growth regulators under stress conditions could be the possible means for reversing the effects of abiotic stress. Phytohormones such as auxine and cytokinine are known to be involved in the regulation of plant response to the adverse effects of stress conditions. Previous studies have shown that endogenous hormones are essential regulators for translocation and partitioning of photoassimilates for grain filling in cereal crops, and therefore could be involved in the regulation of grain weight and yield. Materials and Methods The experiment was carried out in three separately environments included non-drought stress environment (irrigation after soil moisture reached to 75% field capacity, drought stress in vegetative stage (irrigation after soil moisture reached to 50% field capacity in V4 to tasseling stage, but irrigation after soil moisture reached to 75% field capacity in pollination to physiological maturity stage and drought stress in reproductive stage (irrigation after soil moisture reached to 75% field capacity in V4 to tasseling stage and irrigation after soil moisture reached to 50% field capacity in pollination to physiological maturity stage. Cytokinin hormone in three levels (control, spraying in V5 –V6 and V8-V10 stages and auxin hormone in three levels (control, spraying in silk emergence stage and 15 days after that were laid out as a factorial design based on randomized complete block with three replications in each environment at Seed and Plant Improvement Institute (SPII

Analysis of DNA methylation of perennial ryegrass under drought using the methylation-sensitive amplification polymorphism (MSAP) technique.

Science.gov (United States)

Tang, Xiao-Mei; Tao, Xiang; Wang, Yan; Ma, Dong-Wei; Li, Dan; Yang, Hong; Ma, Xin-Rong

2014-12-01

Perennial ryegrass (Lolium perenne), an excellent grass for forage and turf, is widespread in temperate regions. Drought is an important factor that limits its growth, distribution, and yield. DNA methylation affects gene expression and plays an important role in adaptation to adverse environments. In this study, the DNA methylation changes in perennial ryegrass under drought stress were assessed using methylation-sensitive amplified polymorphism (MSAP). After 15 days of drought stress treatment, the plant height was less than half of the control, and the leaves were smaller and darker. Genome-wide, a total of 652 CCGG sites were detected by MSAP. The total methylation level was 57.67 and 47.39 % in the control and drought treatment, respectively, indicating a decrease of 10.28 % due to drought exposure. Fifteen differentially displayed DNA fragments in MSAP profiles were cloned for sequencing analysis. The results showed that most of the genes involved in stress responses. The relative expression levels revealed that three demethylated fragments were up-regulated. The expression of a predicted retrotransposon increased significantly, changing from hypermethylation to non-methylation. Although the extent of methylation in two other genes decreased, the sites of methylation remained, and the expression increased only slightly. All of these results suggested that drought stress decreased the total DNA methylation level in perennial ryegrass and demethylation up-regulated related gene expressions and that the extent of methylation was negatively correlated with expression. Overall, the induced epigenetic changes in genome probably are an important regulatory mechanism for acclimating perennial ryegrass to drought and possibly other environmental stresses.

Interspecific variation in functional traits of oak seedlings (Quercus ilex, Quercus trojana, Quercus virgiliana) grown under artificial drought and fire conditions.

Science.gov (United States)

Chiatante, D; Tognetti, R; Scippa, G S; Congiu, T; Baesso, B; Terzaghi, M; Montagnoli, A

2015-07-01

To face summer drought and wildfire in Mediterranean-type ecosystems, plants adopt different strategies that involve considerable rearrangements of biomass allocation and physiological activity. This paper analyses morphological and physiological traits in seedlings of three oak species (Quercus ilex, Quercus trojana and Quercus virgiliana) co-occurring under natural conditions. The aim of this study was to evaluate species-specific characteristics and the response of these oak seedlings to drought stress and fire treatment. Seedlings were kept in a growth chamber that mimicked natural environmental conditions. All three species showed a good degree of tolerance to drought and fire treatments. Differences in specific biomass allocation patterns and physiological traits resulted in phenotypic differences between species. In Q. ilex, drought tolerance depended upon adjustment of the allocation pattern. Q. trojana seedlings undergoing mild to severe drought presented a higher photosystem II (PSII) efficiency than control seedlings. Moreover, Q. trojana showed a very large root system, which corresponded to higher soil area exploitation, and bigger leaf midrib vascular bundles than the other two species. Morphological and physiological performances indicated Q. trojana as the most tolerant to drought and fire. These characteristics contribute to a high recruitment potential of Q. trojana seedlings, which might be the reason for the dominance of this species under natural conditions. Drought increase as a result of climate change is expected to favour Q. trojana, leading to an increase in its spatial distribution.

Improved tolerance to post-anthesis drought stress by pre-drought priming at vegetative stages in drought-tolerant and -sensitive wheat cultivars.

Science.gov (United States)

Abid, Muhammad; Tian, Zhongwei; Ata-Ul-Karim, Syed Tahir; Liu, Yang; Cui, Yakun; Zahoor, Rizwan; Jiang, Dong; Dai, Tingbo

2016-09-01

Wheat crop endures a considerable penalty of yield reduction to escape the drought events during post-anthesis period. Drought priming under a pre-drought stress can enhance the crop potential to tolerate the subsequent drought stress by triggering a faster and stronger defense mechanism. Towards these understandings, a set of controlled moderate drought stress at 55-60% field capacity (FC) was developed to prime the plants of two wheat cultivars namely Luhan-7 (drought tolerant) and Yangmai-16 (drought sensitive) during tillering (Feekes 2 stage) and jointing (Feekes 6 stage), respectively. The comparative response of primed and non-primed plants, cultivars and priming stages was evaluated by applying a subsequent severe drought stress at 7 days after anthesis. The results showed that primed plants of both cultivars showed higher potential to tolerate the post-anthesis drought stress through improved leaf water potential, more chlorophyll, and ribulose-1, 5-bisphosphate carboxylase/oxygenase contents, enhanced photosynthesis, better photoprotection and efficient enzymatic antioxidant system leading to less yield reductions. The primed plants of Luhan-7 showed higher capability to adapt the drought stress events than Yangmai-16. The positive effects of drought priming to sustain higher grain yield were pronounced in plants primed at tillering than those primed at jointing. In consequence, upregulated functioning of photosynthetic apparatus and efficient enzymatic antioxidant activities in primed plants indicated their superior potential to alleviate a subsequently occurring drought stress, which contributed to lower yield reductions than non-primed plants. However, genotypic and priming stages differences in response to drought stress also contributed to affect the capability of primed plants to tolerate the post-anthesis drought stress conditions in wheat. Copyright © 2016. Published by Elsevier Masson SAS.

Identification and comparative analysis of differential gene expression in soybean leaf tissue under drought and flooding stress revealed by RNA-Seq

Science.gov (United States)

Soybean is the second largest crop in the US. Its yield directly impacts US agricultural economics. Drought and flooding are two major causes for soybean yield loss. To better understand their underlying molecular regulatory mechanisms, we sequenced the transcriptomes of soybean grown in drought a...

Non-linear effects of drought under shade: reconciling physiological and ecological models in plant communities

NARCIS (Netherlands)

Holmgren, M.; Gomez-Aparicio, L.; Quero, J.L.; Valladares, F.

2012-01-01

The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical

Dynamic transcriptome landscape of sesame (Sesamum indicum L. under progressive drought and after rewatering

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Komivi Dossa

2017-03-01

Full Text Available Drought is one of the most important abiotic stresses that impair sesame (Sesamum indicum L. productivity mainly when it occurs at flowering stage. However up to now, very few studies have attempted to investigate the molecular responses of sesame to drought stress. In this experiment, two genotypes having contrasting responses to drought (tolerant and sensitive were submitted to progressive drought followed by recovering stage at flowering stage. RNAs were isolated from roots of plants before drought stress, at 3-time points during progressive drought, after rewatering, and sequenced using Illumina HiSeq 4000 platform. These RNA-Seq resources (BioSample IDs: SAMN06130606 and SAMN06130607 provided an opportunity to elucidate the molecular responses of sesame to drought and find out some candidate genes for drought tolerance improvement.

The Effect of Salicylic Acid and Gibberellin on Seed Reserve Utilization, Germination and Enzyme Activity of Sorghum (Sorghum bicolor L. Seeds Under Drought Stress

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Roghayyeh Sheykhbaglou

2014-03-01

Full Text Available Seed priming methods have been used to increases germination characteristics under stress conditions. The study aimed was to determine the effect of salicylic acid and gibberellin on seed reserve utilization, germination and enzyme activity of sorghum (Sorghum bicolor L. seeds under drought stress. Factorial experiment was carried out in completely randomized design with three replications. The first factor was the seed treatments (unpriming, salicylic acid and gibberellin and the second factor was drought stress (0, -4, -8 and -12 bar. The results indicated that for these traits: germination percentage, germination index, weight of utilized (mobilized seed, seed reserve utilization efficiency, seedling dry weight and seed reserve depletion percentage was a significant treatment Ч drought interaction. Thus priming improved study traits in Sorghum (Sorghum bicolor L. seeds under drought stress. Also, priming improves enzyme activity as compared to the unprimed seeds.

Photosynthetic limitation and mechanisms of photoprotection under drought and recovery of Calotropis procera, an evergreen C3 from arid regions.

Science.gov (United States)

Rivas, Rebeca; Frosi, Gabriella; Ramos, Diego G; Pereira, Silvia; Benko-Iseppon, Ana M; Santos, Mauro G

2017-09-01

Calotropis procera is a C 3 plant native from arid environmental zones. It is an evergreen, shrubby, non-woody plant with intense photosynthetic metabolism during the dry season. We measured photosynthetic parameters and leaf biochemical traits, such as gas exchange, photochemical parameters, A/C i analysis, organic solutes, and antioxidant enzymes under controlled conditions in potted plants during drought stress, and following recovery conditions to obtain a better insight in the drought stress responses of C. procera. Indeed, different processes contribute to the drought stress resilience of C. procera and to the fast recovery after rehydration. The parameters analyzed showed that C. procera has a high efficiency for energy dissipation. The photosynthetic machinery is protected by a robust antioxidant system and photoprotective mechanisms such as alternative pathways for electrons (photorespiration and day respiration). Under severe drought stress, increased stomatal limitation and decreased biochemical limitation permitted C. procera to maintain maximum rate of Rubisco carboxylation (V c,max ) and photosynthetic rate (A max ). On the other hand, limitation of stomatal or mesophyll CO 2 diffusion did not impair fast recovery, maintaining V c,max , chloroplast CO 2 concentration (C c ) and mesophyll conductance (g m ) unchanged while electron flow used for RuBP carboxylation (J c ) and A max increased. The ability to tolerate drought stress and the fast recovery of this evergreen C 3 species was also due to leaf anti-oxidative stress enzyme activity, and photosynthetic pigments. Thus, these different drought tolerance mechanisms allowed high performance of photosynthetic metabolism by drought stressed plants during the re-watering period. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Path analysis of phenotypic traits in young cacao plants under drought conditions.

Science.gov (United States)

Santos, Emerson Alves Dos; Almeida, Alex-Alan Furtado de; Branco, Marcia Christina da Silva; Santos, Ivanildes Conceição Dos; Ahnert, Dario; Baligar, Virupax C; Valle, Raúl René

2018-01-01

Drought is worldwide considered one of the most limiting factors of Theobroma cacao production, which can be intensified by global climate changes. In this study, we aimed to investigate the phenotypic correlation among morphological characteristics of cacao progenies submitted to irrigation and drought conditions and their partitions into direct and indirect effects. Path analysis with phenotypic plasticity index was used as criteria for estimation of basic and explanatory variables. The experiment was conducted in a greenhouse at the Cacao Research Center (CEPEC), Ilhéus, Bahia, Brazil, in a randomized block 21 x 2 factorial arrangement [21 cacao progenies obtained from complete diallel crosses and two water regimes (control and drought)] and six replications. In general, drought conditions influenced biomass production in most progenies, causing significant reductions in total leaf area, leaf number, leaf biomass, fine-roots length (diameter cacao progenies drought tolerant.

Establishment of a transgenic hairy root system in wild and domesticated watermelon (Citrullus lanatus) for studying root vigor under drought.

Science.gov (United States)

Kajikawa, Masataka; Morikawa, Kaoru; Abe, Yosuke; Yokota, Akiho; Akashi, Kinya

2010-07-01

Root vigor is an important trait for the growth of terrestrial plants, especially in water-deficit environments. Although deserts plants are known for their highly developed root architecture, the molecular mechanism responsible for this trait has not been determined. Here we established an efficient protocol for the genetic manipulation of two varieties of watermelon plants: a desert-grown wild watermelon that shows vigorous root growth under drought, and a domesticated cultivar showing retardation of root growth under drought stress. Agrobacterium rhizogenes-mediated transgenic hairy roots were efficiently induced and selected from the hypocotyls of these plants. Transgenic GUS expression was detected in the roots by RT-PCR and histochemical GUS staining. Moreover, a liquid culture system for evaluating their root growth was also established. Interestingly, growth of the hairy roots derived from domesticated variety of watermelon strongly inhibited under high osmotic condition, whereas the hairy roots derived from wild variety of watermelon retained substantial growth rates under the stress condition. The new protocol presented here offers a powerful tool for the comparative study of the molecular mechanism underlying drought-induced root growth in desert plants.

Physiological and Fluorescence Reaction of Four Rice Genotypes to Exogenous Application of IAA and Kinetin under Drought Stress

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Mostafa SALEHIFAR

2017-09-01

Full Text Available To assess the effects of IAA and Kinetin plant growth regulators in order to improve the drought tolerance in rice seedlings (Oryza sativa L., a factorial experiment was carried out based on complete randomized design with three replications. The experimental factors included different rice genotypes [‘Gharib’, ‘Khazar’, ‘Sepidrood’ and ‘IR83750 -131-1’ (‘IR83750’ ], drought stress from 1 to 4 code of the Vergara coding system and control (normal irrigation and growth regulators in three levels (IAA and Kinetin through foliar spraying and non-application as control. The results indicated, under normal irrigation condition together with IAA application, ‘IR83750’ rice had the highest number of tillers and leaf greenness, with mean of 18.27 and 49.46, respectively. The highest amount of leaf relative water content 95.11 percent was related to ‘Sepidrood’. Under drought stress condition, the highest electrolyte leakage (36.59 percent was observed in ‘Gharib’. In drought condition, the highest leaf drying score was related to ‘Gharib’ in both years, but the highest score of leaf rolling index (9 was observed in ‘Gharib’ and ‘Khazar’. The present findings showed that drought stress had harmful effects in all examined genotypes and the impact in susceptible genotypes (‘Gharib’ and ‘Khazar’ was more than ‘IR83750’ and ‘Sepidrood’. Application of growth regulators (IAA and Kin improved conditions for the growth of all genotypes. Therefore, using the tolerant genotypes along with growth regulators can improve the rice growth traits.

Network Candidate Genes in Breeding for Drought Tolerant Crops

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Christoph Tim Krannich

2015-07-01

Full Text Available Climate change leading to increased periods of low water availability as well as increasing demands for food in the coming years makes breeding for drought tolerant crops a high priority. Plants have developed diverse strategies and mechanisms to survive drought stress. However, most of these represent drought escape or avoidance strategies like early flowering or low stomatal conductance that are not applicable in breeding for crops with high yields under drought conditions. Even though a great deal of research is ongoing, especially in cereals, in this regard, not all mechanisms involved in drought tolerance are yet understood. The identification of candidate genes for drought tolerance that have a high potential to be used for breeding drought tolerant crops represents a challenge. Breeding for drought tolerant crops has to focus on acceptable yields under water-limited conditions and not on survival. However, as more and more knowledge about the complex networks and the cross talk during drought is available, more options are revealed. In addition, it has to be considered that conditioning a crop for drought tolerance might require the production of metabolites and might cost the plants energy and resources that cannot be used in terms of yield. Recent research indicates that yield penalty exists and efficient breeding for drought tolerant crops with acceptable yields under well-watered and drought conditions might require uncoupling yield penalty from drought tolerance.

The Effects of Foliar Application of Methanol on Morphological Characteristics of Bean (Phaseolus vulgaris L. under Drought Stress Condition

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N. Armand

2016-02-01

Full Text Available Introduction Available water is an important factor for plant growth in arid environments. Results indicated that foliar application of methanol is believed to be more important than the drought tolerance in C3 plant. Since bean is a C3 plant, it performs light respiration under intense heat, light and water stress due to internal leaf CO2 concentration reduction and oxygen concentration increase. Light respiration can cause up to 20% loss of carbon in plants and decrease the yield. Increasing concentration of carbon dioxide can neutralize the effect caused by drought stress. Thus, the use of substances that can cause an increase in the concentration of carbon dioxide in the plant, leads to improving the yield under the drought conditions. One of the ways of increasing the concentration of carbon dioxide in plants is by using compounds such as methanol, ethanol, propanol, butanol as well as use of the amino acids of glycine, glutamate and aspartate. Plants can easily absorb methanol sprayed on leaves and use it as a carbon source added to atmospheric carbon. Methanol is relatively smaller compared to the CO2 molecules, so it can be easily absorbed and utilized by plants. Materials and Methods In order to evaluate the effects of foliar application of methanol on some morphological characteristics of bean under drought stress, a factorial experiment was conducted based on completely randomized block design with three replications in 2014 at the Khatam Alanbia University of Behbahan. The treatment of spraying methanol was at 4 levels include control (without spraying, 10, 20 and 30% v/v methanol which added 2 g l-1 glycine to each of solutions. Adding glycine to aqueous solution of methanol leads to prevention of damages caused by the toxicity of methanol. The drought factors including control (100% field of capacity, moderate drought stress (50% field of capacity and severe drought stress (25% field of capacity were considered. In this experiment

Spatio-temporal drought characteristics of the tropical Paraiba do Sul River Basin and responses to the Mega Drought in 2014-2016

Science.gov (United States)

Nauditt, Alexandra; Metzke, Daniel; Ribbe, Lars

2017-04-01

The Paraiba do Sul River Basin (56.000 km2) supplies water to the Brazilian states Sao Paulo and Rio de Janeiro. Their large metropolitan areas were strongly affected by a Mega drought during the years 2014 and 2015 with severe implications for domestic water supply, the hydropower sector as well as for rural agricultural downstream regions. Longer drought periods are expected to become more frequent in the future. However, drought characteristics, low flow hydrology and the reasons for the recurrent water scarcity in this water abundant tropical region are still poorly understood. In order to separate the impact of human abstractions from hydro-climatic and catchment storage related hydrological drought propagation, we assessed the spatio-temporal distribution of drought severity and duration establishing relationships between SPI, SRI and discharge threshold drought anomalies for all subcatchments of the PdS based on a comprehensive hydro-meteorological data set of the Brazilian National Water Agency ANA. The water allocation model "Water Evaluation and Planning System (WEAP)" was established on a monthly basis for the entire Paraiba do Sul river basin incorporating human modifications of the hydrological system as major (hydropower) reservoirs and their operational rules, water diversions and major abstractions. It simulates reasonable discharges and reservoir levels comparable to the observed values. To evaluate the role of climate variability and drought responses for hydrological drought events, scenarios were developed to simulate discharge and reservoir level the impact of 1. Varying meteorological drought frequencies and durations and 2. Implementing operational rules as a response to drought. Uncertainties related to the drought assessment, modelling, parameter and input data were assessed. The outcome of this study for the first time provides an overview on the heterogeneous spatio-temporal drought characteristics of the Paraiba do Sul river basin and

Response of bread wheat genotypes to drought simulation under a ...

African Journals Online (AJOL)

From this study, it is possible to select drought tolerant cultivars using mobile rain shelters by drought simulations in Kenya. Key Words: Duma, irrigation, dryland, moisture stress. Résumé La sélection des génotypes tolérant a la sécheresse pour les terres arides et semi-arides (ASALS) du Kenya, lesquelles consistent a ...

Effect on Quality Characteristics of Tomatoes Grown Under Well-Watered and Drought Stress Conditions.

Science.gov (United States)

Klunklin, Warinporn; Savage, Geoffrey

2017-07-25

Tomatoes are one of the most nutritionally and economically important crops in New Zealand and around the world. Tomatoes require large amounts of water to grow well and are adversely affected by drought stress. However, few studies have evaluated the physicochemical characteristics of commercial tomatoes grown under water stress conditions. Four tomato cultivars (Incas, Marmande, Scoresby Dwarf, and Window Box Red) were grown in a greenhouse under well-watered and drought stress conditions and the tomatoes were harvested when ripe. The physicochemical properties and antioxidant contents of the fruits were compared. There were significant differences between cultivars in quality characteristics-such as dry matter, total soluble solids, and pH parameters-but there were no differences in the quality characteristics between the two treatments of the fruits ( p > 0.05); however, there were significant differences ( p < 0.05) in the antioxidant compositions (lycopene, total phenolics, and flavonoids) and antioxidant activities (DPPH and ABTS) of the fruits of both cultivars and treatments. Overall, these results indicated that tomatoes increased their bioactive compounds without changing any quality characteristics when exposed to water stress conditions.

The Effect of Osmo and Hormone Priming on Germination and Seed Reserve Utilization of Millet Seeds under Drought Stress

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Maasoumeh Asadi Aghbolaghi

2014-03-01

Full Text Available The objective of this research was to evaluate the effect of seed priming with osmo and hormone priming on growth and seed reserve utilization of millet seeds under drought stress. Treatments were combinations of 4 levels of drought stress (0, -4, -8 and -12 bar and 3 levels of seed priming and control with 3 replications. Results showed that with increase in drought stress, germination components such as germination percentage, germination index, mean time to germination, normal seedling percentage, seedling length, seedling dry weight, weight of utilized (mobilized seed and seed reserve utilization efficiency decreased, but seed priming showed lower reduction. The highest germination characteristics and seed reserve utilization was obtained by priming in control conditions. It is concluded that priming results in improvement in germination components of millet in drought stress conditions.

RADIATION USE EFFICIENCY IN SPRING BARLEY UNDER DROUGHT: A CROSSTALK BETWEEN SURVIVAL STRATEGY AND CANOPY STRUCTURE

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Peter FERUS

2010-10-01

Full Text Available In order to evaluate effects of different survival strategy and canopy structure on cereal radiation use efficiency (RUE under drought during grain filling, a pot experiment in spring barley (Hordeum vulgare L. of cultivar Dobla (able for escape, no productive tiller and Kompakt (one productive tiller was conducted. There was no difference in current RUE for leaf dry mass (RUEL between main stems of tested cultivars, observed. However, in productive tillers of cultivar Kompakt it was approximately double. Taking together, RUEL for whole plants was significantly higher in cultivar Kompakt than in cultivar Dobla. Current RUE for spike dry mass (RUES in hydrated plants was markedly higher than RUEL, in main stems of cultivar Kompakt with round double values of cultivar Dobla. Productive tillers of cultivar Kompakt were the most efficient PAR (photosynthetic active radiation utilizator for spike growth. Drought decreased RUES in cultivar Kompakt (in main stems as well as productive tillers to a half but in cultivar Dobla 20 %, only. Evaluating final RUE for spikes, almost fivefold higher values in hydrated plants of cultivar Kompakt fell to double ones under drought. In this context, important role played the productive tiller. Thus, model of more intensively tillering cereal crop seems to be more efficient in radiation use.

Selection of tomato mutants (lycopersicon esculentum mill) under conditions of drought stress

International Nuclear Information System (INIS)

Gonzalez, Maria Caridad; Mansoor, Ali; Suarez, Lorenzo; Mukandama, Jean P.; Rodriguez, Yanet

2001-01-01

At the National Institute of Agricultural Sciences were evaluated under conditions of drought estres an M5 population obtained starting from the irradiation of seeds of the Amalia and INCA 9-1varieties with dose of 300 and 500 Gy of rays gamma of 60 Co. The number of clusters for plant, mass average of the fruits, number of fruits for plant and yield for plant, the content of total soluble solids and the acidity of the fruits was evaluated observing differ highly significant among the different ones lines and the respective donating studied. Promissory genotipos of high productive potential was selected under this condition

Global hydrological droughts in the 21st century under a changing hydrological regime

NARCIS (Netherlands)

Wanders, Niko|info:eu-repo/dai/nl/364253940; Wada, Yoshi|info:eu-repo/dai/nl/341387819; van Lanen, H.A.J

2015-01-01

Climate change very likely impacts future hydrological drought characteristics across the world. Here, we quantify the impact of climate change on future low flows and associated hydrological drought characteristics on a global scale using an alternative drought identification approach that

Evaluation and characterization of advanced rice mutant line of rice (Oryza sativa), MR219-4 and MR219-9 under drought condition

International Nuclear Information System (INIS)

Abdul Rahim Harun; Zarith Shafika Kamarudin; Abdullah, M.Z.; Anna, L.P.K.; Sobri Hussain; Rusli Ibrahim; Khairuddin abdul Rahim

2012-01-01

Two advance rice mutant lines, MR219-4 and MR219-9 derived from mutagenesis of Oryza sativa cv. MR219 with gamma radiation at 300 Gy were evaluated in simulated drought condition in the greenhouse at Malaysian Nuclear Agency. The mutants were evaluated simultaneously with ARN1, a drought resistant variety and MR211 a susceptible cultivar as a check. Randomized complete block design with three replicates was used in the experiment. The evaluation and selection were done based on leaf rolling and leaf drying as well as other agronomic traits, such as, number of tillers per plant, plant height, flag leaf area, grain weight per plant, grain yield per plant, 100-grain weight, harvest index, panicle length and plant biomass. The mutants MR219-4 showed moderate tolerance and MR219-9 showed tolerance to drought respectively as compare to the check variety (ARN1, MR211) and control MR219. Leaf rolling, leaf drying, days to flowering and days to maturity are valuable secondary traits that may provide additional information for selection because of associating with the plant survival under water stress. Further research on expression of drought-tolerant lines under different drought conditions is essential in order to identify particular traits that are associated with drought tolerance and high yield potential. Similarly the importance of secondary traits, relative to other putative traits for drought tolerance, needs to be tested in various environments. (author)

The role of ecophysiology in determining monoterpene concentrations and emissions from pinyon pine under drought conditions

Science.gov (United States)

Trowbridge, A. M.; Adams, H. D.; Breshears, D. D.; Stoy, P.; Monson, R. K.

2012-12-01

While much research has focused on the primary metabolic mechanisms underlying pinyon pine's sensitivity to severe and abrupt drought conditions, there remains a gap in our knowledge concerning how the resulting shift in carbon allocation toward plant secondary compounds, particularly monoterpenes, affects both atmospheric process and ecological species interactions. Because of the large global emission rate of monoterpenes and their effect on atmospheric chemistry, identifying the primary controls over and sensitivities to environmental change is critical for global emission models. Furthermore, monoterpenes are also known to impact insect behavior and act as defense compounds against herbivores, contributing to fluctuations in the population densities of herbivores either directly through toxicity, or indirectly by influencing an insect's susceptibility to parasitism. While pinyon mortality events are thought to be exacerbated by their susceptibility to herbivores resulting from weakened secondary chemical defenses, the impact of current and predicted drought on the chemical defense status of pinyons and the potential consequences for atmospheric composition and ecological interactions remains unknown. We performed a manipulative field study to untangle the effects of drought on plant carbon assimilation, growth, and defense throughout the year. Transplanting pinyons from their natural habitat into a desert environment, we were able to increase mean annual temperature by ~4 degrees C. Throughout the growing season, we measured pinyon physiology and monoterpene composition and emissions under different water (well-watered, ambient, or drought-stresed) and temperature (natural pinyon habitat or desert transplants) regimes. We hypothesized that increased drought would increase tissue concentrations in accordance with the carbon-nutrient balance hypothesis (CNBH). Furthermore, we predicted that higher temperatures and lower water availability together would influence

Leaf area index drives soil water availability and extreme drought-related mortality under elevated CO2 in a temperate grassland model system.

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Manea, Anthony; Leishman, Michelle R

2014-01-01

The magnitude and frequency of climatic extremes, such as drought, are predicted to increase under future climate change conditions. However, little is known about how other factors such as CO2 concentration will modify plant community responses to these extreme climatic events, even though such modifications are highly likely. We asked whether the response of grasslands to repeat extreme drought events is modified by elevated CO2, and if so, what are the underlying mechanisms? We grew grassland mesocosms consisting of 10 co-occurring grass species common to the Cumberland Plain Woodland of western Sydney under ambient and elevated CO2 and subjected them to repeated extreme drought treatments. The 10 species included a mix of C3, C4, native and exotic species. We hypothesized that a reduction in the stomatal conductance of the grasses under elevated CO2 would be offset by increases in the leaf area index thus the retention of soil water and the consequent vulnerability of the grasses to extreme drought would not differ between the CO2 treatments. Our results did not support this hypothesis: soil water content was significantly lower in the mesocosms grown under elevated CO2 and extreme drought-related mortality of the grasses was greater. The C4 and native grasses had significantly higher leaf area index under elevated CO2 levels. This offset the reduction in the stomatal conductance of the exotic grasses as well as increased rainfall interception, resulting in reduced soil water content in the elevated CO2 mesocosms. Our results suggest that projected increases in net primary productivity globally of grasslands in a high CO2 world may be limited by reduced soil water availability in the future.

Evaluation of drought tolerance indices for the selection of Iranian ...

African Journals Online (AJOL)

Drought is an important factor limiting crop production in arid and semi-arid conditions. Drought indices which provide a measure of drought based on yield loss under drought condition in comparison to normal condition was used for screening drought-tolerant genotypes. This study was conducted to determine drought ...

Unprecedented drought over tropical South America in 2016: significantly under-predicted by tropical SST.

Science.gov (United States)

Erfanian, Amir; Wang, Guiling; Fomenko, Lori

2017-07-19

Tropical and sub-tropical South America are highly susceptible to extreme droughts. Recent events include two droughts (2005 and 2010) exceeding the 100-year return value in the Amazon and recurrent extreme droughts in the Nordeste region, with profound eco-hydrological and socioeconomic impacts. In 2015-2016, both regions were hit by another drought. Here, we show that the severity of the 2015-2016 drought ("2016 drought" hereafter) is unprecedented based on multiple precipitation products (since 1900), satellite-derived data on terrestrial water storage (since 2002) and two vegetation indices (since 2004). The ecohydrological consequences from the 2016 drought are more severe and extensive than the 2005 and 2010 droughts. Empirical relationships between rainfall and sea surface temperatures (SSTs) over the tropical Pacific and Atlantic are used to assess the role of tropical oceanic variability in the observed precipitation anomalies. Our results indicate that warmer-than-usual SSTs in the Tropical Pacific (including El Niño events) and Atlantic were the main drivers of extreme droughts in South America, but are unable to explain the severity of the 2016 observed rainfall deficits for a substantial portion of the Amazonia and Nordeste regions. This strongly suggests potential contribution of non-oceanic factors (e.g., land cover change and CO2-induced warming) to the 2016 drought.

A phenological timetable of oak growth under experimental drought and air warming.

Directory of Open Access Journals (Sweden)

Thomas M Kuster

Full Text Available Climate change is expected to increase temperature and decrease summer precipitation in Central Europe. Little is known about how warming and drought will affect phenological patterns of oaks, which are considered to possess excellent adaptability to these climatic changes. Here, we investigated bud burst and intra-annual shoot growth of Quercus robur, Q. petraea and Q. pubescens grown on two different forest soils and exposed to air warming and drought. Phenological development was assessed over the course of three growing seasons. Warming advanced bud burst by 1-3 days °C⁻¹ and led to an earlier start of intra-annual shoot growth. Despite this phenological shift, total time span of annual growth and shoot biomass were not affected. Drought changed the frequency and intensity of intra-annual shoot growth and advanced bud burst in the subsequent spring of a severe summer drought by 1-2 days. After re-wetting, shoot growth recovered within a few days, demonstrating the superior drought tolerance of this tree genus. Our findings show that phenological patterns of oaks are modified by warming and drought but also suggest that ontogenetic factors and/or limitations of water and nutrients counteract warming effects on the biomass and the entire span of annual shoot growth.

Recovery of Physiological Traits in Saplings of Invasive Bischofia Tree Compared with Three Species Native to the Bonin Islands under Successive Drought and Irrigation Cycles.

Science.gov (United States)

Yazaki, Kenichi; Kuroda, Katsushi; Nakano, Takashi; Kitao, Mitsutoshi; Tobita, Hiroyuki; Ogasa, Mayumi Y; Ishida, Atsushi

2015-01-01

Partial leaf shedding induced by hydraulic failure under prolonged drought can prevent excess water consumption, resulting in delayed recovery of carbon productivity following rainfall. To understand the manner of water use of invasive species in oceanic island forests under a fluctuating water regime, leaf shedding, multiple physiological traits, and the progress of embolism in the stem xylem under repeated drought-irrigation cycles were examined in the potted saplings of an invasive species, Bischofia javanica Blume, and three endemic native species, Schima mertensiana (Sieb. Et Zucc,) Koitz., Hibiscus glaber Matsum, and Distylium lepidotum Nakai, from the Bonin Islands, Japan. The progress of xylem embolism was observed by cryo-scanning electron microscopy. The samples exhibited different processes of water saving and drought tolerance based on the different combinations of partial leaf shedding involved in embolized conduits following repeated de-rehydration. Predawn leaf water potential largely decreased with each successive drought-irrigation cycle for all tree species, except for B. javanica. B. javanica shed leaves conspicuously under drought and showed responsive stomatal conductance to VPD, which contributed to recover leaf gas exchange in the remaining leaves, following a restored water supply. In contrast, native tree species did not completely recover photosynthetic rates during the repeated drought-irrigation cycles. H. glaber and D. lepidotum preserved water in vessels and adjusted leaf osmotic rates but did not actively shed leaves. S. mertensiana exhibited partial leaf shedding during the first cycle with an osmotic adjustment, but they showed less responsive stomatal conductance to VPD. Our data indicate that invasive B. javanica saplings can effectively use water supplied suddenly under drought conditions. We predict that fluctuating precipitation in the future may change tree distributions even in mesic or moist sites in the Bonin Islands.

Recovery of Physiological Traits in Saplings of Invasive Bischofia Tree Compared with Three Species Native to the Bonin Islands under Successive Drought and Irrigation Cycles.

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Kenichi Yazaki

Full Text Available Partial leaf shedding induced by hydraulic failure under prolonged drought can prevent excess water consumption, resulting in delayed recovery of carbon productivity following rainfall. To understand the manner of water use of invasive species in oceanic island forests under a fluctuating water regime, leaf shedding, multiple physiological traits, and the progress of embolism in the stem xylem under repeated drought-irrigation cycles were examined in the potted saplings of an invasive species, Bischofia javanica Blume, and three endemic native species, Schima mertensiana (Sieb. Et Zucc, Koitz., Hibiscus glaber Matsum, and Distylium lepidotum Nakai, from the Bonin Islands, Japan. The progress of xylem embolism was observed by cryo-scanning electron microscopy. The samples exhibited different processes of water saving and drought tolerance based on the different combinations of partial leaf shedding involved in embolized conduits following repeated de-rehydration. Predawn leaf water potential largely decreased with each successive drought-irrigation cycle for all tree species, except for B. javanica. B. javanica shed leaves conspicuously under drought and showed responsive stomatal conductance to VPD, which contributed to recover leaf gas exchange in the remaining leaves, following a restored water supply. In contrast, native tree species did not completely recover photosynthetic rates during the repeated drought-irrigation cycles. H. glaber and D. lepidotum preserved water in vessels and adjusted leaf osmotic rates but did not actively shed leaves. S. mertensiana exhibited partial leaf shedding during the first cycle with an osmotic adjustment, but they showed less responsive stomatal conductance to VPD. Our data indicate that invasive B. javanica saplings can effectively use water supplied suddenly under drought conditions. We predict that fluctuating precipitation in the future may change tree distributions even in mesic or moist sites in the

Effect of drought stress on water status, electrolyte leakage and enzymatic antioxidants of kochia (kochia scoparia) under saline condition

International Nuclear Information System (INIS)

Masoumi, A.; Kafi, M.; Khazaei, Z.; Davari, K.

2010-01-01

Drought stress is considered as the main factor of yield limitations in arid and semi-arid areas, where drought and salinity stresses are usually combined. Kochia species have recently attracted the attention of researchers as forage and fodder crop in marginal lands worldwide due to its drought and salt tolerant characters. This field experiment was performed at the Salinity Research Station (36 deg. 15'N, 59 deg. 28' E) of Ferdowsi University, ashhad, Iran in 2008, in a split plot based on randomized complete block design with three replications. Three levels of drought stress (control, no irrigation in vegetative stage (recovery treatment) and no irrigation at reproductive stage for one month (stress treatment)), and two Kochia ecotypes (Birjand and Borujerd) were allocated as main and sub-plots, respectively. Relative water content (RWC), membrane permeability and antioxidant enzymes were assayed at the beginning of anthesis. Stress treatment caused a significant decrease in the leaf RWC and increase in electrolyte leakage compared with control and recovered conditions. Furthermore, stress treatment caused a significant increase in antioxidant enzyme activities except of superoxide dismutase (SOD) and peroxidase (POX). The Birjand ecotype was significantly more tolerant to drought than Borujerd ecotype. According to the results, there were no difference between recovered plants and control treatment, therefore, Kochia can recover quickly after removing drought stress. Kochia showed high tolerance against drought and salinity stresses and different antioxidant enzymes had different behavior under stress conditions. (author)

Interdependence of plant water status with photosynthetic performance and root defense responses in Vigna radiata (L.) Wilczek under progressive drought stress and recovery.

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Sengupta, Debashree; Guha, Anirban; Reddy, Attipalli Ramachandra

2013-10-05

The present study investigates the interdependence of plant water status with foliar and root responses in Vigna radiata L.Wilczek under progressive drought. Vegetatively-mature V. radiata plants were subjected to water withdrawal for 3 and 6days (D3 and D6, respectively) and then re-watered subsequently for 6days (6R) for stress-recovery. Changes in plant water status were expressed in terms of leaf and root moisture contents (LMC and RMC, respectively) and leaf relative water content (LRWC). Progressive drought caused apparent decrease in LRWC, LMC and RMC depicting significant level of dehydration of leaf and root tissues. Stomatal limitation alone could not account for the observed decrease in net CO2 assimilation rates (Pn) due to comparatively less decrease in sub-stomatal CO2 (Ci) concentrations with respect to other gas exchange parameters indicating possible involvement of non-stomatal limitations. Analysis of polyphasic chl a fluorescence kinetics during progressive drought showed decreased energy connectivity among PSII units as defined by a positive L-band with highest amplitude during D6. Efficiency of electron flux from OEC towards PSII acceptor side was not significantly affected during drought conditions as evidenced by the absence of a positive K-band. Increasing root-level water-limitation enforced a gradual oxidative stress through H2O2 accumulation and membrane lipid peroxidation in V. radiata roots exhibiting drastic enhancement of proline content and a significant but gradual increase in ascorbic acid content as well as guaiacol peroxidase activity under progressive drought. Expression analysis of Δ(1) pyrroline-5-carboxylate synthetase (P5CS) through real time PCR and enzyme activity studies showed a strong positive correlation between VrP5CS gene expression, enzyme activity and proline accumulation in the roots of V. radiata under progressive drought and recovery. Drought-induced changes in root moisture content (RMC) showed positive linear

Cytokinins induce transcriptional reprograming and improve Arabidopsis plant performance under drought and salt stress conditions.

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Natali Shirron

2016-10-01

Full Text Available In nature, annual plants respond to abiotic stresses by activating a specific genetic program leading to early flowering and accelerated senescence. Although, in nature, this phenomenon supports survival under unfavorable environmental conditions, it may have negative agro-economic impacts on crop productivity. Overcoming this genetic programing by cytokinins (CK has recently been shown in transgenic plants that overproduce CK. These transgenic plants displayed a significant increase in plant productivity under drought stress conditions. We investigated the role of CK in reverting the transcriptional program that is activated under abiotic stress conditions and allowing sustainable plant growth. We employed 2 complementary approaches: Ectopic overexpression of CK, and applying exogenous CK to detached Arabidopsis leaves. Transgenic Arabidopsis plants transformed with the isopentyltransferase (IPT gene under the regulation of the senescence associated receptor kinase (SARK promoter displayed a significant drought resistance. A transcriptomic analysis using RNA sequencing was performed to explore the response mechanisms under elevated CK levels during salinity stress. This analysis showed that under such stress, CK triggered transcriptional reprograming that resulted in attenuated stress-dependent inhibition of vegetative growth and delayed premature plant senescence. Our data suggest that elevated CK levels led to stress tolerance by retaining the expression of genes associated with plant growth and metabolism whose expression typically decreases under stress conditions. In conclusion, we hypothesize that CK allows sustainable plant growth under unfavorable environmental conditions by activating gene expression related to growth processes and by preventing the expression of genes related to the activation of premature senescence.

Interannual variations in needle and sapwood traits of Pinus edulis branches under an experimental drought.

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Guérin, Marceau; Martin-Benito, Dario; von Arx, Georg; Andreu-Hayles, Laia; Griffin, Kevin L; Hamdan, Rayann; McDowell, Nate G; Muscarella, Robert; Pockman, William; Gentine, Pierre

2018-02-01

In the southwestern USA, recent large-scale die-offs of conifers raise the question of their resilience and mortality under droughts. To date, little is known about the interannual structural response to droughts. We hypothesized that piñon pines ( Pinus edulis ) respond to drought by reducing the drop of leaf water potential in branches from year to year through needle morphological adjustments. We tested our hypothesis using a 7-year experiment in central New Mexico with three watering treatments (irrigated, normal, and rain exclusion). We analyzed how variation in "evaporative structure" (needle length, stomatal diameter, stomatal density, stomatal conductance) responded to watering treatment and interannual climate variability. We further analyzed annual functional adjustments by comparing yearly addition of needle area (LA) with yearly addition of sapwood area (SA) and distance to tip ( d ), defining the yearly ratios SA:LA and SA:LA/ d . Needle length ( l ) increased with increasing winter and monsoon water supply, and showed more interannual variability when the soil was drier. Stomatal density increased with dryness, while stomatal diameter was reduced. As a result, anatomical maximal stomatal conductance was relatively invariant across treatments. SA:LA and SA:LA/ d showed significant differences across treatments and contrary to our expectation were lower with reduced water input. Within average precipitation ranges, the response of these ratios to soil moisture was similar across treatments. However, when extreme soil drought was combined with high VPD, needle length, SA:LA and SA:LA/ d became highly nonlinear, emphasizing the existence of a response threshold of combined high VPD and dry soil conditions. In new branch tissues, the response of annual functional ratios to water stress was immediate (same year) and does not attempt to reduce the drop of water potential. We suggest that unfavorable evaporative structural response to drought is compensated

Effects of drought on avian community structure

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Thomas P. Albright; Anna M. Pidgeon; Chadwick D. Rittenhouse; Murray K. Clayton; Curtis H. Flather; Patrick D. Culbert; Brian D. Wardlow; Volker C. Radeloff

2010-01-01

Droughts are expected to become more frequent under global climate change. Avifauna depend on precipitation for hydration, cover, and food. While there are indications that avian communities respond negatively to drought, little is known about the response of birds with differing functional and behavioural traits, what time periods and indicators of drought are most...

Future Drought Projections over the Iberian Peninsula using Drought Indices

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Garcia-Valdecasas Ojeda, M.; Yeste Donaire, P.; Góngora García, T. M.; Gámiz-Fortis, S. R.; Castro-Diez, Y.; Esteban-Parra, M. J.

2017-12-01

Currently, drought events are the cause of numerous annual economic losses. In a context of climate change, it is expected an increase in the severity and the frequency of drought occurrences, especially in areas such as the Mediterranean region. This study makes use of two drought indices in order to analyze the potential changes on future drought events and their effects at different time scales over a vulnerable region, the Iberian Peninsula. The indices selected were the Standardized Precipitation Evapotranspiration Index (SPEI), which takes into account the global warming through the temperature, and the Standardized Precipitation Index (SPI), based solely on precipitation data, at a spatial resolution of 0.088º ( 10 km). For their computation, current (1980-2014) and future (2021-2050 and 2071-2100) high resolution simulations were carried out using the Weather Research and Forecasting (WRF) model over a domain centered in the Iberian Peninsula, and nested in the 0.44 EUROCORDEX region. WRF simulations were driven by two different global bias-corrected climate models: the version 1 of NCAR's Community Earth System Model (CESM1) and the Max Planck Institute's Earth System Model (MPI-ESM-LR), and under two different Representative Concentration Pathway (RCP) scenarios: RCP 4.5 and RCP 8.5. Future projections were analyzed regarding to changes in mean, median and variance of drought indices with respect to the historical distribution, as well as changes in the frequency and duration of moderate and severe drought events. In general, results suggest an increase in frequency and severity of drought, especially for 2071-2100 period in the RCP 8.5 scenario. Results also shown an increase of drought phenomena more evident using the SPEI. Conclusions from this study could provide a valuable contribution to the understanding of how the increase of the temperature would affect the drought variability in the Mediterranean regions which is necessary for a suitable

Beam wandering statistics of twin thin laser beam propagation under generalized atmospheric conditions.

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Pérez, Darío G; Funes, Gustavo

2012-12-03

Under the Geometrics Optics approximation is possible to estimate the covariance between the displacements of two thin beams after they have propagated through a turbulent medium. Previous works have concentrated in long propagation distances to provide models for the wandering statistics. These models are useful when the separation between beams is smaller than the propagation path-regardless of the characteristics scales of the turbulence. In this work we give a complete model for these covariances, behavior introducing absolute limits to the validity of former approximations. Moreover, these generalizations are established for non-Kolmogorov atmospheric models.

Inoculation of Brassica oxyrrhina with plant growth promoting bacteria for the improvement of heavy metal phytoremediation under drought conditions.

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Ma, Ying; Rajkumar, Mani; Zhang, Chang; Freitas, Helena

2016-12-15

The aim of this study was to investigate the effects of drought resistant serpentine rhizobacteria on plant growth and metal uptake by Brassica oxyrrhina under drought stress (DS) condition. Two drought resistant serpentine rhizobacterial strains namely Pseudomonas libanensis TR1 and Pseudomonas reactans Ph3R3 were selected based on their ability to stimulate seedling growth in roll towel assay. Further assessment on plant growth promoting (PGP) parameters revealed their ability to produce indole-3-acetic acid, siderophore and 1-aminocyclopropane-1-carboxylate deaminase. Moreover, both strains exhibited high resistance to various heavy metals, antibiotics, salinity and extreme temperature. Inoculation of TR1 and Ph3R3 significantly increased plant growth, leaf relative water and pigment content of B. oxyrrhina, whereas decreased concentrations of proline and malondialdehyde in leaves under metal stress in the absence and presence of DS. Regardless of soil water conditions, TR1 and Ph3R3 greatly improved organ metal concentrations, translocation and bioconcentration factors of Cu and Zn. The successful colonization and metabolic activities of P. libanensis TR1 and P. reactans Ph3R3 represented positive effects on plant development and metal phytoremediation under DS. These results indicate that these strains could be used as bio-inoculants for the improvement of phytoremediation of metal polluted soils under semiarid conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Maize water status and physiological traits as affected by root endophytic fungus Piriformospora indica under combined drought and mechanical stresses.

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Hosseini, Fatemeh; Mosaddeghi, Mohammad Reza; Dexter, Anthony Roger; Sepehri, Mozhgan

2018-05-01

Under combined drought and mechanical stresses, mechanical stress primarily controlled physiological responses of maize. Piriformospora indica mitigated the adverse effects of stresses, and inoculated maize experienced less oxidative damage and had better adaptation to stressful conditions. The objective of this study was to investigate the effect of maize root colonization by an endophytic fungus P. indica on plant water status, physiological traits and root morphology under combined drought and mechanical stresses. Seedlings of inoculated and non-inoculated maize (Zea mays L., cv. single cross 704) were cultivated in growth chambers filled with moistened siliceous sand at a matric suction of 20 hPa. Drought stress was induced using PEG 6000 solution with osmotic potentials of 0, - 0.3 and - 0.5 MPa. Mechanical stress (i.e., penetration resistances of 1.05, 4.23 and 6.34 MPa) was exerted by placing weights on the surface of the sand medium. After 30 days, leaf water potential (LWP) and relative water content (RWC), root and shoot fresh weights, root volume (RV) and diameter (RD), leaf proline content, leaf area (LA) and catalase (CAT) and ascorbate peroxidase (APX) activities were measured. The results show that exposure to individual drought and mechanical stresses led to higher RD and proline content and lower plant biomass, RV and LA. Moreover, increasing drought and mechanical stress severity increased APX activity by about 1.9- and 3.1-fold compared with the control. When plants were exposed to combined stresses, mechanical stress played the dominant role in controlling plant responses. P. indica-inoculated plants are better adapted to individual and combined stresses. The inoculated plants had greater RV, LA, RWC, LWP and proline content under stressful conditions. In comparison with non-inoculated plants, inoculated plants showed lower CAT and APX activities which means that they experienced less oxidative stress induced by stressful conditions.

Fatigue Crack Propagation Under Variable Amplitude Loading Analyses Based on Plastic Energy Approach

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Sofiane Maachou

2014-04-01

Full Text Available Plasticity effects at the crack tip had been recognized as “motor” of crack propagation, the growth of cracks is related to the existence of a crack tip plastic zone, whose formation and intensification is accompanied by energy dissipation. In the actual state of knowledge fatigue crack propagation is modeled using crack closure concept. The fatigue crack growth behavior under constant amplitude and variable amplitude loading of the aluminum alloy 2024 T351 are analyzed using in terms energy parameters. In the case of VAL (variable amplitude loading tests, the evolution of the hysteretic energy dissipated per block is shown similar with that observed under constant amplitude loading. A linear relationship between the crack growth rate and the hysteretic energy dissipated per block is obtained at high growth rates. For lower growth rates values, the relationship between crack growth rate and hysteretic energy dissipated per block can represented by a power law. In this paper, an analysis of fatigue crack propagation under variable amplitude loading based on energetic approach is proposed.

Joint pattern of seasonal hydrological droughts and floods ...

Indian Academy of Sciences (India)

Under the current condition of climate change, droughts and floods occur more frequently, and events in which flooding occurs after a prolonged drought or a drought occurs after an extreme flood may have a more severe impact on natural systems and human lives. This challenges the traditional approach wherein droughts ...

Regional to global changes in drought and implications for future changes under global warming

Science.gov (United States)

Sheffield, J.; Wood, E. F.; Kam, J.

2012-12-01

Drought can have large impacts on multiple sectors, including agriculture, water resources, ecosystems, transport, industry and tourism. In extreme cases, regional drought can lead to food insecurity and famine, and in intensive agricultural regions, extend to global economic impacts in a connected world. Recent droughts globally have been severe and costly but whether they are becoming more frequent and severe, and the attribution of this, is a key question. Observational evidence at large scales, such as satellite remote sensing are often subject to short-term records and inhomogeneities, and ground based data are sparse in many regions. Reliance on model output is also subject to error and simplifications in the model physics that can, for example, amplify the impact of global warming on drought. This presentation will show the observational and model evidence for changes in drought, with a focus on the interplay between precipitation and atmospheric evaporative demand and its impact on the terrestrial water cycle and drought. We discuss the fidelity of climate models to reproduce our best estimates of drought variability and its drivers historically, and the implications of this on uncertainties in future projections of drought from CMIP5 models, and how this has changed since CMIP3.

Foliar urea application affects nitric oxide burst and glycine betaine metabolism in two maize cultivars under drought

International Nuclear Information System (INIS)

Zhang, L.; Zhang, X.; Wang, K.; Zhao, Y.; Zhai, Y.; Gao, M.

2011-01-01

Foliar urea has been proved to act a better role in alleviation of the negative effects of drought stress (DS). However, the modulation mechanism of foliar urea are not conclusive in view of nitric oxide (NO) burst and glycine betaine metabolism and their relationship. Two maize ( Zea mays L.) cultivars (Zhengdan 958, JD958, Jundan 20, ZD20) were grown in hydroponic medium, which were treated with spraying of urea concentration of 15 g L/sup -1/ and two water regimes (non-stress and DS simulated by the addition of polyethylene glycol (PEG, 15% w/v, MW 6000). The ten-day DS treatment increased betaine aldehyde dehydrogenase (BADH) activity, choline content and nitric oxide (NO) content acted as the key enzyme, initial substrate and a nitrogenous signal substance respectively in GB synthesis metabolism, thus, induced to great GB accumulation. The accumulation of NO reached the summit earlier than that of GB. The more positive/less negative responses were recorded in JD958 as compared with ZD20 to DS. Addition of foliar ur ea could increase accumulation of choline and BADH activity as well as NO content, thereby, increase GB accumulation under DS. These positive effects of urea applying foliarly on all parameters measured were more pronounced in cultivar JD20 than those in ZD958 under drought. It is, therefore, concluded that increases of both BADH activity and choline content possibly resulted in enhancement of GB accumulation. Foliar urea application could provoke better GB accumulation by modulation of GB metabolism, possibly mediating by NO burst as a signal molecule during drought, especially in the drought sensitive maize cultivar. (author)

Land-atmosphere interaction and disaster-causing process of drought in northern China: observation and experiment (DroughtPEX_China)

Science.gov (United States)

Li, Yaohui

2017-04-01

Drought is one of the most common and frequent nature disasters in the world, particularly in China under the continental monsoonal climate with great variation. About thirty percent of economic loss caused by natural disasters is contributed by droughts in China, which is by far the most damaging weather disasters because of its long duration and extensive hazard areas. Droughts not only have a serious impact on the agriculture, water resources, ecology, natural environment, but also seriously affect the socio-economic such as human health, energy and transportation. Worsely, under the background of climate change, droughts in show increases in frequency, duration and scope in many places around the world, particularly northern China. Nowadays, droughts have aroused extensive concern of the scientists, governments and international community, and became one of the important scientific issues in geoscience research. However, most of researches on droughts in China so far were focused on the causes or regulars of one type of droughts (the atmosphere, agriculture or hydrological) from the perspective of the atmospheric circulation anomalies. Few of them considered a whole cycle of the drought-forming process from atmosphere-land interaction to agricultural/ecological one in terms of the land-atmosphere interaction; meanwhile, the feedback mechanism with the drought and land-atmosphere interaction is still unclear as well. All of them is because of lack of the relevant comprehensive observation experiment. "Land-atmosphere interaction and disaster-causing process of drought in northern China: observation and experiment" (DroughtPEX_China)is just launched in this requirement and background. DroughtPEX_China is supported by Special Scientific Research Fund of Public Welfare Industry (Meteorological) of China (Grant No.GYHY201506001)—"Drought Meteorology Scientific Research Project—the disaster-causing process and mechanism of drought in northern China". This project

Seasonal Drought Prediction: Advances, Challenges, and Future Prospects

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Hao, Zengchao; Singh, Vijay P.; Xia, Youlong

2018-03-01

Drought prediction is of critical importance to early warning for drought managements. This review provides a synthesis of drought prediction based on statistical, dynamical, and hybrid methods. Statistical drought prediction is achieved by modeling the relationship between drought indices of interest and a suite of potential predictors, including large-scale climate indices, local climate variables, and land initial conditions. Dynamical meteorological drought prediction relies on seasonal climate forecast from general circulation models (GCMs), which can be employed to drive hydrological models for agricultural and hydrological drought prediction with the predictability determined by both climate forcings and initial conditions. Challenges still exist in drought prediction at long lead time and under a changing environment resulting from natural and anthropogenic factors. Future research prospects to improve drought prediction include, but are not limited to, high-quality data assimilation, improved model development with key processes related to drought occurrence, optimal ensemble forecast to select or weight ensembles, and hybrid drought prediction to merge statistical and dynamical forecasts.

Transcriptome Profiling of the Potato (Solanum tuberosum L.) Plant under Drought Stress and Water-Stimulus Conditions.

Science.gov (United States)

Gong, Lei; Zhang, Hongxia; Gan, Xiaoyan; Zhang, Li; Chen, Yuchao; Nie, Fengjie; Shi, Lei; Li, Miao; Guo, Zhiqian; Zhang, Guohui; Song, Yuxia

2015-01-01

transduction pathways. Our data provide more direct information for future study on the interaction between key genes involved in various metabolic pathways under drought stress in potato.

Transcriptome Profiling of the Potato (Solanum tuberosum L. Plant under Drought Stress and Water-Stimulus Conditions.

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Lei Gong

transduction pathways. Our data provide more direct information for future study on the interaction between key genes involved in various metabolic pathways under drought stress in potato.

Evaluation of Spring Wheat Recombinant Inbred Lines under Drought Stress

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M. Moghaddaszadeh-Ahrabi

2012-07-01

Full Text Available Iran is one of arid and semi-arid regions of the world. Wheat as a strategic agricultural products faces water deficiency in most areas of the country. Therefore, identification of the resistant varieties to drought stress is one of main aims for breeders. To assess effect of drought stress at heading on 72 spring wheat recombinant inbred lines derived from American Yecora Rojo (high yielder, dwarf and early maturity as paternal parent and Iranian No. 49 line (tall and late maturiting as maternal parent cross were studied. The experiment was conducted at the Research Station of the University of Tabriz using a randomized complete block design with two replications during 2009 growing season. Based on the results from combined analysis of variance significant difference was observed among lines for all of traits studied, except for harvest index, grain number per spike and days to heading. There was significant difference between normal and drought stress conditions. Since the interaction between line and conditions was insignificant for all traits, it does therefore, provide the possibility of comparing the lines without regard to irrigation levels. Based on the means of, the traits it was found that the lines 96, 122, 123 and 155 were superior. MP, GMP and STI indices were recognized to be suitable indices to identify superior lines. With respect to these indices, lines 96, 122, 123, 138, 149 and 155 were found superior as compared with remaining lines. Based on stepwise regression analysis of grain yield with other traits, respectively grain number per spike, number of spikes/m2 and 1000 kernel weight were inserted into final model as effective variables on grain yield, which made 81/9 percent of the grain yield variation. Path analysis of grain yield and related traits, based on stepwise regression, demonstrated the significant positive direct effect for grain number per spike, number of spikes/m2 and 1000 kernel weight on grain yield

Effect of Salinity and Drought Stresses on Germination Stage and Growth of Black Cumin (Bunium Persicum Boiss

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H. R. Saeedi Goraghani

2017-06-01

Full Text Available Introduction Range plants have important and crucial roles in medicinal industry andtogether with scarcity and low quality of the water and soil resources, prevent a quick recovery of the soil plant covering. Because of these restrictions, it is important to consider the use of salt and drought tolerant species for plantation and to preserve plant cover. In this sense, the use of native species such as black cumin (Bunium persicum Boiss may be of interest due to their medicinal characteristics and potential ability to adapt to adverse conditions (dry and saline conditions. Black cumin (B. persicum as a medicinal plant plays a vital role in Iranian medicine so there is a need to know about the factors affecting their growth and propagation. Materials and Methods To investigate the effects of drought and salt stresses on germination and growth in black cumin two separate experiments were conducted. Drought stress was applied through incubation in four different concentrations of PEG 6000 that provide solutions with water potentials ranging from -0.2 to -0.8 MPa (including control and four levels of dryness. Salinity treatments (including control and four levels of salinity were prepared by adding molar concentrations of NaCl to provide a range of salinity from 50 to 300 mM. Germination percentage and speed was calculated by computation of germinated seeds every day. Growth parameters (rootlet, shoot and seedling length total, allometric index and seed vigority were obtained accordingly. Results and Discussion Seeds under both drought and salt stress showed significant reduction in germination percentage, germination rate, radicle length, plumule length, and alometric and seed vigor indices. This trend was much pronounced under high levels of NaCl and low levels of water potentials, so that germination at Ψs = -0.6 MP was completely stopped. Conclusions Assessment of drought and salt stresses on germination and growth in black cumin is very

Hydro-climate and ecological behaviour of the drought of Amazonia in 2005.

Science.gov (United States)

Marengo, J A; Nobre, C A; Tomasella, J; Cardoso, M F; Oyama, M D

2008-05-27

In 2005, southwestern Amazonia experienced the effects of an intense drought that affected life and biodiversity. Several major tributaries as well as parts of the main river itself contained only a fraction of their normal volumes of water, and lakes were drying up. The consequences for local people, animals and the forest itself are impossible to estimate now, but they are likely to be serious. The analyses indicate that the drought was manifested as weak peak river season during autumn to winter as a consequence of a weak summertime season in southwestern Amazonia; the winter season was also accompanied by rainfall that sometimes reached 25% of the climatic value, being anomalously warm and dry and helping in the propagation of fires. Analyses of climatic and hydrological records in Amazonia suggest a broad consensus that the 2005 drought was linked not to El Niño as with most previous droughts in the Amazon, but to warming sea surface temperatures in the tropical North Atlantic Ocean.

Evaluation of common bean (Phaseolus vulgaris L. genotypes for drought stress adaptation in Ethiopia

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Kwabena Darkwa

2016-10-01

Full Text Available Drought stress linked with climate change is one of the major constraints faced by common bean farmers in Africa and elsewhere. Mitigating this constraint requires the selection of resilient varieties that withstand drought threats to common bean production. This study assessed the drought response of 64 small red-seeded genotypes of common bean grown in a lattice design replicated twice under contrasting moisture regimes, terminal drought stress and non-stress, in Ethiopia during the dry season from November 2014 to March 2015. Multiple plant traits associated with drought were assessed for their contribution to drought adaptation of the genotypes. Drought stress determined by a drought intensity index was moderate (0.3. All the assessed traits showed significantly different genotypic responses under drought stress and non-stress conditions. Eleven genotypes significantly (P ≤ 0.05 outperformed the drought check cultivar under both drought stress and non-stress conditions in seed yielding potential. Seed yield showed positive and significant correlations with chlorophyll meter reading, vertical root pulling resistance force, number of pods per plant, and seeds per pod under both soil moisture regimes, indicating their potential use in selection of genotypes yielding well under drought stress and non-stress conditions. Clustering analysis using Mahalanobis distance grouped the genotypes into four groups showing high and significant inter-cluster distance, suggesting that hybridization between drought-adapted parents from the groups will provide the maximum genetic recombination for drought tolerance in subsequent generations.

Drought priming effects on alleviating later damages of heat and drought stress in different wheat cultivars

DEFF Research Database (Denmark)

Mendanha, Thayna; Hyldgaard, Benita; Ottosen, Carl-Otto

The ongoing change is climate; in particular the increase of drought and heat waves episodes are a major challenge in the prospect of food safety. Under many field conditions, plants are usually exposed to mild intermittent stress episodes rather than a terminal stress event. Previous, but limited...... studies suggest that plants subjected to early stress (primed) can be more resistant to future stress exposure than those not stressed during seedling stage. In our experiment we aimed to test if repeated mild drought stresses could improve heat and drought tolerance during anthesis heat and drought...... stresses in wheat cultivars. Two wheat cultivars, Gladius and Paragon, were grown in a fully controlled gravimetric platform and subjected to either no stress (control) or two (P) drought cycles during seedling stage, at three and five complete developed leaves. Each cycle consisted of withholding water...

Evaluation of growth characters and yield components for six durum wheat lines (triticum durum deaf) selected from M4 and M5 - irradiated population under drought conditions

International Nuclear Information System (INIS)

Nesiem, M. R. A.; Kassem, M. K. M.; Basyouny, M. A. E.

2012-12-01

Grain of two durum wheat cultivars, Sohag 3 and Beni Suef 3 were irradiated with gamma ray doses 0, 150, 250 and 350 Gy to obtain new durum wheat lines, characterized by high yielding and drought tolerance. Irradiated grains were cultivated in the field under normal and drought conditions 2005 - 2010 seasons. 20 grain (M 1 ) from each treatment was planed as in the first season. In the second season (M 2 ), grains of 61 plants were selected as thy had the following higher criteria, i.e yield, grain yield / plant, plant height, tillering and 100 grains weight. The selected variants should exceed by 50% or more than control. Grains of the 61 selected plants were individually sown under normal and drought condition. At the end of this season, six selected putative line had superiority over their parents. The S1 and S2 lines had an excellent grain yield per plant under normal condition but S3 and S4 lines had superiority for grain yield per plant under drought condition as compared to parents Sohag3. B1 and B2 lines had the superiority for grain per plant under normal condition comparing with the parent Beni Suef3. In the fourth season (M4),growth, chemical compositions and yield as well as its components of the six putative lines as well as the parents Sohag 3 and Beni Suef 3 were determined under normal and drought conditions. The results showed a significant under normal and drought conditions. The results showed a significant increase in the number of leaves on the main stem and tillering number / plant for S1, S2, B1, B2 as compared with their corresponding parent under normal condition. Also, S3 and S4 line shad the same results comparing with the parent Sohag3 under drought condition. The results of S3 and S4 showed an accumulation of organic protective asmolytes such as sugar, proline and free amino acid. As well as N, P, K, and Ca concentrations in shoots and roots as compared to the parent Sohag 3 . The putative line S1, A2 and B1 showed significant increase

Macrocrack propagation in concrete specimens under sustained loading: Study of the physical mechanisms

Energy Technology Data Exchange (ETDEWEB)

Rossi, Pierre, E-mail: pierre.rossi@lcpc.fr; Boulay, Claude; Tailhan, Jean-Louis; Martin, Eric; Desnoyers, Dominic

2014-09-15

This study presents a series of 4-point bending tests performed to describe the delayed behavior of unreinforced pre-cracked beams under low, moderate and high sustained loading levels. The deflection creep rate, the failure time and the load level were assessed. A linear relation, in a semi-log scale, was found for the deflection creep rate at high load levels. In addition, a linear relation, in a log–log scale, between the secondary deflection creep rate and failure time was observed. Besides, it was shown that the secondary creep deflection rate increases with the sustained loading level and the macrocrack propagation rate when macrocrack propagation occurs during the sustained loading. Physical mechanisms are proposed to explain these results and may be summarized as follows: the delayed behavior of an unreinforced cracked concrete specimen under sustained loading is mainly due to the cracking evolution, thus the creation of microcracks and/or the propagation of a macrocrack.

Macrocrack propagation in concrete specimens under sustained loading: Study of the physical mechanisms

International Nuclear Information System (INIS)

Rossi, Pierre; Boulay, Claude; Tailhan, Jean-Louis; Martin, Eric; Desnoyers, Dominic

2014-01-01

This study presents a series of 4-point bending tests performed to describe the delayed behavior of unreinforced pre-cracked beams under low, moderate and high sustained loading levels. The deflection creep rate, the failure time and the load level were assessed. A linear relation, in a semi-log scale, was found for the deflection creep rate at high load levels. In addition, a linear relation, in a log–log scale, between the secondary deflection creep rate and failure time was observed. Besides, it was shown that the secondary creep deflection rate increases with the sustained loading level and the macrocrack propagation rate when macrocrack propagation occurs during the sustained loading. Physical mechanisms are proposed to explain these results and may be summarized as follows: the delayed behavior of an unreinforced cracked concrete specimen under sustained loading is mainly due to the cracking evolution, thus the creation of microcracks and/or the propagation of a macrocrack

Anatomic and physiological modifications in seedlings of Coffea arabica cultivar Siriema under drought conditions

Directory of Open Access Journals (Sweden)

Emanuelle Ferreira Melo

2014-02-01

Full Text Available Due to the weather changes prognostic for the coming years, the understanding of water deficit and physiological responses of plants to drought becomes an important requirement in order to develop technologies such as mechanisms to assist plants to cope with longer drought periods, which will be essential to maintenance of Brazilian and worldwide production. This study aimed to evaluate ecophysiological and anatomical aspects as well as the nitrate reductase activity in Siriema coffee seedlings subjected to four treatments: Daily irrigated, non-irrigated, re-irrigated 24 hours and re-irrigated 48 hours after different stress periods. Non-irrigation promoted a reduction in leaf water potential being accented from the ninth day of evaluation onwards. Re-irrigation promoted a partial recovery of the plant water potential. Non-irrigated plants showed an increase in stomatal resistance and reduction of transpiration and nitrate reductase activity. In the roots, there was a decrease in nitrate reductase activity under water stress. Leaf anatomical modifications were significant only for the adaxial surface epidermis and palisade parenchyma thickness, this latter characteristic being higher in control plants. Stomatal density and polar and equatorial diameter ratios showed the highest values in plants under water stress. In the roots, differences only in the cortex thickness being bigger in the non-irrigated treatment could be observed. Therefore, Siriema coffee plants under water stress show physiological, biochemical and anatomical modifications that contribute to the tolerance of this genotype to these conditions.

Drought-induced xylem cavitation and hydraulic deterioration: risk factors for urban trees under climate change?

Science.gov (United States)

Savi, Tadeja; Bertuzzi, Stefano; Branca, Salvatore; Tretiach, Mauro; Nardini, Andrea

2015-02-01

Urban trees help towns to cope with climate warming by cooling both air and surfaces. The challenges imposed by the urban environment, with special reference to low water availability due to the presence of extensive pavements, result in high rates of mortality of street trees, that can be increased by climatic extremes. We investigated the water relations and xylem hydraulic safety/efficiency of Quercus ilex trees growing at urban sites with different percentages of surrounding impervious pavements. Seasonal changes of plant water potential and gas exchange, vulnerability to cavitation and embolism level, and morpho-anatomical traits were measured. We found patterns of increasing water stress and vulnerability to drought at increasing percentages of impervious pavement cover, with a consequent reduction in gas exchange rates, decreased safety margins toward embolism development, and increased vulnerability to cavitation, suggesting the occurrence of stress-induced hydraulic deterioration. The amount of impermeable surface and chronic exposure to water stress influence the site-specific risk of drought-induced dieback of urban trees under extreme drought. Besides providing directions for management of green spaces in towns, our data suggest that xylem hydraulics is key to a full understanding of the responses of urban trees to global change. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Study the chemical composition and agronomic traits for some durum wheat lines (Triticum durum) selected from M4-irradiated populations under drought stress

International Nuclear Information System (INIS)

Khalil, M.K.; Nesiem, M.R.A.; Kasem, M.K.M.; Basyouny, M.A.E.

2010-01-01

Field and laboratory experiments were carried out during four successive seasons 2005-2009 to access the effectiveness of gamma rays on inducing new drought tolerance lines from two durum wheat cultivars, i.e. Sohag 3 and Beni Suef 3. Irradiated grains (0, 150, 250 and 350 Gy) of both cultivars were sown and at harvest, 20 grains (M1) from each treatment were planted as in the first season. In the second season, grains of 61 plants were selected as they had the following higher criteria, i.e. yield, grain yield/plant, plant height, tillering and 100 grains weight. The selected variants should exceed by 50 % or more the control. Grains of the 61 selected plants were individually sown under drought or non-stress conditions, at the end of this season, six selected putative lines had superiority over their parents. The S1 and S2 lines have an excellent grain yield per plant under non stress condition as compared to Sohag3. The S3 and S4 lines have the superiority for grain yield per plant under drought condition as compared to Sohag 3. The B1 and B2 lines have the superiority for grain yield per plant under non stress condition comparing with Beni Suef 3. In the fourth season, growth, chemical composition and yield of the six putative lines as well as Sohag 3 and Beni Suef 3 were determined under non stress and drought conditions. The results showed a significant increase in the number of leaves on the main stem and tillering number/plant for S1, S2, B1 and B2 as compared each with their corresponding parent under non stress condition. Also, S3 and S4 lines had the same results comparing with Sohag 3 under drought condition. The results of S3 and S4 showed and accumulation of organic protective osmolytes such as sugar proline and free amino acids. As well as N, P, K and Ca concentrations in shoots and roots as compared to Sohag 3 .The putative lines S1, S2 and B1 showed a significant increase for grain yield per plant comparing with their controls under non stress

Fatigue crack propagation under combined cyclic mechanical loading and electric field in piezoelectric ceramics

International Nuclear Information System (INIS)

Shirakihara, Kaori; Tanaka, Keisuke; Akiniwa, Yoshiaki; Suzuki, Yasuyoshi; Mukai, Hirokatsu

2006-01-01

Fatigue crack propagation tests of PZT specimens were performed under cyclic four-point bending with and without superposition of electric fields. The specimens were poled in the longitudinal direction (PL specimens) perpendicular to the crack plane. The crack propagation rate for the case of open circuit was faster than that for the case of short circuit. The application of a negative or positive electric field parallel to the poling direction accelerated the crack propagation rate, and the amount of acceleration was larger for the case of the negative field. The change of the crack propagation rate with crack extension can be divided into three regions. In the region I, the crack propagation rate decreases with increasing crack length, and then turn to increase in the region III. In the region II, the propagation rate is nearly constant. The mechanisms of fatigue crack propagation were correlated to domain switching near the crack tip. The grain boundary fracture was predominant in the low-rate region, while transgranular fracture became abundant on the unstable fracture surface. (author)

Civil conflict sensitivity to growing-season drought.

Science.gov (United States)

von Uexkull, Nina; Croicu, Mihai; Fjelde, Hanne; Buhaug, Halvard

2016-11-01

To date, the research community has failed to reach a consensus on the nature and significance of the relationship between climate variability and armed conflict. We argue that progress has been hampered by insufficient attention paid to the context in which droughts and other climatic extremes may increase the risk of violent mobilization. Addressing this shortcoming, this study presents an actor-oriented analysis of the drought-conflict relationship, focusing specifically on politically relevant ethnic groups and their sensitivity to growing-season drought under various political and socioeconomic contexts. To this end, we draw on new conflict event data that cover Asia and Africa, 1989-2014, updated spatial ethnic settlement data, and remote sensing data on agricultural land use. Our procedure allows quantifying, for each ethnic group, drought conditions during the growing season of the locally dominant crop. A comprehensive set of multilevel mixed effects models that account for the groups' livelihood, economic, and political vulnerabilities reveals that a drought under most conditions has little effect on the short-term risk that a group challenges the state by military means. However, for agriculturally dependent groups as well as politically excluded groups in very poor countries, a local drought is found to increase the likelihood of sustained violence. We interpret this as evidence of the reciprocal relationship between drought and conflict, whereby each phenomenon makes a group more vulnerable to the other.

Estimating drought risk across Europe from reported drought impacts, drought indices, and vulnerability factors

Science.gov (United States)

Blauhut, Veit; Stahl, Kerstin; Stagge, James Howard; Tallaksen, Lena M.; De Stefano, Lucia; Vogt, Jürgen

2016-07-01

Drought is one of the most costly natural hazards in Europe. Due to its complexity, drought risk, meant as the combination of the natural hazard and societal vulnerability, is difficult to define and challenging to detect and predict, as the impacts of drought are very diverse, covering the breadth of socioeconomic and environmental systems. Pan-European maps of drought risk could inform the elaboration of guidelines and policies to address its documented severity and impact across borders. This work tests the capability of commonly applied drought indices and vulnerability factors to predict annual drought impact occurrence for different sectors and macro regions in Europe and combines information on past drought impacts, drought indices, and vulnerability factors into estimates of drought risk at the pan-European scale. This hybrid approach bridges the gap between traditional vulnerability assessment and probabilistic impact prediction in a statistical modelling framework. Multivariable logistic regression was applied to predict the likelihood of impact occurrence on an annual basis for particular impact categories and European macro regions. The results indicate sector- and macro-region-specific sensitivities of drought indices, with the Standardized Precipitation Evapotranspiration Index (SPEI) for a 12-month accumulation period as the overall best hazard predictor. Vulnerability factors have only limited ability to predict drought impacts as single predictors, with information about land use and water resources being the best vulnerability-based predictors. The application of the hybrid approach revealed strong regional and sector-specific differences in drought risk across Europe. The majority of the best predictor combinations rely on a combination of SPEI for shorter and longer accumulation periods, and a combination of information on land use and water resources. The added value of integrating regional vulnerability information with drought risk prediction

Relationship between Aflatoxin Contamination and Physiological Responses of Corn Plants under Drought and Heat Stress

Directory of Open Access Journals (Sweden)

Nacer Bellaloui

2012-11-01

Full Text Available Increased aflatoxin contamination in corn by the fungus Aspergillus flavus is associated with frequent periods of drought and heat stress during the reproductive stages of the plants. The objective of this study was to evaluate the relationship between aflatoxin contamination and physiological responses of corn plants under drought and heat stress. The study was conducted in Stoneville, MS, USA under irrigated and non-irrigated conditions. Five commercial hybrids, P31G70, P33F87, P32B34, P31B13 and DKC63-42 and two inbred germplasm lines, PI 639055 and PI 489361, were evaluated. The plants were inoculated with Aspergillus flavus (K-54 at mid-silk stage, and aflatoxin contamination was determined on the kernels at harvest. Several physiological measurements which are indicators of stress response were determined. The results suggested that PI 639055, PI 489361 and hybrid DKC63-42 were more sensitive to drought and high temperature stress in the non-irrigated plots and P31G70 was the most tolerant among all the genotypes. Aflatoxin contamination was the highest in DKC63-42 and PI 489361 but significantly lower in P31G70. However, PI 639055, which is an aflatoxin resistant germplasm, had the lowest aflatoxin contamination, even though it was one of the most stressed genotypes. Possible reasons for these differences are discussed. These results suggested that the physiological responses were associated with the level of aflatoxin contamination in all the genotypes, except PI 639055. These and other physiological responses related to stress may help examine differences among corn genotypes in aflatoxin contamination.

Relationship between aflatoxin contamination and physiological responses of corn plants under drought and heat stress.

Science.gov (United States)

Kebede, Hirut; Abbas, Hamed K; Fisher, Daniel K; Bellaloui, Nacer

2012-11-20

Increased aflatoxin contamination in corn by the fungus Aspergillus flavus is associated with frequent periods of drought and heat stress during the reproductive stages of the plants. The objective of this study was to evaluate the relationship between aflatoxin contamination and physiological responses of corn plants under drought and heat stress. The study was conducted in Stoneville, MS, USA under irrigated and non-irrigated conditions. Five commercial hybrids, P31G70, P33F87, P32B34, P31B13 and DKC63-42 and two inbred germplasm lines, PI 639055 and PI 489361, were evaluated. The plants were inoculated with Aspergillus flavus (K-54) at mid-silk stage, and aflatoxin contamination was determined on the kernels at harvest. Several physiological measurements which are indicators of stress response were determined. The results suggested that PI 639055, PI 489361 and hybrid DKC63-42 were more sensitive to drought and high temperature stress in the non-irrigated plots and P31G70 was the most tolerant among all the genotypes. Aflatoxin contamination was the highest in DKC63-42 and PI 489361 but significantly lower in P31G70. However, PI 639055, which is an aflatoxin resistant germplasm, had the lowest aflatoxin contamination, even though it was one of the most stressed genotypes. Possible reasons for these differences are discussed. These results suggested that the physiological responses were associated with the level of aflatoxin contamination in all the genotypes, except PI 639055. These and other physiological responses related to stress may help examine differences among corn genotypes in aflatoxin contamination.

Bacterial mediated amelioration of drought stress in drought tolerant ...

African Journals Online (AJOL)

yogendra

2015-02-23

Feb 23, 2015 ... for a beneficial effect of PGPRs application in enhancing drought tolerance of rice under water deficit conditions. ..... involvement of PGPRs in ROS metabolism in rice plants. ... osmoregulatory solute in plants (Kumar et al., 2011). ..... Pseudomonas fluorescens mediated saline resistance in groundnut.

Proteomic studies of drought stress response in Fabaceae

Directory of Open Access Journals (Sweden)

Tanja ZADRAŽNIK

2015-11-01

Full Text Available Drought stress is a serious threat to crop production that influences plant growth and development and subsequently causes reduced quantity and quality of the yield. Plant stress induces changes in cell metabolism, which includes differential expression of proteins. Proteomics offer a powerful approach to analyse proteins involved in drought stress response of plants. Analyses of changes in protein abundance of legumes under drought stress are very important, as legumes play an important role in human and animal diet and are often exposed to drought. The presented results of proteomic studies of selected legumes enable better understanding of molecular mechanisms of drought stress response. The study of drought stress response of plants with proteomic approach may contribute to the development of potential drought-response markers and to the development of drought-tolerant cultivars of different legume crop species.

Global hydrological droughts in the 21st century under a changing hydrological regime

Directory of Open Access Journals (Sweden)

N. Wanders

2015-01-01

Full Text Available Climate change very likely impacts future hydrological drought characteristics across the world. Here, we quantify the impact of climate change on future low flows and associated hydrological drought characteristics on a global scale using an alternative drought identification approach that considers adaptation to future changes in hydrological regime. The global hydrological model PCR-GLOBWB was used to simulate daily discharge at 0.5° globally for 1971–2099. The model was forced with CMIP5 climate projections taken from five global circulation models (GCMs and four emission scenarios (representative concentration pathways, RCPs, from the Inter-Sectoral Impact Model Intercomparison Project. Drought events occur when discharge is below a threshold. The conventional variable threshold (VTM was calculated by deriving the threshold from the period 1971–2000. The transient variable threshold (VTMt is a non-stationary approach, where the threshold is based on the discharge values of the previous 30 years implying the threshold to vary every year during the 21st century. The VTMt adjusts to gradual changes in the hydrological regime as response to climate change. Results show a significant negative trend in the low flow regime over the 21st century for large parts of South America, southern Africa, Australia and the Mediterranean. In 40–52% of the world reduced low flows are projected, while increased low flows are found in the snow-dominated climates. In 27% of the global area both the drought duration and the deficit volume are expected to increase when applying the VTMt. However, this area will significantly increase to 62% when the VTM is applied. The mean global area in drought, with the VTMt, remains rather constant (11.7 to 13.4%, compared to the substantial increase when the VTM is applied (11.7 to 20%. The study illustrates that an alternative drought identification that considers adaptation to an altered hydrological regime has a

Genotypic variation in growth and physiological response to drought stress and re-watering reveals the critical role of recovery in drought adaptation in maize seedlings

Directory of Open Access Journals (Sweden)

Daoqian eChen

2016-01-01

Full Text Available Non-irrigated crops in temperate climates and irrigated crops in arid climates are subjected to continuous cycles of water stress and re-watering. Thus, fast and efficient recovery from water stress may be among the key determinants of plant drought adaptation. The present study was designed to comparatively analyze the roles of drought resistance and drought recovery in drought adaptation and to investigate the physiological basis of genotypic variation in drought adaptation in maize (Zea mays seedlings. As the seedlings behavior in growth associate with yield under drought, it could partly reflect the potential of drought adaptability. Growth and physiological responses to progressive drought stress and recovery were observed in seedlings of ten maize lines. The results showed that drought adaptability is closely related to drought recovery (r = 0.714**, but not to drought resistance (r = 0.332. Drought induced decreases in leaf water content, water potential, osmotic potential, gas exchange parameters, chlorophyll content, Fv/Fm and nitrogen content, and increased H2O2 accumulation and lipid peroxidation. After recovery, most of these physiological parameters rapidly returned to normal levels. The physiological responses varied between lines. Further correlation analysis indicated that the physiological bases of drought resistance and drought recovery are definitely different, and that maintaining higher chlorophyll content (r = 0.874*** and Fv/Fm (r = 0.626* under drought stress contributes to drought recovery. Our results suggest that both drought resistance and recovery are key determinants of plant drought adaptation, and that drought recovery may play a more important role than previously thought. In addition, leaf water potential, chlorophyll content and Fv/Fm could be used as efficient reference indicators in the selection of drought-adaptive genotypes.

Differential acclimation of enzymatic antioxidant metabolism and photosystem II photochemistry in tall fescue under drought and heat and the combined stresses

Directory of Open Access Journals (Sweden)

Aoyue eBi

2016-04-01

Full Text Available Quality inferiority in cool-season turfgrass due to drought, heat and a combination of both stresses is predicted to be more prevalent in the future. Understanding the various response to heat and drought stress will assist in the selection and breeding of tolerant grass varieties. The objective of this study was to investigate the behavior of antioxidant metabolism and photosystem II (PSII photochemistry in two tall fescue genotypes (PI 234881 and PI 578718 with various thermotolerance capacities. Wide variations were found between heat-tolerant PI 578718 and heat-sensitive PI 234881 for leaf relative water content, malondialdehyde and electrolyte leakage under drought, high-temperature or a combination of both stresses. The sensitivity of PI 234881 exposed to combined stresses was associated with lower superoxide dismutase activity and higher H2O2 accumulation than that in PI 578718. Various antioxidant enzymes displayed positive correlation with chlorophyll content, but negative with membrane injury index at most of the stages in both tall fescue genotypes. The JIP-test analysis in PI 578718 indicated a significant improvement in ABS/RC, TR0/RC, RE0/RC, RE0/ABS values as compared to the control regime, which indicated that PI 578718 had a high potential to protect the PSII system under drought and high temperature stress. And the PS II photochemistry in PI 234881 was damaged significantly compared with PI578718. Moreover, quantitative RT-PCR revealed that heat and drought stresses deduced the gene expression of psbB and psbC, but induced the expression of psbA. These findings to some extent confirmed that the various adaptations of physiological traits may contribute to breeding in cold-season turfgrass in response to drought, high-temperature and a combination of both stresses.

Genetic analysis of drought stress response in Arabidopsis thaliana and Brassica rapa

NARCIS (Netherlands)

El-Soda, M.

2013-01-01

Drought is the major abiotic stress affecting plant growth and limiting crop productivity worldwide. Plants have evolved three adaptive strategies, drought escape, drought avoidance and drought tolerance, to cope with drought. Knowledge on how Quantitative Trait Loci (QTL), or genes underlying

Quantitative Trait Loci Associated with Drought Tolerance in Brachypodium distachyon

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Yiwei Jiang

2017-05-01

Full Text Available The temperate wild grass Brachypodium distachyon (Brachypodium serves as model system for studying turf and forage grasses. Brachypodium collections show diverse responses to drought stress, but little is known about the genetic mechanisms of drought tolerance of this species. The objective of this study was to identify quantitative trait loci (QTLs associated with drought tolerance traits in Brachypodium. We assessed leaf fresh weight (LFW, leaf dry weight (LDW, leaf water content (LWC, leaf wilting (WT, and chlorophyll fluorescence (Fv/Fm under well-watered and drought conditions on a recombinant inbred line (RIL population from two parents (Bd3-1 and Bd1-1 known to differ in their drought adaptation. A linkage map of the RIL population was constructed using 467 single nucleotide polymorphism (SNP markers obtained from genotyping-by-sequencing. The Bd3-1/Bd1-1 map spanned 1,618 cM and had an average distance of 3.5 cM between adjacent single nucleotide polymorphisms (SNPs. Twenty-six QTLs were identified in chromosome 1, 2, and 3 in two experiments, with 14 of the QTLs under well-watered conditions and 12 QTLs under drought stress. In Experiment 1, a QTL located on chromosome 2 with a peak at 182 cM appeared to simultaneously control WT, LWC, and Fv/Fm under drought stress, accounting for 11–18.7% of the phenotypic variation. Allelic diversity of candidate genes DREB2B, MYB, and SPK, which reside in one multi-QTL region, may play a role in the natural variation in whole plant drought tolerance in Brachypodium. Co-localization of QTLs for multiple drought-related traits suggest that the gene(s involved are important regulators of drought tolerance in Brachypodium.

Resilient Leaf Physiological Response of European Beech (Fagus sylvatica L. to Summer Drought and Drought Release

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Ellen E. Pflug

2018-02-01

Full Text Available Drought is a major environmental constraint to trees, causing severe stress and thus adversely affecting their functional integrity. European beech (Fagus sylvatica L. is a key species in mesic forests that is commonly expected to suffer in a future climate with more intense and frequent droughts. Here, we assessed the seasonal response of leaf physiological characteristics of beech saplings to drought and drought release to investigate their potential to recover from the imposed stress and overcome previous limitations. Saplings were transplanted to model ecosystems and exposed to a simulated summer drought. Pre-dawn water potentials (ψpd, stomatal conductance (gS, intercellular CO2 concentration (ci, net-photosynthesis (AN, PSII chlorophyll fluorescence (PItot, non-structural carbohydrate concentrations (NSC; soluble sugars, starch and carbon isotope signatures were measured in leaves throughout the growing season. Pre-dawn water potentials (ψpd, gS, ci, AN, and PItot decreased as drought progressed, and the concentration of soluble sugars increased at the expense of starch. Carbon isotopes in soluble sugars (δ13CS showed a distinct increase under drought, suggesting, together with decreased ci, stomatal limitation of AN. Drought effects on ψpd, ci, and NSC disappeared shortly after re-watering, while full recovery of gS, AN, and PItot was delayed by 1 week. The fast recovery of NSC was reflected by a rapid decay of the drought signal in δ13C values, indicating a rapid turnover of assimilates and a reactivation of carbon metabolism. After recovery, the previously drought-exposed saplings showed a stimulation of AN and a trend toward elevated starch concentrations, which counteracted the previous drought limitations. Overall, our results suggest that the internal water relations of beech saplings and the physiological activity of leaves are restored rapidly after drought release. In the case of AN, stimulation after drought may partially

Effect of the fungus Piriformospora indica on physiological characteristics and root morphology of wheat under combined drought and mechanical stresses.

Science.gov (United States)

Hosseini, Fatemeh; Mosaddeghi, Mohammad Reza; Dexter, Anthony Roger

2017-09-01

This study was done to evaluate the effects of the root-colonizing endophytic fungus Piriformospora indica on wheat growth under combined drought and mechanical stresses. Inoculated (colonized) and non-inoculated (uncolonized) wheat (Triticum aestivum L. cv. Chamran) seedlings were planted in growth chambers filled with moist sand (at a matric suction of 20 hPa). Slight, moderate and severe mechanical stresses (i.e., penetration resistance, Q p , of 1.17, 4.17 and 5.96 MPa, respectively) were produced by a dead-load technique (i.e., placing a weight on the sand surface) in the root medium. Slight, moderate and severe drought stresses were induced using PEG 6000 solutions with osmotic potentials of 0, -0.3 and -0.5 MPa, respectively. After 30 days, plant physiological characteristics and root morphology were measured. An increase in Q p from 1.17 to 5.96 MPa led to greater leaf proline concentration and root diameter, and lower relative water content (RWC), leaf water potential (LWP), chlorophyll contents and root volume. Moreover, severe drought stress decreased root and shoot fresh weights, root volume, leaf area, RWC, LWP and chlorophyll content compared to control. Catalase (CAT) and ascorbate peroxidase (APX) activities under severe drought stress were about 1.5 and 2.9 times greater than control. Interaction of the stresses showed that mechanical stress primarily controls plant water status and physiological responses. However, endophyte presence mitigated the adverse effects of individual and combined stresses on plant growth. Colonized plants were better adapted and had greater root length and volume, RWC, LWP and chlorophyll contents under stressful conditions due to higher absorption sites for water and nutrients. Compared with uncolonized plants, colonized plants showed lower CAT activity implying that wheat inoculated with P. indica was more tolerant and experienced less oxidative damage induced by drought and/or mechanical stress. Copyright �

Phosphorous Application Improves Drought Tolerance of Phoebe zhennan

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Akash Tariq

2017-09-01

Full Text Available Phoebe zhennan (Gold Phoebe is a threatened tree species in China and a valuable and important source of wood and bioactive compounds used in medicine. Apart from anthropogenic disturbances, several biotic constraints currently restrict its growth and development. However, little attention has been given to building adaptive strategies for its conservation by examining its morphological and physio-biochemical responses to drought stress, and the role of fertilizers on these responses. A randomized experimental design was used to investigate the effects of two levels of irrigation (well-watered and drought-stressed and phosphorous (P fertilization treatment (with and without P to assess the morphological and physio-biochemical responses of P. zhennan seedlings to drought stress. In addition, we evaluated whether P application could mitigate the negative impacts of drought on plant growth and metabolism. Drought stress had a significant negative effect on the growth and metabolic processes of P. zhennan. Despite this, reduced leaf area, limited stomatal conductance, reduced transpiration rate, increased water use efficiency, enhanced antioxidant enzymes activities, and osmolytes accumulation suggested that the species has good adaptive strategies for tolerating drought stress. Application of P had a significant positive effect on root biomass, signifying its improved water extracting capacity from the soil. Moreover, P fertilization significantly increased leaf relative water content, net photosynthetic rate, and maximal quantum efficiency of PSII under drought stress conditions. This may be attributable to several factors, such as enhanced root biomass, decreased malondialdehyde content, and the up-regulation of chloroplast pigments, osmolytes, and nitrogenous compounds. However, P application had only a slight or negligible effect on the growth and metabolism of well-watered plants. In conclusion, P. zhennan has a strong capability for drought

Biogenic volatile organic compounds (BVOCs) emission of Scots pine under drought stress - a 13CO2 labeling study to determine de novo and pool emissions under different treatments

Science.gov (United States)

Lüpke, M.

2015-12-01

Plants emit biogenic volatile organic compounds (BVOCs) to e.g. communicate and to defend herbivores. Yet BVOCs also impact atmospheric chemistry processes, and lead to e.g. the built up of secondary organic aerosols. Abiotic stresses, such as drought, however highly influence plant physiology and subsequently BVOCs emission rates. In this study, we investigated the effect of drought stress on BVOCs emission rates of Scots pine trees, a de novo and pool emitter, under controlled climate chamber conditions within a dynamic enclosure system consisting of four plant chambers. Isotopic labeling with 13CO2 was used to detect which ratio of emissions of BVOCs derives from actual synthesis and from storage organs under different treatments. Additionally, the synthesis rate of the BVOCs synthesis can be determined. The experiment consisted of two campaigns (July 2015 and August 2015) of two control and two treated trees respectively in four controlled dynamic chambers simultaneously. Each campaign lasted for around 21 days and can be split into five phases: adaptation, control, dry-out, drought- and re-watering phase. The actual drought phase lasted around five days. During the campaigns two samples of BVOCs emissions were sampled per day and night on thermal desorption tubes and analyzed by a gas chromatograph coupled with a mass spectrometer and a flame ionization detector. Additionally, gas exchange of water and CO2, soil moisture, as well as leaf and chamber temperature was monitored continuously. 13CO2 labeling was performed simultaneously in all chambers during the phases control, drought and re-watering for five hours respectively. During the 13CO2 labeling four BVOCs emission samples per chamber were taken to identify the labeling rate on emitted BVOCs. First results show a decrease of BVOCs emissions during the drought phase and a recovery of emission after re-watering, as well as different strength of reduction of single compounds. The degree of labeling with 13

Structural adjustment and drought in Zambia.

Science.gov (United States)

Mulwanda, M

1995-06-01

While drought is not uncommon in Zambia, the country is now facing the worst drought in history. The monetary and social costs will be enormous. Although it is too early to measure the economic and social costs of the drought on Zambia, it is obvious that the impact is catastrophic on a country whose economy is under pressure. The drought will affect the structural adjustment programme (SAP) unveiled by the new government which has embraced the market economy. The country has imported, and will continue to import, large quantities of maize and other foodstuffs, a situation likely to strain the balance of payments. Earlier targets with regard to export earnings, reductions in the budget deficit, and GDP growth as contained in the Policy Framework Paper (PFP) are no longer attainable due to the effects of the drought.

Drought priming at vegetative growth stages improves tolerance to drought and heat stresses occurring during grain filling in spring wheat

DEFF Research Database (Denmark)

Wang, Xiao; Vignjevic, Marija; Liu, Fulai

2015-01-01

Plants of spring wheat (Triticum aestivum L. cv. Vinjett) were exposed to moderate water deficit at the vegetative growth stages six-leaf and/or stem elongation to investigate drought priming effects on tolerance to drought and heat stress events occurring during the grain filling stage. Compared......Plants of spring wheat (Triticum aestivum L. cv. Vinjett) were exposed to moderate water deficit at the vegetative growth stages six-leaf and/or stem elongation to investigate drought priming effects on tolerance to drought and heat stress events occurring during the grain filling stage...... of abscisic acid in primed plants under drought stress could contribute to higher grain yield compared to the non-primed plants. Taken together, the results indicate that drought priming during vegetative stages improved tolerance to both drought and heat stress events occurring during grain filling in wheat....

Groundwater quality surrounding Lake Texoma during short-term drought conditions

International Nuclear Information System (INIS)

Kampbell, Donald H.; An, Youn-Joo; Jewell, Ken P.; Masoner, Jason R.

2003-01-01

Stressors such as nitrates and total salts in ground water could potentially become a health or environmental problem during drought conditions. - Water quality data from 55 monitoring wells during drought conditions surrounding Lake Texoma, located on the border of Oklahoma and Texas, was compared to assess the influence of drought on groundwater quality. During the drought month of October, water table levels were three feet (0.9 m) lower compared with several months earlier under predrought climate conditions. Detection frequencies of nitrate (> 0.1 mg/l), orthophosphates (> 0.1 mg/l), chlorides (> MCL), and sulfates (> MCL) all increased during drought. Orthophosphate level was higher during drought. Largest increases in concentration were nitrate under both agriculture lands and in septic tank areas. An increase in ammonium-nitrogen was only detected in the septic tank area. The study showed that stressors such as nitrate and total salts could potentially become a health or environmental problem during drought

Qtl mapping of wheat doubled haploids for chlorophyll content and chlorophyll fluorescence kinetics under drought stress imposed at anthesis stage

International Nuclear Information System (INIS)

Ilyas, M.; Ilyas, N.; Arshad, M.; Kazi, A.G.

2014-01-01

Drought stress is one of the major environmental constraints to crop plants including wheat worldwide. Synthetic hexaploid can act as a vehicle for improving crop tolerance against biotic and abiotic stresses. Doubled haploid population consisting of one hundred and forty individuals derived from cross of Opata and SH223 was used in the present study to identify genomic regions associated with various quantitative attributes of physiological nature. Doubled haploid mapping population was phenotyped for chlorophyll content and chlorophyll fluorescence kinetics under control and drought stress imposed at anthesis stage. Genotyping of population was accomplished by utilizing two hundred and sixty one polymorphic Gaterslaben wheat microsatellites and Beltsville agriculture research center simple sequence repeats. Linkage map of doubled haploid population comprising of 19 linkage groups and covering map length of two thousands six hundred and twenty six (2626) cM was constructed using map maker software. Major and minor QTLs associated with quantitative traits were identified using QGene software. Major QTL for chlorophyll content (QTc.wwc-1B-S11) of doubled haploid mapping population under anthesis drought stress was mapped on chromosome 1B and explained 10.09 percent of phenotypic variation at LOD score of 5.5. Seven major and minor QTLs for PCFK of doubled haploids were identified on chromosome 1B, 7A and 7D under control and drought stress at anthesis stage. The identified QTLs are of prime importance for high resolution mapping in synthetic hexaploid wheat. Genomic synteny of doubled haploids was observed with rice chromosome 2, 4, 7 and maize chromosome 7 owing to occurrence of orthologous QTLs for chlorophyll content and chlorophyll fluorescence respectively. (author)

Activated Expression of WRKY57 Confers Drought Tolerance in Arabidopsis

Institute of Scientific and Technical Information of China (English)

Yanjuan Jiang; Gang Liang; Diqiu Yu

2012-01-01

Drought is one of the most serious environmental factors that limit the productivity of agricultural crops worldwide.However,the mechanism underlying drought tolerance in plants is unclear.WRKY transcription factors are known to function in adaptation to abiotic stresses.By screening a pool of WRKY-associated T-DNA insertion mutants,we isolated a gain-of-function mutant,acquired drought tolerance (adt),showing improved drought tolerance.Under drought stress conditions,adt accumulated higher levels of ABA than wild-type plants.Stomatal aperture analysis indicated that adt was more sensitive to ABA than wild-type plants.Molecular genetic analysis revealed that a T-DNA insertion in adt led to activated expression of a WRKY gene that encodes the WRKR57 protein.Constitutive expression of WRKY57 also conferred similar drought tolerance.Consistently with the high ABA content and enhanced drought tolerance,three stress-responsive genes (RD29A,NCED3,and ABA3) were up-regulated in adt.ChIP assays demonstrated that WRKY57 can directly bind the W-box of RD29A and NCED3 promoter sequences.In addition,during ABA treatment,seed germination and early seedling growth of adt were inhibited,whereas,under high osmotic conditions,adt showed a higher seed germination frequency.In summary,our results suggested that the activated expression of WRKY57 improved drought tolerance of Arabidopsis by elevation of ABA levels.Establishment of the functions of WRKY57 will enable improvement of plant drought tolerance through gene manipulation approaches.

Expression profiles of sugarcane under drought conditions: Variation in gene regulation

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Júlio César Farias de Andrade

2015-01-01

Full Text Available AbstractDrought is a major factor in decreased sugarcane productivity because of the resulting morphophysiological effects that it causes. Gene expression studies that have examined the influence of water stress in sugarcane have yielded divergent results, indicating the absence of a fixed pattern of changes in gene expression. In this work, we investigated the expression profiles of 12 genes in the leaves of a drought-tolerant genotype (RB72910 of sugarcane and compared the results with those of other studies. The genotype was subjected to 80–100% water availability (control condition and 0–20% water availability (simulated drought. To analyze the physiological status, the SPAD index, Fv/Fm ratio, net photosynthesis (A, stomatal conductance (gs and stomatal transpiration (E were measured. Total RNA was extracted from leaves and the expression of SAMDC, ZmPIP2-1 protein, ZmTIP4-2 protein, WIP protein, LTP protein, histone H3, DNAj, ferredoxin I, β-tubulin, photosystem I, gene 1 and gene 2 was analyzed by quantitative real-time PCR (RT-PCR. Important differences in the expression profiles of these genes were observed when compared with other genotypes, suggesting that complex defense mechanisms are activated in response to water stress. However, there was no recognizable pattern for the changes in expression of the different proteins associated with tolerance to drought stress.

Effect of random microstructure on crack propagation in cortical bone tissue under dynamic loading

International Nuclear Information System (INIS)

Gao, X; Li, S; Adel-Wahab, A; Silberschmidt, V

2013-01-01

A fracture process in a cortical bone tissue depends on various factors, such as bone loss, heterogeneous microstructure, variation of its material properties and accumulation of microcracks. Therefore, it is crucial to comprehend and describe the effect of microstructure and material properties of the components of cortical bone on crack propagation in a dynamic loading regime. At the microscale level, osteonal bone demonstrates a random distribution of osteons imbedded in an interstitial matrix and surrounded by a thin layer known as cement line. Such a distribution of osteons can lead to localization of deformation processes. The global mechanical behavior of bone and the crack-propagation process are affected by such localization under external loads. Hence, the random distribution of microstructural features plays a key role in the fracture process of cortical bone. The purpose of this study is two-fold: firstly, to develop two-dimensional microstructured numerical models of cortical bone tissue in order to examine the interaction between the propagating crack and bone microstructure using an extended finite-element method under both quasi-static and dynamic loading conditions; secondly, to investigate the effect of randomly distributed microstructural constituents on the crack propagation processes and crack paths. The obtained results of numerical simulations showed the influence of random microstructure on the global response of bone tissue at macroscale and on the crack-propagation process for quasi-static and dynamic loading conditions

Differential effects of Pseudomonas mendocina and Glomus intraradices on lettuce plants physiological response and aquaporin PIP2 gene expression under elevated atmospheric CO2 and drought.

Science.gov (United States)

Alguacil, Maria Del Mar; Kohler, Josef; Caravaca, Fuensanta; Roldán, Antonio

2009-11-01

Arbuscular mycorrhizal (AM) symbiosis and plant-growth-promoting rhizobacterium (PGPR) can alleviate the effects of water stress in plants, but it is unknown whether these benefits can be maintained at elevated CO2. Therefore, we carried out a study where seedlings of Lactuca sativa were inoculated with the AM fungus (AMF) Glomus intraradices N.C. Schenk & G.S. Sm. or the PGPR Pseudomonas mendocina Palleroni and subjected to two levels of watering and two levels of atmospheric CO2 to ascertain their effects on plant physiological parameters and gene expression of one PIP aquaporin in roots. The inoculation with PGPR produced the greatest growth in lettuce plants under all assayed treatments as well as the highest foliar potassium concentration and leaf relative water content under elevated [CO2] and drought. However, under such conditions, the PIP2 gene expression remained almost unchanged. G. intraradices increased significantly the AMF colonization, foliar phosphorus concentration and leaf relative water content in plants grown under drought and elevated [CO2]. Under drought and elevated [CO2], the plants inoculated with G. intraradices showed enhanced expression of the PIP2 gene as compared to P. mendocina or control plants. Our results suggest that both microbial inoculation treatments could help to alleviate drought at elevated [CO2]. However, the PIP2 gene expression was increased only by the AMF but not by the PGPR under these conditions.

Modeling the Effects of Drought Events on Forest Ecosystem Functioning Historically and Under Scenarios of Climate Change

Science.gov (United States)

Ren, J.; Hanan, E. J.; Kolden, C.; Abatzoglou, J. T.; Tague, C.; Liu, M.; Adam, J. C.

2017-12-01

Drought events have been increasing across the western United States in recent years. Many studies have shown that, in the context of climate change, droughts will continue to be stronger, more frequent, and prolonged in the future. However, the response of forest ecosystems to droughts, particularly multi-year droughts, is not well understood. The objectives of this study are to examine how drought events of varying characteristics (e.g. intensity, duration, frequency, etc.) have affected the functioning of forest ecosystems historically, and how changing drought characteristics (including multi-year droughts) may affect forest functioning in a future climate. We utilize the Regional Hydro-Ecological Simulation System (RHESSys) to simulate impacts of both historical droughts and scenarios of future droughts on forest ecosystems. RHESSys is a spatially-distributed and process-based model that captures the interactions between coupled biogeochemical and hydrologic cycles at catchment scales. Here our case study is the Trail Creek catchment of the Big Wood River basin in Idaho, the Northwestern USA. For historical simulations, we use the gridded meteorological data of 1979 to 2016; for future climate scenarios, we utilize downscaled data from GCMs that have been demonstrated to capture drought events in the Northwest of the USA. From these climate projections, we identify various types of drought in intensity and duration, including multi-year drought events. We evaluate the following responses of ecosystems to these events: 1) evapotranspiration and streamflow; 2) gross primary productivity; 3) the post-drought recovery of plant biomass; and 4) the forest functioning and recovery after multi-year droughts. This research is part of an integration project to examine the roles of drought, insect outbreak, and forest management activities on wildfire activity and its impacts. This project will provide improved information for forest managers and communities in the wild

Analysis of Droughts of Northwest of Iran Using the Reconnaissance Drought Index

Directory of Open Access Journals (Sweden)

behrouz hosseini

2016-02-01

Full Text Available Introduction: Drought is a creeping natural phenomenon, which can occur in any region. Such phenomenon not only affects the region subjected to drought, but its adverse effects can also be extended to other adjacent regions. This phenomenon mainly starts with water deficiency (say less than long- term mean of variable under study such as rainfall, streamflow, groundwater level or soil moisture and progress in time. This period can be ended by increasing the rainfall and reaching the mean level. Even after the ending of a drought period, its adverse effects can be continued for several months. Although, it is not possible (at least at this time to prevent the occurrence of drought in a given region, it is not impossible to alleviate the drought consequences by scientific water management. Such a management should be employed before drought initiation as well as during it and continue on even after the end of the drought period. The frequency of the main drought characteristics is a major concern of this study. The Northwest of Iran recently encountered severe and prolonged droughts, such that a major portion of the Urmia Lake surface disappeared during the last drought in recent years. In order to study drought characteristics, we used the Reconnaissance Drought Index (RDI. This index is based on annual rainfall and potential reference crop evapotranspiration (abbreviated by PET here. This study employed the Monte Carlo simulation technique for synthetic data generation for analysis. Materials and Methods: The information from the 17 synoptic weather stations located in the North-west of Iran was used for drought analysis. Data was gathered from the Islamic Republic of Iran’s Meteorological Organization (IRIMO. In the first stage of research, the ratio of long term mean annual precipitation to evapotranspiration was calculated for each of the stations. For this purpose, the Penman-Montheis (FAO 56 method was selected for PET estimation. In the

Drought Characteristic Analysis Based on an Improved PDSI in the Wei River Basin of China

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Lei Zou

2017-03-01

Full Text Available In this study, to improve the efficiency of the original Palmer Drought Severity Index (PDSI_original, we coupled the Soil and Water Assessment tool (SWAT and PDSI_original to construct a drought index called PDSI_SWAT. The constructed PDSI_SWAT is applied in the Wei River Basin (WRB of China during 1960–2012. The comparison of the PDSI_SWAT with four other commonly used drought indices reveals the effectiveness of the PDSI_SWAT in describing the drought propagation processes in WRB. The whole WRB exhibits a dry trend, with more significant trends in the northern, southeastern and western WRB than the remaining regions. Furthermore, the drought frequencies show that drought seems to occur more likely in the northern part than the southern part of WRB. The principle component analysis method based on the PDSI_SWAT reveals that the whole basin can be further divided into three distinct sub-regions with different drought variability, i.e., the northern, southeastern and western part. Additionally, these three sub-regions are also consistent with the spatial pattern of drought shown by the drought frequency. The wavelet transform analysis method indicates that the El Niño-Southern Oscillation (ENSO events have strong impacts on inducing droughts in the WRB. The results of this study could be beneficial for a scientific water resources management and drought assessment in the current study area and also provide a valuable reference for other areas with similar climatic characteristics.

Key mechanisms of metabolic changes in mountain pine and larch under drought in the Swiss National Park

Science.gov (United States)

Churakova, Olga; Bigler, Christof; Bryukhanova, Marina; Siegwolf, Rolf

2014-05-01

intrinsic water use efficiency. Carbon isotopes ratios of specific sugar compounds such as sucrose, raffinose, fructose, ribose and pinitol in needle and wood samples will help to evaluate the impact of drought on the carbohydrate balance and carbon allocation. Analyzing the oxygen isotopic compositions of soil water, sap water (water in branches) and precipitation we will determine the role of the different water sources for tree growth under drought conditions. The proposed work will provide a unique opportunity to assess the survival potential of mountain pine and larch trees exposed to drought that will help to estimate risks of modern climatic changes and forest damage. This project was supported by Marie Heim-Vögtlin Programme PMPDP2_145507/1 granted to Olga Churakova (Sidorova). References: Allen CD et al. (2010) A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests Forest Ecology and Management 259:660-684 Bigler C, Rigling A (2013) Precision and accuracy of tree-ring-based death dates of mountain pines in the Swiss National Park. Trees - Structure and Function. 27: 1703-1712 CH 2011 Swiss Climate Change Scenarios CH2011. In. C2SM, MeteoSwiss, ETH, NCCR Climate, and OcCC, p 88

Mitochondrial Biogenesis in Diverse Cauliflower Cultivars under Mild and Severe Drought. Impaired Coordination of Selected Transcript and Proteomic Responses, and Regulation of Various Multifunctional Proteins

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Michał Rurek

2018-04-01

Full Text Available Mitochondrial responses under drought within Brassica genus are poorly understood. The main goal of this study was to investigate mitochondrial biogenesis of three cauliflower (Brassica oleracea var. botrytis cultivars with varying drought tolerance. Diverse quantitative changes (decreases in abundance mostly in the mitochondrial proteome were assessed by two-dimensional gel electrophoresis (2D PAGE coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS. Respiratory (e.g., complex II, IV (CII, CIV and ATP synthase subunits, transporter (including diverse porin isoforms and matrix multifunctional proteins (e.g., components of RNA editing machinery were diversely affected in their abundance under two drought levels. Western immunoassays showed additional cultivar-specific responses of selected mitochondrial proteins. Dehydrin-related tryptic peptides (found in several 2D spots immunopositive with dehydrin-specific antisera highlighted the relevance of mitochondrial dehydrin-like proteins for the drought response. The abundance of selected mRNAs participating in drought response was also determined. We conclude that mitochondrial biogenesis was strongly, but diversely affected in various cauliflower cultivars, and associated with drought tolerance at the proteomic and functional levels. However, discussed alternative oxidase (AOX regulation at the RNA and protein level were largely uncoordinated due to the altered availability of transcripts for translation, mRNA/ribosome interactions, and/or miRNA impact on transcript abundance and translation.

Mitochondrial Biogenesis in Diverse Cauliflower Cultivars under Mild and Severe Drought. Impaired Coordination of Selected Transcript and Proteomic Responses, and Regulation of Various Multifunctional Proteins

Science.gov (United States)

Rurek, Michał; Czołpińska, Magdalena; Staszak, Aleksandra Maria; Nowak, Witold; Krzesiński, Włodzimierz; Spiżewski, Tomasz

2018-01-01

Mitochondrial responses under drought within Brassica genus are poorly understood. The main goal of this study was to investigate mitochondrial biogenesis of three cauliflower (Brassica oleracea var. botrytis) cultivars with varying drought tolerance. Diverse quantitative changes (decreases in abundance mostly) in the mitochondrial proteome were assessed by two-dimensional gel electrophoresis (2D PAGE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Respiratory (e.g., complex II, IV (CII, CIV) and ATP synthase subunits), transporter (including diverse porin isoforms) and matrix multifunctional proteins (e.g., components of RNA editing machinery) were diversely affected in their abundance under two drought levels. Western immunoassays showed additional cultivar-specific responses of selected mitochondrial proteins. Dehydrin-related tryptic peptides (found in several 2D spots) immunopositive with dehydrin-specific antisera highlighted the relevance of mitochondrial dehydrin-like proteins for the drought response. The abundance of selected mRNAs participating in drought response was also determined. We conclude that mitochondrial biogenesis was strongly, but diversely affected in various cauliflower cultivars, and associated with drought tolerance at the proteomic and functional levels. However, discussed alternative oxidase (AOX) regulation at the RNA and protein level were largely uncoordinated due to the altered availability of transcripts for translation, mRNA/ribosome interactions, and/or miRNA impact on transcript abundance and translation. PMID:29642585

Lags in hydrologic recovery following an extreme drought: Assessing the roles of climate and catchment characteristics

Science.gov (United States)

Yang, Yuting; McVicar, Tim R.; Donohue, Randall J.; Zhang, Yongqiang; Roderick, Michael L.; Chiew, Francis H. S.; Zhang, Lu; Zhang, Junlong

2017-06-01

Drought, generally characterized by below-average water supply, propagates through the hydrologic system with consequent ecological and societal impacts. Compared with other drought aspects, the recovery of drought especially in the hydrological components, which directly relates to the recovery of water resources for agricultural, ecological and human needs, is less-understood. Here, taking the Millennium drought in southeast Australia (˜1997-2009) as an illustrating case, we comprehensively examined multiple aspects of the meteorological (i.e., precipitation) and hydrological (i.e., streamflow and base flow) droughts across 130 unimpaired catchments using long-term hydro-meteorological observations. Results show that the duration and intensity of the meteorological drought are both lengthened and amplified in the hydrological drought, suggesting a nonstationarity in the rainfall-runoff relationship during a prolonged drought. Additionally, we find a time lag commonly exists between the end of the meteorological droughts and the end of the hydrological drought, with the recovery of base flow showing a longer lag than the recovery of streamflow. The recovery rate of precipitation after drought was found to be the dominant factor that controls the recovery of hydrological droughts while catchment landscape (i.e., valley bottom flatness) plays an important but secondary role in controlling the lags in the hydrological recovery. Other hydro-climatic factors and catchment properties appear to have only minor influences governing hydrological drought recovery. Our findings highlight a delayed response in the terrestrial components of the hydrological cycle to precipitation after prolonged drought, and provide valuable scientific guidance to water resources management and water security assessment in regions facing future droughts.

Field Performance of Five Soybean Mutants Under Drought Stress Conditions and Molecular Analysis Using SSR Markers

Directory of Open Access Journals (Sweden)

Y Yuliasti

2017-08-01

Full Text Available The objectives of this research wereto evaluate (1 the performance of soybean mutant lines under drought stress conditions, and(2 the genetic diversity and relationship among the mutant lines using SSR markers.The field evaluation was conducted during the dry season of 2011 and 2012 at the experimental Farm of Mataram University, West Nusa Tenggara, Indonesia. The field experiment was set up in a randomized block design. Ten mutant lines and two control varieties were evaluated in four replications. Genetic distance among evaluated lines were determined based on allelic diversity analysis using 40 simple sequence repeat (SSR loci. Under drought stress conditions, two mutant lines, Kdl3 and Kdl8,showed a better performance compared to the other ones. The high yielding mutant lines were Kdl3and Kdl8, which yielded 1.75 t ha-1and 1.69 t ha-1, respectively, compared to the parent and national control, Panderman 1.43 t ha-1 and Muria 1.32 t ha-1. These mutant linesrequired 30.75 to 32days to flower and 79.75 to 83.75 day to harvest with relatively short plant height 28.25 and 23.35 cmrespectively. Those mutant characters were better than those of the other three mutants, the original parents, and the control soybean species. Since the evaluated soybean mutant lines yielded more under drought stress conditions than the standard varieties, they can be used and registered as drought-tolerant soybean mutants. Moreover, the evaluated soybean accessions showed a wide genetic distance. The accessions were clustered into two groups according to their genetic background, namelygroup I (the Panderman with three mutant lines and group II (the Muria with two mutant lines. Twenty-three out of 40 evaluated SSR loci, including AW31, BE806, CMAC7L, S080, S126, S57, S171, S224, S285, S294, S393, S294, S383, S511, S511, S520, S540, S547, S551, S571, S577, and S578, provided polymorphic alleles between the parents and their mutants and could be used to differentiate

Effect of SiO2 nanoparticles on drought resistance in hawthorn seedlings

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Ashkavand Peyman

2015-12-01

Full Text Available Drought is a significant factor limiting crop production in arid regions while hawthorns (Crataegus sp. are an important component of such region’s forests. Therefore, treatments that increase hawthorn drought resistance may also increase transplanting success. Thus, the physiological and biochemical responses of hawthorn seedlings to a factorial combination of different concentrations of silica nanoparticles (SNPs at 0, 10, 50 and 100 mg L−1 and three soil moisture treatments (without stress, moderate stress and severe stress were investigated. Seedlings were irrigated with one of the four concentrations of SNPs for 45 days before exposing them to drought stress. Photosynthesis parameters, malondialdehyde (MDA, relative water content (RWC, membrane electrolyte leakage (ELI as well as chlorophyll, carotenoid, carbohydrate and proline content were determined. At the end of the experiment, positive effects by SNP pre-treatment on physiological indexes were observed during drought stress. Under drought conditions, the effect of SNPs on photosynthetic rate and stomatal conductance was evident. Although the SNPs increased plant biomass, xylem water potential and MDA content, especially under drought conditions, RWC and ELI were not affected by the SNP pre-treatments. Seedlings pre-treated with SNPs had a decreased carbohydrate and proline content under all water regimes, but especially so under drought. Total chlorophyll content and carotenoid content did not change among the treatments. Generally, the findings imply that SNPs play a positive role in maintaining critical physiological and biochemical functions in hawthorn seedlings under drought stress conditions. However, more studies are needed before the physiological and biochemical basis of induced drought resistance can be determined.

Drought Tolerance in Modern and Wild Wheat

Science.gov (United States)

Budak, Hikmet; Kantar, Melda; Yucebilgili Kurtoglu, Kuaybe

2013-01-01

The genus Triticum includes bread (Triticum aestivum) and durum wheat (Triticum durum) and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress. Improvement for drought tolerance can be achieved by the introduction of drought-grelated genes and QTLs to modern wheat cultivars. Therefore, identification of candidate molecules or loci involved in drought tolerance is necessary, which is undertaken by “omics” studies and QTL mapping. In this sense, wild counterparts of modern varieties, specifically wild emmer wheat (T. dicoccoides), which are highly tolerant to drought, hold a great potential. Prior to their introgression to modern wheat cultivars, drought related candidate genes are first characterized at the molecular level, and their function is confirmed via transgenic studies. After integration of the tolerance loci, specific environment targeted field trials are performed coupled with extensive analysis of morphological and physiological characteristics of developed cultivars, to assess their performance under drought conditions and their possible contributions to yield in certain regions. This paper focuses on recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on improvement of wheat cultivars for drought tolerance. PMID:23766697

Drought Tolerance in Modern and Wild Wheat

Directory of Open Access Journals (Sweden)

Hikmet Budak

2013-01-01

Full Text Available The genus Triticum includes bread (Triticum aestivum and durum wheat (Triticum durum and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress. Improvement for drought tolerance can be achieved by the introduction of drought-grelated genes and QTLs to modern wheat cultivars. Therefore, identification of candidate molecules or loci involved in drought tolerance is necessary, which is undertaken by “omics” studies and QTL mapping. In this sense, wild counterparts of modern varieties, specifically wild emmer wheat (T. dicoccoides, which are highly tolerant to drought, hold a great potential. Prior to their introgression to modern wheat cultivars, drought related candidate genes are first characterized at the molecular level, and their function is confirmed via transgenic studies. After integration of the tolerance loci, specific environment targeted field trials are performed coupled with extensive analysis of morphological and physiological characteristics of developed cultivars, to assess their performance under drought conditions and their possible contributions to yield in certain regions. This paper focuses on recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on improvement of wheat cultivars for drought tolerance.

Effect of polyethylene glycol induced drought stress on physio-hormonal attributes of soybean

International Nuclear Information System (INIS)

Hamayun, M.; Khan, A.L.; Ahmad, N.; Lee, In-Jung; Khan, S.A.; Shinwari, Z.K.

2010-01-01

Drought stress is a major abiotic constraint limiting crop production world wide. In current study, we investigated the adverse effects of drought stress on growth, yield and endogenous phytohormones of soybean. Polyethylene glycol (PEG) solutions of elevated strength (8% and 16%) were used for drought stress induction. Drought stress period span for two weeks each at pre and post flowering growth stage. It was observed that soybean growth and yield attributes significantly reduced under drought stress at both pre and post flowering period, while maximum reduction was caused by PEG (16%) applied at pre flowering time. The endogenous bioactive GA/sub 1/ and GA/sub 4/ content decreased under elevated drought stress. On the other hand, jasmonic acid (JA), salicylic acid (SA) and abscisic acid (ABA) content increased under drought stress. On the basis of current study, we concluded that application of earlier drought stress severely reduced growth and yield attributes of soybean when compared to its later application. Furthermore, increases in the endogenous contents of JA, SA and ABA in response to drought stress demonstrate the involvement of these hormones in drought stress resistance. (author)

Stomatal conductance, mesophyll conductance, and transpiration efficiency in relation to leaf anatomy in rice and wheat genotypes under drought.

Science.gov (United States)

Ouyang, Wenjing; Struik, Paul C; Yin, Xinyou; Yang, Jianchang

2017-11-02

Increasing leaf transpiration efficiency (TE) may provide leads for growing rice like dryland cereals such as wheat (Triticum aestivum). To explore avenues for improving TE in rice, variations in stomatal conductance (gs) and mesophyll conductance (gm) and their anatomical determinants were evaluated in two cultivars from each of lowland, aerobic, and upland groups of Oryza sativa, one cultivar of O. glaberrima, and two cultivars of T. aestivum, under three water regimes. The TE of upland rice, O. glaberrima, and wheat was more responsive to the gm/gs ratio than that of lowland and aerobic rice. Overall, the explanatory power of the particular anatomical trait varied among species. Low stomatal density mostly explained the low gs in drought-tolerant rice, whereas rice genotypes with smaller stomata generally responded more strongly to drought. Compared with rice, wheat had a higher gm, which was associated with thicker mesophyll tissue, mesophyll and chloroplasts more exposed to intercellular spaces, and thinner cell walls. Upland rice, O. glaberrima, and wheat cultivars minimized the decrease in gm under drought by maintaining high ratios of chloroplasts to exposed mesophyll cell walls. Rice TE could be improved by increasing the gm/gs ratio via modifying anatomical traits. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Drought resistance across California ecosystems: Evaluating changes in carbon dynamics using satellite imagery

Science.gov (United States)

Malone, Sparkle; Tulbure, Mirela; Pérez-Luque, Antonio J.; Assal, Timothy J.; Bremer, Leah; Drucker, Debora; Hillis, Vicken; Varela, Sara; Goulden, Michael

2016-01-01

Drought is a global issue that is exacerbated by climate change and increasing anthropogenic water demands. The recent occurrence of drought in California provides an important opportunity to examine drought response across ecosystem classes (forests, shrublands, grasslands, and wetlands), which is essential to understand how climate influences ecosystem structure and function. We quantified ecosystem resistance to drought by comparing changes in satellite-derived estimates of water-use efficiency (WUE = net primary productivity [NPP]/evapotranspiration [ET]) under normal (i.e., baseline) and drought conditions (ΔWUE = WUE2014 − baseline WUE). With this method, areas with increasing WUE under drought conditions are considered more resilient than systems with declining WUE. Baseline WUE varied across California (0.08 to 3.85 g C/mm H2O) and WUE generally increased under severe drought conditions in 2014. Strong correlations between ΔWUE, precipitation, and leaf area index (LAI) indicate that ecosystems with a lower average LAI (i.e., grasslands) also had greater C-uptake rates when water was limiting and higher rates of carbon-uptake efficiency (CUE = NPP/LAI) under drought conditions. We also found that systems with a baseline WUE ≤ 0.4 exhibited a decline in WUE under drought conditions, suggesting that a baseline WUE ≤ 0.4 might be indicative of low drought resistance. Drought severity, precipitation, and WUE were identified as important drivers of shifts in ecosystem classes over the study period. These findings have important implications for understanding climate change effects on primary productivity and C sequestration across ecosystems and how this may influence ecosystem resistance in the future.

Physiological response cascade of spring wheat to soil warming and drought

DEFF Research Database (Denmark)

Weldearegay, Dawit Fisseha; Yan, F.; Rasmussen, Søren Kjærsgaard

2016-01-01

Climate change is affecting wheat production in Northern Europe; in particular, drought and soil warming during anthesis may cause significant yield losses of the crop. In a search for genotypes tolerant to these stresses, the physiological responses of three spring wheat cultivars to increased...... D and HD had significant effects. The variable most sensitive to soil drying was gs, followed by A, Ψl, and RWC. Among the three cultivars, earlier stomatal closure during drought in Alora could be a good adaptive strategy to conserve soil water for a prolonged drought, but may not be of benefit...... under intermittent drought conditions. Later stomatal closure and decline in A for Scirocco under HD and D stresses would be a favourable trait to sustain productivity under intermittent drought. A lower soil-water threshold of gs associated with a later decrease in A for Scirocco implies...

Arbuscular mycorrhizal symbiosis induces strigolactone biosynthesis under drought and improves drought tolerance in lettuce and tomato

NARCIS (Netherlands)

Ruiz-Lozano, J.M.; Aroca, R.; Zamarreno, A.M.; Molina, S.; Andreo Jimenez, B.; Porcel, R.; Garcia-Mina, J.M.; Ruyter-Spira, C.P.; Lopez-Raez, J.A.

2016-01-01

Arbuscular mycorrhizal (AM) symbiosis alleviates drought stress in plants. However, the intimate mechanisms involved, as well as its effect on the production of signalling molecules associated with the host plant–AM fungus interaction remains largely unknown. In the present work, the effects of

Effect of Filter Cake on Morphophysiological and Yield of Sweet Corn Under Late Season Drought Stress Condition

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S. A. Siadat

2015-06-01

Full Text Available In order to investigate the effect of Filter Cake application on some morpho-physiological characteristics and yield of sweet corn (Zea mays var saccharata under different irrigation regimes, an experiment was conducted in Ramin Agriculture and Natural Resources University, Khuzestan, in 2012. The experiment was arranged in split-plot design in RCBD (Completely Randomized Block Design with three replications. Treatments were drought stress (irrigation after 25, 50 and 75% depletion of available water content in main plots and Filter Cake (0, 10, 20 and 30 tonha-1 arranged in sub-plots. Results showed that drought stress increased electrolyte leakage (EL and proline content (PC while height of plant, relative water content (RWC, chlorophyll stability index and ear and grain yield were decreased. The intensive drought stress had the greatest effect on EL and PC (54% increase, and decreased ear and grain yield by21 and 37% compared to control, respectively. Application of filter cake on non-stress condition increased height of plant and economic yield. But Filter Cake in intensive stress reduced RWC and yield and increased EL compared to control. Also, the application of 30 tonha-1 of Filter Cake in intensive stress condition decreased ear and grain yield by 14.5 and 10.7% respectively. Thus, positive effect of Filter Cake application was clear on non-stress condition, but on drought stress condition it decreased the economic yield.

Effects of salt-drought stress on growth and physiobiochemical characteristics of Tamarix chinensis seedlings.

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Liu, Junhua; Xia, Jiangbao; Fang, Yanming; Li, Tian; Liu, Jingtao

2014-01-01

The present study was designed to clarify the effects of salinity and water intercross stresses on the growth and physiobiochemical characteristics of Tamarix chinensis seedlings by pots culture under the artificial simulated conditions. The growth, activities of SOD, POD, and contents of MDA and osmotic adjusting substances of three years old seedlings of T. chinensis were studied under different salt-drought intercross stress. Results showed that the influence of salt stress on growth was greater than drought stress, the oxidation resistance of SOD and POD weakened gradually with salt and drought stresses intensified, and the content of MDA was higher under severe drought and mild and moderate salt stresses. The proline contents increased with the stress intensified but only significantly higher than control under the intercross stresses of severe salt-severe drought. It implied that T. chinensis could improve its stress resistance by adjusted self-growth and physiobiochemical characteristics, and the intercross compatibility of T. chinensis to salt and drought stresses can enhance the salt resistance under appropriate drought stress, but the dominant factors influencing the physiological biochemical characteristics of T. chinensis were various with the changing of salt-drought intercross stresses gradients.

Effects of Salt-Drought Stress on Growth and Physiobiochemical Characteristics of Tamarix chinensis Seedlings

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Junhua Liu

2014-01-01

Full Text Available The present study was designed to clarify the effects of salinity and water intercross stresses on the growth and physiobiochemical characteristics of Tamarix chinensis seedlings by pots culture under the artificial simulated conditions. The growth, activities of SOD, POD, and contents of MDA and osmotic adjusting substances of three years old seedlings of T. chinensis were studied under different salt-drought intercross stress. Results showed that the influence of salt stress on growth was greater than drought stress, the oxidation resistance of SOD and POD weakened gradually with salt and drought stresses intensified, and the content of MDA was higher under severe drought and mild and moderate salt stresses. The proline contents increased with the stress intensified but only significantly higher than control under the intercross stresses of severe salt-severe drought. It implied that T. chinensis could improve its stress resistance by adjusted self-growth and physiobiochemical characteristics, and the intercross compatibility of T. chinensis to salt and drought stresses can enhance the salt resistance under appropriate drought stress, but the dominant factors influencing the physiological biochemical characteristics of T. chinensis were various with the changing of salt-drought intercross stresses gradients.

Growth and antioxidant system under drought stress in Chickpea (Cicer arietinum L. as sustained by salicylic acid

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B.K. Sarma

2011-12-01

Full Text Available Drought is one of the major factors limiting chickpea production in arid and semi arid regions. There is meagre information available regarding genotypic variation for drought tolerance in chickpea genotypes. Present investigation was carried out to find out the influence of salicylic acid (SA on drought tolerance in four chickpea genotypes. Reduction in relative injury was observed in plants treated with SA @1.5 mM as compared to control seedlings. Relationship between relative water content (RWC, membrane permeability (MP, ascorbic acid (AsA, proline, lipid peroxidation (LPO, hydrogen peroxide (H2O2, catalase (CAT, peroxidase (POX, superoxide dismutase (SOD, ascorbate peroxidase (APX was determined in order to find out whether these parameters can be used as selection criteria for drought tolerance in this crop. Results indicate wide variation in tolerance to drought stress amongst chickpea cultivars at both the critical stages i.e. pre- and post-anthesis. On the basis of growth and antioxidant activity better genotypes Tyson and ICC-4958 appear to be adapted to drought stress tolerance. Early drought stress (pre-anthesis drought was found to be more damaging than the late drought stress (post- anthesis drought.

Conditional and unconditional QTL mapping of drought-tolerance ...

Indian Academy of Sciences (India)

2013-08-12

Aug 12, 2013 ... drought tolerance has been the yield obtained under drought conditions .... loci distributed in 27 linkage groups with six linkage gaps, and it covered ...... time in maize; they identified numerous minor-effect QTLs that were ...

Testing the sensitivity of trade linkages in Europe to compound drought events

Science.gov (United States)

Veldkamp, Ted; Koks, Elco; Thissen, Mark; Wahl, Thomas; Haigh, Ivan; Muis, Sanne; Ward, Philip

2017-04-01

Droughts can be defined as spatially extensive events that are characterized by temporal deficits in precipitation, soil moisture or streamflow, and have the potential to cause large direct and indirect economic losses. Many European countries face drought as an economically important hazard, with agriculture, livestock, forestry, energy, industry, and water sectors particularly at risk, causing economic losses of 139 billion US over the past 30 years. Apart from these direct impacts, business production and the flow of goods and services can be affected indirectly by droughts. With consequences that can propagate through the economic system affecting regions not directly hit by the drought event itself, or in time-periods long after the original drought event occurred. In this study, we evaluate the sensitivity of existing trade linkages between the different NUTS-2 regions in Europe to the coupled occurrence of hydro-meteorological drought events, and their associated production losses. Using a multi-regional supply-use model for Europe, we have, on a product level, insight in the existing trade linkages between NUTS-2 regions. Using this information in combination with historical drought data, we assessed and identified for a selection of water related products: 1) the dependency-structures of the NUTS-2 regions within Europe for the import and export of products (and therein water); 2) the coupled nature of drought events occurring in regions that are linked via these trade-patterns; 3) the probability of not meeting demands (on a product level) due to drought events and the associated (indirect economic) impacts; and 4) regions that lose or benefit from their selection of trade-partners given the coupled nature of drought events, as well as the net effects for Europe as a whole.

Extreme drought decouples silicon and carbon geochemical linkages in lakes.

Science.gov (United States)

Li, Tianyang; Li, Siyue; Bush, Richard T; Liang, Chuan

2018-09-01

Silicon and carbon geochemical linkages were usually regulated by chemical weathering and organism activity, but had not been investigated under the drought condition, and the magnitude and extent of drought effects remain poorly understood. We collected a comprehensive data set from a total of 13 sampling sites covering the main water body of the largest freshwater lake system in Australia, the Lower Lakes. Changes to water quality during drought (April 2008-September 2010) and post-drought (October 2010-October 2013) were compared to reveal the effects of drought on dissolved silica (DSi) and bicarbonate (HCO 3 - ) and other environmental factors, including sodium (Na + ), pH, electrical conductivity (EC), chlorophyll a (Chl-a), total dissolved solids (TDS), dissolved inorganic nitrogen (DIN), total nitrogen (TN), total phosphorus (TP) and water levels. Among the key observations, concentrations of DSi and DIN were markedly lower in drought than in post-drought period while pH, EC and concentrations of HCO 3 - , Na + , Chl-a, TDS, TN, TP and the ratio TN:TP had inverse trends. Stoichiometric ratios of DSi:HCO 3 - , DSi:Na + and HCO 3 - :Na + were significantly lower in the drought period. DSi exhibited significantly negative relationships with HCO 3 - , and DSi:Na + was strongly correlated with HCO 3 - :Na + in both drought and post-drought periods. The backward stepwise regression analysis that could avoid multicollinearity suggested that DSi:HCO 3 - ratio in drought period had significant relationships with fewer variables when compared to the post-drought, and was better predictable using nutrient variables during post-drought. Our results highlight the drought effects on variations of water constituents and point to the decoupling of silicon and carbon geochemical linkages in the Lower Lakes under drought conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

Regulation of glutamine synthetase isoforms in two differentially drought-tolerant rice (Oryza sativa L.) cultivars under water deficit conditions.

Science.gov (United States)

Singh, Kamal Krishna; Ghosh, Shilpi

2013-02-01

KEY MESSAGE : The regulation of GS isoforms by WD was organ specific. Two GS isoforms i.e. OsGS1;1 and OsGS2 were differentially regulated in IR-64 (drought-sensitive) and Khitish (drought-tolerant) cultivars of rice. Water deficit (WD) has adverse effect on rice (Oryza sativa L.) and acclimation requires essential reactions of primary metabolism to continue. Rice plants utilize ammonium as major nitrogen source, which is assimilated into glutamine by the reaction of Glutamine synthetase (GS, EC 6.3.1.2). Rice plants possess one gene (OsGS2) for chloroplastic GS2 and three genes (OsGS1;1, OsGS1;2 and OsGS1;3) for cytosolic GS1. Here, we report the effect of WD on regulation of GS isoforms in drought-sensitive (cv. IR-64) and drought-tolerant (cv. Khitish) rice cultivars. Under WD, total GS activity in root and leaf decreased significantly in IR-64 seedlings in comparison to Khitish seedlings. The reduced GS activity in IR-64 leaf was mainly due to decrease in GS2 activity, which correlated with decrease in corresponding transcript and polypeptide contents. GS1 transcript and polypeptide accumulated in leaf during WD, however, GS1 activity was maintained at a constant level. Total GS activity in stem of both the varieties was insensitive to WD. Among GS1 genes, OsGS1;1 expression was differently regulated by WD in the two rice varieties. Its transcript accumulated more abundantly in IR-64 leaf than in Khitish leaf. Following WD, OsGS1;1 mRNA level in stem and root tissues declined in IR-64 and enhanced in Khitish. A steady OsGS1;2 expression patterns were noted in leaf, stem and root of both the cultivars. Results suggest that OsGS2 and OsGS1;1 expression may contribute to drought tolerance of Khitish cultivar under WD conditions.

Breeding sunflower for drought tolerance: genetic variability for drought torrance in sunflower (Helianthus Annuus L.)

International Nuclear Information System (INIS)

Hussain, M.K.; Ilyas, M.; Rehman, O.U.

1994-01-01

Five inbred lines and their all possible crosses excluding reciprocals were evaluated for tolerance to drought and effect of drought adversely influenced the traits of leaf area, days to maturity, head diameter, 100-achene weight and achene yield per plant, whereas number of leaves per plant and plant height were comparatively less affected. Average performance of sunflower cross/hybrids was far more better than parental lines. Inbred lines GIMSUN-420x-431 and GIMSUN-498x-477 produced higher achene yield under drought conditions and showed less loses than other. Effect of drought on various growth stages showed that button (R1 stage) was the most critical as compared to 50% flowering (R5 stage) and seed formation (R6 stage) which reduced leaf area, head diameter, 100-achene weight and achene yield per plant by 40-59, 32-14 and 31-07 percent respectively. (author)

Developing drought impact functions for drought risk management

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S. Bachmair

2017-11-01

Full Text Available Drought management frameworks are dependent on methods for monitoring and prediction, but quantifying the hazard alone is arguably not sufficient; the negative consequences that may arise from a lack of precipitation must also be predicted if droughts are to be better managed. However, the link between drought intensity, expressed by some hydrometeorological indicator, and the occurrence of drought impacts has only recently begun to be addressed. One challenge is the paucity of information on ecological and socioeconomic consequences of drought. This study tests the potential for developing empirical drought impact functions based on drought indicators (Standardized Precipitation and Standardized Precipitation Evaporation Index as predictors and text-based reports on drought impacts as a surrogate variable for drought damage. While there have been studies exploiting textual evidence of drought impacts, a systematic assessment of the effect of impact quantification method and different functional relationships for modeling drought impacts is missing. Using Southeast England as a case study we tested the potential of three different data-driven models for predicting drought impacts quantified from text-based reports: logistic regression, zero-altered negative binomial regression (hurdle model, and an ensemble regression tree approach (random forest. The logistic regression model can only be applied to a binary impact/no impact time series, whereas the other two models can additionally predict the full counts of impact occurrence at each time point. While modeling binary data results in the lowest prediction uncertainty, modeling the full counts has the advantage of also providing a measure of impact severity, and the counts were found to be reasonably predictable. However, there were noticeable differences in skill between modeling methodologies. For binary data the logistic regression and the random forest model performed similarly well based on

Drained coastal peatlands: A potential nitrogen source to marine ecosystems under prolonged drought and heavy storm events-A microcosm experiment.

Science.gov (United States)

Wang, Hongjun; Richardson, Curtis J; Ho, Mengchi; Flanagan, Neal

2016-10-01

Over the past several decades there has been a massive increase in coastal eutrophication, which is often caused by increased runoff input of nitrogen from landscape alterations. Peatlands, covering 3% of land area, have stored about 12-21% of global soil organic nitrogen (12-20Pg N) around rivers, lakes and coasts over millennia and are now often drained and farmed. Their huge nitrogen pools may be released by intensified climate driven hydrologic events-prolonged droughts followed by heavy storms-and later transported to marine ecosystems. In this study, we collected peat monoliths from drained, natural, and restored coastal peatlands in the Southeastern U.S., and conducted a microcosm experiment simulating coupled prolonged-drought and storm events to (1) test whether storms could trigger a pulse of nitrogen export from drought-stressed peatlands and (2) assess how differentially hydrologic managements through shifting plant communities affect nitrogen export by combining an experiment of nitrogen release from litter. During the drought phase, we observed a significant temporal variation in net nitrogen mineralization rate (NMR). NMR spiked in the third month and then decreased rapidly. This pattern indicates that drought duration significantly affects nitrogen mineralization in peat. NMR in the drained site reached up to 490±110kgha(-1)year(-1), about 5 times higher than in the restored site. After the 14-month drought phase, we simulated a heavy storm by bringing peat monoliths to saturation. In the discharge waters, concentrations of total dissolved nitrogen in the monoliths from the drained site (72.7±16.3mgL(-1)) was about ten times as high as from the restored site. Our results indicate that previously drained peatlands under prolonged drought are a potent source of nitrogen export. Moreover, drought-induced plant community shifts to herbaceous plants substantially raise nitrogen release with lasting effects by altering litter quality in peatlands

Drought, Agriculture, and Labor: Understanding Drought Impacts and Vulnerability in California

Science.gov (United States)

Greene, C.

2015-12-01

Hazardous drought impacts are a product of not only the physical intensity of drought, but also the economic, social, and environmental characteristics of the region exposed to drought. Drought risk management requires understanding the complex links between the physical and human dimensions of drought. Yet, there is a research gap in identifying and explaining the socio-economic complexities of drought in the context of the first world, especially for economic and socially marginal groups who rely on seasonal and temporary jobs. This research uses the current drought in California as a case study to identify the socioeconomic impacts of drought on farmworker communities in California's San Joaquin Valley, with a specific focus on the relationship between drought and agricultural labor. Through both a narrative analysis of drought coverage in newspaper media, drought policy documents, and interviews with farmworkers, farmers, community based organizations, and government officials in the San Joaquin Valley, this research aims to highlight the different understandings and experiences of the human impacts of drought and drought vulnerability in order to better inform drought risk planning and policy.

Ectomycorrhizal inoculation with Pisolithus tinctorius reduces stress induced by drought in cork oak.

Science.gov (United States)

Sebastiana, Mónica; da Silva, Anabela Bernardes; Matos, Ana Rita; Alcântara, André; Silvestre, Susana; Malhó, Rui

2018-04-01

We investigated whether the performance of cork oak under drought could be improved by colonization with the ectomycorrhizal fungus Pisolithus tinctorius. Results show that inoculation alone had a positive effect on plant height, shoot biomass, shoot basal diameter, and root growth. Under drought, root growth of mycorrhizal plants was significantly increased showing that inoculation was effective in increasing tolerance to drought. In accordance, mycorrhizal plants subjected to drought showed less symptoms of stress when compared to non-mycorrhizal plants, such as lower concentration of soluble sugars and starch, increased ability to maintain fatty acid content and composition, and increased unsaturation level of membrane lipids. After testing some of the mechanisms suggested to contribute to the enhanced tolerance of mycorrhizal plants to drought, we could not find any by which Pisolithus tinctorius could benefit cork oak, at least under the drought conditions imposed in our experiment. Inoculation did not increase photosynthesis under drought, suggesting no effect in sustaining stomatal opening at low soil water content. Similarly, plant water status was not affected by inoculation suggesting that P. tinctorius does not contribute to an increased plant water uptake during drought. Inoculation did increase nitrogen concentration in plants but it was independent of the water status. Furthermore, no significant mycorrhizal effect on drought-induced ROS production or osmotic adjustment was detected, suggesting that these factors are not important for the improved drought tolerance triggered by P. tinctorius.

Differential gene expression in soybean leaf tissues at late developmental stages under drought stress revealed by genome-wide transcriptome analysis.

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Dung Tien Le

many photosynthesis-related genes, which contribute to growth retardation under drought stress, may serve as an adaptive mechanism for plant survival. This study has identified excellent drought-responsive candidate genes for in-depth characterization and future development of improved drought-tolerant transgenic soybeans.

Drought-Tolerant Plant Growth-Promoting Rhizobacteria Associated with Foxtail Millet in a Semi-arid Agroecosystem and Their Potential in Alleviating Drought Stress

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Xuguang Niu

2018-01-01

Full Text Available The application of plant growth promoting rhizobacteria (PGPR to agro-ecosystems is considered to have the potential for improving plant growth in extreme environments featured by water shortage. Herein, we isolated bacterial strains from foxtail millet (Setaria italica L., a drought-tolerant crop cultivated in semiarid regions in the northeast of China. Four isolates were initially selected for their ability to produce ACC deaminase as well as drought tolerance. The isolates were identified as Pseudomonas fluorescens, Enterobacter hormaechei, and Pseudomonas migulae on the basis of 16S rRNA sequence analysis. All of these drought-tolerant isolates were able to produce EPS (exopolysaccharide. Inoculation with these strains stimulated seed germination and seedling growth under drought stress. Pseudomonas fluorescens DR7 showed the highest level of ACC deaminase and EPS-producing activity. DR7 could efficiently colonize the root adhering soil, increased soil moisture, and enhance the root adhering soil/root tissue ratio. These results suggest drought tolerant PGPR from foxtail millet could enhance plant growth under drought stress conditions and serve as effective bioinoculants to sustain agricultural production in arid regions.

Drought Duration Biases in Current Global Climate Models

Science.gov (United States)

Moon, Heewon; Gudmundsson, Lukas; Seneviratne, Sonia

2016-04-01

Several droughts in the recent past are characterized by their increased duration and intensity. In particular, substantially prolonged droughts have brought major societal and economic losses in certain regions, yet climate change projections of such droughts in terms of duration is subject to large uncertainties. This study analyzes the biases of drought duration in state-of-the-art global climate model (GCM) simulations from the 5th phase of Coupled Model Intercomparison Project (CMIP5). Drought durations are defined as negative precipitation anomalies and evaluated with three observation-based datasets in the period of 1901-2010. Large spread in biases of GCMs is commonly found in all regions, with particular strong biases in North East Brazil, Africa, Northern Australia, Central America, Central and Northern Europe, Sahel and Asia. Also in most regions, the interquartile range of bias lies below 0, meaning that the GCMs tend to underestimate drought durations. Meanwhile in some regions such as Western South America, the Amazon, Sahel, West and South Africa, and Asia, considerable inconsistency among the three observation-based datasets were found. These results indicate substantial uncertainties and errors in current GCMs for simulating drought durations as well as a large spread in observation-based datasets, both of which are found to be particularly strong in those regions that are often considered to be hot spots of projected future drying. The underlying sources of these uncertainties need to be identified in further study and will be applied to constrain GCM-based drought projections under climate change.

Drought effect on growth, gas exchange and yield, in two strains of local barley Ardhaoui, under water deficit conditions in southern Tunisia.

Science.gov (United States)

Thameur, Afwa; Lachiheb, Belgacem; Ferchichi, Ali

2012-12-30

Two local barley strains cv. Ardhaoui originated from Tlalit and Switir, sourthern Tunisia were grown in pots in a glasshouse assay, under well-watered conditions for a month. Plants were then either subjected to water deficit (treatment) or continually well-watered (control). Control pots were irrigated several times each week to maintain soil moisture near field capacity (FC), while stress pots experienced soil drying by withholding irrigation until they reached 50% of FC. Variation in relative water content, leaf area, leaf appearance rate and leaf gas exchange (i.e. net CO(2) assimilation rate (A), transpiration (E), and stomatal conductance (gs)) in response to water deficit was investigated. High leaf relative water content (RWC) was maintained in Tlalit by stomatal closure and a reduction of leaf area. Reduction in leaf area was due to decline in leaf gas exchange during water deficit. Tlalit was found to be drought tolerant and able to maintain higher leaf RWC under drought conditions. Water deficit treatment reduced stomatal conductance by 43% at anthesis. High net CO(2) assimilation rate under water deficit was associated with high RWC (r = 0.998; P gas exchange parameters were found, which can give some indications on the degree of drought tolerance. Thus, the ability of the low leaf area plants to maintain higher RWC could explain the differences in drought tolerance in studied barley strains. Results showed that Tlalit showed to be more efficient and more productive than Switir. Copyright © 2012 Elsevier Ltd. All rights reserved.

Propagation of edge waves in a thinly layered laminated medium with stress couples under initial stresses

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Pijush Pal Roy

1987-01-01

Full Text Available The propagation of edge waves in a thinly layered laminated medium with stress couples under initial stresses is examined. Based upon an approximate representation of a laminated medium by an equivalent anisotropic continuum with average initial and couple stresses, an explicit form of frequency equation is obtained to derive the phase velocity of edge waves. Edge waves exist under certain conditions. The inclusion of couple stresses increases the velocity of wave propagation. For a specific compression, the presence of couple stresses increases the velocity of wave propagation with the increase of wave number, whereas the reverse is the case when there is no couple stress. Numerical computation is performed with graphical representations. Several special cases are also examined.

Evaluation of Chitosan Nanoparticles Effects on Yield and Yield Components of Barley (Hordeum vulgare L. under Late Season Drought Stress

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Faride Behboudi

2018-01-01

Full Text Available As a step towards the profitable employment of nanoparticles (NPs in agriculture, effects of chitosan NPs was probed on barley plants under late season drought stress. A factorial experiment was performed based on a randomized complete block design with three replications. The experimental factors included the chitosan NPs concentrations (0 (control, 30, 60 and 90 ppm, application methods (foliar and soil application and irrigation regimes (well-watered and withholding of irrigation for 15 days after pollination. The barley seeds were separately planted in pots. Then, the NPs were added to them through the soil and foliar application at three stages. The results indicated that using the chitosan NPs, especially 60 and 90 ppm, significantly increased the leaf area (LA, the leaf color (SPAD, the number of grain per spike, the grain yield and the harvest index compared to the control. Also, drought stress significantly decreased the yield and yield components compared to the well-watered plants. In contrast, using the chitosan NPs in plants under drought stress significantly increased the relative water content (RWC, the 1000-grain weight, the grain protein, the proline content, the catalase (CAT and the superoxide dismutase (SOD compared to the control. There was no a significant difference between two methods of using NPs in most studied traits. The results highlighted that using the chitosan NPs, especially 60 and 90 ppm, in both irrigation regimes can significantly improve the majority of the studied traits compared to the control and mitigate the harmful effects of drought stress.

Spatiotemporal Drought Analysis and Drought Indices Comparison in India

Science.gov (United States)

Janardhanan, A.

2017-12-01

Droughts and floods are an ever-occurring phenomenon that has been wreaking havoc on humans since the start of time. As droughts are on a very large scale, studying them within a regional context can minimize confounding factors such as climate change. Droughts and floods are extremely erratic and very difficult to predict and therefore necessitate modeling through advanced statistics. The SPI (Standard Precipitation Index) and the SPEI (Standard Precipitation Evapotranspiration Index) are two ways to temporally model drought and flood patterns across each metrological sub basin in India over a variety of different time scales. SPI only accounts for precipitation values, while the SPEI accounts for both precipitation and temperature and is commonly regarded as a more reliable drought index. Using monthly rainfall and temperature data from 1871-2016, these two indices were calculated. The results depict the drought and flood severity index, length of drought, and average SPI or SPEI value for each meteorological sub region in India. A Wilcox Ranksum test was then conducted to determine whether these two indices differed over the long term for drought analysis. The drought return periods were analyzed to determine if the population mean differed between the SPI and SPEI values. Our analysis found no statistical difference between SPI and SPEI with regards to long-term drought analysis. This indicates that temperature is not needed when modeling drought on a long-term time scale and that SPI is just as effective as SPEI, which has the potential to save a lot of time and resources on calculating drought indices.

Transgenerational variations in DNA methylation induced by drought stress in two rice varieties with distinguished difference to drought resistance.

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Xiaoguo Zheng

Full Text Available Adverse environmental conditions have large impacts on plant growth and crop production. One of the crucial mechanisms that plants use in variable and stressful natural environments is gene expression modulation through epigenetic modification. In this study, two rice varieties with different drought resistance levels were cultivated under drought stress from tilling stage to seed filling stage for six successive generations. The variations in DNA methylation of the original generation (G0 and the sixth generation (G6 of these two varieties in normal condition (CK and under drought stress (DT at seedling stage were assessed by using Methylation Sensitive Amplification Polymorphism (MSAP method. The results revealed that drought stress had a cumulative effect on the DNA methylation pattern of both varieties, but these two varieties had different responses to drought stress in DNA methylation. The DNA methylation levels of II-32B (sensitive and Huhan-3 (resistant were around 39% and 32%, respectively. Genome-wide DNA methylation variations among generations or treatments accounted for around 13.1% of total MSAP loci in II-32B, but was only approximately 1.3% in Huhan-3. In II-32B, 27.6% of total differentially methylated loci (DML were directly induced by drought stress and 3.2% of total DML stably transmitted their changed DNA methylation status to the next generation. In Huhan-3, the numbers were 48.8% and 29.8%, respectively. Therefore, entrainment had greater effect on Huhan-3 than on II-32B. Sequence analysis revealed that the DML were widely distributed on all 12 rice chromosomes and that it mainly occurred on the gene's promoter and exon region. Some genes with DML respond to environmental stresses. The inheritance of epigenetic variations induced by drought stress may provide a new way to develop drought resistant rice varieties.

A novel gene of Kalanchoe daigremontiana confers plant drought resistance.

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Wang, Li; Zhu, Chen; Jin, Lin; Xiao, Aihua; Duan, Jie; Ma, Luyi

2018-02-07

Kalanchoe (K.) daigremontiana is important for studying asexual reproduction under different environmental conditions. Here, we describe a novel KdNOVEL41 (KdN41) gene that may confer drought resistance and could thereby affect K. daigremontiana development. The detected subcellular localization of a KdN41/Yellow Fluorescent Protein (YFP) fusion protein was in the nucleus and cell membrane. Drought, salt, and heat stress treatment in tobacco plants containing the KdN41 gene promoter driving β-glucuronidase (GUS) gene transcription revealed that only drought stress triggered strong GUS staining in the vascular tissues. Overexpression (OE) of the KdN41 gene conferred improved drought resistance in tobacco plants compared to wild-type and transformed with empty vector plants by inducing higher antioxidant enzyme activities, decreasing cell membrane damage, increasing abscisic acid (ABA) content, causing reinforced drought resistance related gene expression profiles. The 3,3'-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining results also showed less relative oxygen species (ROS) content in KdN41-overexpressing tobacco leaf during drought stress. Surprisingly, by re-watering after drought stress, KdN41-overexpressing tobacco showed earlier flowering. Overall, the KdN41 gene plays roles in ROS scavenging and osmotic damage reduction to improve tobacco drought resistance, which may increase our understanding of the molecular network involved in developmental manipulation under drought stress in K. daigremontiana.

The Effect of Ascorbic Acid Treatment on Viability and Vigor Maize (Zea mays L. Seedling under Drought Stress

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HAMIDAH HAMAMA

2010-09-01

Full Text Available This study was conducted in the laboratory and the field to examine the effects of ascorbic acid treatment on germination and seedling growth under drought stress. The laboratory works consisted of two experiments and were designed to determine the critical osmotic potential of maize and to determine the optimum ascorbic acid concentration. The field study was designed to examine the effects of soaking seed in ascorbic acid on seedling growth under drought stress. Drought condition was simulated by PEG-6000 and regulation of water treatment. During the first experiment, interactions of both osmotic potential and varieties were significant at all variables. Germination percentage and speed of germination were significantly decreased by increasing of osmotic potential. The second experiment showed that interactions of both factors were significant at all variables except vigor index, the length of shoot, primary, and seminal root. The results showed that the ascorbic acid treatment improved the germination percentage, the speed of germination and the vigor index compared with the control, besides the increase in length of shoot, primary and seminal root and number of seminal root. However, the best result was showed by 55 mM ascobic acid. The result of field experiment showed that interactions were not always significant and 55 mM ascorbic acid treatment increased the seedling height, the number of leaves and leaf area but it had no effect on the water deficit and the root length.

Drought occurence

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John W. Coulston

2007-01-01

Why Is Drought Important? Drought is an important forest disturbance that occurs regularly in the Western United States and irregularly in the Eastern United States (Dale and others 2001). Moderate drought stress tends to slow plant growth while severedrought stress can also reduce photosynthesis (Kareiva and others 1993). Drought can also interact with...

Comprehensive drought characteristics analysis based on a nonlinear multivariate drought index

Science.gov (United States)

Yang, Jie; Chang, Jianxia; Wang, Yimin; Li, Yunyun; Hu, Hui; Chen, Yutong; Huang, Qiang; Yao, Jun

2018-02-01

It is vital to identify drought events and to evaluate multivariate drought characteristics based on a composite drought index for better drought risk assessment and sustainable development of water resources. However, most composite drought indices are constructed by the linear combination, principal component analysis and entropy weight method assuming a linear relationship among different drought indices. In this study, the multidimensional copulas function was applied to construct a nonlinear multivariate drought index (NMDI) to solve the complicated and nonlinear relationship due to its dependence structure and flexibility. The NMDI was constructed by combining meteorological, hydrological, and agricultural variables (precipitation, runoff, and soil moisture) to better reflect the multivariate variables simultaneously. Based on the constructed NMDI and runs theory, drought events for a particular area regarding three drought characteristics: duration, peak, and severity were identified. Finally, multivariate drought risk was analyzed as a tool for providing reliable support in drought decision-making. The results indicate that: (1) multidimensional copulas can effectively solve the complicated and nonlinear relationship among multivariate variables; (2) compared with single and other composite drought indices, the NMDI is slightly more sensitive in capturing recorded drought events; and (3) drought risk shows a spatial variation; out of the five partitions studied, the Jing River Basin as well as the upstream and midstream of the Wei River Basin are characterized by a higher multivariate drought risk. In general, multidimensional copulas provides a reliable way to solve the nonlinear relationship when constructing a comprehensive drought index and evaluating multivariate drought characteristics.

Possible Future Climate Change Impacts on the Hydrological Drought Events in the Weihe River Basin, China

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Fei Yuan

2016-01-01

Full Text Available Quantitative evaluation of future climate change impacts on hydrological drought characteristics is one of important measures for implementing sustainable water resources management and effective disaster mitigation in drought-prone regions under the changing environment. In this study, a modeling system for projecting the potential future climate change impacts on hydrological droughts in the Weihe River basin (WRB in North China is presented. This system consists of a large-scale hydrological model driven by climate outputs from three climate models (CMs for future streamflow projections, a probabilistic model for univariate drought assessment, and a copula-based bivariate model for joint drought frequency analysis under historical and future climates. With the observed historical climate data as the inputs, the Variable Infiltration Capacity hydrological model projects an overall runoff reduction in the WRB under the Intergovernmental Panel on Climate Change A1B scenario. The univariate drought assessment found that although fewer hydrological drought events would occur under A1B scenario, drought duration and severity tend to increase remarkably. Moreover, the bivariate drought assessment reveals that future droughts in the same return period as the baseline droughts would become more serious. With these trends in the future, the hydrological drought situation in the WRB would be further deteriorated.

Impact of interspecific competition and drought on the allocation of new assimilates in trees.

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Hommel, R; Siegwolf, R; Zavadlav, S; Arend, M; Schaub, M; Galiano, L; Haeni, M; Kayler, Z E; Gessler, A

2016-09-01

In trees, the interplay between reduced carbon assimilation and the inability to transport carbohydrates to the sites of demand under drought might be one of the mechanisms leading to carbon starvation. However, we largely lack knowledge on how drought effects on new assimilate allocation differ between species with different drought sensitivities and how these effects are modified by interspecific competition. We assessed the fate of (13) C labelled assimilates in above- and belowground plant organs and in root/rhizosphere respired CO2 in saplings of drought-tolerant Norway maple (Acer platanoides) and drought-sensitive European beech (Fagus sylvatica) exposed to moderate drought, either in mono- or mixed culture. While drought reduced stomatal conductance and photosynthesis rates in both species, both maintained assimilate transport belowground. Beech even allocated more new assimilate to the roots under moderate drought compared to non-limited water supply conditions, and this pattern was even more pronounced under interspecific competition. Even though maple was a superior competitor compared to beech under non-limited soil water conditions, as indicated by the changes in above- and belowground biomass of both species in the interspecific competition treatments, we can state that beech was still able to efficiently allocate new assimilate belowground under combined drought and interspecific competition. This might be seen as a strategy to maintain root osmotic potential and to prioritise root functioning. Our results thus show that beech tolerates moderate drought stress plus competition without losing its ability to supply belowground tissues. It remains to be explored in future work if this strategy is also valid during long-term drought exposure. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Drought risk assessment under climate change is sensitive to methodological choices for the estimation of evaporative demand.

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Dewes, Candida F; Rangwala, Imtiaz; Barsugli, Joseph J; Hobbins, Michael T; Kumar, Sanjiv

2017-01-01

Several studies have projected increases in drought severity, extent and duration in many parts of the world under climate change. We examine sources of uncertainty arising from the methodological choices for the assessment of future drought risk in the continental US (CONUS). One such uncertainty is in the climate models' expression of evaporative demand (E0), which is not a direct climate model output but has been traditionally estimated using several different formulations. Here we analyze daily output from two CMIP5 GCMs to evaluate how differences in E0 formulation, treatment of meteorological driving data, choice of GCM, and standardization of time series influence the estimation of E0. These methodological choices yield different assessments of spatio-temporal variability in E0 and different trends in 21st century drought risk. First, we estimate E0 using three widely used E0 formulations: Penman-Monteith; Hargreaves-Samani; and Priestley-Taylor. Our analysis, which primarily focuses on the May-September warm-season period, shows that E0 climatology and its spatial pattern differ substantially between these three formulations. Overall, we find higher magnitudes of E0 and its interannual variability using Penman-Monteith, in particular for regions like the Great Plains and southwestern US where E0 is strongly influenced by variations in wind and relative humidity. When examining projected changes in E0 during the 21st century, there are also large differences among the three formulations, particularly the Penman-Monteith relative to the other two formulations. The 21st century E0 trends, particularly in percent change and standardized anomalies of E0, are found to be sensitive to the long-term mean value and the amplitude of interannual variability, i.e. if the magnitude of E0 and its interannual variability are relatively low for a particular E0 formulation, then the normalized or standardized 21st century trend based on that formulation is amplified

Unstable propagation behavior of a ductile crack in SUS-304 stainless steel under high compliance tensile loading

International Nuclear Information System (INIS)

Tomoda, Yoshio

1981-01-01

In relation to the safe maintenance of nuclear power plants, it is necessary to prevent reactor coolant pipings from burst type failure caused by the unstable propagation of defects and cracks, such as stress corrosion cracking and fatigue cracks. In ductile materials, crack propagation is stable in tensile loading under fixed grip condition, when a specimen is controlled to deform in proportion to the increase of tensile load. However, it has been known that the instability of ductile cracks occurs after tensile load reached the maximum, especially under constant loading condition arising in the loading devices with high compliance or low tensile rigidity. In order to confirm the reliability of SUS 304 stainless pipes subjected to SCC, the crack propagation behavior was examined with the specimens having center cracks, using both testing machines with high compliance and low compliance. The instability of ductile cracks and the propagation velocity of unstable cracks were analyzed, and the calculated results were compated with the experimental results. Not only the compliance of testing machines but also the conditions of specimens affected the propagation of cracks. (Kako, I.)

Physiological and molecular responses to drought in Petunia: the importance of stress severity

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Kim, Jongyun

2012-01-01

Plant responses to drought stress vary depending on the severity of stress and the stage of drought progression. To improve the understanding of such responses, the leaf physiology, abscisic acid (ABA) concentration, and expression of genes associated with ABA metabolism and signalling were investigated in Petunia × hybrida. Plants were exposed to different specific substrate water contents (θ = 0.10, 0.20, 0.30, or 0.40 m3·m–3) to induce varying levels of drought stress. Plant responses were investigated both during the drying period (θ decreased to the θ thresholds) and while those threshold θ were maintained. Stomatal conductance (gs) and net photosynthesis (A) decreased with decreasing midday leaf water potential (Ψleaf). Leaf ABA concentration increased with decreasing midday Ψleaf and was negatively correlated with gs (r = –0.92). Despite the increase in leaf ABA concentration under drought, no significant effects on the expression of ABA biosynthesis genes were observed. However, the ABA catabolism-related gene CYP707A2 was downregulated, primarily in plants under severe drought (θ = 0.10 m3∙m–3), suggesting a decrease in ABA catabolism under severe drought. Expression of phospholipase Dα (PLDα), involved in regulating stomatal responses to ABA, was enhanced under drought during the drying phase, but there was no relationship between PLDα expression and midday Ψleaf after the θ thresholds had been reached. The results show that drought response of plants depends on the severity of drought stress and the phase of drought progression. PMID:23077204

Oak sprouts grow better than seedlings under drought stress

Czech Academy of Sciences Publication Activity Database

Pietras, Justyna; Stojanović, Marko; Knott, R.; Pokorný, Radek

2016-01-01

Roč. 9, č. 4 (2016), s. 529-535 ISSN 1971-7458 R&D Projects: GA MŠk(CZ) EE2.3.20.0267 Institutional support: RVO:67179843 Keywords : drought stress * sap flow * transpiration * biomass Production * sessile Oak * sprout * seedling Subject RIV: EF - Botanics Impact factor: 1.623, year: 2016

Glutathione reductase in leaves of cowpea: cloning of two cDNAs, expression and enzymatic activity under progressive drought stress, desiccation and abscisic acid treatment.

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Contour-Ansel, Dominique; Torres-Franklin, Maria Lucia; Cruz DE Carvalho, Maria Helena; D'Arcy-Lameta, Agnès; Zuily-Fodil, Yasmine

2006-12-01

Reactive oxygen species are frequently produced when plants are exposed to abiotic stresses. Among the detoxication systems, two enzymes, ascorbate peroxidase and glutathione reductase (GR) play key roles. GR has also a central role in keeping the reduced glutathione pool during stress thus allowing the adjustments on the cellular redox reactions. The aim of this work was to study the variations in cytosolic and dual-targeted GR gene expression in the leaves of cowpea plants submitted to progressive drought, rapid desiccation and application of exogenous abscisic acid (ABA). Two cowpea (Vigna unguiculata) cultivars, one drought-resistant ('EPACE-1'), the other drought-sensitive ('1183') were submitted to progressive drought stress by withholding irrigation. Cut-off leaves were air-dried or treated with exogenous ABA. Two GR cDNAs, one cytosolic, the other dual-targeted to chloroplasts and mitochondria were isolated by PCR and cloned in plasmid vectors. Reverse-transcription PCR was used to study the variations in GR gene expression. Two new cDNAs encoding a putative dual-targeted and a cytosolic GR were cloned and sequenced from leaves of V. unguiculata. Drought stress induced an up-regulation of the expression of the cytosolic GR gene directly related to the intensity of the stress in both cultivars. The expression of dual-targeted GR was up-regulated by the drought treatment in the susceptible cultivar only. Under a fast desiccation, the '1183' cultivar responded later than the 'EPACE-1', although in 'EPACE-1' it was the cytosolic isoform which responded and in '1183' the dual-targeted one. Exogenous ABA enhanced significantly the activity and expression levels of GR in both cultivars after treatment for 24 h. These results demonstrate a noticeable activation in both cultivars of the antioxidant metabolism under a progressive water stress, which involves both GR genes in the case of the susceptible cultivar. Under a fast desiccation, the susceptible cultivar

Biochar soil amendment on alleviation of drought and salt stress in plants: a critical review.

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Ali, Shafaqat; Rizwan, Muhammad; Qayyum, Muhammad Farooq; Ok, Yong Sik; Ibrahim, Muhammad; Riaz, Muhammad; Arif, Muhammad Saleem; Hafeez, Farhan; Al-Wabel, Mohammad I; Shahzad, Ahmad Naeem

2017-05-01

Drought and salt stress negatively affect soil fertility and plant growth. Application of biochar, carbon-rich material developed from combustion of biomass under no or limited oxygen supply, ameliorates the negative effects of drought and salt stress on plants. The biochar application increased the plant growth, biomass, and yield under either drought and/or salt stress and also increased photosynthesis, nutrient uptake, and modified gas exchange characteristics in drought and salt-stressed plants. Under drought stress, biochar increased the water holding capacity of soil and improved the physical and biological properties of soils. Under salt stress, biochar decreased Na + uptake, while increased K + uptake by plants. Biochar-mediated increase in salt tolerance of plants is primarily associated with improvement in soil properties, thus increasing plant water status, reduction of Na + uptake, increasing uptake of minerals, and regulation of stomatal conductance and phytohormones. This review highlights both the potential of biochar in alleviating drought and salt stress in plants and future prospect of the role of biochar under drought and salt stress in plants.

Contribution of arbuscular mycorrhizal fungi and/or bacteria to enhancing plant drought tolerance under natural soil conditions: effectiveness of autochthonous or allochthonous strains.

Science.gov (United States)

Ortiz, N; Armada, E; Duque, E; Roldán, A; Azcón, R

2015-02-01

Autochthonous microorganisms [a consortium of arbuscular-mycorrhizal (AM) fungi and Bacillus thuringiensis (Bt)] were assayed and compared to Rhizophagus intraradices (Ri), Bacillus megaterium (Bm) or Pseudomonas putida (Psp) and non-inoculation on Trifolium repens in a natural arid soil under drought conditions. The autochthonous bacteria Bt and the allochthonous bacteria Psp increased nutrients and the relative water content and decreased stomatal conductance, electrolyte leakage, proline and APX activity, indicating their abilities to alleviate the drought stress. Mycorrhizal inoculation significantly enhanced plant growth, nutrient uptake and the relative water content, particularly when associated with specific bacteria minimizing drought stress-imposed effects. Specific combinations of autochthonous or allochthonous inoculants also contributed to plant drought tolerance by changing proline and antioxidative activities. However, non-inoculated plants had low relative water and nutrients contents, shoot proline accumulation and glutathione reductase activity, but the highest superoxide dismutase activity, stomatal conductance and electrolyte leakage. Microbial activities irrespective of the microbial origin seem to be coordinately functioning in the plant as an adaptive response to modulated water stress tolerance and minimizing the stress damage. The autochthonous AM fungi with Bt or Psp and those allochthonous Ri with Bm or Psp inoculants increased water stress alleviation. The autochthonous Bt showed the greatest ability to survive under high osmotic stress compared to the allochthonous strains, but when single inoculated or associated with Ri or AM fungi were similarly efficient in terms of physiological and nutritional status and in increasing plant drought tolerance, attenuating and compensating for the detrimental effect of water limitation. Copyright © 2014 Elsevier GmbH. All rights reserved.

Evaluation of Chlorophyll Fluorescence and Biochemical Traits of Lettuce under Drought Stress and Super Absorbent or Bentonite Application

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Akram Valizadeh Ghale Beig

2014-03-01

Full Text Available The effects of two superabsorbents (natural-bentonite and (synthetic-A 200 on the chlorophyll fluorescence index, proline accumulation, phenolic compounds, antioxidant activity and total carbohydrate in lettuce (Lactuca sativa L. was evaluated. For this purpose, a factorial experiment using completely randomized design with superabsorbents at 3 levels (0, 0.15, 0.30 w/w%, drought stress at 2 levels (60 and 100% of field capacity and 4 replicates was conducted. Results showed that photosystem photochemical efficiency (Fv/Fm II under drought stress (60% FC as well as lower levels of bentonite superabsorbent polymer reduced. The minimum and maximum proline content were obtained in 0.3% bentonite, 100% FC and 0 benetonite, 60% FC, respectively. The lowest and highest phenolic compounds was corresponded to the highest levels in both super absorbents and control respectively, so that the super absorbent and bentonite, reduced phenolic compounds by 62.65 and 66.21% compared to control. 0 and 0.15 wt % bentonite in high drought stress (60% FC showed the highest and 0.3 wt % bentonite and 100% FC attained the lowest level of antioxidant activity. Control bentonite treatment beds at 60% FC and beds containing 0.3 wt. % bentonite in 100% FC, showed the lowest and the highest total carbohydrate content respectively. Results of this study indicate that bentonite can reduce the negative effects of drought stress similar to artificial super absorbent.

Drought Variability in the Eastern Australia and New Zealand Summer Drought Atlas (ANZDA, CE 1500-2012) Modulated by the Interdecadal Pacific Oscillation

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Palmer, Jonathan G.; Cook, Edward R.; Turney, Chris S. M.; Allen, Kathy; Fenwick, Pavla; Cook, Benjamin I.; O'Donnell, Alison; Lough, Janice; Grierson, Pauline; Baker, Patrick

2015-01-01

Agricultural production across eastern Australia and New Zealand is highly vulnerable to drought, but there is a dearth of observational drought information prior to CE (Christian Era) 1850. Using a comprehensive network of 176 drought-sensitive tree-ring chronologies and one coral series, we report the first Southern Hemisphere gridded drought atlas extending back to CE 1500. The austral summer (December-February) Palmer drought sensitivity index reconstruction accurately reproduces historically documented drought events associated with the first European settlement of Australia in CE 1788, and the leading principal component explains over 50 percent of the underlying variance. This leading mode of variability is strongly related to the Interdecadal Pacific Oscillation tripole index (IPO), with a strong and robust antiphase correlation between (1) eastern Australia and the New Zealand North Island and (2) the South Island. Reported positive, negative, and neutral phases of the IPO are consistently reconstructed by the drought atlas although the relationship since CE 1976 appears to have weakened.

Drought Risk Identification: Early Warning System of Seasonal Agrometeorological Drought

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Dalecios, Nicolas; Spyropoulos, Nicos V.; Tarquis, Ana M.

2014-05-01

By considering drought as a hazard, drought types are classified into three categories, namely meteorological or climatological, agrometeorological or agricultural and hydrological drought and as a fourth class the socioeconomic impacts can be considered. This paper addresses agrometeorological drought affecting agriculture within the risk management framework. Risk management consists of risk assessment, as well as a feedback on the adopted risk reduction measures. And risk assessment comprises three distinct steps, namely risk identification, risk estimation and risk evaluation. This paper deals with the quantification and monitoring of agrometeorological drought, which constitute part of risk identification. For the quantitative assessment of agrometeorological or agricultural drought, as well as the computation of spatiotemporal features, one of the most reliable and widely used indices is applied, namely the Vegetation Health Index (VHI). The computation of VHI is based on satellite data of temperature and the Normalized Difference Vegetation Index (NDVI). The spatiotemporal features of drought, which are extracted from VHI are: areal extent, onset and end time, duration and severity. In this paper, a 20-year (1981-2001) time series of NOAA/AVHRR satellite data is used, where monthly images of VHI are extracted. Application is implemented in Thessaly, which is the major agricultural region of Greece characterized by vulnerable and drought-prone agriculture. The results show that every year there is a seasonal agrometeorological drought with a gradual increase in the areal extent and severity with peaks appearing usually during the summer. Drought monitoring is conducted by monthly remotely sensed VHI images. Drought early warning is developed using empirical relationships of severity and areal extent. In particular, two second-order polynomials are fitted, one for low and the other for high severity drought, respectively. The two fitted curves offer a seasonal

Effects of planting density and drought on the productivity of tea clones ( Camellia sinensis L.): Yield responses

Science.gov (United States)

Kigalu, Julius M.

Tea is an important cash crop in Tanzania, contributing over US$ 45 million of annual exports and grown by over 30 000 smallholder households, and a further 10 000 people are employed by large estate producers. Over 70% of the national tea production comes from the Southern Highlands of Tanzania where expansion of tea estates under limited suitable land for tea is expected for the next two decades. Thus a client-demand driven field experiment was established in January 1993 to study and advice tea growers on the effects of plant density on the productivity and water use of young tea. The experiment comprised of two types of vegetative propagated tea plants (known as “clones”) of contrasting growth behaviour (AHP S15/10: spreading type and BBK35: erect), six plant densities (labelled D1: 8300 plants ha -1 to D6: 83 300 plants ha -1) and seven irrigation or drought levels (labelled I0: un irrigated, to I6: well irrigated condition) as the treatments. Clone AHP S15/10, with larger crop cover than clone BBK35, consistently out-yielded clone BBK35 at all densities and under both well watered and drought stressed conditions. The corresponding yields from clone BBK35 were 2620 and 5960 kg ha -1. Reciprocal of yield per plant- and asymptotic yield-density relationships were used to explain these responses to density. Yields from clone AHP S15/10 during the period of drought treatments decreased as the maximum soil water deficit increased at all densities, but there were no yield responses to drought from clone BBK35 at the low densities. The study recommends planting densities of 20 000 and 40 000 plants ha -1 for clones AHP S15/10, respectively for well irrigated conditions and a density of 20 000 plants ha -1 for both clones under un-irrigated environments.

Propagating nonpremixed edge-flames in a counterflow, annular slot burner under DC electric fields

KAUST Repository

Tran, Vu Manh

2016-09-11

Characteristics of propagating nonpremixed edge-flames were investigated in a counterflow, annular slot burner. A high-voltage direct current (DC) was applied to the lower part of the burner and the upper part was grounded, creating electric field lines perpendicular to the direction of edge-flame propagation. Upon application of an electric field, an ionic wind is caused by the migration of positive and negative ions to lower and higher electrical potential sides of a flame, respectively. Under an applied DC, we found a significant decrease in edge-flame displacement speeds unlike several previous studies, which showed an increase in displacement speed. Within a moderate range of field intensity, we found effects on flame propagation speeds to be negligible after correcting the flame displacement speed with respect to the unburned flow velocity ahead of the flame edge. This indicates that the displacement speed of an edge-flame strongly depends on ionic wind and that an electric field has little or no impact on propagation speed. The ionic wind also influenced the location of the stoichiometric contour in front of the propagating edge in a given configuration such that a propagating edge was relocated to the higher potential side due to an imbalance between ionic winds originating from positive and negative ions. In addition, we observed a steadily wrinkled flame following transient propagation of the edge-flame, a topic for future research. © 2016 The Combustion Institute

Drought impact on vegetation growth and mortality

Science.gov (United States)

Xu, C.; Wang, M.; Allen, C. D.; McDowell, N. G.; Middleton, R. S.

2017-12-01

carbon loss from dead trees. Our results clearly demonstrate the importance of drought impact on forest carbon stocks at the continental level and will provide critical data for future model improvement to better predict the vegetation mortality under droughts.

Spatio-Temporal Patterns of the 2010–2015 Extreme Hydrological Drought across the Central Andes, Argentina

Directory of Open Access Journals (Sweden)

Juan Antonio Rivera

2017-08-01

Full Text Available During the period 2010–2015, the semi-arid Central Andes in Argentina (CAA experienced one of the most severe and long-lasting hydrological droughts on record. Since the snowmelt is the most important source of water, the reduced snowfall over the mountains propagated the drought signal through the streamflows in the adjacent foothills east of the Andes ranges. Motivated by the widespread impacts on the socio-economic activities in the region, this study aims to characterize the recent hydrological drought in terms of streamflow deficits. Based on streamflow data from 20 basins, we used the standardized streamflow index (SSI to characterize hydrological droughts during the period 1971–2016. We found that the regional extent of the 2010–2015 hydrological drought was limited to the basins located north of 38° S, with mean duration of 67 months and maximum drought severity exhibiting a heterogeneous pattern in terms of spatial distribution and time of occurrence. The drought event reached extreme conditions in 14 of the 15 basins in the CAA, being record-breaking drought in six of the basins. This condition was likely driven by a cooling in the tropical Pacific Ocean resembling La Niña conditions, which generated a decrease in snowfall over the Andes due to suppressed frontal activity.

Dose-dependent response of Trichoderma harzianum in improving drought tolerance in rice genotypes.

Science.gov (United States)

Pandey, Veena; Ansari, Mohammad W; Tula, Suresh; Yadav, Sandep; Sahoo, Ranjan K; Shukla, Nandini; Bains, Gurdeep; Badal, Shail; Chandra, Subhash; Gaur, A K; Kumar, Atul; Shukla, Alok; Kumar, J; Tuteja, Narendra

2016-05-01

This study demonstrates a dose-dependent response of Trichoderma harzianum Th-56 in improving drought tolerance in rice by modulating proline, SOD, lipid peroxidation product and DHN / AQU transcript level, and the growth attributes. In the present study, the effect of colonization of different doses of T. harzianum Th-56 strain in rice genotypes were evaluated under drought stress. The rice genotypes treated with increasing dose of T. harzianum strain Th-56 showed better drought tolerance as compared with untreated control plant. There was significant change in malondialdehyde, proline, higher superoxide dismutase level, plant height, total dry matter, relative chlorophyll content, leaf rolling, leaf tip burn, and the number of scorched/senesced leaves in T. harzianum Th-56 treated rice genotypes under drought stress. This was corroborated with altered expression of aquaporin and dehydrin genes in T. harzianum Th-56 treated rice genotypes. The present findings suggest that a dose of 30 g/L was the most effective in improving drought tolerance in rice, and its potential exploitation will contribute to the advancement of rice genotypes to sustain crop productivity under drought stress. Interaction studies of T. harzianum with three aromatic rice genotypes suggested that PSD-17 was highly benefitted from T. harzianum colonization under drought stress.

Integrating ecophysiology and forest landscape models to improve projections of drought effects under climate change.

Science.gov (United States)

Gustafson, Eric J; De Bruijn, Arjan M G; Pangle, Robert E; Limousin, Jean-Marc; McDowell, Nate G; Pockman, William T; Sturtevant, Brian R; Muss, Jordan D; Kubiske, Mark E

2015-02-01

Fundamental drivers of ecosystem processes such as temperature and precipitation are rapidly changing and creating novel environmental conditions. Forest landscape models (FLM) are used by managers and policy-makers to make projections of future ecosystem dynamics under alternative management or policy options, but the links between the fundamental drivers and projected responses are weak and indirect, limiting their reliability for projecting the impacts of climate change. We developed and tested a relatively mechanistic method to simulate the effects of changing precipitation on species competition within the LANDIS-II FLM. Using data from a field precipitation manipulation experiment in a piñon pine (Pinus edulis) and juniper (Juniperus monosperma) ecosystem in New Mexico (USA), we calibrated our model to measurements from ambient control plots and tested predictions under the drought and irrigation treatments against empirical measurements. The model successfully predicted behavior of physiological variables under the treatments. Discrepancies between model output and empirical data occurred when the monthly time step of the model failed to capture the short-term dynamics of the ecosystem as recorded by instantaneous field measurements. We applied the model to heuristically assess the effect of alternative climate scenarios on the piñon-juniper ecosystem and found that warmer and drier climate reduced productivity and increased the risk of drought-induced mortality, especially for piñon. We concluded that the direct links between fundamental drivers and growth rates in our model hold great promise to improve our understanding of ecosystem processes under climate change and improve management decisions because of its greater reliance on first principles. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Fatigue Crack Propagation Behavior of RC Beams Strengthened with CFRP under High Temperature and High Humidity Environment

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Dongyang Li

2017-01-01

Full Text Available Numerical and experimental methods were applied to investigate fatigue crack propagation behavior of reinforced concrete (RC beams strengthened with a new type carbon fiber reinforced polymer (CFRP named as carbon fiber laminate (CFL subjected to hot-wet environment. J-integral of a central crack in the strengthened beam under three-point bending load was calculated by ABAQUS. In finite element model, simulation of CFL-concrete interface was based on the bilinear cohesive zone model under hot-wet environment and indoor atmosphere. And, then, fatigue crack propagation tests were carried out under high temperature and high humidity (50°C, 95% R · H environment pretreatment and indoor atmosphere (23°C, 78% R · H to obtain a-N curves and crack propagation rate, da/dN, of the strengthened beams. Paris-Erdogan formula was developed based on the numerical analysis and environmental fatigue tests.

Induction of drought tolerant mutants of rice

International Nuclear Information System (INIS)

El-Hissewy, A.A.; Abd Allah, A.

2001-01-01

The ultimate goal of crop breeding is to develop varieties with a high yield potential and desirable agronomic characteristics. In Egypt, the most important qualities sought by breeders have been high yield potential, resistance to major diseases and insects, and improved grain and eating quality. However, breeding efforts should concentrate on varieties with the potential to minimize yield losses under unfavorable conditions such as drought, and to maximize yields when conditions are favorable. Rice (Oryza sativa L.) in Egypt is completely irrigated and a significant portion of the rice cultivated area is subject to water deficit resulting from an inadequate or insufficient irrigation supply. Drought tolerance is a complex trait in that it results from the interaction of histological and physiological characters of plant with environmental factors, both above-ground and under-ground. Accordingly, root characters are closely related to drought tolerance. Little attention has been paid in Egyptian breeding programs to root characters and their relation to shoot characters. Furthermore, induced mutations are considered as one of the most important methods to induce useful mutants, especially with improved root characters, to overcome the drought problem. The present investigation aimed to study the effect of different doses of gamma rays on several characters of three Egyptian rice varieties, i.e. 'Giza 171', 'Giza 175' and 'Giza 176' and to induce one or more mutants possessing drought tolerance

The transcriptional regulatory network in the drought response and its crosstalk in abiotic stress responses including drought, cold and heat

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Kazuo eNakashima

2014-05-01

Full Text Available Drought negatively impacts plant growth and the productivity of crops around the world. Understanding the molecular mechanisms in the drought response is important for improvement of drought tolerance using molecular techniques. In plants, abscisic acid (ABA is accumulated under osmotic stress conditions caused by drought, and has a key role in stress responses and tolerance. Comprehensive molecular analyses have shown that ABA regulates the expression of many genes under osmotic stress conditions, and the ABA-responsive element (ABRE is the major cis-element for ABA-responsive gene expression. Transcription factors (TFs are master regulators of gene expression. ABRE-binding protein (AREB and ABRE-binding factor (ABF TFs control gene expression in an ABA-dependent manner. SNF1-related protein kinases 2, group A 2C-type protein phosphatases, and ABA receptors were shown to control the ABA signaling pathway. ABA-independent signaling pathways such as dehydration-responsive element-binding protein (DREB TFs and NAC TFs are also involved in stress responses including drought, heat and cold. Recent studies have suggested that there are interactions between the major ABA signaling pathway and other signaling factors in stress responses. The important roles of these transcription factors in crosstalk among abiotic stress responses will be discussed. Control of ABA or stress signaling factor expression can improve tolerance to environmental stresses. Recent studies using crops have shown that stress-specific overexpression of TFs improves drought tolerance and grain yield compared with controls in the field.

The transcriptional regulatory network in the drought response and its crosstalk in abiotic stress responses including drought, cold, and heat.

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Nakashima, Kazuo; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

2014-01-01

Drought negatively impacts plant growth and the productivity of crops around the world. Understanding the molecular mechanisms in the drought response is important for improvement of drought tolerance using molecular techniques. In plants, abscisic acid (ABA) is accumulated under osmotic stress conditions caused by drought, and has a key role in stress responses and tolerance. Comprehensive molecular analyses have shown that ABA regulates the expression of many genes under osmotic stress conditions, and the ABA-responsive element (ABRE) is the major cis-element for ABA-responsive gene expression. Transcription factors (TFs) are master regulators of gene expression. ABRE-binding protein and ABRE-binding factor TFs control gene expression in an ABA-dependent manner. SNF1-related protein kinases 2, group A 2C-type protein phosphatases, and ABA receptors were shown to control the ABA signaling pathway. ABA-independent signaling pathways such as dehydration-responsive element-binding protein TFs and NAC TFs are also involved in stress responses including drought, heat, and cold. Recent studies have suggested that there are interactions between the major ABA signaling pathway and other signaling factors in stress responses. The important roles of these TFs in crosstalk among abiotic stress responses will be discussed. Control of ABA or stress signaling factor expression can improve tolerance to environmental stresses. Recent studies using crops have shown that stress-specific overexpression of TFs improves drought tolerance and grain yield compared with controls in the field.

Global drought and severe drought-affected populations in 1.5 and 2 °C warmer worlds

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Liu, Wenbin; Sun, Fubao; Lim, Wee Ho; Zhang, Jie; Wang, Hong; Shiogama, Hideo; Zhang, Yuqing

2018-03-01

The 2015 Paris Agreement proposed a more ambitious climate change mitigation target on limiting global warming to 1.5 °C instead of 2 °C above preindustrial levels. Scientific investigations on environmental risks associated with these warming targets are necessary to inform climate policymaking. Based on the Coupled Model Intercomparison Project phase 5 (CMIP5) climate models, we present the first risk-based assessment of changes in global drought and the impact of severe drought on populations from additional 1.5 and 2 °C warming conditions. Our results highlight the risk of drought on a global scale and in several hotspot regions such as the Amazon, northeastern Brazil, southern Africa and Central Europe at both 1.5 and 2 °C global warming relative to the historical period, showing increases in drought durations from 2.9 to 3.2 months. Correspondingly, more total and urban populations would be exposed to severe droughts globally (+132.5 ± 216.2 million and +194.5 ± 276.5 million total population and +350.2 ± 158.8 million and +410.7 ± 213.5 million urban populations in 1.5 and 2 °C warmer worlds) and regionally (e.g., East Africa, West Africa and South Asia). Less rural populations (-217.7 ± 79.2 million and -216.2 ± 82.4 million rural populations in 1.5 and 2 °C warmer worlds) would be exposed to severe drought globally under climate warming, population growth and especially the urbanization-induced population migration. By keeping global warming at 1.5 °C above the preindustrial levels instead of 2 °C, there is a decrease in drought risks (i.e., less drought duration, less drought intensity and severity but relatively more frequent drought) and the affected total, urban and rural populations would decrease globally and in most regions. While challenging for both East Africa and South Asia, the benefits of limiting warming to below 1.5 °C in terms of global drought risk and impact reduction are significant.

Time-dependent leaf proteome alterations of Brachypodium distachyon in response to drought stress.

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Tatli, Ozge; Sogutmaz Ozdemir, Bahar; Dinler Doganay, Gizem

2017-08-01

For the first time, a comprehensive proteome analysis was conducted on Brachypodium leaves under drought stress. Gradual changes in response to drought stress were monitored. Drought is one of the major stress factors that dramatically affect the agricultural productivity worldwide. Improving the yield under drought is an urgent challenge in agriculture. Brachypodium distachyon is a model species for monocot plants such as wheat, barley and several potential biofuel grasses. In the current study, a comprehensive proteome analysis was conducted on Brachypodium leaves under different levels of drought application. To screen gradual changes upon drought, Brachypodium leaves subjected to drought for 4, 8 and 12 days were collected for each treatment day and relative water content of the leaves was measured for each time point. Cellular responses of Brachypodium were investigated through a proteomic approach involving two dimensional difference gel electrophoresis (2D-DIGE) and mass spectrometry (MS). Among 497 distinct spots in Brachypodium protein repertoire, a total of 13 differentially expressed proteins (DEPs) were identified as responsive to drought by mass spectrometry and classified according to their functions using bioinformatics tools. The biological functions of DEPs included roles in photosynthesis, protein folding, antioxidant mechanism and metabolic processes, which responded differentially at each time point of drought treatment. To examine further transcriptional expression of the genes that code identified protein, quantitative real time PCR (qRT-PCR) was performed. Identified proteins will contribute to the studies involving development of drought-resistant crop species and lead to the delineation of molecular mechanisms in drought response.

Genetic Gains in Yield and Yield Related Traits under Drought Stress and Favorable Environments in a Maize Population Improved Using Marker Assisted Recurrent Selection

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Folusho Bankole

2017-05-01

Full Text Available The objective of marker assisted recurrent selection (MARS is to increase the frequency of favorable marker alleles in a population before inbred line extraction. This approach was used to improve drought tolerance and grain yield (GY in a biparental cross of two elite drought tolerant lines. The testcrosses of randomly selected 50 S1 lines from each of the three selection cycles (C0, C1, C2 of the MARS population, parental testcrosses and the cross between the two parents (F1 were evaluated under drought stress (DS and well watered (WW well as under rainfed conditions to determine genetic gains in GY and other agronomic traits. Also, the S1 lines derived from each selection types were genotyped with single nucleotide polymorphism (SNP markers. Testcrosses derived from C2 produced significantly higher grain field under DS than those derived from C0 with a relative genetic gain of 7% per cycle. Also, the testcrosses of S1 lines from C2 showed an average genetic gain of 1% per cycle under WW condition and 3% per cycle under rainfed condition. Molecular analysis revealed that the frequency of favorable marker alleles increased from 0.510 at C0 to 0.515 at C2, while the effective number of alleles (Ne per locus decreased from C0 (1.93 to C2 (1.87. Our results underscore the effectiveness of MARS for improvement of GY under DS condition.

Process connectivity reveals ecohydrologic sensitivity to drought and rainfall pulses

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Goodwell, A. E.; Kumar, P.

2017-12-01

Ecohydrologic fluxes within atmosphere, canopy and soil systems exhibit complex and joint variability. This complexity arises from direct and indirect forcing and feedback interactions that can cause fluctuations to propagate between water, energy, and nutrient fluxes at various time scales. When an ecosystem is perturbed in the form of a single storm event, an accumulating drought, or changes in climate and land cover, this aspect of joint variability may dictate responsiveness and resilience of the entire system. A characterization of the time-dependent and multivariate connectivity between processes, fluxes, and states is necessary to identify and understand these aspects of ecohydrologic systems. We construct Temporal Information Partitioning Networks (TIPNets), based on information theory measures, to identify time-dependencies between variables measured at flux towers along elevation and climate gradients in relation to their responses to moisture-related perturbations. Along a flux tower transect in the Reynolds Creek Critical Zone Observatory (CZO) in Idaho, we detect a significant network response to a large 2015 dry season rainfall event that enhances microbial respiration and latent heat fluxes. At a transect in the Southern Sierra CZO in California, we explore network properties in relation to drought responses from 2011 to 2015. We find that both high and low elevation sites exhibit decreased connectivity between atmospheric and soil variables and latent heat fluxes, but the higher elevation site is less sensitive to this altered connectivity in terms of average monthly heat fluxes. Through a novel approach to gage the responsiveness of ecosystem fluxes to shifts in connectivity, this study aids our understanding of ecohydrologic sensitivity to short-term rainfall events and longer term droughts. This study is relevant to ecosystem resilience under a changing climate, and can lead to a greater understanding of shifting behaviors in many types of

Comportement des plants issus de différents modes de propagation du coïx (Coïx lacryma-Jobi L.

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Naku Mbumba, MD.

1984-01-01

Full Text Available The influence of propagating material on growth and production of Job's tears plants. It was found from this work that Job's tears plants grown from different propagation methods have different growth characteristics. Seedlings develop more uniformly from season to season, are more drought resistant and less susceptible to stem borers, than plants propagated by vegetative means. namely suckers and cuttings. Furthermore, seed production is higher with seedlings than with vegetatively propagated plants, while the reverse is true for forage production.

Silicon does not alleviate the adverse effects of drought stress in soybean plants

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Viviane Ruppenthal

2016-12-01

Full Text Available Beneficial effects of silicon (Si in the plants growth under conditions of drought stress have been associated with to uptake and accumulation ability of element by different species. However, the effects of Si on soybean under water stress are still incipient and inconclusive. This study investigated the effect of Si application as a way to confer greater soybean tolerance to drought stress. The experiment was carried out in 20-L pots under greenhouse conditions. Treatments were arranged in a randomized block design in a 2 × 4 factorial: two water regimes (no stress or water stress and four Si rates (0, 50, 100 and 200 mg kg–1. Soybean plants were grown until beginning flowering (R1 growth stage with soil moisture content near at the field capacity, and then it started the differentiation of treatments under drought by the suspension of water supply. Changes in relative water content (RWC in leaf, electrolyte leakage from cells, peroxidase activity, plant nutrition and growth were measured after 7 days of drought stress and 3 days recovery. The RWC in soybean leaves decreased with Si rates in the soil. Silicon supply in soil with average content of this element, reduced dry matter production of soybean under well-irrigated conditions and caused no effect on dry matter under drought stress. The nitrogen uptake by soybean plants is reduced with the Si application under drought stress. The results indicated that the Si application stimulated the defense mechanisms of soybean plants, but was not sufficient to mitigate the negative effects of drought stress on the RWC and dry matter production.

Enhancing drought tolerance in C(4) crops.

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Lopes, Marta S; Araus, Jose Luis; van Heerden, Philippus D R; Foyer, Christine H

2011-05-01

Adaptation to abiotic stresses is a quantitative trait controlled by many different genes. Enhancing the tolerance of crop plants to abiotic stresses such as drought has therefore proved to be somewhat elusive in terms of plant breeding. While many C(4) species have significant agronomic importance, most of the research effort on improving drought tolerance has focused on maize. Ideally, drought tolerance has to be achieved without penalties in yield potential. Possibilities for success in this regard are highlighted by studies on maize hybrids performed over the last 70 years that have demonstrated that yield potential and enhanced stress tolerance are associated traits. However, while our understanding of the molecular mechanisms that enable plants to tolerate drought has increased considerably in recent years, there have been relatively few applications of DNA marker technologies in practical C(4) breeding programmes for improved stress tolerance. Moreover, until recently, targeted approaches to drought tolerance have concentrated largely on shoot parameters, particularly those associated with photosynthesis and stay green phenotypes, rather than on root traits such as soil moisture capture for transpiration, root architecture, and improvement of effective use of water. These root traits are now increasingly considered as important targets for yield improvement in C(4) plants under drought stress. Similarly, the molecular mechanisms underpinning heterosis have considerable potential for exploitation in enhancing drought stress tolerance. While current evidence points to the crucial importance of root traits in drought tolerance in C(4) plants, shoot traits may also be important in maintaining high yields during drought.

Assessing changes in drought characteristics with standardized indices

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Vidal, Jean-Philippe; Najac, Julien; Martin, Eric; Franchistéguy, Laurent; Soubeyroux, Jean-Michel

2010-05-01

Standardized drought indices like the Standardized Precipitation Index (SPI) are more and more frequently adopted for drought reconstruction, monitoring and forecasting, and the SPI has been recently recommended by the World Meteorological Organization to characterize meteorological droughts. Such indices are based on the statistical distribution of a hydrometeorological variable (e.g., precipitation) in a given reference climate, and a drought event is defined as a period with continuously negative index values. Because of the way these indices are constructed, some issues may arise when using them in a non-stationnary climate. This work thus aims at highlighting such issues and demonstrating the different ways these indices may - or may not - be applied and interpreted in the context of an anthropogenic climate change. Three major points are detailed through examples taken from both a high-resolution gridded reanalysis dataset over France and transient projections from the ARPEGE general circulation model downscaled over France. The first point deals with the choice of the reference climate, and more specifically its type (from observations/reanalysis or from present-day modelled climate) and its record period. Second, the interpretation of actual changes are closely linked with the type of the selected drought feature over a future period: mean index value, under-threshold frequency, or drought event characteristics (number, mean duration and magnitude, seasonality, etc.). Finally, applicable approaches as well as related uncertainties depend on the availability of data from a future climate, whether in the form of a fully transient time series from present-day or only a future time slice. The projected evolution of drought characteristics under climate change must inform present decisions on long-term water resources planning. An assessment of changes in drought characteristics should therefore provide water managers with appropriate information that can help

Temporal Changes in Community Resilience to Drought Hazard

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Mihunov, V.

2017-12-01

The threat of droughts and their associated impacts on the landscape and human communities have long been recognized. While considerable research on the climatological aspect of droughts has been conducted, studies on the resilience of human communities to the effects of drought remain limited. Understanding how different communities respond to and recover from the drought hazard, i.e. their community resilience, should inform the development of better strategies to cope with the hazard. This research assesses community resilience to drought hazard in South-Central U.S. and captures the temporal changes of community resilience in the region facing the climate change. First, the study applies the Resilience Inference Measurement (RIM) framework using the existing drought incidence, crop damage, socio-economic and food-water-energy nexus variables, which allows to assign county-level resilience scores in the study region and derive variables contributing to the resilience. Second, it captures the temporal changes in community resilience by using the model extracted from the RIM study and socio-economic data from several consecutive time periods. The resilience measurement study should help understand the complex process underlying communities' response to the drought impacts. The results identify gaps in resilience planning and help the improvement of the community resilience to the droughts of increasing frequency and intensity.

Exploring potential of pearl millet germplasm association panel for association mapping of drought tolerance traits.

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Deepmala Sehgal

Full Text Available A pearl millet inbred germplasm association panel (PMiGAP comprising 250 inbred lines, representative of cultivated germplasm from Africa and Asia, elite improved open-pollinated cultivars, hybrid parental inbreds and inbred mapping population parents, was recently established. This study presents the first report of genetic diversity in PMiGAP and its exploitation for association mapping of drought tolerance traits. For diversity and genetic structure analysis, PMiGAP was genotyped with 37 SSR and CISP markers representing all seven linkage groups. For association analysis, it was phenotyped for yield and yield components and morpho-physiological traits under both well-watered and drought conditions, and genotyped with SNPs and InDels from seventeen genes underlying a major validated drought tolerance (DT QTL. The average gene diversity in PMiGAP was 0.54. The STRUCTURE analysis revealed six subpopulations within PMiGAP. Significant associations were obtained for 22 SNPs and 3 InDels from 13 genes under different treatments. Seven SNPs associations from 5 genes were common under irrigated and one of the drought stress treatments. Most significantly, an important SNP in putative acetyl CoA carboxylase gene showed constitutive association with grain yield, grain harvest index and panicle yield under all treatments. An InDel in putative chlorophyll a/b binding protein gene was significantly associated with both stay-green and grain yield traits under drought stress. This can be used as a functional marker for selecting high yielding genotypes with 'stay green' phenotype under drought stress. The present study identified useful marker-trait associations of important agronomics traits under irrigated and drought stress conditions with genes underlying a major validated DT-QTL in pearl millet. Results suggest that PMiGAP is a useful panel for association mapping. Expression patterns of genes also shed light on some physiological mechanisms underlying

Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches

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Van Loon, Anne F.; Stahl, Kerstin; Di Baldassarre, Giuliano; Clark, Julian; Rangecroft, Sally; Wanders, Niko; Gleeson, Tom; Van Dijk, Albert I. J. M.; Tallaksen, Lena M.; Hannaford, Jamie; Uijlenhoet, Remko; Teuling, Adriaan J.; Hannah, David M.; Sheffield, Justin; Svoboda, Mark; Verbeiren, Boud; Wagener, Thorsten; Van Lanen, Henny A. J.

2016-09-01

In the current human-modified world, or Anthropocene, the state of water stores and fluxes has become dependent on human as well as natural processes. Water deficits (or droughts) are the result of a complex interaction between meteorological anomalies, land surface processes, and human inflows, outflows, and storage changes. Our current inability to adequately analyse and manage drought in many places points to gaps in our understanding and to inadequate data and tools. The Anthropocene requires a new framework for drought definitions and research. Drought definitions need to be revisited to explicitly include human processes driving and modifying soil moisture drought and hydrological drought development. We give recommendations for robust drought definitions to clarify timescales of drought and prevent confusion with related terms such as water scarcity and overexploitation. Additionally, our understanding and analysis of drought need to move from single driver to multiple drivers and from uni-directional to multi-directional. We identify research gaps and propose analysis approaches on (1) drivers, (2) modifiers, (3) impacts, (4) feedbacks, and (5) changing the baseline of drought in the Anthropocene. The most pressing research questions are related to the attribution of drought to its causes, to linking drought impacts to drought characteristics, and to societal adaptation and responses to drought. Example questions include (i) What are the dominant drivers of drought in different parts of the world? (ii) How do human modifications of drought enhance or alleviate drought severity? (iii) How do impacts of drought depend on the physical characteristics of drought vs. the vulnerability of people or the environment? (iv) To what extent are physical and human drought processes coupled, and can feedback loops be identified and altered to lessen or mitigate drought? (v) How should we adapt our drought analysis to accommodate changes in the normal situation (i.e. what

Cuticular wax accumulation is associated with drought tolerance in wheat near-isogenic lines

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Jianmin Song

2016-11-01

Full Text Available Previous studies have shown that wheat grain yield is seriously affected by drought stress, and leaf cuticular wax is reportedly associated with drought tolerance. However, most studies have focused on cuticular wax biosynthesis and model species. The effects of cuticular wax on wheat drought tolerance have rarely been studied. The aims of the current study were to study the effects of leaf cuticular wax on wheat grain yield under drought stress using the above-mentioned wheat NILs and to discuss the possible physiological mechanism of cuticular wax on high grain yield under drought stress. Compared to water-irrigated (WI conditions, the cuticular wax content (CWC in glaucous and non-glaucous NILs under drought-stress (DS conditions both increased; mean increase values were 151.1% and 114.4%, respectively, which was corroborated by scanning electronic microscopy images of large wax particles loaded on the surfaces of flag leaves. The average yield of glaucous NILs was higher than that of non-glaucous NILs under DS conditions in 2014 and 2015; mean values were 7368.37 kg·ha-1 and 7103.51 kg·ha-1. This suggested that glaucous NILs were more drought-tolerant than non-glaucous NILs (P = 0.05, which was supported by the findings of drought tolerance indices TOL and SSI in both years, the relatively high water potential and relative water content, and the low ELWL. Furthermore, the photosynthesis rate (Pn of glaucous and non-glaucous wheat NILs under DS conditions decreased by 7.5% and 9.8%, respectively; however, glaucous NILs still had higher mean values of Pn than those of non-glaucous NILs, which perhaps resulted in the higher yield of glaucous NILs. This could be explained by the fact that glaucous NILs had a smaller Fv/Fm reduction, a smaller PI reduction and a greater ABS/RC increase than non-glaucous NILs under DS conditions. This is the first report to show that wheat cuticular wax accumulation is associated with drought tolerance. Moreover

Real-Time Optimal Flood Control Decision Making and Risk Propagation Under Multiple Uncertainties

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Zhu, Feilin; Zhong, Ping-An; Sun, Yimeng; Yeh, William W.-G.

2017-12-01

Multiple uncertainties exist in the optimal flood control decision-making process, presenting risks involving flood control decisions. This paper defines the main steps in optimal flood control decision making that constitute the Forecast-Optimization-Decision Making (FODM) chain. We propose a framework for supporting optimal flood control decision making under multiple uncertainties and evaluate risk propagation along the FODM chain from a holistic perspective. To deal with uncertainties, we employ stochastic models at each link of the FODM chain. We generate synthetic ensemble flood forecasts via the martingale model of forecast evolution. We then establish a multiobjective stochastic programming with recourse model for optimal flood control operation. The Pareto front under uncertainty is derived via the constraint method coupled with a two-step process. We propose a novel SMAA-TOPSIS model for stochastic multicriteria decision making. Then we propose the risk assessment model, the risk of decision-making errors and rank uncertainty degree to quantify the risk propagation process along the FODM chain. We conduct numerical experiments to investigate the effects of flood forecast uncertainty on optimal flood control decision making and risk propagation. We apply the proposed methodology to a flood control system in the Daduhe River basin in China. The results indicate that the proposed method can provide valuable risk information in each link of the FODM chain and enable risk-informed decisions with higher reliability.

Rooting traits of peanut genotypes with different yield responses to terminal drought

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Drought at pod filling can severely reduce yield of peanut. Better root systems can reduce yield loss from drought. However, the relationship of root characters with yield under terminal drought is not well understood. The objective of this study was to investigate the responses of peanut genotyp...

Drought's legacy: multiyear hydraulic deterioration underlies widespread aspen forest die-off and portends increased future risk.

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Anderegg, William R L; Plavcová, Lenka; Anderegg, Leander D L; Hacke, Uwe G; Berry, Joseph A; Field, Christopher B

2013-04-01

Forest mortality constitutes a major uncertainty in projections of climate impacts on terrestrial ecosystems and carbon-cycle feedbacks. Recent drought-induced, widespread forest die-offs highlight that climate change could accelerate forest mortality with its diverse and potentially severe consequences for the global carbon cycle, ecosystem services, and biodiversity. How trees die during drought over multiple years remains largely unknown and precludes mechanistic modeling and prediction of forest die-off with climate change. Here, we examine the physiological basis of a recent multiyear widespread die-off of trembling aspen (Populus tremuloides) across much of western North America. Using observations from both native trees while they are dying and a rainfall exclusion experiment on mature trees, we measure hydraulic performance over multiple seasons and years and assess pathways of accumulated hydraulic damage. We test whether accumulated hydraulic damage can predict the probability of tree survival over 2 years. We find that hydraulic damage persisted and increased in dying trees over multiple years and exhibited few signs of repair. This accumulated hydraulic deterioration is largely mediated by increased vulnerability to cavitation, a process known as cavitation fatigue. Furthermore, this hydraulic damage predicts the probability of interyear stem mortality. Contrary to the expectation that surviving trees have weathered severe drought, the hydraulic deterioration demonstrated here reveals that surviving regions of these forests are actually more vulnerable to future droughts due to accumulated xylem damage. As the most widespread tree species in North America, increasing vulnerability to drought in these forests has important ramifications for ecosystem stability, biodiversity, and ecosystem carbon balance. Our results provide a foundation for incorporating accumulated drought impacts into climate-vegetation models. Finally, our findings highlight the

Quantitative trait loci for yield and morphological traits in maize under drought stress

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Nikolić Ana

2011-01-01

Full Text Available Drought is one of the most important factors contributing to crop yield loss. In order to develop maize varieties with drought tolerance, it is necessary to explore the genetic basis. Mapping quantitative trait loci (QTL that control the yield and associate agronomic traits is one way of understanding drought genetics. QTLs associated with grain yield (GY, leaf width (LW3, LW4 plant height (PH, ear height (EH, leaf number (NL, tassel branch number (TBN and tassel length (TL were studied with composite interval mapping. A total of 43 QTLs were detected, distributed on all chromosomes, except chromosome 9. Phenotypic variability determined for the identified QTLs for all the traits was in the range from 20.99 to 87.24%. Mapping analysis identified genomic regions associated with two traits in a manner that was consistent with phenotypic correlation among traits, supporting either pleiotropy or tight linkage among QTLs.

Ecological and meteorological drought monitoring in East Asia

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Kim, J. B.; Um, M. J.; Kim, Y.; Chae, Y.

2016-12-01

terrestrial drought severity index. Bulletin of the American Meteorological Society 94(1): 83-98. Acknowledgement This study was supported by the Korea Meteorological Administration R&D Program under Grant KMIPA 2015-6180. Corresponding Author: yeonjoo.kim@yonsei.ac.kr

Osmo and hydro priming improvement germination characteristics and enzyme activity of Mountain Rye (Secale montanum seeds under drought stress

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Ansari O.

2012-11-01

Full Text Available Impacts of various concentrations of polyetylenglycol 6000 (PEG 6000(0, -9, -11, -13 and -15 bar and hydro priming on Mountain Rye (secale montanum germination characteristic and enzyme activity were evaluated under drought stress in the seed laboratory of Natural Resources Faculty, University of Tehran, Karaj, Iran. Analyze of variance for hydro priming showed that temperature × time of priming interaction was significantly for germination percentage (GP, normal seedling percentage (NSP, coefficient of velocity of germination (CVG, seedling vigor index (SVI, coefficient of allometry (AC and seedling length (SL under drought stress and for osmo priming showed that Concentration of PEG × Temperature × Time of priming interaction was significantly for all traits under drought stress. Results of interaction effects for hydro priming showed that the highest GP (53% and NSP (23.5% were attained from hydro priming for 16h at 15 ◦C and the highest CVG (0.21 and AC (0.49 were attained from hydro priming for 8h at 10 ◦C, also hydro priming for 8h at 15 ◦C increased SL (3.15 as compared to the unprimed.Osmo priming with concentration of -15 bar PEG for 24h at 15 ◦C increased GP (80.5 %, GI (17.9, NSP (45 %, SVI (257.85 and SL (5.73 cm and decreased MTG as compared to the unprimed and other treatments of osmo priming. The highest CVG was attained from concentration of -9 bar PEG for 24h at 10 ◦C. the highest AC was attained from concentration of -9 bar PEG for 12h at 15 ◦C. Also osmo and hydro priming increased catalase (CAT and ascorbate peroxidase (APX as compared to the unprimed.

Transcriptional Responses in root and leaf of Prunus persica Under Drought Stress Using RNA Sequencing

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Najla Ksouri

2016-11-01

Full Text Available Prunus persica L. Batch, or peach, is one of the most important crops and it is widely established in irrigated arid and semi-arid regions. However, due to variations in the climate and the increased aridity, drought has become a major constraint, causing crop losses worldwide. The use of drought-tolerant rootstocks in modern fruit production appears to be a useful method of alleviating water deficit problems. However, the transcriptomic variation and the major molecular mechanisms that underlie the adaptation of drought-tolerant rootstocks to water shortage remain unclear. Hence, in this study, high-throughput sequencing (RNA-seq was performed to assess the transcriptomic changes and the key genes involved in the response to drought in root tissues (GF677 rootstock and leaf tissues (graft, var. Catherina subjected to 16 days of drought stress. In total, 12 RNA libraries were constructed and sequenced. This generated a total of 315M raw reads from both tissues, which allowed the assembly of 22,079 and 17,854 genes associated with the root and leaf tissues, respectively. Subsets of 500 differentially expressed genes (DEGs in roots and 236 in leaves were identified and functionally annotated with 56 gene ontology (GO terms and 99 metabolic pathways, which were mostly associated with aminobenzoate degradation and phenylpropanoid biosynthesis. The GO analysis highlighted the biological functions that were exclusive to the root tissue, such as locomotion, hormone metabolic process, and detection of stimulus, indicating the stress-buffering role of the GF677 rootstock. Furthermore, the complex regulatory network involved in the drought response was revealed, involving proteins that are associated with signaling transduction, transcription and hormone regulation, redox homeostasis, and frontline barriers. We identified two poorly characterized genes in P. persica: growth-regulating factor 5 (GRF5, which may be involved in cellular expansion, and AtHB12

Spatiotemporal variation of long-term drought propensity through reliability-resilience-vulnerability based Drought Management Index

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Chanda, Kironmala; Maity, Rajib; Sharma, Ashish; Mehrotra, Rajeshwar

2014-10-01

This paper characterizes the long-term, spatiotemporal variation of drought propensity through a newly proposed, namely Drought Management Index (DMI), and explores its predictability in order to assess the future drought propensity and adapt drought management policies for a location. The DMI was developed using the reliability-resilience-vulnerability (RRV) rationale commonly used in water resources systems analysis, under the assumption that depletion of soil moisture across a vertical soil column is equivalent to the operation of a water supply reservoir, and that drought should be managed not simply using a measure of system reliability, but should also take into account the readiness of the system to bounce back from drought to a normal state. Considering India as a test bed, 5 year long monthly gridded (0.5° Lat × 0.5° Lon) soil moisture data are used to compute the RRV at each grid location falling within the study domain. The Permanent Wilting Point (PWP) is used as the threshold, indicative of transition into water stress. The association between resilience and vulnerability is then characterized through their joint probability distribution ascertained using Plackett copula models for four broad soil types across India. The joint cumulative distribution functions (CDF) of resilience and vulnerability form the basis for estimating the DMI as a five-yearly time series at each grid location assessed. The status of DMI over the past 50 years indicate that drought propensity is consistently low toward northern and north eastern parts of India but higher in the western part of peninsular India. Based on the observed past behavior of DMI series on a climatological time scale, a DMI prediction model comprising deterministic and stochastic components is developed. The predictability of DMI for a lead time of 5 years is found to vary across India, with a Pearson correlation coefficient between observed and predicted DMI above 0.6 over most of the study area

Blended Drought Index: Integrated Drought Hazard Assessment in the Cuvelai-Basin

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Robert Luetkemeier

2017-07-01

Full Text Available Drought is one of the major threats to societies in Sub-Saharan Africa, as the majority of the population highly depends on rain-fed subsistence agriculture and traditional water supply systems. Hot-spot areas of potential drought impact need to be identified to reduce risk and adapt a growing population to a changing environment. This paper presents the Blended Drought Index (BDI, an integrated tool for estimating the impact of drought as a climate-induced hazard in the semi-arid Cuvelai-Basin of Angola and Namibia. It incorporates meteorological and agricultural drought characteristics that impair the population’s ability to ensure food and water security. The BDI uses a copula function to combine common standardized drought indicators that describe precipitation, evapotranspiration, soil moisture and vegetation conditions. Satellite remote sensing products were processed to analyze drought frequency, severity and duration. As the primary result, an integrated drought hazard map was built to spatially depict drought hot-spots. Temporally, the BDI correlates well with millet/sorghum yield (r = 0.51 and local water consumption (r = −0.45 and outperforms conventional indicators. In the light of a drought’s multifaceted impact on society, the BDI is a simple and transferable tool to identify areas highly threatened by drought in an integrated manner.

Adaptation responses to increasing drought frequency

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Loch, A. J.; Adamson, D. C.; Schwabe, K.

2016-12-01

Using state contingent analysis we discuss how and why irrigators adapt to alternative water supply signals. This analysis approach helps to illustrate how and why producers currently use state-general and state-allocable inputs to adapt and respond to known and possible future climatic alternative natures. Focusing on the timing of water allocations, we explore inherent differences in the demand for water by two key irrigation sectors: annual and perennial producers which in Australia have allowed a significant degree of risk-minimisation during droughts. In the absence of land constraints, producers also had a capacity to respond to positive state outcomes and achieve super-normal profits. In the future, however, the probability of positive state outcomes is uncertain; production systems may need to adapt to minimise losses and/or achieve positive returns under altered water supply conditions that may arise as a consequence of more frequent drought states. As such, producers must assess whether altering current input/output choice sets in response to possible future climate states will enhance their long-run competitive advantage for both expected new normal and extreme water supply outcomes. Further, policy supporting agricultural sector climate change resilience must avoid poorly-designed strategies that increase producer vulnerability in the face of drought. Our analysis explores the reliability of alternative water property right bundles and how reduced allocations across time influence alternative responses by producers. We then extend our analysis to explore how management strategies could adapt to two possible future drier state types: i) where an average reduction in water supply is experienced; and ii) where the frequency of droughts increase. The combination of these findings are subsequently used to discuss the role water reform policy has to deal with current and future climate scenarios. We argue current policy strategies could drive producers to

Winter North Atlantic Oscillation impact on European precipitation and drought under climate change

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Tsanis, I.; Tapoglou, E.

2018-01-01

The North Atlantic Oscillation (NAO) is responsible for the climatic variability in the Northern Hemisphere, in particular, in Europe and is related to extreme events, such as droughts. The purpose of this paper is to study the correlation between precipitation and winter (December-January-February-March (DJFM)) NAO both for the historical period (1951-2000) and two future periods (2001-2050 and 2051-2100). NAO is calculated for these three periods by using sea level pressure, while precipitation data from seven climate models following the representative concentration pathway (RCP) 8.5 are also used in this study. An increasing trend in years with positive DJFM NAO values in the future is defined by this data, along with higher average DJFM NAO values. The correlation between precipitation and DJFM NAO is high, especially in the Northern (high positive) and Southern Europe (high negative). Therefore, higher precipitation in Northern Europe and lower precipitation in Southern Europe are expected in the future. Cross-spectral analysis between precipitation and DJFM NAO time series in three different locations in Europe revealed the best coherence in a dominant cycle between 3 and 4 years. Finally, the maximum drought period in terms of consecutive months with drought is examined in these three locations. The results can be used for strategic planning in a sustainable water resources management plan, since there is a link between drought events and NAO.

The effect of severe drought and management after drought on the ...

African Journals Online (AJOL)

The False Thornveld of the Eastern Cape experienced a particularly intense drought during the 1982/1983 growing season. Extensive grass mortality took place during the drought. After the drought, recovery was particularly sensitive to the post-drought management treatment applied. Veld that was grazed immediately ...

Redox markers for drought-induced nodule senescence, a process occurring after drought-induced senescence of the lowest leaves in soybean (Glycine max).

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Marquez-Garcia, Belén; Shaw, Daniel; Cooper, James William; Karpinska, Barbara; Quain, Marian Dorcas; Makgopa, Eugene Matome; Kunert, Karl; Foyer, Christine Helen

2015-09-01

Water is an increasingly scarce resource that limits crop productivity in many parts of the world, and the frequency and severity of drought are predicted to increase as a result of climate change. Improving tolerance to drought stress is therefore important for maximizing future crop yields. The aim of this study was to compare the effects of drought on soybean (Glycine max) leaves and nodules in order to define phenotypic markers and changes in cellular redox state that characterize the stress response in different organs, and to characterize the relationships between leaf and nodule senescence during drought. Leaf and crown nodule metabolite pools were measured together with leaf and soil water contents, and leaf chlorophyll, total protein contents and chlorophyll a fluorescence quenching parameters in nodulated soybeans that were grown under either well-watered conditions or deprived of water for up to 21 d. Ureides, ascorbate, protein, chlorophyll and the ratios of variable chlorophyll a fluorescence (Fv') to maximal chlorophyll a fluorescence (Fm') fell to levels below detection in the oldest leaves after 21 d of drought. While these drought-induced responses were not observed in the youngest leaf ranks, the Fv'/Fm' ratios, pyridine nucleotide levels and the reduction state of the ascorbate pool were lower in all leaf ranks after 21 d of drought. In contrast to leaves, total nodule protein, pyridine nucleotides, ureides, ascorbate and glutathione contents increased as a result of the drought treatment. However, the nodule ascorbate pool was significantly less reduced as a result of drought. Higher levels of transcripts encoding two peroxiredoxins were detected in nodules exposed to drought stress but senescence-associated transcripts and other mRNAs encoding redox-related proteins were similar under both conditions. While the physiological impact of the drought was perceived throughout the shoot, stress-induced senescence occurred only in the oldest

Drought-associated changes in climate and their relevance for ecosystem experiments and models

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H. J. De Boeck

2011-05-01

Full Text Available Drought periods can have important impacts on plant productivity and ecosystem functioning, but climatic conditions other than the lack of precipitation during droughts have never been quantified and have therefore not been considered explicitly in both experimental and modeling studies. Here, we identify which climatic characteristics deviate from normal during droughts and how these deviations could affect plant responses. Analysis of 609 years of daily data from nine Western European meteorological stations reveals that droughts in the studied region are consistently associated with more sunshine (+45 %, increased mean (+1.6 °C and maximum (+2.8 °C air temperatures and vapour pressure deficits that were 51 % higher than under normal conditions. These deviations from normal increase significantly as droughts progress. Using the process-model ORCHIDEE, we simulated droughts consistent with the results of the dataset analysis and compared water and carbon exchange of three different vegetation types during such natural droughts and droughts in which only the precipitation was affected. The comparison revealed contrasting responses: carbon loss was higher under natural drought in grasslands, while increased carbon uptake was found especially in decidious forests. This difference was attributed to better access to water reserves in forest ecosystems which prevented drought stress. This demonstrates that the warmer and sunnier conditions naturally associated with droughts can either improve growth or aggravate drought-related stress, depending on water reserves. As the impacts of including or excluding climatic parameters that correlate with drought are substantial, we propose that both experimental and modeling efforts should take into account other environmental factors than merely precipitation.

The effect of triazole induced photosynthetic pigments and biochemical constituents of Zea mays L. (Maize) under drought stress

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Rajasekar, Mahalingam; Rabert, Gabriel Amalan; Manivannan, Paramasivam

2016-06-01

In this investigation, pot culture experiment was carried out to estimate the ameliorating effect of triazole compounds, namely Triadimefon (TDM), Tebuconazole (TBZ), and Propiconazole (PCZ) on drought stress, photosynthetic pigments, and biochemical constituents of Zea mays L. (Maize). From 30 days after sowing (DAS), the plants were subjected to 4 days interval drought (DID) stress and drought with TDM at 15 mg l-1, TBZ at 10 mg l-1, and PCZ at 15 mg l-1. Irrigation at 1-day interval was kept as control. Irrigation performed on alternative day. The plant samples were collected on 40, 50, and 60 DAS and separated into root, stem, and leaf for estimating the photosynthetic pigments and biochemical constituents. Drought and drought with triazole compounds treatment increased the biochemical glycine betaine content, whereas the protein and the pigments contents chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid, and anthocyanin decreased when compared to control. The triazole treatment mitigated the adverse effects of drought stress by increasing the biochemical potentials and paved the way to overcome drought stress in corn plant.

Cavitation propagation in water under tension

Science.gov (United States)

Noblin, Xavier; Yip Cheung Sang, Yann; Pellegrin, Mathieu; Materials and Complex Fluids Team

2012-11-01

Cavitation appears when pressure decreases below vapor pressure, generating vapor bubbles. It can be obtain in dynamical ways (acoustic, hydraulic) but also in quasi-static conditions. This later case is often observed in nature, in trees, or during the ejection of ferns spores. We study the cavitation bubbles nucleation dynamics and its propagation in a confined microfabricated media. This later is an ordered array of microcavities made in hydrogel filled with water. When the system is put into dry air, it dehydrates, water leaves the cavities and tension (negative pressure) builds in the cavities. This can be sustained up to a critical pressure (of order -20 MPa), then cavitation bubbles appear. We follow the dynamics using ultra high speed imaging. Events with several bubbles cavitating in a few microseconds could be observed along neighboring cells, showing a propagation phenomenon that we discuss. ANR CAVISOFT 2010-JCJC-0407 01.

Understanding abiotic stress tolerance mechanisms in soybean: a comparative evaluation of soybean response to drought and flooding stress.

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Mutava, Raymond N; Prince, Silvas Jebakumar K; Syed, Naeem Hasan; Song, Li; Valliyodan, Babu; Chen, Wei; Nguyen, Henry T

2015-01-01

Many sources of drought and flooding tolerance have been identified in soybean, however underlying molecular and physiological mechanisms are poorly understood. Therefore, it is important to illuminate different plant responses to these abiotic stresses and understand the mechanisms that confer tolerance. Towards this goal we used four contrasting soybean (Glycine max) genotypes (PI 567690--drought tolerant, Pana--drought susceptible, PI 408105A--flooding tolerant, S99-2281--flooding susceptible) grown under greenhouse conditions and compared genotypic responses to drought and flooding at the physiological, biochemical, and cellular level. We also quantified these variations and tried to infer their role in drought and flooding tolerance in soybean. Our results revealed that different mechanisms contribute to reduction in net photosynthesis under drought and flooding stress. Under drought stress, ABA and stomatal conductance are responsible for reduced photosynthetic rate; while under flooding stress, accumulation of starch granules played a major role. Drought tolerant genotypes PI 567690 and PI 408105A had higher plastoglobule numbers than the susceptible Pana and S99-2281. Drought stress increased the number and size of plastoglobules in most of the genotypes pointing to a possible role in stress tolerance. Interestingly, there were seven fibrillin proteins localized within the plastoglobules that were up-regulated in the drought and flooding tolerant genotypes PI 567690 and PI 408105A, respectively, but down-regulated in the drought susceptible genotype Pana. These results suggest a potential role of Fibrillin proteins, FBN1a, 1b and 7a in soybean response to drought and flooding stress. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Crack Propagation Calculations for Optical Fibers under Static Bending and Tensile Loads Using Continuum Damage Mechanics

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Chen, Yunxia; Cui, Yuxuan; Gong, Wenjun

2017-01-01

Static fatigue behavior is the main failure mode of optical fibers applied in sensors. In this paper, a computational framework based on continuum damage mechanics (CDM) is presented to calculate the crack propagation process and failure time of optical fibers subjected to static bending and tensile loads. For this purpose, the static fatigue crack propagation in the glass core of the optical fiber is studied. Combining a finite element method (FEM), we use the continuum damage mechanics for the glass core to calculate the crack propagation path and corresponding failure time. In addition, three factors including bending radius, tensile force and optical fiber diameter are investigated to find their impacts on the crack propagation process and failure time of the optical fiber under concerned situations. Finally, experiments are conducted and the results verify the correctness of the simulation calculation. It is believed that the proposed method could give a straightforward description of the crack propagation path in the inner glass core. Additionally, the predicted crack propagation time of the optical fiber with different factors can provide effective suggestions for improving the long-term usage of optical fibers. PMID:29140284

Towards a Seamless Framework for Drought Analysis and Prediction from Seasonal to Climate Change Time Scales (Plinius Medal Lecture)

Science.gov (United States)

Sheffield, Justin

2013-04-01

surface models. Current research is focused on several aspects, including: 1) quantifying the uncertainties in historic drought reconstructions; 2) analysis of drought propagation through the coupled hydrological/vegetation system; 3) the utility of new data sources such as on the ground sensors and new satellite products for terrestrial hydrology and vegetation, for improved monitoring and prediction, especially in poorly observed regions; 4) advancing predictive skill for all aspects of drought occurrence through diagnosis of the driving mechanisms and feedbacks of historic droughts; and 5) quantification and reduction of uncertainties in future projections of drought under climate change. The steps towards the development of a seamless framework for analysis and prediction in the context of this research are discussed.

Elevated CO2 Reduced Floret Death in Wheat Under Warmer Average Temperatures and Terminal Drought

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Dias de Oliveira, Eduardo; Palta, Jairo A.; Bramley, Helen; Stefanova, Katia; Siddique, Kadambot H. M.

2015-01-01

Elevated CO2 often increases grain yield in wheat by enhancing grain number per ear, which can result from an increase in the potential number of florets or a reduction in the death of developed florets. The hypotheses that elevated CO2 reduces floret death rather than increases floret development, and that grain size in a genotype with more grains per unit area is limited by the rate of grain filling, were tested in a pair of sister lines contrasting in tillering capacity (restricted- vs. free-tillering). The hypotheses were tested under elevated CO2, combined with +3°C above ambient temperature and terminal drought, using specialized field tunnel houses. Elevated CO2 increased net leaf photosynthetic rates and likely the availability of carbon assimilates, which significantly reduced the rates of floret death and increased the potential number of grains at anthesis in both sister lines by an average of 42%. The restricted-tillering line had faster grain-filling rates than the free-tillering line because the free-tillering line had more grains to fill. Furthermore, grain-filling rates were faster under elevated CO2 and +3°C above ambient. Terminal drought reduced grain yield in both lines by 19%. Elevated CO2 alone increased the potential number of grains, but a trade-off in yield components limited grain yield in the free-tillering line. This emphasizes the need for breeding cultivars with a greater potential number of florets, since this was not affected by the predicted future climate variables. PMID:26635837

Elevated CO2 reduced floret death in wheat under warmer average temperatures and terminal drought.

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Eduardo eDias de Oliveira

2015-11-01

Full Text Available Elevated CO2 often increases grain yield in wheat by enhancing grain number per ear, which can result from an increase in the potential number of florets or a reduction in the death of developed florets. The hypotheses that elevated CO2 reduces floret death rather than increases floret development, and that grain size in a genotype with more grains per unit area is limited by the rate of grain filling, were tested in a pair of sister lines contrasting in tillering capacity (restricted- vs free-tillering. The hypotheses were tested under elevated CO2, combined with +3 C above ambient temperature and terminal drought, using specialized field tunnel houses. Elevated CO2 increased net leaf photosynthetic rates and likely the availability of carbon assimilates, which significantly reduced the rates of floret death and increased the potential number of grains at anthesis in both sister lines by an average of 42%. The restricted-tillering line had faster grain-filling rates than the free-tillering line because the free-tillering line had more grains to fill. Furthermore, grain-filling rates were faster under elevated CO2 and +3 C above ambient. Terminal drought reduced grain yield in both lines by 19%. Elevated CO2 alone increased the potential number of grains, but a trade-off in yield components limited grain yield in the free-tillering line. This emphasizes the need for breeding cultivars with a greater potential number of florets, since this was not affected by the predicted future climate variables.

Comparison of the spatial and temporal variability of drought indices ...

African Journals Online (AJOL)

The science and dynamics underlying drought is complex, yet understandable if approached carefully using scientific method. In this paper, scientific perspective was applied to explain and compare drought indices in Somalia and Lake Chad Basin (LCB). Geographic information system (GIS) was used to analyze ...

Analysis of future drought characteristics in China using the regional climate model CCLM

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Huang, Jinlong; Zhai, Jianqing; Jiang, Tong; Wang, Yanjun; Li, Xiucang; Wang, Run; Xiong, Ming; Su, Buda; Fischer, Thomas

2018-01-01

In this paper, the intensity, area and duration of future droughts in China are analyzed using the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). The SPI and SPEI are used to evaluate the simulation ability of drought characteristics with the regional climate model COSMO-CLM (CCLM). The projected intensity and duration of future drought events are analyzed for the period 2016-2050 under three different respective concentration pathways (RCPs). The simulated and projected drought events are analyzed by applying the intensity-area-duration method. The results show that CCLM has a robust capability to simulate the average drought characteristics, while some regional disparities are not well captured, mainly the simulation of more drought events of shorter duration in Northwest China. For the future period 2016-2050, more intense dryness conditions are projected for China. An increase in evapotranspiration is found all over China, while a reduction in precipitation is apparent in the southern river basins. The increase in evapotranspiration plays an important role in the changes of future droughts over the northern river basins and southern river basins. Under RCP2.6, drought events of longer duration and with higher frequency are projected for the southwest and southeast of China. Under RCP4.5 and RCP8.5, a continuing tendency to more dry conditions is projected along a dryness band stretching from the southwest to the northeast of China. More frequent drought events of longer duration are projected in the southwestern river basins. For all future droughts, larger extents are projected, especially for events with long-term duration. The projected long-term drought events will occur more often and more severe than during the baseline period, and their central locations will likely shift towards Southeast China. The results of this study can be used to initiate and strengthen drought adaptation measures at

The Potential Connectivity of Waterhole Networks and the Effectiveness of a Protected Area under Various Drought Scenarios

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O’Farrill, Georgina; Gauthier Schampaert, Kim; Rayfield, Bronwyn; Bodin, Örjan; Calmé, Sophie; Sengupta, Raja; Gonzalez, Andrew

2014-01-01

Landscape connectivity is considered a priority for ecosystem conservation because it may mitigate the synergistic effects of climate change and habitat loss. Climate change predictions suggest changes in precipitation regimes, which will affect the availability of water resources, with potential consequences for landscape connectivity. The Greater Calakmul Region of the Yucatan Peninsula (Mexico) has experienced a 16% decrease in precipitation over the last 50 years, which we hypothesise has affected water resource connectivity. We used a network model of connectivity, for three large endangered species (Baird’s tapir, white-lipped peccary and jaguar), to assess the effect of drought on waterhole availability and connectivity in a forested landscape inside and adjacent to the Calakmul Biosphere Reserve. We used reported travel distances and home ranges for our species to establish movement distances in our model. Specifically, we compared the effects of 10 drought scenarios on the number of waterholes (nodes) and the subsequent changes in network structure and node importance. Our analysis revealed that drought dramatically influenced spatial structure and potential connectivity of the network. Our results show that waterhole connectivity and suitable habitat (area surrounding waterholes) is lost faster inside than outside the reserve for all three study species, an outcome that may drive them outside the reserve boundaries. These results emphasize the need to assess how the variability in the availability of seasonal water resource may affect the viability of animal populations under current climate change inside and outside protected areas. PMID:24830392

The potential connectivity of waterhole networks and the effectiveness of a protected area under various drought scenarios.

Directory of Open Access Journals (Sweden)

Georgina O'Farrill

Full Text Available Landscape connectivity is considered a priority for ecosystem conservation because it may mitigate the synergistic effects of climate change and habitat loss. Climate change predictions suggest changes in precipitation regimes, which will affect the availability of water resources, with potential consequences for landscape connectivity. The Greater Calakmul Region of the Yucatan Peninsula (Mexico has experienced a 16% decrease in precipitation over the last 50 years, which we hypothesise has affected water resource connectivity. We used a network model of connectivity, for three large endangered species (Baird's tapir, white-lipped peccary and jaguar, to assess the effect of drought on waterhole availability and connectivity in a forested landscape inside and adjacent to the Calakmul Biosphere Reserve. We used reported travel distances and home ranges for our species to establish movement distances in our model. Specifically, we compared the effects of 10 drought scenarios on the number of waterholes (nodes and the subsequent changes in network structure and node importance. Our analysis revealed that drought dramatically influenced spatial structure and potential connectivity of the network. Our results show that waterhole connectivity and suitable habitat (area surrounding waterholes is lost faster inside than outside the reserve for all three study species, an outcome that may drive them outside the reserve boundaries. These results emphasize the need to assess how the variability in the availability of seasonal water resource may affect the viability of animal populations under current climate change inside and outside protected areas.

GRACE-Assimilated Drought Indicators for the U.S. Drought Monitor

Science.gov (United States)

Rui, Hualan; Vollmer, Bruce; Teng, Bill; Loeser, Carlee; Beaudoing, Hiroko; Rodell, Matt

2018-01-01

The Gravity Recovery and Climate Experiment (GRACE) mission detects changes in Earth's gravity field by precisely monitoring the changes in distance between two satellites orbiting the Earth in tandem. Scientists at NASA's Goddard Space Flight Center generate GRACE-assimilated groundwater and soil moisture drought indicators each week, for drought monitor-related studies and applications. The GRACE-assimilated Drought Indicator Version 2.0 data product (GRACE-DA-DM V2.0) is archived at, and distributed by, the NASA GES DISC (Goddard Earth Sciences Data and Information Services Center). More information about the data and data access is available on the data product landing page at https://disc.gsfc.nasa.gov/datasets /GRACEDADM_CLSM0125US_7D_2.0/summary. The GRACE-DA-DM V2.0 data product contains three drought indicators: Groundwater Percentile, Root Zone Soil Moisture Percentile, and Surface Soil Moisture Percentile. The drought indicators are of wet or dry conditions, expressed as a percentile, indicating the probability of occurrence within the period of record from 1948 to 2012. These GRACE-assimilated drought indicators, with improved spatial and temporal resolutions, should provide a more comprehensive and objective identification of drought conditions. This presentation describes the basic characteristics of the data and data services at NASA GES DISC and collaborative organizations, and uses a few examples to demonstrate the simple ways to explore the GRACE-assimilated drought indicator data.

Hydrogen induced crack propagation in metal under plain-strain deformation

International Nuclear Information System (INIS)

Fishgojt, A.V.; Kolachev, B.A.

1981-01-01

A model of subcritical crack propagation conditioned by the effect of dissolved hydrogen in the case of plane-strain deformation of high-strength materials, is suggested. It is supposed that diffusion takes place in the isotropic material and hydrogen diffuses in the region of tensile stress maximum before crack tip under the effect of the stress gradient. When hydrogen achieves the critical concentration, microcrack growth takes place. Values of crack growth rates experimentally obtained agree with values calculated according to the suggested formula. Calculation and experimental data on the Ti-6Al-4V alloy, are presented [ru

Identification of differentially expressed genes in sunflower (Helianthus annuus) leaves and roots under drought stress by RNA sequencing.

Science.gov (United States)

Liang, Chunbo; Wang, Wenjun; Wang, Jing; Ma, Jun; Li, Cen; Zhou, Fei; Zhang, Shuquan; Yu, Ying; Zhang, Liguo; Li, Weizhong; Huang, Xutang

2017-10-25

Sunflower is recognized as one of the most important oil plants with strong tolerance to drought in the world. In order to study the response mechanisms of sunflower plants to drought stress, gene expression profiling using high throughput sequencing was performed for seedling leaves and roots (sunflower inbred line R5) after 24 h of drought stress (15% PEG 6000). The transcriptome assembled using sequences of 12 samples was used as a reference. 805 and 198 genes were identified that were differentially expressed in leaves and roots, respectively. Another 71 genes were differentially expressed in both organs, in which more genes were up-regulated than down-regulated. In agreement with results obtained for other crops or from previous sunflower studies, we also observed that nine genes may be associated with the response of sunflower to drought. The results of this study may provide new information regarding the sunflower drought response, as well as add to the number of known genes associated with drought tolerance.

Defining Drought Characteristics for Natural Resource Management

Science.gov (United States)

Ojima, D. S.; Senay, G. B.; McNeeley, S.; Morisette, J. T.

2016-12-01

In the north central region of the US, on-going drought studies are investigating factors determining how drought impacts various ecosystem services and challenge natural resource management decisions. The effort reported here stems from research sponsored by the USGS North Central Climate Science Center, to deal with ecosystem response to drought with the goal to see if there are indicators of drought emerging from the ecosystem interactions with various weather patterns, soil moisture dynamics, and the structural aspects of the ecosystem in question. The North Central domain covers a region from the headwaters of the Missouri River Basin to the northern Great Plains. Using spatial and temporal analysis of remote sensing products and mechanistic daily time-step ecosystem model simulations across the northern Great Plains and northern Rockies, analysis of recent drought conditions over the region will be provided. Drought characteristics will be analyzed related to resource management targets, such as water supply, landscape productivity, or habitat needs for key species. Analysis of ecosystem and landscape patterns of drought relative to net primary productivity, surface temperatures, soil moisture content, evaporation, transpiration, and water use efficiency from 2000 through 2014 will be analyzed for different drought and non-drought events. Comparisons between satellite-derived ET and NPP of different Great Plains ecosystems related to simulated ET and NPP will be presented. These comparisons provide indications of the role that soil moisture dynamics, groundwater recharge and rooting depth of different ecosystems have on determining the sensitivity to water stress due to seasonal warming and reduced precipitation across the region. In addition, indications that average annual rainfall levels over certain ecosystems may result in reduced production due to higher rates of water demand under the observed warmer temperatures and the prolonged warming in the spring

Integration of gene-based markers in a pearl millet genetic map for identification of candidate genes underlying drought tolerance quantitative trait loci

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Sehgal Deepmala

2012-01-01

Full Text Available Abstract Background Identification of genes underlying drought tolerance (DT quantitative trait loci (QTLs will facilitate understanding of molecular mechanisms of drought tolerance, and also will accelerate genetic improvement of pearl millet through marker-assisted selection. We report a map based on genes with assigned functional roles in plant adaptation to drought and other abiotic stresses and demonstrate its use in identifying candidate genes underlying a major DT-QTL. Results Seventy five single nucleotide polymorphism (SNP and conserved intron spanning primer (CISP markers were developed from available expressed sequence tags (ESTs using four genotypes, H 77/833-2, PRLT 2/89-33, ICMR 01029 and ICMR 01004, representing parents of two mapping populations. A total of 228 SNPs were obtained from 30.5 kb sequenced region resulting in a SNP frequency of 1/134 bp. The positions of major pearl millet linkage group (LG 2 DT-QTLs (reported from crosses H 77/833-2 × PRLT 2/89-33 and 841B × 863B were added to the present consensus function map which identified 18 genes, coding for PSI reaction center subunit III, PHYC, actin, alanine glyoxylate aminotransferase, uridylate kinase, acyl-CoA oxidase, dipeptidyl peptidase IV, MADS-box, serine/threonine protein kinase, ubiquitin conjugating enzyme, zinc finger C- × 8-C × 5-C × 3-H type, Hd3, acetyl CoA carboxylase, chlorophyll a/b binding protein, photolyase, protein phosphatase1 regulatory subunit SDS22 and two hypothetical proteins, co-mapping in this DT-QTL interval. Many of these candidate genes were found to have significant association with QTLs of grain yield, flowering time and leaf rolling under drought stress conditions. Conclusions We have exploited available pearl millet EST sequences to generate a mapped resource of seventy five new gene-based markers for pearl millet and demonstrated its use in identifying candidate genes underlying a major DT-QTL in this species. The reported gene

Groundwater Drought and Recovery: a Case Study from the United Kingdom

Science.gov (United States)

Peach, D.; McKenzie, A. A.; Bloomfield, J.

2012-12-01

An understanding of the processes leading to the onset, duration and end of hydrological droughts is necessary to help improve the management of stressed or scarce water resources during such periods. In particular, the role and use of groundwater during episodes of drought is crucially important, since groundwater can provide relatively resilient water supplies during early stages of drought but maybe highly susceptible to relatively persistent or sustained droughts. Nevertheless, groundwater is seldom considered in drought analyses, and compared with other types of hydrological drought there have been few studies to date. The few previous studies of groundwater droughts at catchment- and regional-scale have shown that catchment and aquifer characteristics exert a strong influence on the spatio-temporal development of groundwater droughts as water deficit propagates through the terrestrial water cycle. In this context, the relationships between hydrogeological heterogeneity, catchment engineering infrastructure (storage), and decisions related to water resource management during drought events all shape the evolution and consequences of groundwater droughts. Here we examine the evolution of a recent regionally significant two-year drought across the United Kingdom (UK) and use it to investigate these relationships. We identify the drivers, characterise the development and spatio-temporal extent of the groundwater drought. In particular, we focus on the unusually rapid end and recovery from drought during what would normally be a period of groundwater recession. The UK, and in particular southern England, relies extensively on groundwater for public water supply, agricultural and industrial use, as well as for sustaining river flows that are essential to ecosystem health. In normal years relatively consistent rainfall patterns prevail, recharging aquifers over winter when evapotranspiration is minimal. However, by March 2012 large parts of the southern UK had

Response of antioxidant system to drought stress and re-watering in Alfalfa during branching

Science.gov (United States)

Tina, R. R.; Shan, X. R.; Wang, Y.; Guo, S. Y.; Mao, B.; Wang, W.; Wu, H. Y.; Zhao, T. H.

2017-11-01

This paper aimed to reveal the response mechanism of active oxygen metabolism and antioxidant enzyme activities in Alfalfa under drought stress and re-watering, and the pot experiment was used, to explore the changes of H2O2, O2·-, electrolyte leakage conductivity and MDA, SOD, POD, CAT activity in Golden Empress (tolerant cultivar) and Sanditi (non-tolerant cultivar) under drought stress and re-watering during branching stage. Three water gradients were set up: CK (Maximum field capacity of 75%±5%), T1 (Maximum field capacity of 45%±5%), T2 (Maximum field capacity of 35%±5%) to compare, and the drought rehydration was also studied. Results: the results indicated that H2O2 content, O2·-production rate, relative conductivity and MDA content were higher than the control, and the increase extent of Golden Empress was higher than the Sanditi under drought stress and after re-watering the recovery capability of Golden Empress was also higher than the Sanditi. After 7 days of re-watering, all indexes were restored to the control level, indicating that the re-watering have compensation effect after drought. After drought stress, to weaken the damage of active oxygen Golden Empress was mainly by increasing the activity of POD and SOD, but Sanditi was mainly through the POD and CAT activity increased to effectively remove ROS. Under drought stress, active oxygen in leaves of Alfalfa increased, and thus the membrane system was damaged which lead to the increase of MDA content and relative electric conductivity. Plants play a defensive role by increasing the activity of antioxidant enzymes and scavenging reactive oxygen species. After re-watering, the stress effect was reduced, and the physiological indexes of plants were restored to the control level. In general, tolerant cultivar has stronger antioxidant properties under drought and re-watering.

Tagging genes for drought resistance by DNA markers in wheat (abstract)

International Nuclear Information System (INIS)

Malik, T.A.; Rahman, S.; Zafar, Y.

2005-01-01

Wheat families (F/sub 3) raised from the seed of drought resistant and susceptible F/sub 2/ plants developed from the cross of drought resistant and susceptible parents were grown under greenhouse conditions in polyethylene tubes filled with soil and sand mixture. Drought stress was imposed and monitored at the seedling stage. The relative water content and net photosynthesis was recorded with increasing drought stress until a significant part of the seedling population had zero or negative net photosynthesis. The seedling with zero or negative net photosynthesis were named as drought susceptible and the seedlings at the same drought stress showing net photosynthesis were named as drought resistance. Twenty each of the most susceptible and resistant seedlings were selected for DNA extraction. Random Amplified Polymorphic DNA (RAPD) technique using bulked segregant analysis was used to identify DNA markers linked to drought resistance. The primers OPJ-05, OPJ-14, OPI-20 and OPA-19 produced polymorphic DNA fragments between the contrasting bulks. The polymorphic DNA fragment of 1.55kb produced by the primer OPA-19 was found linked to drought resistance. This DNA marker can be used in markers-assisted selection for drought resistance or to clone drought resistance gene. (author)