Soil weed seed bank in situ and ex situ at a smallholder field in Maranhão State, northeastern Brazil

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Mário Luiz Ribeiro Mesquita

2014-11-01

Full Text Available The objective of this research was to assess the density, floristic composition,  phytosociology and diversity of a soil weed seed bank ex situ by germination in a greenhouse and in situ by weed sampling on a smallholder corn field located in Lago Verde County, Maranhão State. Fifteen pairs of 25 m2 plots were designated. In half of these plots, 90 soil samples were collected with an open metal template measuring 25 x 16 x 3 cm and placed in a greenhouse to germinate. In the other half, 90 weed samples were collected using the same metal template. We recorded a total of 1,998 individuals from 40 species, 31 genera and 16 families, from which 659 individuals germinated in situ and 1,339 exsitu. Density was higher ex situ, with 372 plants m-2. The Cyperaceae family had the highest floristic richness with nine species, followed by the Poaceae with six. The dominant species based on the Importance Value Index were Lindernia crustacea (IVI 27.7% in situ and Scleria lithosperma (IVI 37.0% ex situ. Floristic diversity was higher ex situ, with H’ = 2.66 nats ind-1. These results could help predict infestation potential and could lead to improved weed management strategies in corn-growing areas on smallholdings in Maranhão State, northeastern Brazil.

Variation in Weed Seed Fate Fed to Different Holstein Cattle Groups.

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Salman Rahimi

Full Text Available Weed seeds may maintain their viability when passing through the digestive tract of cattle and can be therefore dispersed by animal movement or the application of manure. Whether different cattle types of the same species can cause differential weed seed fate is largely unknown to us particularly under non-grazed systems similar to Holstein-Friesian dairy farming. We investigated the effect on the seed survival of four weed species in the digestive tracts of four groups of Holstein cattle: lactating cows, feedlot male calves, dry cows and growing heifers. The weed species used were Cuscuta campestris, Polygonum aviculare, Rumex crispus and Sorghum halepense. Cattle excretion was sampled for recovery and viability of seeds at four 24 hourly intervals after seed intake. The highest seed recovery occurred two days after seed intake in all cattle groups. Averaged over weed species, dry and lactating cows had the lowest and highest seed recovery of 36.4% and 74.4% respectively. No significant differences were observed in seed recovery of the four weed species when their seeds were fed to dry cows. Based on a power model fitted to seed viability data, the estimated time to 50% viability loss after seed intake, over all cattle groups ranged from 65 h (R. crispus to 76 h (P. aviculare. Recovered seeds from the dung of feedlot male calves showed the highest mortality among cattle groups. Significant correlation was found between seed viability and ruminal pH (r = 0.86; P<0.05. This study shows that management programs aiming to minimize weed infestation caused by livestock should account for the variation amongst cattle groups in seed persistence. Our findings can be used as a guideline for evaluating the potential risk of the spread of weeds via the application of cattle manure.

Interspecific variation in persistence of buried weed seeds follows trade-offs among physiological, chemical, and physical seed defenses.

Science.gov (United States)

Davis, Adam S; Fu, Xianhui; Schutte, Brian J; Berhow, Mark A; Dalling, James W

2016-10-01

Soil seedbanks drive infestations of annual weeds, yet weed management focuses largely on seedling mortality. As weed seedbanks increasingly become reservoirs of herbicide resistance, species-specific seedbank management approaches will be essential to weed control. However, the development of seedbank management strategies can only develop from an understanding of how seed traits affect persistence.We quantified interspecific trade-offs among physiological, chemical, and physical traits of weed seeds and their persistence in the soil seedbank in a common garden study. Seeds of 11 annual weed species were buried in Savoy, IL, from 2007 through 2012. Seedling recruitment was measured weekly and seed viability measured annually. Seed physiological (dormancy), chemical (phenolic compound diversity and concentration; invertebrate toxicity), and physical traits (seed coat mass, thickness, and rupture resistance) were measured.Seed half-life in the soil ( t 0.5 ) showed strong interspecific variation ( F 10,30  = 15, p  central role of seed dormancy in controlling seed persistence.A quantitative comparison between our results and other published work indicated that weed seed dormancy and seedbank persistence are linked across diverse environments and agroecosystems. Moreover, among seedbank-forming early successional plant species, relative investment in chemical and physical seed defense varies with seedbank persistence. Synthesis and applications . Strong covariance among weed seed traits and persistence in the soil seedbank indicates potential for seedbank management practices tailored to specific weed species. In particular, species with high t 0.5 values tend to invest less in chemical defenses. This makes them highly vulnerable to physical harvest weed seed control strategies, with small amounts of damage resulting in their full decay.

Variation in Weed Seed Fate Fed to Different Holstein Cattle Groups.

Science.gov (United States)

Rahimi, Salman; Mashhadi, Hamid Rahimian; Banadaky, Mehdi Dehghan; Mesgaran, Mohsen Beheshtian

2016-01-01

Weed seeds may maintain their viability when passing through the digestive tract of cattle and can be therefore dispersed by animal movement or the application of manure. Whether different cattle types of the same species can cause differential weed seed fate is largely unknown to us particularly under non-grazed systems similar to Holstein-Friesian dairy farming. We investigated the effect on the seed survival of four weed species in the digestive tracts of four groups of Holstein cattle: lactating cows, feedlot male calves, dry cows and growing heifers. The weed species used were Cuscuta campestris, Polygonum aviculare, Rumex crispus and Sorghum halepense. Cattle excretion was sampled for recovery and viability of seeds at four 24 hourly intervals after seed intake. The highest seed recovery occurred two days after seed intake in all cattle groups. Averaged over weed species, dry and lactating cows had the lowest and highest seed recovery of 36.4% and 74.4% respectively. No significant differences were observed in seed recovery of the four weed species when their seeds were fed to dry cows. Based on a power model fitted to seed viability data, the estimated time to 50% viability loss after seed intake, over all cattle groups ranged from 65 h (R. crispus) to 76 h (P. aviculare). Recovered seeds from the dung of feedlot male calves showed the highest mortality among cattle groups. Significant correlation was found between seed viability and ruminal pH (r = 0.86; Pweed infestation caused by livestock should account for the variation amongst cattle groups in seed persistence. Our findings can be used as a guideline for evaluating the potential risk of the spread of weeds via the application of cattle manure.

Revisão de modelos matemáticos da dinâmica do banco de sementes de plantas daninhas em agrossistemas Review of mathematical models of weed seed bank dynamics

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L.S. Vismara

2007-03-01

Full Text Available O crescimento das plantas obedece a certos princípios fisiológicos, que podem ser descritos em termos quantitativos, até certo ponto, por equações matemáticas. No ambiente agrícola, a dinâmica do banco de sementes está fortemente relacionada ao estabelecimento de espécies daninhas e pode ser descrita por um sistema de equações que relaciona a densidade de plântulas com a densidade de sementes produzidas em áreas de cultivo. O objetivo deste artigo foi descrever, através de modelos matemáticos citados na literatura, as características do comportamento dinâmico do banco de sementes de populações de plantas daninhas em sistemas agrícolas.Plant growth follows certain physiological principles that can be quantitatively described, up to a certain extent, by mathematical equations. In agrosystems, seed bank dynamics is strongly related to the establishment of weed species and can be described as a system of equations that relates seedling density with the density of seeds produced in cultivation areas. The objective of this work is to describe, using mathematical models cited in the literature, the characteristics of the dynamic behavior of weed seed bank populations in agrosystems.

Weed seed spread and its prevention: The role of roadside wash down.

Science.gov (United States)

Bajwa, Ali Ahsan; Nguyen, Thi; Navie, Sheldon; O'Donnell, Chris; Adkins, Steve

2018-02-15

Vehicles are one of the major vectors of long-distance weed seed spread. Viable seed removed from vehicles at roadside wash down facilities was studied at five locations in central Queensland, Australia over a 3-year period. Seed from 145 plant species, belonging to 34 different families, were identified in the sludge samples obtained from the wet particulate matter collection pit of the wash down facilities. Most of the species were annual forbs (50%) with small or very small seed size (weed was observed in these samples. More parthenium weed seed were found in the Rolleston facility and in the spring, but its seed was present in all facilities and in all seasons. The average number of viable seed found within every ton of dry particulate matter removed from vehicles was ca. 68,000. Thus, a typical wash down facility was removing up to ca. 335,000 viable seed from vehicles per week, of which ca. 6700 were parthenium weed seed. Furthermore, 61% of these seed (ca. 200,000) were from introduced species, and about half of these (35% of total) were from species considered to be weeds. Therefore, the roadside wash down facilities found throughout Queensland can remove a substantial amount of viable weed seed from vehicles, including the invasive parthenium weed, and the use of such facilities should be strongly encouraged. Copyright © 2017 Elsevier Ltd. All rights reserved.

7 CFR 201.65 - Noxious weed seeds in interstate commerce.

Science.gov (United States)

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false Noxious weed seeds in interstate commerce. 201.65 Section 201.65 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING... ACT FEDERAL SEED ACT REGULATIONS Tolerances § 201.65 Noxious weed seeds in interstate commerce...

Evaluating the potential for weed seed dispersal based on waterfowl consumption and seed viability.

Science.gov (United States)

Farmer, Jaime A; Webb, Elisabeth B; Pierce, Robert A; Bradley, Kevin W

2017-12-01

Migratory waterfowl have often been implicated in the movement of troublesome agronomic and wetland weed species. However, minimal research has been conducted to investigate the dispersal of agronomically important weed species by waterfowl. The two objectives for this project were to determine what weed species are being consumed by ducks and snow geese, and to determine the recovery rate and viability of 13 agronomic weed species after passage through a duck's digestive system. Seed recovered from digestive tracts of 526 ducks and geese harvested during a 2-year field study had 35 020 plants emerge. A greater variety of plant species emerged from ducks each year (47 and 31 species) compared to geese (11 and 3 species). Viable seed from 11 of 13 weed species fed to ducks in a controlled feeding study were recovered. Viability rate and gut retention times indicated potential dispersal up to 2900 km from the source depending on seed characteristics and variability in waterfowl dispersal distances. Study results confirm that waterfowl are consuming seeds from a variety of agronomically important weed species, including Palmer amaranth, which can remain viable after passage through digestive tracts and have potential to be dispersed over long distances by waterfowl. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Effect of weed management and seed rate on crop growth under direct dry seeded rice systems in Bangladesh.

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Sharif Ahmed

Full Text Available Weeds are a major constraint to the success of dry-seeded rice (DSR. The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free and rice seeding rate (20, 40, 60, 80, and 100 kg ha(-1 on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha(-1 in the 2012 and 2013 seasons, respectively were obtained at the seeding rate of 40 kg ha(-1 and thereafter, yield decreased slightly beyond 40 kg seed ha(-1. Under partially-weedy conditions, yield increased by 30 to 33% (2.0-2.2 and 2.9-3.2 t ha(-1 in the 2012 and 2013 seasons, respectively with increase in seeding rate from 20 to 100 kg ha(-1. In the partially-weedy plots, weed biomass decreased by 41-60% and 54-56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha(-1. Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition.

Effect of Weed Management and Seed Rate on Crop Growth under Direct Dry Seeded Rice Systems in Bangladesh

Science.gov (United States)

Ahmed, Sharif; Salim, Muhammad; Chauhan, Bhagirath S.

2014-01-01

Weeds are a major constraint to the success of dry-seeded rice (DSR). The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet) seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free) and rice seeding rate (20, 40, 60, 80, and 100 kg ha−1) on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha−1 in the 2012 and 2013 seasons, respectively) were obtained at the seeding rate of 40 kg ha−1 and thereafter, yield decreased slightly beyond 40 kg seed ha−1. Under partially-weedy conditions, yield increased by 30 to 33% (2.0–2.2 and 2.9–3.2 t ha−1 in the 2012 and 2013 seasons, respectively) with increase in seeding rate from 20 to 100 kg ha−1. In the partially-weedy plots, weed biomass decreased by 41–60% and 54–56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha−1. Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition. PMID:25000520

Effect of weed management and seed rate on crop growth under direct dry seeded rice systems in Bangladesh.

Science.gov (United States)

Ahmed, Sharif; Salim, Muhammad; Chauhan, Bhagirath S

2014-01-01

Weeds are a major constraint to the success of dry-seeded rice (DSR). The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet) seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free) and rice seeding rate (20, 40, 60, 80, and 100 kg ha(-1)) on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha(-1) in the 2012 and 2013 seasons, respectively) were obtained at the seeding rate of 40 kg ha(-1) and thereafter, yield decreased slightly beyond 40 kg seed ha(-1). Under partially-weedy conditions, yield increased by 30 to 33% (2.0-2.2 and 2.9-3.2 t ha(-1) in the 2012 and 2013 seasons, respectively) with increase in seeding rate from 20 to 100 kg ha(-1). In the partially-weedy plots, weed biomass decreased by 41-60% and 54-56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha(-1). Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition.

7 CFR 201.52 - Noxious-weed seeds.

Science.gov (United States)

2010-01-01

... 64499, Dec. 14, 1994] germination tests in the administration of the act ... 7 Agriculture 3 2010-01-01 2010-01-01 false Noxious-weed seeds. 201.52 Section 201.52 Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT...

Crop–weed competition

DEFF Research Database (Denmark)

Gallandt, Eric R.; Weiner, Jacob

2015-01-01

importantly, weed density and time of emergence relative to the crop. Practices that (1) reduce the density of weeds, (2) maximise occupation of space or uptake of resources by the crop or (3) establish an early-season size advantage of the crop over the weeds will minimise the competitive effects of weeds...... on crops. Longer term management of crop–weed competition can be achieved through crop rotations, specifically crop sequences that reduce the weed seed bank, and therefore seedling density, and prevent proliferation of perennial weeds. Key ConceptsKey Concepts * Plant growth requires sunlight, water...... an early-season competitive advantage to the crop and (3) maximising resource capture by the crop using competitive species, competitive cultivars, high sowing densities, optimal spatial arrangement, intercropping complimentary species or transplanting....

Floristic diversity of the soil weed seed bank in a rice-growing area of Brazil: in situ and ex situ evaluation

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Mário Luiz Ribeiro Mesquita

2013-09-01

Full Text Available The objective of this study was to compare the ex situ and in situ floristic diversity of the soil weed seed bank of a rice field in northeastern Brazil. In a rice field in the county of Bacabal, located in the state of Maranhão, thirty 25-m² plots were laid out. From 15 plots, soil samples (6/plot; n = 90 were taken with a soil probe (25 × 16 × 3 cm and placed in aluminum trays in the greenhouse. From the remaining 15 plots, weed samples (6/plot; n = 90 were taken with the same soil probe. The number of seeds was estimated by germination. We evaluated the numbers of species and individuals, as well as the density, frequency, abundance and importance value (IV for each species. Diversity was computed by the Shannon index (H'. We recorded 13,892 individuals (among 20 families, 40 genera and 60 species, of which 11,530 (among 50 species germinated ex situ and 2,362 (among 34 species germinated in situ. The family Cyperaceae had the highest number of species (16, followed by Poaceae (10. The dominant species, in situ and ex situ, were Schoenoplectus juncoides (IV=47.4% and Ludwigia octovalvis (IV=34.8%, respectively. Floristic diversity was higher ex situ (H'=2.66. The information obtained here could help determine the infestation potential of these species, which could lead to improved management strategies.

Opportunities and challenges for harvest weed seed control in global cropping systems.

Science.gov (United States)

Walsh, Michael J; Broster, John C; Schwartz-Lazaro, Lauren M; Norsworthy, Jason K; Davis, Adam S; Tidemann, Breanne D; Beckie, Hugh J; Lyon, Drew J; Soni, Neeta; Neve, Paul; Bagavathiannan, Muthukumar V

2017-11-28

The opportunity to target weed seeds during grain harvest was established many decades ago following the introduction of mechanical harvesting and the recognition of high weed-seed retention levels at crop maturity; however, this opportunity remained largely neglected until more recently. The introduction and adoption of harvest weed seed control (HWSC) systems in Australia has been in response to widespread occurrence of herbicide-resistant weed populations. With diminishing herbicide resources and the need to maintain highly productive reduced tillage and stubble-retention practices, growers began to develop systems that targeted weed seeds during crop harvest. Research and development efforts over the past two decades have established the efficacy of HWSC systems in Australian cropping systems, where widespread adoption is now occurring. With similarly dramatic herbicide resistance issues now present across many of the world's cropping regions, it is timely for HWSC systems to be considered for inclusion in weed-management programs in these areas. This review describes HWSC systems and establishing the potential for this approach to weed control in several cropping regions. As observed in Australia, the inclusion of HWSC systems can reduce weed populations substantially reducing the potential for weed adaptation and resistance evolution. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Seeding method and rate influence on weed suppression in aerobic ...

African Journals Online (AJOL)

High weed pressure is amongst the major constraints to the extensive adoption of aerobic rice system as a water-wise technique. Towards developing a sustainable weed management strategy, seeding method and rate may substantially contribute to weed suppression and reduce herbicide use and weeding cost. A trough ...

Onion and weed response to mustard (Sinapis alba) seed meal

Science.gov (United States)

Weed control in organic onion production is often difficult and expensive, requiring numerous cultivations and extensive hand-weeding. Onion safety and weed control with mustard seed meal (MSM) derived from Sinapis alba was evaluated in greenhouse and field trials. MSM applied at 110, 220, and 440 g...

Skylarks trade size and energy content in weed seeds to maximize total ingested lipid biomass.

Science.gov (United States)

Gaba, Sabrina; Collas, Claire; Powolny, Thibaut; Bretagnolle, François; Bretagnolle, Vincent

2014-10-01

The trade-off between forage quality and quantity has been particularly studied in herbivore organisms, but much less for seed eating animals, in particular seed-eating birds which constitute the bulk of wintering passerines in European farmlands. The skylark is one of the commonest farmland birds in winter, mainly feeding on seeds. We focus on weed seeds for conservation and management purposes. Weed seeds form the bulk of the diet of skylarks during winter period, and although this is still a matter for discussion, weed seed predation by granivorous has been suggested as an alternative to herbicides used to regulate weed populations in arable crops. Our objectives were to identify whether weed seed traits govern foraging decisions of skylarks, and to characterize key seed traits with respect to size, which is related to searching and handling time, and lipid content, which is essential for migratory birds. We combined a single-offer experiment and a multiple-offer one to test for feeding preferences of the birds by estimating seed intake on weed seed species differing in their seed size and seed lipid content. Our results showed (1) a selective preference for smaller seeds above a threshold of seed size or seed size difference in the pair and, (2) a significant effect of seed lipid biomass suggesting a trade-off between foraging for smaller seeds and selecting seeds rich in lipids. Skylarks foraging decision thus seems to be mainly based on seed size, that is presumably a 'proxy' for weed seed energy content. However, there are clearly many possible combinations of morphological and physiological traits that must play crucial role in the plant-bird interaction such as toxic compound or seed coat. Copyright © 2014 Elsevier B.V. All rights reserved.

Soil seed banks Banco de sementes do solo

Directory of Open Access Journals (Sweden)

P.J. Christoffoleti

1998-01-01

Full Text Available The goal of this literature review is to discuss some of the major aspects of the soil seed bank, from its characteristics down to methodological aspects of its determination. Soil seed bank is the reservoir of viable seeds or of vegetative propagules that are present in the soil and that are able to recompose a natural vegetation. In the agroecossystems the soil seed bank is related to weeds, and the knowledge of its size and composition in terms of species can be used in the prediction of future infestations, to built simulation models of population establishment through time and also the definition of soil and cultural management programs, in order to have a rational use of herbicides.O objetivo desta revisão é discorrer sobre alguns pontos importantes no estudo do banco de sementes no solo, desde as sua características até aspectos metodológicos para sua determinação. Denomina-se de banco de sementes a reserva destas ou de propágulos vegetativos viáveis presentes no solo e que são capazes de recompor uma vegetação. Nos sistemas agrícolas o banco está relacionado com o estudo das plantas daninhas; o conhecimento do seu tamanho e das espécies que o compõem poderá ser utilizado na previsão de infestações futuras, na construção de modelos de estabelecimentos populacionais no tempo e consequentemente na definição de programas de manejo de solo e culturais, visando racionalizar a utilização de herbicidas.

Role of Weed Emergence Time for the Relative Seed Production in Maize

Directory of Open Access Journals (Sweden)

Stefano Benvenuti

2007-03-01

Full Text Available Trials were carried out in 2000 and 2001 to investigate the effect of weed emergence time on weed seed production in a maize field. Datura stramonium L., Solanum nigrum L. and Abutilon theophrasti Medicus were selected for their importance as summer weeds. Emergence time was found to be crucial since delay would involve an unfavourable light environment determined by crop canopy elongation and resulting shade production. Only the early emergence of D. stramonium and A. theophrasti showed the capacity to exposing their leaves over the crop canopy. Generally the weed seed production under shade conditions decreased for the reduction of the fruit per plant since the number of seed per plant showed only a light reduction. However, while D. stramonium and A. theophrasti compete with the crop by increasing height, Solanum nigrum tends to adjust to shade without excessive reduction in number of seeds produced. Thus in D. stramonium and A. theophrasti late emergence reduced seed production to only 15%, while S. nigrum maintained 25% of the seed production level generally observed with greater light exposure. This environmental adaptation was confirmed by the less marked decrease in S. nigrum harvest index. Agroecological involvements are discussed.

Role of Weed Emergence Time for the Relative Seed Production in Maize

Directory of Open Access Journals (Sweden)

Stefano Benvenuti

Full Text Available Trials were carried out in 2000 and 2001 to investigate the effect of weed emergence time on weed seed production in a maize field. Datura stramonium L., Solanum nigrum L. and Abutilon theophrasti Medicus were selected for their importance as summer weeds. Emergence time was found to be crucial since delay would involve an unfavourable light environment determined by crop canopy elongation and resulting shade production. Only the early emergence of D. stramonium and A. theophrasti showed the capacity to exposing their leaves over the crop canopy. Generally the weed seed production under shade conditions decreased for the reduction of the fruit per plant since the number of seed per plant showed only a light reduction. However, while D. stramonium and A. theophrasti compete with the crop by increasing height, Solanum nigrum tends to adjust to shade without excessive reduction in number of seeds produced. Thus in D. stramonium and A. theophrasti late emergence reduced seed production to only 15%, while S. nigrum maintained 25% of the seed production level generally observed with greater light exposure. This environmental adaptation was confirmed by the less marked decrease in S. nigrum harvest index. Agroecological involvements are discussed.

Annual losses of weed seeds due to predation in organic cereal fields

NARCIS (Netherlands)

Westerman, P.R.; Wes, J.S.; Kropff, M.J.; Werf, van der W.

2003-01-01

1. Post-dispersal seed losses in annual arable weed species are poorly quantified, but may be of significance for natural population control, especially if they can be manipulated. We hypothesized that weed seed predation on the soil surface was significant, so we measured rates in the field to

Effect of weed patch size on seed removal by harvester ants

Directory of Open Access Journals (Sweden)

Westermann, Paula R.

2014-02-01

Full Text Available In dryland cereals in North-eastern Spain, the harvester ant, Messor barbarus L., is responsible for removal of a large proportion of the newly produced weed seeds (40-100%. The probability that seeds will be found by the ants may be influenced by weed patch size. To investigate this source of variability, 30 seed patches were created in each of three, 50 × 50 m, blocks in a cereal field after harvest, by sequentially seeding (10, 16 and 17 August 2010 with 2000 seeds m-2 of Avena sativa L.. Patch size varied from 0.25 to 9 m2. Twenty four hours after seeding, the remaining seeds were collected and seed removal rates estimated. Average seed removal rate was lowest in the smallest (78-94% and highest in the largest patches (99-100%. Differences were mainly caused by the fact that some of the smaller patches (9.7% were not found. However, when patches were found, they were exploited at equal rates (98-100%. As predicted, the probability of finding a patch increased slightly, but significantly, with increasing patch size. When a patch was found, it was almost always fully exploited, resulting in very high seed removal rates, irrespective of patch size. These results indicate that the size of the seed patch is only a minor source of variation influencing this form of biological control of weeds.

Weed seed germination in winter cereals under contrasting tillage systems

DEFF Research Database (Denmark)

Scherner, Ananda

2015-01-01

to accumulate in the top soil layer and timing of herbicide applications sometimes seems to target the emergence pattern of these weeds poorly. In contrast to the management of most diseases and pests, weed management should be considered in a time frame. The abilities to produce above and below ground...... of weeds. An important component in IWM is to understand and ultimately predict weed emergence patterns in relation to the cropping system and the tillage method applied. A better understanding of the cumulative emergence patterns of weed species in winter crops under different tillage regimes will help......Grass weeds and Gallium aparine are major weed problems in North European arable cropping systems with high proportions of winter crops, especially winter wheat (Clarke et al., 2000; Melander et al., 2008). Problems are accentuated where inverting tillage is omitted, as weed seeds tend...

Microscale Insight into Microbial Seed Banks.

Science.gov (United States)

Locey, Kenneth J; Fisk, Melany C; Lennon, J T

2016-01-01

Microbial dormancy leads to the emergence of seed banks in environmental, engineered, and host-associated ecosystems. These seed banks act as reservoirs of diversity that allow microbes to persist under adverse conditions, including extreme limitation of resources. While microbial seed banks may be influenced by macroscale factors, such as the supply of resources, the importance of microscale encounters between organisms and resource particles is often overlooked. We hypothesized that dimensions of spatial, trophic, and resource complexity determine rates of encounter, which in turn, drive the abundance, productivity, and size of seed banks. We tested this using >10,000 stochastic individual based models (IBMs) that simulated energetic, physiological, and ecological processes across combinations of resource, spatial, and trophic complexity. These IBMs allowed realistic dynamics and the emergence of seed banks from ecological selection on random variation in species traits. Macroscale factors like the supply and concentration of resources had little effect on resource encounter rates. In contrast, encounter rates were strongly influenced by interactions between dispersal mode and spatial structure, and also by the recalcitrance of resources. In turn, encounter rates drove abundance, productivity, and seed bank dynamics. Time series revealed that energetically costly traits can lead to large seed banks and that recalcitrant resources can lead to greater stability through the formation of seed banks and the slow consumption of resources. Our findings suggest that microbial seed banks emerge from microscale dimensions of ecological complexity and their influence on resource limitation and energetic costs.

Defense enzyme responses in dormant wild oat and wheat caryopses challenged with a seed decay pathogen

Science.gov (United States)

Seed dormancy and resistance to seed decay organisms are fundamental ecological strategies for weed seed persistence in the weed seed-bank. Seeds have well-established physical, chemical, and biological defense mechanisms that protect their food reserves from decay-inducing organisms and herbivores....

Irradiation effects for the growth inhibition of weed seeds invaded from foreign countries

International Nuclear Information System (INIS)

Takatani, Yasuyuki; Ito, Hitoshi

1999-01-01

Weeds of foreign origin have been invaded through imported maize or dried grass which using for animal feeds, and causing serious damages to agricultural crops and farm animals in Japan. These weeds are spreading mainly through animal feeds to feces. For the purpose to decrease the damage from these weeds, we investigated the gamma-irradiation effect on 7 species of the weed seed to suppress the germination or elongation of stem and root. After the irradiation of the weed seeds, all species kept the ability of germination even at 4 kGy in petri dish cultivation, whereas decreased the germination ratio in some species. However, many species of weed decreased the ability on elongation of stem or root below l kGy irradiation. Furthermore, all of species lost the ability on the development of root hair and appearance of first leaf after germination of seeds below 1 kGy irradiation. From this study, necessary dose for growth inhibition was estimated to be 1 kGy which should be able to apply with combination treatment of the animal feeds for elimination of pathogenic bacteria such as salmonellae at 3 to 5 kGy irradiation. (author)

Weed populations and their buried seeds in rice fields of the MUDA area

International Nuclear Information System (INIS)

Ismail Sahid; Noor Faezah Zainuddin; Ho Nai Kin

2002-01-01

A total of 25 weed species belonging to 15 families were found in rice fields near Kampung Tandop, in the Muda Irrigation Scheme, Kedah, Malaysia. The dominant weeds in dry-seeded rice were Utricularia aurea Lour., Fimbristylis miliacea (L.) vahl., Echinochloa crusgalli (L.) Beauv., Monochoria vaginalis (Burm. Q Presl. and Najas graminea (Del.) Redl. In wet-seeded rice, the dominant species were N. graminea, Lemna minor L., Sphenoclea zeylanica Gaertn., U. aured, and Sagittaria guayanensis H. B. K., while in volunteer seedling rice fields, the dominant species were Echinochloa colonum (L.) Link., Fimbristylis alboviridis C. B. Clarke, E miliacea, Cyperus babakan Steud. and Fuirena umbellata Rottb. Dry-seeded rice fields contained the highest number of weed seeds (930 910/m 2 in the top 15 cm of soil); volunteer seedling rice fields contained 793.162/m 2 and wet-seeded rice fields 712 228/m 2 . In general, the seed numbers declined with increasing soil depth. At 1015 cm depth, seeds of U aurea and S. zeylanica were the most abundant in dry and wet-seeded rice fields, whilst seeds of Scirpusjuncoides Roxb. and E miliacea were most abundant in volunteer seedling fields. (Author)

Banco de sementes de plantas daninhas em solo cultivado com pastagens de Brachiaria brizantha e Brachiaria humidicola de diferentes idades Weed seed bank in soil cultivated with pasture of Brachiaria brizantha and Brachiaria humidicola of different ages

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D.S.M. Silva

2001-08-01

Full Text Available Estudou-se o banco de sementes do solo de uma pastagem de Brachiaria brizantha com 4 anos de idade e de pastagens de Brachiaria humidicola com 4, 15 e 20 anos de idade, localizadas no nordeste do Estado do Pará. Objetivou-se avaliar a influência da espécie forrageira e da idade da pastagem no tamanho e na composição do banco de sementes de plantas daninhas do solo. Cada pastagem foi dividida em cinco áreas de aproximadamente 500 m², sendo retiradas, de cada área, 10 subamostras de solo na profundidade de 0-10 cm. Cada amostra composta das 10 subamostras de solo foi homogeneizada, identificada, distribuída em bandeja de plástico e levada para germinar em casa de vegetação durante um período de 15 meses. O banco de sementes do solo da pastagem de B. brizantha foi em torno de 10 vezes menor que o da pastagem de B. humidicola de mesma idade. Com relação ao efeito da idade da pastagem, entre as pastagens de B. humidicola, o banco de sementes foi menor naquela de 20 anos de idade (1.247 sementes m-2, não tendo sido detectada diferença significativa entre as pastagens de 15 (11.602 sementes m-2 e 4 (9.486 sementes m-2 anos de idade. As famílias botânicas Cyperaceae, Rubiaceae e Labiateae foram as de maior predominância entre as plantas daninhas infestantes da área, em todos os tratamentos estudados.The objective of this work was to study the soil seed bank of a four-year-old Brachiaria brizantha pasture soil, and in pasture soils of four, 15 and 20 year-old Brachiaria humidicola, in northeastern Pará, Brazil, to evaluate the influence of the forage species and pasture age on weed seed bank size and composition. Each pasture area was divided into five plots of about 500 m², from which 10 soil sub-samples were collected at a depth of 0-10 cm. The soil from each plot was mixed, identified, placed in plastic trays, and put to germinate in a greenhouse during a 15-month period. The seed bank of the four-year-old B. brizantha pasture

Seeds of Brassicaceae weeds have an inherent or inducible response to the germination stimulant karrikinolide.

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Long, Rowena L; Stevens, Jason C; Griffiths, Erin M; Adamek, Markus; Gorecki, Marta J; Powles, Stephen B; Merritt, David J

2011-10-01

Karrikinolide (KAR(1)) is a smoke-derived chemical that can trigger seeds to germinate. A potential application for KAR(1) is for synchronizing the germination of weed seeds, thereby enhancing the efficiency of weed control efforts. Yet not all species germinate readily with KAR(1), and it is not known whether seemingly non-responsive species can be induced to respond. Here a major agronomic weed family, the Brassicaceae, is used to test the hypothesis that a stimulatory response to KAR(1) may be present in physiologically dormant seeds but may not be expressed under all circumstances. Seeds of eight Brassicaceae weed species (Brassica tournefortii, Raphanus raphanistrum, Sisymbrium orientale, S. erysimoides, Rapistrum rugosum, Lepidium africanum, Heliophila pusilla and Carrichtera annua) were tested for their response to 1 µm KAR(1) when freshly collected and following simulated and natural dormancy alleviation, which included wet-dry cycling, dry after-ripening, cold and warm stratification and a 2 year seed burial trial. Seven of the eight Brassicaceae species tested were stimulated to germinate with KAR(1) when the seeds were fresh, and the remaining species became responsive to KAR(1) following wet-dry cycling and dry after-ripening. Light influenced the germination response of seeds to KAR(1), with the majority of species germinating better in darkness. Germination with and without KAR(1) fluctuated seasonally throughout the seed burial trial. KAR(1) responses are more complex than simply stating whether a species is responsive or non-responsive; light and temperature conditions, dormancy state and seed lot all influence the sensitivity of seeds to KAR(1), and a response to KAR(1) can be induced. Three response types for generalizing KAR(1) responses are proposed, namely inherent, inducible and undetected. Given that responses to KAR(1) were either inherent or inducible in all 15 seed lots included in this study, the Brassicaceae may be an ideal target for

Development and appraisal of economical and sustainable approach for weed management in drill seeded aerobic rice (oryza sativa l.)

International Nuclear Information System (INIS)

Saqib, M.; Akbar, N.; Ehsanullah, A.; Ghafoor, A.

2012-01-01

Conventional rice cultivation by puddling and transplanting is a labor intensive activity. Water scarcity is a threat for the sustain ability of transplanted rice. In many areas of Asia, rice transplantation of rice is being replaced by direct seeding as farmers tried to solve the problems of labor cost and water scarcity but weed control is one of the major constraints to direct seeding. So, to control weeds in direct seeded rice present studies were designed. A two years study was conducted to develop sustainable and economical methods for managing weeds in aerobic rice grown by dry direct-seeding at Student's Farm, Department of Agronomy, University of Agriculture, Faisalabad during the years 2008 and 2009. Experiment was laid out in RCBD with five weed management strategies: hand weeding, hoeing with kasula, inter-row cultivation with tine cultivator, inter-row cultivation with spike hoe and chemical control with Nominee 100 SC along with control (no weeding). Weed dry weight was 300 g m/sup -2/, 257 g m/sup -2/, 225 g m/sup -2/ and 157 g m/sup -2/ less in hand weeding, hoeing, tine cultivator and Nominee 100 SC respectively than no weeding. Paddy yield was 221%, 203%, 181% and 105% more in hand weeding, hoeing, tine cultivator and Nominee 100 SC respectively than no weeding. (author)

[Dynamics of seed rain of Tripterygium hypoglaucum and soil seed bank].

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Zhang, Zhi-Wei; Wei, Yong-Sheng; Liu, Xiang; Su, Shu; Qu, Xian-You; Wang, Chang-Hua

2017-11-01

Tripterygium hypoglaucum is an endangered species in arid areas of Xiannvshan Chongqing, China. The dynamic characteristics of seed rain and soil seed bank of T. hypoglaucum were studied in this paper．Results showed that T. hypoglaucum years of mature seeds distribution number up to October; the seed rain occurred from the last ten-day of September to in the first ten-day of November and the peak of scattered seed rain concentrated in the October．The numbers of soil seed bank at 2-5 cm soil layer,mainly concentrated in the 1.5-3.5 m range. T. hypoglaucum seeds to the wind as a force for transmission, the transmission ability is strong, but in the process of natural reproduction, full mature seed rate is low, the soil seed bank seeds seed short-lived factors these were unfavorable for the natural reproduction of T. hypoglaucum population. Copyright© by the Chinese Pharmaceutical Association.

Response of rice genotypes to weed competition in dry direct-seeded rice in India.

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Mahajan, Gulshan; Ramesha, Mugalodi S; Chauhan, Bhagirath S

2014-01-01

The differential weed-competitive abilities of eight rice genotypes and the traits that may confer such attributes were investigated under partial weedy and weed-free conditions in naturally occurring weed flora in dry direct-seeded rice during the rainy seasons of 2011 and 2012 at Ludhiana, Punjab, India. The results showed genotypic differences in competitiveness against weeds. In weed-free plots, grain yield varied from 6.6 to 8.9 t ha(-1) across different genotypes; it was lowest for PR-115 and highest for the hybrid H-97158. In partial weedy plots, grain yield and weed biomass at flowering varied from 3.6 to 6.7 t ha(-1) and from 174 to 419 g m(-2), respectively. In partial weedy plots, grain yield was lowest for PR-115 and highest for PR-120. Average yield loss due to weed competition ranged from 21 to 46% in different rice genotypes. The study showed that early canopy closure, high leaf area index at early stage, and high root biomass and volume correlated positively with competitiveness. This study suggests that some traits (root biomass, leaf area index, and shoot biomass at the early stage) could play an important role in conferring weed competitiveness and these traits can be explored for dry-seeded rice.

Potential for seed bank formation of two weed species from Brazilian Amazonia Potencial para a formação de banco de sementes de duas espécies de plantas daninhas da Amazônia brasileira

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Moacyr B. Dias-Filho

1999-08-01

Full Text Available The potential for seed bank formation of two perennial weed species, Ipomoea asarifolia (Desr. Roem. & Schult. (Convolvulaceae and Stachytarpheta cayennensis (Rich. M. Vahl (Verbenaceae, both common in Amazonia , was evaluated in a degraded pasture area in eastern Brazilian Amazonia . Seeds were enclosed in nylon mesh packets and placed at the soil surface or buried at 5 or 10 cm deep. The number of viable seeds was recorded at 6, 10, 14 and 18 months after burial. Results showed that S. cayennensis has the ability to form persistent soil seed bank, while I. asarifolia seeds do not build up in the soil seed bank. For S. cayennensis and, to some extent, for I. asarifolia, seed survival was highest at greater burial depths.O potencial para a formação de banco de sementes de duas espécies perenes de plantas daninhas, Ipomoea asarifolia (Desr. Roem. & Schult. (Convolvulaceae e Stachytarpheta cayennensis (Rich. M. Vahl (Verbenaceae, ambas comuns na Amazônia, foi avaliado em uma área de pastagem degradada na Amazônia oriental brasileira. As sementes foram inseridas em envelopes de tela de nylon e colocadas na superfície do solo ou enterradas a cinco ou 10 cm de profundidade. O número de sementes viáveis foi avaliado aos 6, 12, 14 e 18 meses após o início do ensaio. Os resultados mostraram que S. cayennensis tem o potencial para formar banco de sementes persistente, enquanto que as sementes de I. asarifolia não apresentam esse potencial. Em S. cayennensis e, de certo modo, em I. asarifolia, a sobrevivência de sementes foi maior nas maiores profundidades.

Are weeds hitchhiking a ride on your car? A systematic review of seed dispersal on cars.

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Michael Ansong

Full Text Available When traveling in cars, we can unintentionally carry and disperse weed seed; but which species, and where are they a problem? To answer these questions, we systematically searched the scientific literature to identify all original research studies that assess seed transported by cars and listed the species with seed on/in cars. From the 13 studies that fit these criteria, we found 626 species from 75 families that have seed that can be dispersed by cars. Of these, 599 are listed as weeds in some part of the world, with 439 listed as invasive or naturalized alien species in one or more European countries, 248 are invasive/noxious weeds in North America, 370 are naturalized alien species in Australia, 167 are alien species in India, 77 are invasive species in China and 23 are declared weeds/invaders in South Africa. One hundred and one are classified as internationally important environmental weeds. Although most (487 were only recorded once, some species such as Chenopodium album, Poa pratensis and Trifolium repens were common among studies. Perennial graminoids seem to be favoured over annual graminoids while annual forbs are favoured over perennial forbs. Species characteristics including seed size and morphology and where the plants grew affected the probability that their seed was transported by cars. Seeds can be found in many different places on cars including under the chassis, front and rear bumpers, wheel wells and rims, front and back mudguards, wheel arches, tyres and on interior floor mats. With increasing numbers of cars and expanding road networks in many regions, these results highlight the importance of cars as a dispersal mechanism, and how it may favour invasions by some species over others. Strategies to reduce the risk of seed dispersal by cars include reducing seed on cars by mowing road verges and cleaning cars.

Effect of Different Dormancy Breaking Treatments on Seed Germination of Salsifis (Teragopogon collinus and Flixweed ( Descurainia Sophia as Two Weed Species

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marzie mazhari

2017-01-01

Full Text Available Introduction: Weeds limit crops growth, development and yield through adjacency and competing and seed dormancy is a problem in controlling of weeds. Man has been always tried to optimize crop yield through weeds controlling. Weeds seed bank in the soil can affected weed management and their control methods. So identifying seed bank characters has important role in choice of management methods in seeds of many plant species which cannot germinate despite favorable environmental conditions. Main reasons for this problem, which is termed as seed dormancy, are hard and impermeable seed coat and presence of immature or dormant embryo. To break dormancy, a variety of methods are in vogue worldwide these days. Of all different methods of breaking dormancy, treatment of seed with certain chemicals including different types of plant growth regulators (PGRs is contemplated as the most effective one. Gibberellic acid (GA3 is the most widely used PGR to improve seed germination in different plant species. Also, nitrate (such as KNO3 clearly stimulates the germination of dormant seeds. KNO3 is the most widely used chemical for promoting germination. Solutions of KNO3 are common in routine germination testing and are recommended by the Association of Official Seed Analysts and the International Seed Testing Association (ISTA for germination tests of many species.Stratification refers to the method of placing seeds in layers alternating with layers of a moisture retaining medium, such as sand, peat or vermiculite, and keeping them at a cool temperature for a certain period, but it varies considerably from species to species. The combination of high moisture and low temperature appears to trigger off biochemical changes which transform complex food substances into simpler forms utilized by the embryo when it renews growth at germination. The use of the word “stratification” has recently been extended to include all forms of cold, moist treatment whether or

Weed supression by smother crops and selective herbicides

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Severino Francisco José

2004-01-01

Full Text Available Using a smother crop is thought to suppress weed density and to add other beneficial effects in sustainable agricultural systems. Weed suppression ought to be considered an essential component of integrated weed management. However, very little is known about the effects of green manure plants on weeds. This study evaluated the influence of three green manure species on weed suppression and selectivity of herbicides. A field experiment was designed to determine the effect of the green manure species Crotalaria juncea, Arachis pintoi and pigeon pea on the weeds Brachiaria decumbens, guineagrass and hairy beggarticks, and on the natural weed infestation in the inter rows area of an avocado orchard. The weed species were suppressed differently by each green manure species. Soil samples collected from the field experiment presented a residual effect, of at least 30 d, in suppressing weed seed bank recruitment; this residual effect was caused by the residues of the green manure present in the soil. When the green manure was incorporated into the top 5 cm of soil or left on the surface, in a greenhouse experiment, the emergence of weed seeds was significantly inhibited, depending on the species, and on the amount and depth of green manure incorporation. Greenhouse experiments indicate that pre-emergence herbicides cause lower phytotoxicity than post-emergence Arachis pintoi. Smother crops using green manure species, when well established in an area, provide additional weed control to the cropping system and are effective and valuable tools in integrated weed management.

Regenerative role of seed banks following an intense soil disturbance

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Luzuriaga, Arantzazu L.; Escudero, Adrián; Olano, José Miguel; Loidi, Javier

2005-02-01

Our main aim was to determine the contribution of the seed bank to vegetation regeneration following a disturbance consisting in a deep ploughing and a thorough homogenisation of a perennial grassland. In the seed bank prior to disturbance, seed distribution through the vertical soil profile was evaluated to determine the initial seed species structure. Then, several characteristics of the shallow seed bank and the extant vegetation were evaluated prior and following field disturbance: seed species composition and abundance, and species composition of the aboveground vegetation. The contribution of seed rain versus seed bank was evaluated by means of the comparison of the vegetation developed in plots filled with sterilised soil (seed bank removal) and the vegetation developed in non-sterilised plots in the field. The distribution of seeds through the profile indicated a sharp decline in abundance with depth, and it was probably linked to propagule morphology, with small and rounded seeds proner to being buried deeper than larger seeds. In the grassland prior to disturbance, the aboveground vegetation and seed bank species composition showed very low similarity index, most likely because during the 5 years following field abandonment, sheep pressure had caused a faster change in aboveground vegetation species composition than in seed bank species composition. Ploughing and homogenisation of the grassland led to low seed abundance in the shallow soil layer caused by dilution of the seed bank. Regardless of impoverishment in seed abundance and species richness, comparison between sterilised and non-sterilised plots showed that the seed bank acted as an effective source of colonising species and determined the aboveground species composition. To summarise, this study outlines the importance of considering several characteristics of the seed bank, such as species composition and seed abundance, in the understanding of the function of seed bank and dynamics of the

Functional morphology and seed anatomy of the invasive weed, benghal dayflower (Commelina benghalensis): Implications for dispersal by mourning doves

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Benghal dayflower (BD) is an exotic weed that reduces yields in many agricultural crops. Potential dispersal of this weed by migratory Mourning doves was investigated in this study. Evidence shows that doves feed on BD seeds, with some birds containing hundreds of seeds. Seeds extracted from harvest...

Maximizing the phylogenetic diversity of seed banks.

Science.gov (United States)

Griffiths, Kate E; Balding, Sharon T; Dickie, John B; Lewis, Gwilym P; Pearce, Tim R; Grenyer, Richard

2015-04-01

Ex situ conservation efforts such as those of zoos, botanical gardens, and seed banks will form a vital complement to in situ conservation actions over the coming decades. It is therefore necessary to pay the same attention to the biological diversity represented in ex situ conservation facilities as is often paid to protected-area networks. Building the phylogenetic diversity of ex situ collections will strengthen our capacity to respond to biodiversity loss. Since 2000, the Millennium Seed Bank Partnership has banked seed from 14% of the world's plant species. We assessed the taxonomic, geographic, and phylogenetic diversity of the Millennium Seed Bank collection of legumes (Leguminosae). We compared the collection with all known legume genera, their known geographic range (at country and regional levels), and a genus-level phylogeny of the legume family constructed for this study. Over half the phylogenetic diversity of legumes at the genus level was represented in the Millennium Seed Bank. However, pragmatic prioritization of species of economic importance and endangerment has led to the banking of a less-than-optimal phylogenetic diversity and prioritization of range-restricted species risks an underdispersed collection. The current state of the phylogenetic diversity of legumes in the Millennium Seed Bank could be substantially improved through the strategic banking of relatively few additional taxa. Our method draws on tools that are widely applied to in situ conservation planning, and it can be used to evaluate and improve the phylogenetic diversity of ex situ collections. © 2014 Society for Conservation Biology.

Weed seed inactivation in soil mesocosms via biosolarization with mature compost and tomato processing waste amendments.

Science.gov (United States)

Achmon, Yigal; Fernández-Bayo, Jesús D; Hernandez, Katie; McCurry, Dlinka G; Harrold, Duff R; Su, Joey; Dahlquist-Willard, Ruth M; Stapleton, James J; VanderGheynst, Jean S; Simmons, Christopher W

2017-05-01

Biosolarization is a fumigation alternative that combines passive solar heating with amendment-driven soil microbial activity to temporarily create antagonistic soil conditions, such as elevated temperature and acidity, that can inactivate weed seeds and other pest propagules. The aim of this study was to use a mesocosm-based field trial to assess soil heating, pH, volatile fatty acid accumulation and weed seed inactivation during biosolarization. Biosolarization for 8 days using 2% mature green waste compost and 2 or 5% tomato processing residues in the soil resulted in accumulation of volatile fatty acids in the soil, particularly acetic acid, and >95% inactivation of Brassica nigra and Solanum nigrum seeds. Inactivation kinetics data showed that near complete weed seed inactivation in soil was achieved within the first 5 days of biosolarization. This was significantly greater than the inactivation achieved in control soils that were solar heated without amendment or were amended but not solar heated. The composition and concentration of organic matter amendments in soil significantly affected volatile fatty acid accumulation at various soil depths during biosolarization. Combining solar heating with organic matter amendment resulted in accelerated weed seed inactivation compared with either approach alone. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Studies on the Effect of Type and Solarization Period on Germination Percentage of Four Weed Species

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J. Rostam

2011-01-01

Full Text Available Abstract In order to study the effects of soil solarization on weed control, an experiment with factorial arrangement in a randomized complete block design with four replications was conducted in a fallow farm in Daregaz in 2008. Factors included solarization duration (0, 2, 4 and 6 weeks and soil moisture content (dry and moist. Soil seed bank was sampled (in two depth, 0-10 and 10-20 cm prior to the experiment and immediately after applying treatments, and germination percentage of weed species were determined. Results of this study showed that seed germination percentage in 10 cm soil depth was influenced by soil moisture and solarization and their interactions, while in 20 cm soil depth only solarization period affected the weed seed germination. Germination percentage in moist soil was less than that in dry soil. Seed germination percentage declined more by increasing solarization duration, so that the greatest decline was obtained after 6 weeks solarization. Solarization decreased germination percentage in moist soil more than that in dry soil. Overall, the results of this experiment indicated that solarization of moist soil for 6 weeks was the most effective treatment in controlling common lambsquatres (Chenopodium album, common purslane (Portulaca oleracea, redroot pigweed (Amaranthus retroflexus, and wild mustard (Sinapis arvensis, while solarization of dry soil for 2 weeks was the least effective treatment for weed control. Keywords: Solarization, Soil moisture, Seed bank

Grazing disturbance increases transient but decreases persistent soil seed bank.

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Ma, Miaojun; Walck, Jeffrey L; Ma, Zhen; Wang, Lipei; Du, Guozhen

2018-04-30

Very few studies have examined whether the impacts of grazing disturbance on soil seed banks occur directly or indirectly through aboveground vegetation and soil properties. The potential role of the seed bank in alpine wetland restoration is also unknown. We used SEM (structural equation modeling) to explore the direct effect of grazing disturbance on the seed bank and the indirect effect through aboveground vegetation and soil properties. We also studied the role of the seed bank on the restoration potential in wetlands with various grazing intensities: low (fenced, winter grazed only), medium (seasonally grazed), and high (whole-year grazed). For the seed bank, species richness and density per plot showed no difference among grazing intensities for each depth (0-5, 5-10, 10-15 cm) and for the whole depth (0-15 cm) in spring and summer. There was no direct effect of grazing disturbance on seed bank richness and density both in spring and summer, and also no indirect effect on the seed bank through its direct effect on vegetation richness and abundance. Grazing disturbance indirectly increased spring seed bank density but decreased summer seed bank density through its direct effect (negative correlation) on soil moisture and total nitrogen and its indirect effect on vegetation abundance. Species composition of the vegetation changed with grazing regime, but that of the seed bank did not. An increased trend of similarity between the seed bank and aboveground vegetation with increased grazing disturbance was found in the shallow depth and in the whole depth only in spring. Although there was almost no change in seed bank size with grazing intensities, grazing disturbance increased the quantity of transient seeds but decreased persistent seeds. Persistent seeds stored in the soil could play a crucial role in vegetation regeneration and in restoration of degraded wetland ecosystems. The seed bank should be an integral part of alpine wetland restoration programs. �

Bio-herbicide effect of salt marsh tolerant Enterobacter sp. I-3 on weed seed germination and seedling growth

International Nuclear Information System (INIS)

Radhakrishan, R.; Lee, I.J.

2017-01-01

Weeds are major challenges in crop cultivation and cause yield loss. The bacteria based bio-herbicides are emerging against chemical herbicides. This study was aimed to explore the bio-herbicide effect of salt marsh tolerant Enterobacter sp. I-3 on various weed species. The efficacy of I-3 bacterial isolates against weed growth was compared with I-4-5 bacterial strain. The bacterial strains, I-3 and I-4-5 inhibited the seed germination of Cyperus microiria Maxim. Enterobacter sp. I-3 showed higher weed control activity than I-4-5. It was confirmed with growth reduction of C. microiria Maxim. The seed germination of Digitaria sanguinalis L. weed was accelerated during the interaction of I-4-5 and it was drastically declined by I-3 bacterial culture. However, Alopecurus aequalis Sobol. seeds treated with either I-3 or I-4-5 bacterial culture showed no significant germination inhibition. The results of this study suggested that salt marsh tolerant Enterobacter sp. I-3 can be applied as bacterial herbicides to control weeds in agricultural fields. (author)

Impact of an invasive weed, Parthenium hysterophorus, on a pasture community in south east Queensland, Australia.

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Nguyen, Thi; Bajwa, Ali Ahsan; Belgeri, Amalia; Navie, Sheldon; O'Donnell, Chris; Adkins, Steve

2017-12-01

Parthenium weed is a highly invasive alien species in more than 40 countries around the world. Along with severe negative effects on human and animal health and crop production, it also causes harm to ecosystem functioning by reducing the native plant species biodiversity. However, its impacts on native plant species, especially in pasture communities, are less known. Given parthenium weed causes substantial losses to Australian pastures' productivity, it is crucial to estimate its impact on pasture communities. This study evaluates the impact of parthenium weed upon species diversity in a pasture community at Kilcoy, south east Queensland, Australia. Sub-sites containing three levels of parthenium weed density (i.e. high, low and zero) were chosen to quantify the above- and below-ground plant community structure. Species richness, diversity and evenness were all found to be significantly reduced as the density of parthenium weed increased; an effect was evident even when parthenium weed was present at relatively low densities (i.e. two plants m -2 ). This trend was observed in the summer season as well as in winter season when this annual weed was absent from the above-ground plant community. This demonstrates the strong impact that parthenium weed has upon the community composition and functioning throughout the year. It also shows the long-term impact of parthenium weed on the soil seed bank where it had displaced several native species. So, management options used for parthenium weed should also consider the reduction of parthenium weed seed bank along with controlling its above-ground populations.

Study of viability on the destruction of weed seeds in the soil by microwave radiation

International Nuclear Information System (INIS)

Velazquez-Marti, B.; Osca, J.M.; Jorda, C.; Marzal, A.

2003-01-01

This work has been carried out to study the thermic effects over weed seeds in typical orchard soil irradiated by its surface with microwave. A previous treatment was carried out in a domestic microwave oven, using 660-watt power. With this laboratory oven, we have investigated three kind of weed seeds: Lolium perenne, Sinopsis alba and Setaria sativa. These previous experiments showed a important decrease of germination with short irradiating times. After previous treatment, a microwave applicator, designed to achieve wide distribution of superficial irradiation energy, was evaluated. This applicator is powered by a 4-kilowatt magnetron through a slotted waveguide. With this oven, we have investigated two kind of weed seeds at several depths: Lolium perenne and Brassica napus var. oleifera. For a soil column, temperature increments reduce seeds germination to a maximum of 5 centimetres. Deeper, the increments of temperature are very low for short irradiating times, so it will be negligible for our purpose. This applicator lets approach better to real treatments focused into the development of a continuous microwave oven for disinfecting seedbed and greenhouse crop substratum. (author) [es

ECOPHYSIOLOGICAL ANALYSIS OF GENIPA AMERICANA L. SEEDS IN AN INDUCED SOIL SEED BANK

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Francesca Salla

2016-03-01

Full Text Available This work studied the behavior of G. americana L. (Rubiaceae seeds in an induced soil seed bank. This study was conducted in Lavras-MG in a seasonal semideciduous forest of the Federal University of Lavras. Seeds collected in the area were cleaned and analyzed (water content, viability and desiccation tolerance. Soil banks were installed in two distinct areas (top of hill and riparian forest located in the understory of the forest. Seeds were placed in nylon nets and covered with a thin litter layer that was previously removed for this purpose. Monthly assessment of germination, seedling emergence, seed and soil water content, and the characterization of the initial seedling growth was performed. It was observed that G. americana seeds forms a transitory seed bank, with maintenance of its viability until the fourth month after disposal in natural environment. In general, the seed bank located in the riparian forest area showed the best potential for seedling establishment in a natural environment, which supports the ecological behavior of this species.

Fisher-Wright model with deterministic seed bank and selection.

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Koopmann, Bendix; Müller, Johannes; Tellier, Aurélien; Živković, Daniel

2017-04-01

Seed banks are common characteristics to many plant species, which allow storage of genetic diversity in the soil as dormant seeds for various periods of time. We investigate an above-ground population following a Fisher-Wright model with selection coupled with a deterministic seed bank assuming the length of the seed bank is kept constant and the number of seeds is large. To assess the combined impact of seed banks and selection on genetic diversity, we derive a general diffusion model. The applied techniques outline a path of approximating a stochastic delay differential equation by an appropriately rescaled stochastic differential equation. We compute the equilibrium solution of the site-frequency spectrum and derive the times to fixation of an allele with and without selection. Finally, it is demonstrated that seed banks enhance the effect of selection onto the site-frequency spectrum while slowing down the time until the mutation-selection equilibrium is reached. Copyright © 2016 Elsevier Inc. All rights reserved.

Weed control in organic rice using plastic mulch and water seeding methods in addition to cover crops

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Weeds are a major yield limiting factor in organic rice farming and are more problematic than in conventional production systems. Water seeding is a common method of reducing weed pressure in rice fields as many weeds connot tolerate flooded field conditions. The use of cover crops is another method...

The Effect of Conservation Tillage and Cover Crop Residue on Beneficial Arthropods and Weed Seed Predation in Acorn Squash.

Science.gov (United States)

Quinn, N F; Brainard, D C; Szendrei, Z

2016-12-01

Conservation tillage combined with cover crops or mulching may enhance natural enemy activity in agroecosystems by reducing soil disturbance and increasing habitat structural complexity. In particular, weed seed predation can increase with vegetation cover and reduced tillage, indicating that mulches may improve the quality of the habitat for weed seed foraging. The purpose of this study was to quantify the effects of tillage and mulching for conservation biological control in cucurbit fields. The effects of mulch and reduced tillage on arthropods and rates of weed seed loss from arenas were examined in field trials on sandy soils in 2014 and 2015. Experimental factors included tillage and cover crop, each with two levels: strip-tillage or full-tillage, and cover crop mulch (rye residue) or no cover crop mulch (unmulched). Arthropod abundance on the crop foliage was not affected by tillage or cover crops. Contrary to expectations, epigeal natural enemies of insects and rates of weed seed removal either did not respond to treatments or were greater in full-tilled plots and plots without mulch. Our study demonstrates the potential importance of weed seed predators in reducing weed seedbanks in vegetable agroecosystems, and suggests that early-season tillage may not be detrimental to epigeal predator assemblages. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Selective weed suppression by cover crop residues: effects of seed mass and timing of species’sensitivity

NARCIS (Netherlands)

Kruidhof, H.M.; Gallandt, E.R.; Haramoto, E.R.; Bastiaans, L.

2011-01-01

Laboratory bioassays have shown that large-seeded species better tolerate cover crop residue–mediated stress than small-seeded species. This provides the potential for selective suppression of small-seeded weeds in large-seeded crops. We conducted two field experiments in which seedling emergence of

Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds

NARCIS (Netherlands)

Saska, P.; Werf, van der W.; Vries, de E.; Westerman, P.R.

2008-01-01

Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal

Seed persistence in the field may be predicted by laboratory-controlled aging

NARCIS (Netherlands)

Long, Rowena L.; Panetta, F. Dane; Steadman, Kathryn J.; Probert, Robin; Bekker, Renee M.; Brooks, Simon; Adkins, Steve W.

2008-01-01

Weed management is complicated by the presence of soil seed banks. The complexity of soil-seed interactions means that seed persistence in the field is often difficult to measure, let alone predict. Field trials, although accurate in their context, are time-consuming and expensive to conduct for

Rice and foxtail millet cultivation reconstructed from weed seed assemblages in the Chengtoushan site, central China

International Nuclear Information System (INIS)

Nasu, H.; Yasuda, Y.; Momohara, A.; Jiejun, H.

2005-01-01

Full text: Crop weeds have been successfully used for evaluation of farming practices in archaeological sites and reconstruction of the environmental condition. In rice agricultural sites in East Asia, however, a few studies of crop remains have been attempted. We evaluated the crop husbandry based on plant macrofossils including crop grains and weed seeds in the Chengtoushan site, Hunan Province, central China, which is one of the oldest rice agricultural site around the Yangtze River Basin. In the moat surrounding the site that is located on a loess plateau that juts out into the alluvial plain, we recognized three cultural layers during the Daxi Culture. Plant macrofossils in silty clay deposits in the moat consist of abundant rice and foxtail millet grains with many weed seeds. Radiocarbon age of these fossils shows that rice and foxtail millet cultivation dated back to 6400 cal. years B.P. The weed seed composition characterizes farmland and ruderal environments in the site surrounded by the moat. We assumed foxtail millet and rice cultivation practiced within the site on loess plateau, along with a paddy style rice cultivation in the alluvial lowland outside of the site. (author)

[Soil seed bank research of China mining areas: necessity and challenges].

Science.gov (United States)

Chang, Qing; Zhang, Da-Wei; Li, Xue; Peng, Jian; Guan, Ai-Nong; Liu, Xiao-Si

2011-05-01

Soil seed bank consists of all living seeds existed in soil and its surface litter, especially in topsoil, and can reflect the characteristics of regional biodiversity. As the base of vegetation restoration and potential greening material, topsoil and its seed bank are the limited and non-renewable resources in mining areas. The study of soil seed bank has become one of the hotspots in the research field of vegetation restoration and land reclamation in China mining areas. Owing to the special characteristics of mining industry, the soil seed bank study of mining areas should not only concern with the seed species, quantities, and their relations with ground surface vegetation, but also make use of the research results on the soil seed bank of other fragile habitats. Besides, a breakthrough should be sought in the thinking ways and research approach. This paper analyzed the particularity of mining area's soil seek bank research, summarized the research progress in the soil seed bank of mining areas and other fragile habitats, and put forward the challenges we are facing with. It was expected that this paper could help to reinforce the soil seed bank research of China mining areas, and provide scientific guidelines for taking great advantage of the significant roles of soil seed bank in land reclamation and vegetation restoration in the future.

[Soil seed bank in Keerqin meadow grassland under grazing and harvesting].

Science.gov (United States)

Jiang, Deming; Li, Rongping; Liu, Zhimin; Yan, Qiaoling

2004-10-01

This study on the size and composition of seed bank and its relationship with vegetation showed in Keerqin meadow grassland, the density of soil seed bank was 6158 +/- 1647 grains x m(-2) under grazing and 8312 +/- 2540 grains m(-2) under harvesting. Under grazing, the seed bank was mainly composed of some dwarf and short-life annuals. The seeds of the annuals and biennials accounted for 81.66% of the seeds in seed bank. The four species with largest proportion of seed bank were Chloris virgata, Chenopodium glaucum, Digitaria cilliaris and Setaria viridis, and the proportions were 38.55%, 15.42%, 14.95%, and 9.83%, respectively. The density of perennials in soil seed bank was 1129 +/- 302 grains x m(-2). Under harvesting, the seeds of annuals and biennials accounted for 68.08% of the seed in seed bank, and the proportion of Setaria viridis was 52.7%. In the harvesting meadow grassland, the seed density of perennials was 2653 +/- 811 grains x m(-2). There was no significant correlation between the seed density in soil and the vegetation under grazing, but a significant correlation between the seed density in soil and the species abundance of vegetation under harvesting (r = 0.76, P < 0.01). The index of Shannon-Wiener and richness of grazing meadow grassland were 2.96 and 2.98, respectively, distinctly smaller than 3.10 and 5.09 of harvesting meadow, which showed that free grazing made the diversity of seed bank decrease easily.

WEED SURVEYING OF PHACELIA (PHACELIA TANACETIFOLIA L.) AND EVALUATING THE EFFICIENCY OF THE WEED CONTROL.

Science.gov (United States)

Horváth, E; Szabó, R

2014-01-01

The experiment was set up in an area of 9 ha that was split into 4 plots: in plot 1 the row spacing was 12 cm and the seeding rate was 10 kg; in plot 2 the row spacing was 24 cm and the seeding rate was 10 kg; in plot 3 the row spacing was 24 cm and the seeding rate was 8 kg; in plot 4 the row spacing was 12 cm and the seeding rate was 8 kg. After the weed surveying, the total weed coverage was established as follows: in plot 1 the total weed coverage was 11.34%, in plot 2 it was 12.3%, in plot 3 it was 18%, and in plot 4 the total weed coverage was 15%. Based on the weed survey, on the test area the following dicotyledon weeds belonging to the T4 Raunkiaer plant life-form category occupied the highest percentage: heal-all, black-bindweed, goosefoot. The proportion of the perennial dicotyledons: field bindweed (G3), tuberous pea (G1), white campion (H3) was negligible. In all four cases the weed control was executed using the same herbicide in the same doses and with regard to the weed species it showed the same level of efficiency. The smaller row spacing and higher seeding rate has a beneficial effect on the weed suppressing capacity of the crop, the crop's weed suppressing capacity is better and the development of the weeds becomes worse.

Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

NARCIS (Netherlands)

Mourik, van T.A.; Stomph, T.J.; Murdoch, A.J.

2005-01-01

1. Estimates of seed bank depletion rates are essential for modelling and management of plant populations. The seed bag burial method is often used to measure seed mortality in the soil. However, the density of seeds within seed bags is higher than densities in natural seed banks, which may elevate

Relative importance of vertebrates and invertebrates in epigeaic weed seed predation in organic cereal fields

NARCIS (Netherlands)

Westerman, P.R.; Hofman, A.; Vet, L.E.M.; Van der Werf, W.

2003-01-01

Exclosure trials were conducted in four organic cereal fields in The Netherlands in 1999 and 2000 to determine the relative importance of vertebrates and invertebrates in weed seed predation. The trials showed that seed predation by vertebrates was rather consistent and predictable, occurring on all

Effect of Seed Priming on Sugar Beet Root Yield under Low Irrigation and Presence of Weed

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ali absalan

2017-09-01

Full Text Available Introduction The success of sugar beet as a crop depends on predictable seed germination, early seedling establishment and the rapid development of a leaf canopy which is able to utilize the available solar radiation efficiently. Seed priming has become a common practice to increase the rate and uniformity of field germination and emergence in many important crop plants in unfavorable conditions. Hydro-priming is a simple method of priming treatment that is used of distilled water as priming medium. Humic acid has been used for treatment before seed planting. Washing sugar beet seeds with water also affects the germination and seedling establishment through the elimination of inhibitory compounds on the seed coat. This study was conducted to evaluate the effect of seed priming with different methods at different times and concentrations on germination of sugar beet. Materials and Methods In the spring of 1393, a field trial was conducted simultaneously in two regions of the Jovain and Jajarm. The experimental was conducted as split plot (split-split plot in randomized complete block design with three replications.The main factor was irrigation with four levels of 100, 90, 80 and 70% water, sub-plots are including different methods of priming: control, priming with running water for 48 hours, priming with running water for 48 hours + Humic acid, priming with running water for 48 hours + Seed-start and priming with running water for 48 hours + Humic acid + Fulzym, sub-sub plots are including weeds competition with (absence and presence of weeds. Results and Discussion The results for two regions showed that by reducing the amount of irrigation water sugar beet root yield significantly reduced. Results show that the effect of priming treatment of running water for 48 hours + Seed-start and running water for 48 hours + Humic acid + Fulzym to have achieved the highest sugar beet root yield for two areas. The result of the interaction effect showed

Ecological longevity of Polaskia chende (Cactaceae) seeds in the soil seed bank, seedling emergence and survival.

Science.gov (United States)

Ordoñez-Salanueva, C A; Orozco-Segovia, A; Canales-Martínez, M; Seal, C E; Pritchard, H W; Flores-Ortiz, C M

2017-11-01

Soil seed banks are essential elements of plant population dynamics, enabling species to maintain genetic variability, withstand periods of adversity and persist over time, including for cactus species. However knowledge of the soil seed bank in cacti is scanty. In this study, over a 5-year period we studied the seed bank dynamics, seedling emergence and nurse plant facilitation of Polaskia chende, an endemic columnar cactus of central Mexico. P. chende seeds were collected for a wild population in Puebla, Mexico. Freshly collected seeds were sown at 25 °C and 12-h photoperiod under white light, far-red light and darkness. The collected seeds were divided in two lots, the first was stored in the laboratory and the second was use to bury seeds in open areas and beneath a shrub canopy. Seeds were exhumed periodically over 5 years. At the same time seeds were sown in open areas and beneath shrub canopies; seedling emergence and survival were recorded over different periods of time for 5 years. The species forms long-term persistent soil seed banks. The timing of seedling emergence via germination in the field was regulated by interaction between light, temperature and soil moisture. Seeds entered secondary dormancy at specific times according to the expression of environmental factors, demonstrating irregular dormancy cycling. Seedling survival of P. chende was improved under Acacia constricta nurse plants. Finally, plant facilitation affected the soil seed bank dynamics as it promoted the formation of a soil seed bank, but not its persistence. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Vertical distribution and composition of weed seeds within the plough layer after eleven years of contrasting crop rotation and tillage schemes

DEFF Research Database (Denmark)

Scherner, Ananda; Melander, Bo; Kudsk, Per

2016-01-01

Tillage methods and crop rotation are probably the two most important cropping factors affecting weed communities, particularly when herbicide use is restricted. This study examined weed dynamics following eleven years of different tillage and crop rotation treatments. The aboveground grass weed...... flora was recorded each year and the content and vertical location of individual weed seeds within the plough layer (0–20 cm) were determined after 11 years of continuous mouldboard ploughing (P), pre-sowing tine cultivation to 8–10 cm soil depth (H8-10) and direct drilling (D). The content of weed...... seeds, especially grass weeds, was determined for three distinct soil layers (0–5, 5–10 and 10–20 cm), reflecting the cultivation depths of the tillage treatments. The annual grass weeds, Apera spica-venti and Vulpia myuros, were promoted by non-inversion tillage and in the case of V. myuros also...

Removal and Burial of Weed Seeds by Ants (Hymenoptera: Formicidae) From the Soil Surface of a Cropped Area in Western Australia.

Science.gov (United States)

Minkey, D M; Spafford, H

2016-10-01

Although granivorous ants are known to collect weed seeds from cropping areas in Australia, the fate of these seeds has not been adequately investigated. Seeds of annual ryegrass (Lolium rigidum Gaud.) and wild radish (Raphanus raphanistrum L.) were placed around the nests of five native ant species (Iridomyrmex greensladei Shattuck, Rhytidoponera metallica Smith, Melophorus turneri Forel, Monomorium rothsteini Forel, and Pheidole hartmeyeri Forel) and tracked continuously over a 24-h period. Removal rates and seed preference of the ant species were evaluated. Ant nests were then excavated to determine the placement of seeds that were taken into each nest. Seed preference, seed removal efficiencies, activity, and seed storage all varied between the ant species. Annual ryegrass seed was collected by three species of ants and was removed from the soil surface more efficiently than wild radish seed. Most ant species stored seed below ground at a depth that is inhibitory to emergence, thereby potentially removing that portion of seed from the seed bank, but some seed was placed at germinable depths. Pheidole hartmeyeri was identified as a likely biological control agent for annual ryegrass seeds and wild radish, while Me. turneri and Mo. rothsteini have potential as biocontrol agents for annual ryegrass, but further research is needed. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Does Ferocactus wislizeni (Cactaceae) have a between-year seed bank?

Science.gov (United States)

Bowers, Janice E.

2000-01-01

Field and laboratory experiments at Tumamoc Hill, Tucson, Arizona, U.S.A., demonstrated that Ferocactus wislizeni, a common perennial cactus in the northern Sonoran Desert, has a between-year seed bank. In laboratory studies, F. wislizeni seeds lost dormancy during storage at room temperature and had a light requirement for germination. Field experiments suggested that as much as 2% of the annual seed crop might escape post-dispersal predation even when unprotected; where suitable safe sites exist, a higher percentage might escape. Germination of seed recovered monthly from above- and below-ground components of an artificial seed bank showed that seeds can survive at least 18 months in and on the soil. Seed banks enable F. wislizeni to take advantage of favorable rains and temperatures throughout the growing season, thus increasing the number of opportunities for germination. Moreover, seed banks enable F. wislizeni to respond hugely when the climate seems especially favorable, thus producing the large cohorts necessary to compensate for high seedling mortality. (C) 2000 Academic Press.

Strip Tillage and Early-Season Broadleaf Weed Control in Seeded Onion (Allium cepa

Directory of Open Access Journals (Sweden)

Sarah Gegner-Kazmierczak

2016-03-01

Full Text Available Field experiments were conducted in 2007 and 2008 near Oakes, North Dakota (ND, USA, to evaluate if strip tillage could be incorporated into a production system of seeded onion (Allium cepa to eliminate the standard use of a barley (Hordeum vulgare companion crop with conventional, full width tillage, yet support common early-season weed control programs. A split-factor design was used with tillage (conventional and strip tillage as the main plot and herbicide treatments (bromoxynil, DCPA, oxyfluorfen, and pendimethalin as sub-plots. Neither tillage nor herbicide treatments affected onion stand counts. Common lambsquarters (Chenopodium album densities were lower in strip tillage compared to conventional tillage up to three weeks after the post-emergence applied herbicides. In general, micro-rate post-emergence herbicide treatments provided greater early-season broadleaf weed control than pre-emergence herbicide treatments. Onion yield and grade did not differ among herbicide treatments because the mid-season herbicide application provided sufficient control/suppression of the early-season weed escapes that these initial weed escapes did not impact onion yield or bulb diameter. In 2007, onion in the strip tillage treatment were larger in diameter resulting in greater total and marketable yields compared to conventional tillage. Marketable onion yield was 82.1 Mg ha−1 in strip tillage and 64.9 Mg ha−1 in conventional tillage. Results indicate that strip tillage use in direct-seeded onion production was beneficial, especially when growing conditions were conducive to higher yields and that the use of strip tillage in onion may provide an alternative to using a companion crop as it did not interfere with either early-season weed management system.

1-14 Effect of Plant Spacing and Weeding Frequency on Weed ...

African Journals Online (AJOL)

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2College of Agriculture and Environmental Sciences, Haramaya University, ... pod, hundred seed weight, grain yield, aboveground dry biomass, and ... an infestation by weeds and the performance of crop ... frequencies affect weed management in common bean .... including broad-leaved, sedge and grass weeds (Table.

Composicion y variabilidad espacialdel banco de semillas de malezas en un area agricolade azul (Argentina Composition and spatial variation of a weed seed bank on an agricultural area in Azul, Argentina

Directory of Open Access Journals (Sweden)

Eduardo Requesens

1999-08-01

characterize the weed seed bank of such area in a global way. The whole rank of seed density and the relative abundance distribution and spatial design of species were analyzed. The basic information was obtained applying the germination technique to soil samples corresponding to 20 sites on a regional transect of 14 km. The seed density rank for the study area was 1173-44000 seeds/m2, and 33 species were recorded. Digitaria sanguinalis is the predominant species with 43 % of the seed bank, followed by Polygonum aviculare with 15 %. Both species together with Anagallis arvensis and Setaria viridis constitute the 70 % of the seed bank. The spatial distribution of species along the transect showed a variable aggregation degree, recording a significant positive correlation between the contribution to seed bank and the variance/mean ratio. This correlation demostrates that the most abundant species show a greater spatial variation, although different distribution patterns were observed.

Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions.

Science.gov (United States)

Johansen, Anders; Nielsen, Henrik B; Hansen, Christian M; Andreasen, Christian; Carlsgart, Josefine; Hauggard-Nielsen, Henrik; Roepstorff, Allan

2013-04-01

Anaerobic digestion of residual materials from animals and crops offers an opportunity to simultaneously produce bioenergy and plant fertilizers at single farms and in farm communities where input substrate materials and resulting digested residues are shared among member farms. A surplus benefit from this practice may be the suppressing of propagules from harmful biological pests like weeds and animal pathogens (e.g. parasites). In the present work, batch experiments were performed, where survival of seeds of seven species of weeds and non-embryonated eggs of the large roundworm of pigs, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37°C) and thermophilic (55°C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55°C) was very clear as complete mortality, irrespective of weed species, was reached after less than 2 days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzinckia micrantha still maintained low levels (~1%) of germination ability after 1 week. Chenopodium album was the only weed species which survived 1 week at substantial levels (7%) although after 11 d germination ability was totally lost. Similarly, at 55°C, no Ascaris eggs survived more than 3h of incubation. Incubation at 37°C did not affect egg survival during the first 48 h and it took up to 10 days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites and weeds so that the digestates can be applied without risking spread of these pests. Copyright © 2012 Elsevier Ltd. All rights reserved.

The soil seed bank in abandoned tropical pastures: source of regeneration or invasion? El banco de semillas en pastizales tropicales abandonados: fuente de regeneración o de invasión?

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Leonel López-Toledo

2011-06-01

Full Text Available We assessed the availability of both pioneer and non-native species in the soil seed bank of old-growth forest and recently abandoned pasture, to evaluate whether the soil seed bank in these pastures represents a source of regeneration of species from adjacent old-growth forest or of invasion by non-native species. Our study was conducted at Selva Lacandona, Chiapas, Mexico. Soil samples were randomly collected from 6 sites in old-growth forest, and 6 sites in abandoned pastures. Seedlings from soil samples were identified and classified into pioneer, non-native (weeds/graminoids, and other forest species. Pioneer species seeds were virtually absent in pastures, but represented ~30% of seeds in the forest. Non-native species comprised ~99% of the soil seed bank in pastures. In the forest, soil seed bank density of weeds and graminoids decreased with increasing distance (up to 4 km from agricultural fields, and comprised up to 25% (Mean ± 1SE= 16 ± 7 of the seed bank. Our results show a near total elimination of pioneer species from the soil seed bank in pastures, and considerable invasion of the borders of the Montes Azules reserve by seeds of non-native species. Thus, in the region studied, the soil seed bank in abandoned pastures represents a source of invasion by non-native species into old-growth forest rather than a potential source of forest regeneration.Para evaluar si el banco de semillas en pastizales abandonados representa una fuente de regeneracion o de invasión por especies no-nativas para el bosque maduro se evaluó la presencia de especies pioneras y no-nativas en el banco de semillas de bosque maduro y pastizales recien abandonados en la selva lacandona, Chiapas, México. Se recolectaron muestras de suelo en 6 sitios de bosque maduro y de pastizales abandonados. Las semillas germinadas fueron identificadas y clasificadas en especies pioneras, no-nativas (malezas/graminoides y otras especies de bosque. Las especies pioneras

Grazing impact on desert plants and soil seed banks: Implications for seed-eating animals

Science.gov (United States)

Pol, Rodrigo G.; Sagario, M. Cecilia; Marone, Luis

2014-02-01

We assess whether the knowledge of livestock diet helps to link grazing effects with changes in plant cover and soil seed bank size, aiming at inferring the consequences of grazing on seed-eating animals. Specifically, we test whether continuous and heavy grazing reduce the cover, number of reproductive structures and seed reserves of the same grass species whose seeds are selected and preferred by granivorous animals in the central Monte desert, Argentina. Grass cover and the number of grass spikes usually diminished under grazing conditions in the two localities studied (Telteca and Ñacuñán), and soil seed bank was consistently reduced in all three years evaluated owing to a decline of perennial grass and forb seeds. In particular, the abundance of those seeds selected and preferred by birds and ants (in all cases grass species) declined 70-92% in Ñacuñán, and 52-72% in Telteca. Reduction of perennial grass cover and spike number in grazed sites reinforced the causal link between livestock grazing and the decline of grass soil seed reserves throughout failed plant reproduction. Grass seed bank depletion suggests that grazing may trigger a "cascade" of mechanisms that affect the abundance and persistence of valuable fodder species as well as the availability of seed resources for granivorous animals.

The Effect of Crop Seed Rate and Post Emergence Herbicide Application on Weed control and grain yield of Wheat

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M. Babaei

2017-08-01

Full Text Available Introduction Interference weed with crop is a major concern for production in croplands particularly where modern agricultural practices such as mechanical weeding and the application of herbicides are limited. At present, the aim of weed management is to keep weed population at an acceptable level rather than to keep crop totally free of weeds. Among the weed control methods, the chemical control is the easiest one of the recent origins, as well the most successful alternative method. Materials and methods Field experiments were conducted at Shoushtar Branch, Islamic Azad University, Iran (32 0 3´ N, 480 50´ E during winters of 2012-2013 in order to evaluate the effect of sulfosulfuron and sulfosulfuron plus metsulfuron-methyl at 30 and 45 g a.i. ha-1, respectively, and wheat seed rate at 180, 200 and 220 kg ha-1 on weed control. Experiments were carry out in a randomized complete block design with a factorial arrangement and four replicates. The plot size was 6 m × 2 m. The soil was a clay loam texture, pH 7.4 and 0.6 % organic matter content. In the experimental site, the 30-year average annual rainfall is 321.4 mm, daily average annual air temperature is minimum and maximum 9.5 °C and 46.3 °C, respectively. Wheat cv. Chamran was planted in the first fortnight of November. Seedbed preparation consisted of moldboard plowing, disking and leveling. A basal fertilizer rate of 125 kg ha-1 N (form of urea (46% N, 75 kg ha-1 P2O5 (diammonium phosphate (18% N; 46% P2O5, and 60 kg K2O ha-1 (sulfate of potash (50% K2O was applied. The whole P and K and half of N were applied at sowing. The remaining half of N was top dressed with the irrigation at the booting stage. Results and Discussion As the crop population brings competition for limited resources with the weeds, we tested different seeding rates to increase crop plant density as a measure to control weeds. The weed population was significantly affected by seed rate. In general, there was an

Comparisons of weed community, soil health and economic performance between wheat-maize and garlic-soybean rotation systems under different weed managements

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Mahmud A. Muminov

2018-05-01

Full Text Available This study compared the impacts of different weed managements on weed community, soil health and economic performance between the wheat–maize (WM and garlic–soybean (GS rotations. A total of four treatments (H0T, tillage without herbicide; H0T0, without both herbicide and tillage; HT, both herbicide and tillage; HT0, herbicide without tillage were designed for both rotations. A total of 16 weed species were recorded in the WM rotation, with life forms of 62% for annuals, 12% for annual + perennial and 20% for perennials. While in the GS rotation, there were 17 weed species, with 71% being annuals. When crop rotation changed from WM to GS, the topsoil layer seed bank (0–5 cm decreased by 137%. GS rotation always had higher earthworm densities than that of WM under the same condition. Organic weed control (H0T, H0T0 from both WM and GS added more soil organic matters than the chemical methods (HT and HT0. Economically, up to 69% higher net profit had been achieved in the GS than WM for their organic products. This study provides an ecological basis to guide organic farming practices, especially for weed management in the future.

An Experimental Test of a Biodynamic Method of Weed Suppression: The Biodynamic Seed Peppers

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Bruce Kenneth Kirchoff

2016-04-01

Full Text Available An experimental test of a biodynamic agriculture method of weed suppression was carried out in growth chambers to establish the feasibility of the method as a preliminary to field trials. Four generations of Brassica rapa plants were used in a randomized block design. Treated flats received ashed seeds prepared according to biodynamic indications. Seed weight and counts were measured at the end of each generation, and germination of the control and experimental seed was investigated at the end of generation four. The biodynamic seed peppers, created and applied as described here, had no effect on seed production or viability, and did not effectively inhibit reproduction of the targeted species over the course of four consecutive treatments.

Bioherbicides: Current knowledge on weed control mechanism.

Science.gov (United States)

Radhakrishnan, Ramalingam; Alqarawi, Abdulaziz A; Abd Allah, Elsayed Fathi

2018-04-17

Weed control is a challenging event during crop cultivation. Integrated management, including the application of bioherbicides, is an emerging method for weed control in sustainable agriculture. Plant extracts, allelochemicals and some microbes are utilized as bioherbicides to control weed populations. Bioherbicides based on plants and microbes inhibit the germination and growth of weeds; however,few studies conducted in weed physiology. This review ascribes the current knowledge of the physiological changes in weeds that occur during the exposure to bioherbicides. Plant extracts or metabolites are absorbed by weed seeds, which initiates damage to the cell membrane, DNA, mitosis, amylase activity and other biochemical processes and delays or inhibits seed germination. The growth of weeds is also retarded due to low rates of root-cell division, nutrient uptake, photosynthetic pigment synthesis, and plant growth hormone synthesis, while the productions of reactive oxygen species (ROS) and stress-mediated hormones increase, including irregular antioxidant activity. However, lytic enzymes and toxic substances secreted from microbes degrade the weed seed coat and utilize the endosperm for survival, which inhibits seed germination. The microbes grow through the intercellular spaces to reach the root core, and the deposition of toxins in the cells affects cell division and cellular functions. Some of the metabolites of deleterious microbes cause disease, necrosis and chlorosis,which inhibit the germination and growth of weed seeds by suppressing photosynthesis and gibberellin activities and enhancing ROS, abscisic acid and ethylene. This review explains the effects of bioherbicides (derived from plants and microbes) on weed-plant physiology to elucidate their modes of action. Copyright © 2018 Elsevier Inc. All rights reserved.

Soil seed bank in different habitats of the Eastern Desert of Egypt.

Science.gov (United States)

Gomaa, Nasr H

2012-04-01

The floristic composition and species diversity of the germinable soil seed bank were studied in three different habitats (desert salinized land, desert wadi, and reclaimed land) in the Eastern Desert of Egypt. Moreover, the degree of similarity between the seed bank and the above-ground vegetation was determined. The seed bank was studied in 40 stands representing the three habitats. Ten soil samples (each 25 × 20 cm and 5 cm depth) were randomly taken per stand. The seed bank was investigated by the seedling emergence method. Some 61 species belonging to 21 families and 54 genera were identified in the germinable seed bank. The recorded species include 43 annuals and 18 perennials. Ordination of stands by Detrended Correspondence Analysis (DCA) indicates that the stands of the three habitats are markedly distinguishable and show a clear pattern of segregation on the ordination planes. This indicates variations in the species composition among habitats. The results also demonstrate significant associations between the floristic composition of the seed bank and edaphic factors such as CaCO3, electrical conductivity, organic carbon and soil texture. The reclaimed land has the highest values of species richness, Shannon-index of diversity and the density of the germinable seed bank followed by the habitats of desert wadi and desert salinized land. Motyka's similarity index between the seed bank and the above-ground vegetation is significantly higher in reclaimed land (75.1%) compared to desert wadi (38.4%) and desert salinized land (36.5%).

Efeito da prevenção de produção de sementes pelas plantas daninhas e da aplicação de herbicida em jato dirigido na densidade de infestação na cultura do milho em anos sucessivos Effect of weed seed production prevention and 10-year herbicide direct spray on weed density in corn during sucessive years

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F. Skóra Neto

2001-04-01

reduced weed density over 99%. There was no difference between conventional tillage and no-till for density reduction. Weed density reduction varied but was greater during the first years for all species. Weed density in successive years, when there was weed seed production (check, varied, according to climatic and cultural conditions. Direct spray herbicide application was efficient in controlling weed seed production, when the species were susceptible to the herbicides. Increasing crabgrass density was observed under conventional tillage with direct spray due to poor control. The fitting equation in the treatments without seed production and herbicide direct spray was a negative exponential. Weed density results were confirmed by weed seed bank evaluation.

Soil seed bank evaluation and seedling establishment along a ...

African Journals Online (AJOL)

The effects of rangeland degradation on the size and species composition of the seed bank and seedling establishment in the field were quantified over a two year period (2000–2001 and 2001–2002 growing seasons). Soil seed bank sampling was carried out at three-monthly intervals from 0.25m2 blocks 50mm deep.

How best to quantify soil seed banks in arid rangelands of the Nama Karoo?

Science.gov (United States)

Dreber, Niels

2011-02-01

Sampling design and three sample treatments prior the application of the seedling emergence method were tested in order to find the best method for seed bank quantification in arid Nama Karoo rangelands. I analyzed species composition and seed densities by contrasting undercanopy and open-matrix samples from two soil depths and by comparing the effects of cold-, heat-, and no stratification on germination rates of species in a greenhouse setting. The soil seed bank showed minimal similarity to the standing vegetation, with only 20 plant species germinated. Spatial distribution of seeds was highly heterogeneous. Nearly 90% of germinated seeds were located in 0- to 4-cm compared to >4- to 8-cm soil depth. Undercanopy seed banks contained significantly more species and seeds than open-matrix seed banks. Neither the number nor the diversity of seeds germinated differed significantly among the three treatments. Cold stratification tended to detect more species and seeds only at >4- to 8-cm soil depth. The results highlight the importance of spatial heterogeneity in the accurate evaluation of soil seed banks in the arid Nama Karoo and the importance of considering seasonal variability in the availability of readily germinable seeds. Data also suggest that sample pretreatment in germination trials may give little return for cost and effort, which emphasizes that it is more important to choose the sampling design most likely to give a representative number of seed bank species. Further studies are needed to analyze seed bank dynamics and species-specific germination requirements to promote recruitment of plant taxa underrepresented in the seed bank.

Integrated weed management in wheat

International Nuclear Information System (INIS)

Marwat, K.B.; Khan, M.A.; Nawab, K.; Khattak, A.M.

2011-01-01

The paper summarizes the results of an experiment conducted on wheat at Kohat, Khyber Pakhtunkhwa, Pakistan during winter 2004-05. Randomized complete block design with split-split-plot arrangement was used where wheat line and broadcast sowing were kept in main plots. Seed rates (100 and 150 kg ha-1) were assigned as sub-plots, while four herbicides (Topik, Isoproturon, Puma super and Buctril super) and weed check were assigned to sub-sub-plots. Results revealed that higher biological yield was recorded in line sowing. However, higher wheat seed rate decreased weed biomass and increased biological yield. Herbicides proved to be effective in decreasing weed biomass and enhancing grain yield and its contributing traits. It was suggested that line sowing in combination with higher seeding rate and Buctril super should be used in an integrated weed management fashion. However further studies are required to investigate various ranges of seeding rate and herbicides doses. (author)

Natural metabolites for parasitic weed management.

Science.gov (United States)

Vurro, Maurizio; Boari, Angela; Evidente, Antonio; Andolfi, Anna; Zermane, Nadjia

2009-05-01

Compounds of natural origin, such as phytotoxins produced by fungi or natural amino acids, could be used in parasitic weed management strategies by interfering with the early growth stages of the parasites. These metabolites could inhibit seed germination or germ tube elongation, so preventing attachment to the host plant, or, conversely, stimulate seed germination in the absence of the host, contributing to a reduction in the parasite seed bank. Some of the fungal metabolites assayed were very active even at very low concentrations, such as some macrocyclic trichothecenes, which at 0.1 microM strongly suppressed the germination of Orobanche ramosa L. seeds. Interesting results were also obtained with some novel toxins, such as phyllostictine A, highly active in reducing germ tube elongation and seed germination both of O. ramosa and of Cuscuta campestris Yuncker. Among the amino acids tested, methionine and arginine were particularly interesting, as they were able to suppress seed germination at concentrations lower than 1 mM. Some of the fungal metabolites tested were also able to stimulate the germination of O. ramosa seeds. The major findings in this research field are described and discussed.

Deer browsing delays succession by altering aboveground vegetation and belowground seed banks.

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Antonio DiTommaso

Full Text Available Soil seed bank composition is important to the recovery of natural and semi-natural areas from disturbance and serves as a safeguard against environmental catastrophe. White-tailed deer (Odocoileus virginianus populations have increased dramatically in eastern North America over the past century and can have strong impacts on aboveground vegetation, but their impacts on seed bank dynamics are less known. To document the long-term effects of deer browsing on plant successional dynamics, we studied the impacts of deer on both aboveground vegetation and seed bank composition in plant communities following agricultural abandonment. In 2005, we established six 15 × 15 m fenced enclosures and paired open plots in recently followed agricultural fields near Ithaca, NY, USA. In late October of each of six years (2005-2010, we collected soil from each plot and conducted seed germination cycles in a greenhouse to document seed bank composition. These data were compared to measurements of aboveground plant cover (2005-2008 and tree density (2005-2012. The impacts of deer browsing on aboveground vegetation were severe and immediate, resulting in significantly more bare soil, reduced plant biomass, reduced recruitment of woody species, and relatively fewer native species. These impacts persisted throughout the experiment. The impacts of browsing were even stronger on seed bank dynamics. Browsing resulted in significantly decreased overall species richness (but higher diversity, reduced seed bank abundance, relatively more short-lived species (annuals and biennials, and fewer native species. Both seed bank richness and the relative abundance of annuals/biennials were mirrored in the aboveground vegetation. Thus, deer browsing has long-term and potentially reinforcing impacts on secondary succession, slowing succession by selectively consuming native perennials and woody species and favoring the persistence of short-lived, introduced species that continually

A Methodological Approach for Testing the Viability of Seeds Stored in Short-Term Seed Banks

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Jose A. FORTE GIL

2017-12-01

Full Text Available Efficient management of ‘active’ seed banks – specifically aimed at the short-term storage at room temperature of seeds to be used locally in conservation/regeneration programmes of endemic or endangered plant species – requires establishing the optimal storage time to maintain high seed viability, for each stored species. In this work, germination of seeds of the halophytes Thalictrum maritimum, Centaurea dracunculifolia and Linum maritimum has been investigated. The seeds had been stored for different periods of time in the seed bank of ‘La Albufera’ Natural Park (Valencia, SE Spain after collection in salt marshes of the Park, where small populations of the three species are present. Seeds of T. maritimum and C. dracunculifolia have a relatively short period of viability at room temperature, and should not be stored for more than three years. On the other hand, L. maritimum seeds maintain a high germination percentage and can be kept at room temperature for up to 10 years. T. maritimum seeds, in contrast to those of the other two species, did not germinate in in vitro tests nor when sown directly on a standard substrate, unless a pre-treatment of the seeds was applied, mechanical scarification being the most effective. These results will help to improve the management of the seed bank, to generate more efficiently new plants for reintroduction and reinforcement of populations of these species in their natural ecosystems within the Natural Park.

Soil seed-bank germination patterns in natural pastures under different mineral fertilizer treatments

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Anna Iannucci

2014-11-01

Full Text Available Degraded native grasslands in Mediterranean areas can be improved by encouraging seedling regeneration from soil seed banks using chemical fertilization. The effect of mineral fertilizers on soil seed banks was studied in natural pastures at two locations in southern Italy: Carpino and Rignano Garganico. The aim was to determine if nitrogen (N, phosphorus (P and combined nitrogen and phosphorus (NP fertilization can promote increased soil seed density. The seed-bank size and composition were analysed over two growth cycles (2004-2006 at two periods of the year: at the early summer and at the early autumn. The plant species were classified into three functional groups: grasses, legumes and other species (all other dicots. A two-pool model (ephemeral and base pools derived from the germination patterns was developed to quantify the dynamics of the germinated seed populations. The mean total seed number in the seed bank ranged from 2,915 to 4,782 seed m-2 with higher values in early summer than in early autumn. Mineral fertilizer applications increased the seed-bank size (by 27%, 23% and 46%, for N, P and NP, respectively and modified the composition in both localities. The three plant functional groups showed different potentials for ephemeral and persistent seed-bank production; however, within each plant group, the proportion between the ephemeral and base pool fractions did not change with fertilizer application. These data show that mineral fertilization can have positive effects on the seed-bank size of ungrazed natural pastures, and can be used to improve degraded Mediterranean pastures.

Effects of water level on three wetlands soil seed banks on the Tibetan Plateau.

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Miaojun Ma

Full Text Available BACKGROUND: Although the effect of water level on germination in soil seed banks has been documented in many ecosystems, the mechanism is not fully understood, and to date no empirical studies on this subject exist. Further, no work has been done on the effect of water level on seed banks of drying and saline-alkaline wetlands in alpine areas on the Tibetan Plateau. METHODOLOGY: We examined the effects of water level (0 cm, 5 cm and 10 cm on seed germination and seedling establishment from soil seed banks at 0-5 cm and 5-10 cm depths in typical, drying, and saline-alkaline wetlands. We also explore the potential role of soil seed bank in restoration of drying and saline-alkaline wetlands. PRINCIPAL FINDINGS: Species richness decreased with increase in water level, but there almost no change in seed density. A huge difference exists in species composition of the seed bank among different water levels in all three wetlands, especially between 0 cm and 5 cm and 0 cm and 10 cm. Similarity of species composition between seed bank and plant community was higher in 0 cm water level in drying wetland than in the other two wetlands. The similarity was much higher in 0 cm water level than in 5 cm and 10 cm water levels in all three wetlands. Species composition of the alpine wetland plant community changed significantly after drying and salinization, however, species composition of the seed bank was unchanged regardless of the environment change. CONCLUSIONS/SIGNIFICANCE: Water level greatly affects seed bank recruitment and plant community establishment. Further, different water levels in restored habitats are likely to determine its species composition of the plant community. The seed bank is important in restoration of degraded wetlands. Successful restoration of drying and salinization wetlands could depend on the seed bank.

A simulation model for seasonal changes in dormancy and germination of weed seeds

NARCIS (Netherlands)

Vleeshouwers, L.M.; Bouwmeester, H.J.

2001-01-01

A model has been developed to simulate the annual dormancy cycle of seeds of light-requiring species in the seed bank and the germination of exhumed seeds after irradiation. Simulation of dormancy and germination is based on a physiological model concerning the action of phytochrome in the seed.

Seed dormancy and persistent sediment seed banks of ephemeral freshwater rock pools in the Australian monsoon tropics.

Science.gov (United States)

Cross, Adam T; Turner, Shane R; Renton, Michael; Baskin, Jerry M; Dixon, Kingsley W; Merritt, David J

2015-04-01

Rock pools are small, geologically stable freshwater ecosystems that are both hydrologically and biologically isolated. They harbour high levels of plant endemism and experience environmental unpredictability driven by the presence of water over variable temporal scales. This study examined the hypothesis that the sediment seed bank in monsoon tropical freshwater rock pools would persist through one or more periods of desiccation, with seed dormancy regulating germination timing in response to rock pool inundation and drying events. Seeds were collected from seven dominant rock pool species, and germination biology and seed dormancy were assessed under laboratory conditions in response to light, temperature and germination stimulators (gibberellic acid, karrikinolide and ethylene). Field surveys of seedling emergence from freshwater rock pools in the Kimberley region of Western Australia were undertaken, and sediment samples were collected from 41 vegetated rock pools. Seedling emergence and seed bank persistence in response to multiple wetting and drying cycles were determined. The sediment seed bank of individual rock pools was large (13 824 ± 307 to 218 320 ± 42 412 seeds m(-2) for the five species investigated) and spatially variable. Seedling density for these same species in the field ranged from 13 696 to 87 232 seedlings m(-2). Seeds of rock pool taxa were physiologically dormant, with germination promoted by after-ripening and exposure to ethylene or karrikinolide. Patterns of seedling emergence varied between species and were finely tuned to seasonal temperature and moisture conditions, with the proportions of emergent seedlings differing between species through multiple inundation events. A viable seed bank persisted after ten consecutive laboratory inundation events, and seeds retained viability in dry sediments for at least 3 years. The persistent seed bank in freshwater rock pools is likely to provide resilience to plant

Comparison of germination and seed bank dynamics of dimorphic seeds of the cold desert halophyte Suaeda corniculata subsp. mongolica

Science.gov (United States)

Cao, Dechang; Baskin, Carol C.; Baskin, Jerry M.; Yang, Fan; Huang, Zhenying

2012-01-01

Background and Aims Differences in dormancy and germination requirements have been documented in heteromorphic seeds of many species, but it is unknown how this difference contributes to maintenance and regeneration of populations. The primary aim of this study was to compare the seed bank dynamics, including dormancy cycling, of the two seed morphs (black and brown) of the cold desert halophyte Suaeda corniculata and, if differences were found, to determine their influence on regeneration of the species. Method Seeds of the two seed morphs were buried, exhumed and tested monthly for 24 months over a range of temperatures and salinities, and germination recovery and viability were determined after exposure to salinity and water stress. Seedling emergence and dynamics of the soil seed bank were also investigated for the two morphs. Key Results Black seeds had an annual dormancy/non-dormancy cycle, while brown seeds, which were non-dormant at maturity, remained non-dormant. Black seeds also exhibited an annual cycle in sensitivity of germination to salinity. Seedlings derived from black seeds emerged in July and August and those from brown seeds in May. Seedlings were recruited from 2·6 % of the black seeds and from 2·8 % of the brown seeds in the soil, and only 0·5 % and 0·4 % of the total number of black and brown seeds in the soil, respectively, gave rise to seedlings that survived to produce seeds. Salinity and water stress induced dormancy in black seeds and decreased viability of brown seeds. Brown seeds formed only a transient soil seed bank and black seeds a persistent seed bank. Conclusions The presence of a dormancy cycle in black but not in brown seeds of S. corniculata and differences in germination requirements of the two morphs cause them to differ in their germination dynamics. The study contributes to our limited knowledge of dormancy cycling and seed bank formation in species producing heteromorphic seeds. PMID:22975287

Effect of Weeds and Some Methods for their Control in Seed Production Stands of Sainfoin (Onobrychis viciifolia Scop.

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Tsvetanka Dimitrova

2010-01-01

Full Text Available During the 2007-2009 period in the experimental field of the Institute of Forage Cropsa study was conducted with the purpose of investigating the effect of weeds and somemethods for their control in seed production stands of sainfoin (Onobrychis viciifolia Scop..The trial was carried out on a slightly leached chernozem on an area with a natural backgroundof weed infestation. As a result of the study it was found:Establishment of very uniform and productive seed production stands of sainfoinrequired effective weed control concentrated mainly in the first year when the degree ofweed infestation was the highest and reached to a number of 245 plants/m2 and the freshweed biomass to 1311 g/m2.The chemical control method showed the highest efficacy had the highest efficiencywhen, in the year of stand establishment at the stage of second-fourth true leaf of sainfoin,the treatment was conducted with imazamox 40g/l (Pulsar 40 at the dose of 48 g a.i./haor with the system of Bentazon 600 g/l (Basagran 600 SL – 900 g a.i./ha – fluazifop-P-butylg/l (Fusilad Forte – 120 g a.i./ha. In the years of seed production in spring at the beginningof vegetation, the treatment was conducted with imazamox 40 g/l (Pulsar 40 at the doseof 20 g a.i./ha + adjuvant DESH at the dose of 1000 ml/ha.An alternative to the chemical method is to sow sainfoin under cover of spring barleyachieving more complete use of the area in the first year, a weed suppressive and ecologicaleffect, but some negative residual effect on the crop was also observed;The pure stands of sainfoin with chemical control of weeds had the highest seed productivity,exceeding the zero check by 24 to 28%, followed by the stands with spring barleyas a cover crop with an increase of 12% and the mixed stands of sainfoin with crestedwheatgrass had the lowest productivity.

Ecological weed management by cover cropping : effects on weed growth in autumn and weed establishment in spring

NARCIS (Netherlands)

Kruidhof, H.M.; Bastiaans, L.; Kropff, M.J.

2008-01-01

Cover crops grown in the period between two main crops have potential as an important component of a system-oriented ecological weed management strategy. In late summer and autumn, the cover crop can suppress growth and seed production of weeds, whereas the incorporation of cover crop residues in

Effect of tillage system on yield and weed populations of soybean ( Glycin Max L.).

Science.gov (United States)

Hosseini, Seyed Z; Firouzi, Saeed; Aminpanah, Hashem; Sadeghnejhad, Hamid R

2016-03-01

Field experiment was conducted at Agricultural and Natural Resources Research Center of Golestan Province, Iran, to determine the effects of tillage system and weed management regime on yield and weed populations in soybean ( Glycin max L.). The experimental design was a split plot where the whole plot portion was a randomized complete block with three replicates. Main plots were tillage system: 1- No-till row crop seeding, 2- No-till seed drilling, 3- Tillage with disc harrow and drill planting, 4- Tillage with chisel packer and drill planting. The subplots were weed management regimes: 1-Weed control with herbicide application, 2- Hand weeding, 3- Herbicide application plus hand weeding, and 4- Non-weeding. Results indicated that the main effects of tillage system and weed management regime were significant for seed yield, pod number per plant, seed number per pod, weed density and biomass, while their interaction were significant only for weed density, weed biomass, and seed number per pod. The highest grain yields (3838 kg ha-1) were recorded for No-till row crop seeding. The highest seed yield (3877 kg ha-1) also was recorded for weed control with herbicide and hand weeding treatment, followed by hand weeding (3379 kg ha-1).

Bancos de semillas en el suelo Soil seed banks

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M. De Souza Maia

2006-06-01

Full Text Available En las comunidades vegetales, el banco de semillas en el suelo (BSS constituye el potencial regenerativo. La reposición de los individuos a partir del BSS puede tener un efecto marcado en la composición y en los patrones de vegetación de la comunidad. Numerosas investigaciones se han llevado a cabo en bancos de semillas en hábitats agrícolas o en comunidades naturales. Esta revisión tiene como objetivo analizar los conceptos relacionados a BSS, los procesos de formación de éstos, las implicancias agrícolas y cómo esta información puede ser usada para la conservación de los sistemas productivos.In plant communities, the soil seed bank (SSB represents their regenerative potential. The replacement of individuals from the seed bank may have profound effects on the composition and patterns of the vegetation within the community. Many investigations about seed banks have been made within agricultural habitats or in natural communities. The attempt of this review about the seed banks in the soil is to analyze the concepts related to SSBs, their formation, the agricultural implications and how this information might be used for the conservation of the productive systems.

Adventitious presence of other varieties in oilseed rape (¤Brassica napus¤) from seed banks and certified seed

DEFF Research Database (Denmark)

Jørgensen, T.; Hauser, Thure Pavlo; Bagger Jørgensen, Rikke

2007-01-01

To obtain information on possible sources of contamination of the seed harvest of oilseed rape (Brassica napus L., spp. napus) by other varieties (adventitious presence), we investigated the purity of certified seed lots; the abundance and origin of volunteers; and longevity and origin of seeds...... in the soil seed-bank. This information was acquired through DNA analysis of volunteers collected in the field and seedlings derived from the soil seed-bank. DNA profiles of the volunteers and seedlings were obtained using Inter Simple Sequence Repeat (ISSR) markers, and the profiles were compared with ISSR...... profiles from an assortment of 14 of the most commonly cultivated oilseed rape varieties from 1985 to 2004. This comparison was performed using the assignment program, AFLPOP. The age of the seed bank germinating to become volunteers was assumed from information on previously cultivated oilseed rape...

Characteristics of soil seed bank in plantation forest in the rocky mountain region of Beijing, China

Institute of Scientific and Technical Information of China (English)

HU Zeng-hui; YANG Yang; LENG Ping-sheng; DOU De-quan; ZHANG Bo; HOU Bing-fei

2013-01-01

We investigated characteristics (scales and composition) of soil seed banks at eight study sites in the rocky mountain region of Beijing by seed identification and germination monitoring.We also surveyed the vegetation communities at the eight study sites to explore the role of soil seed banks in vegetation restoration.The storage capacity of soil seed banks at the eight sites ranked from 766.26 to 2461.92 seedsm-2.A total of 23 plant species were found in soil seed banks,of which 63-80％of seeds were herbs in various soil layers and 60％ of seeds were located in the soil layer at 0-5 cm depth.Biodiversity indices indicated clear differences in species diversity of soil seed banks among different plant communities.The species composition of aboveground vegetation showed low similarity with that based on soil seed banks.In the aboveground plant community,the afforestation tree species showed high importance values.The plant species originating from soil seed banks represented natural regeneration,which also showed relatively high importance values.This study suggests that in the rocky mountain region of Beijing the soil seed banks played a key role in the transformation from pure plantation forest to near-natural forest,promoting natural ecological processes,and the role of the seed banks in vegetation restoration was important to the improvement of ecological restoration methods.

Seed ecology of Bromus sterilis L.

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Žďárková, Veronika

2014-02-01

Full Text Available Bromus sterilis L. (barren brome has become a troublesome weed of winter cereals in reduced tillage systems, mainly in South and North America, middle and Western Europe. In the Czech Republic, its importance has increased dramatically over the past 10 years. Barren brome is reported as a problem weed in other winter crops such as oil seed rape, in vineyards and in other cultivated places. In this study, the dormancy and germination under different temperatures, water and light regimes were investigated. Emergence from different depths and persistence in the soil profile were investigated under field conditions. The seeds of Bromus sterilis showed broad ecological valence to hydrothermal factors germinating in the wide range of 5 to 35 °C. Similarly, no strong effect on the germination in an environment with low water potential was observed. The response to light at various temperatures showed that seeds germinated better in darkness. The emergence declined significantly with burial depth (under 40 mm. The loss of primary dormancy was rapid in time and only 50% of the seeds germinated within 8 weeks after collecting from maternal plants. The seeds were not able to survive in the soil seed bank for a longer time and fall seeds lost viability 1 year after burial in a soil profile.

Soil seed banks along elevational gradients in tropical, subtropical and subalpine forests in Yunnan Province, southwest China

Institute of Scientific and Technical Information of China (English)

Xiaqin Luo; Min Cao; Min Zhang; Xiaoyang Song; Jieqiong Li; Akihiro Nakamura; Roger Kitching

2017-01-01

Soil seed banks are a vital part of ecosystems and influence community dynamics and regeneration.Although soil seed banks in different habitats have been reported,how soil seed banks vary with elerational gradients in different climatic zones is still unknown.This paper investigates seed density,species composition and nonconstituent species of forest soil seed banks in Yunnan Province,southwest China.Similarity between the soil seed bank and standing vegetation was also examined.We collected soil samples from sites spanning 12 elevations in tropical rain forests,subtropical evergreen broadleaved forests and subalpine coniferous forests,and transported them to a glasshouse for germination trials for species identification.The soil seed banks of tropical and subtropical forests had much higher seed densities and species richness than those of subalpine forests.Seeds of woody species dominated the soil seed banks of tropical and subtropical forests,while herbs dominated those of subalpine forests.The nonconstituent species in the soil seed banks were all herbs and were most abundant in tropical forests,followed by subtropical forests but were completely absent from subalpine forests.

Soil seed banks along elevational gradients in tropical, subtropical and subalpine forests in Yunnan Province, southwest China

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Xiaqin Luo

2017-10-01

Full Text Available Soil seed banks are a vital part of ecosystems and influence community dynamics and regeneration. Although soil seed banks in different habitats have been reported, how soil seed banks vary with elevational gradients in different climatic zones is still unknown. This paper investigates seed density, species composition and nonconstituent species of forest soil seed banks in Yunnan Province, southwest China. Similarity between the soil seed bank and standing vegetation was also examined. We collected soil samples from sites spanning 12 elevations in tropical rain forests, subtropical evergreen broad-leaved forests and subalpine coniferous forests, and transported them to a glasshouse for germination trials for species identification. The soil seed banks of tropical and subtropical forests had much higher seed densities and species richness than those of subalpine forests. Seeds of woody species dominated the soil seed banks of tropical and subtropical forests, while herbs dominated those of subalpine forests. The nonconstituent species in the soil seed banks were all herbs and were most abundant in tropical forests, followed by subtropical forests but were completely absent from subalpine forests.

Dormancy, germination and emergence of weed seeds, with emphasis on the influence of light : results of a literature survey

NARCIS (Netherlands)

Riemens, M.M.; Scheepens, P.C.; Weide, van der R.Y.

2004-01-01

This note reports the results of an inventory study about the influence of the external factors temperature, light, nitrate, gaseous environment of seeds and moisture on the dormancy, germination and emergence of weed seeds. The inventory was made as a guideline for research aiming at the

Seed bank and big sagebrush plant community composition in a range margin for big sagebrush

Science.gov (United States)

Martyn, Trace E.; Bradford, John B.; Schlaepfer, Daniel R.; Burke, Ingrid C.; Laurenroth, William K.

2016-01-01

The potential influence of seed bank composition on range shifts of species due to climate change is unclear. Seed banks can provide a means of both species persistence in an area and local range expansion in the case of increasing habitat suitability, as may occur under future climate change. However, a mismatch between the seed bank and the established plant community may represent an obstacle to persistence and expansion. In big sagebrush (Artemisia tridentata) plant communities in Montana, USA, we compared the seed bank to the established plant community. There was less than a 20% similarity in the relative abundance of species between the established plant community and the seed bank. This difference was primarily driven by an overrepresentation of native annual forbs and an underrepresentation of big sagebrush in the seed bank compared to the established plant community. Even though we expect an increase in habitat suitability for big sagebrush under future climate conditions at our sites, the current mismatch between the plant community and the seed bank could impede big sagebrush range expansion into increasingly suitable habitat in the future.

A comparison of seed banks across a sand dune successional gradient at Lake Michigan dunes (Indiana, USA)

Science.gov (United States)

Leicht-Young, S. A.; Pavlovic, N.B.; Grundel, R.; Frohnapple, K.J.

2009-01-01

In habitats where disturbance is frequent, seed banks are important for the regeneration of vegetation. Sand dune systems are dynamic habitats in which sand movement provides intermittent disturbance. As succession proceeds from bare sand to forest, the disturbance decreases. At Indiana Dunes National Lakeshore, we examined the seed banks of three habitat types across a successional gradient: foredunes, secondary dunes, and oak savanna. There were differences among the types of species that germinated from each of the habitats. The mean seed bank density increased across the successional gradient by habitat, from 376 to 433 to 968 seeds m-2, but with foredune and secondary dune seed bank densities being significantly lower than the savanna seed bank density. The number of seeds germinated was significantly correlated with soil organic carbon, demonstrating for this primary successional sequence that seed density increases with stage and age. The seed bank had much lower species richness than that of the aboveground vegetation across all habitats. Among sites within a habitat type, the similarity of species germinated from the seed banks was very low, illustrating the variability of the seed bank even in similar habitat types. These results suggest that restoration of these habitats cannot rely on seed banks alone. ?? 2008 Springer Science+Business Media B.V.

Water management as a key component of integrated weed management

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Antonio Berti

2010-09-01

Full Text Available Water management within the cropping system is a key factor for an integrated weed management. Soil moisture affects seed persistence and seed dormancy, thus influencing their germination, the establishment of seedlings as well as the competition at adult stage and the number, vitality and dormancy of the new seeds produced by the weeds. The interactions among water availability and competition are very complex and still not fully understood. A research effort in this sector should the be very relevant for the development of new approaches of weed management, such as “Ecological weed management”, aiming to reduce weed density and competitiveness and, in the medium term, to prevent undesired modifications of the weed flora.

The impact of groundwater level on soil seed bank survival

NARCIS (Netherlands)

Bekker, RM; Oomes, MJM; Bakker, JP

Seed longevity of plant species is an important topic in restoration management, and little is known about the effects of environmental conditions on seed survival and longevity under natural conditions. Therefore, the effect of groundwater level on the survival of seeds in the soil seed bank of a

Selected aspects of tiny vetch [Vicia hirsuta (L. Gray S.F.] seed ecology: generative reproduction and effects of seed maturity and seed storage on seed germination

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Magdalena Kucewicz

2012-12-01

Full Text Available Vicia hirsuta (L. Gray S.F. (tiny vetch is a common and persistent segetal weed. Tiny vetch seeds and pods reach different stages of maturity during the crop harvest season. Some seeds that mature before cereal harvest are shed in the field and deposited in the soil seed bank, while others become incorporated into seed material. The objective of this study was to describe selected aspects of tiny vetch seed ecology: to determine the rate of individual reproduction of vetch plants growing in winter and spring grain crops and to evaluate the germination of seeds at different stages of maturity, subject to storage conditions. The seeds and pods of V. hirsuta were sorted according to their development stages at harvest and divided into two groups. The first group was stored under laboratory conditions for two months. In the autumn of the same year, the seeds were subjected to germination tests. The remaining seeds were stored in a storeroom, and were planted in soil in the spring. The germination rate was evaluated after 8 months of storage. Potential productivity (developed pods and flowers, fruit buds was higher in plants fruiting in winter wheat than in spring barley. Vetch plants produced around 17-26% more pods (including cracked, mature, greenish-brown and green pods and around 25% less buds in winter wheat than in spring barley. Immature seeds were characterized by the highest germination capacity. Following storage under laboratory conditions and stratification in soil, mature seeds germinated at a rate of several percent. After storage in a storeroom, seeds at all three development stages broke dormancy at a rate of 72- 75%. The high germination power of tiny vetch seeds stored in a storeroom indicates that this plant can be classified as an obligatory speirochoric weed species.

SEED BANKS FOR MAGNETIC FLUX COMPRESSION GENERATORS

Energy Technology Data Exchange (ETDEWEB)

Fulkerson, E S

2008-05-14

In recent years the Lawrence Livermore National Laboratory (LLNL) has been conducting experiments that require pulsed high currents to be delivered into inductive loads. The loads fall into two categories (1) pulsed high field magnets and (2) the input stage of Magnetic Flux Compression Generators (MFCG). Three capacitor banks of increasing energy storage and controls sophistication have been designed and constructed to drive these loads. One bank was developed for the magnet driving application (20kV {approx} 30kJ maximum stored energy.) Two banks where constructed as MFCG seed banks (12kV {approx} 43kJ and 26kV {approx} 450kJ). This paper will describe the design of each bank including switching, controls, circuit protection and safety.

Weeding volatiles reduce leaf and seed damage to field-grown soybeans and increase seed isoflavones.

Science.gov (United States)

Shiojiri, Kaori; Ozawa, Rika; Yamashita, Ken-Ichi; Uefune, Masayoshi; Matsui, Kenji; Tsukamoto, Chigen; Tokumaru, Susumu; Takabayashi, Junji

2017-01-30

Field experiments were conducted over 3 years (2012, 2013, and 2015), in which half of the young stage soybean plants were exposed to volatiles from cut goldenrods three times over 2-3 weeks, while the other half remained unexposed. There was a significant reduction in the level of the total leaf damage on exposed soybean plants compared with unexposed ones. In 2015, the proportion of damage to plants by Spodoptera litura larvae, a dominant herbivore, was significantly less in the exposed field plots than in the unexposed plots. Under laboratory conditions, cut goldenrod volatiles induced the direct defenses of soybean plants against S. litura larvae and at least three major compounds, α-pinene, β-myrcene, and limonene, of cut goldenrod volatiles were involved in the induction. The number of undamaged seeds from the exposed plants was significantly higher than that from unexposed ones. Concentrations of isoflavones in the seeds were significantly higher in seeds from the exposed plants than in those from the unexposed plants. Future research evaluating the utility of weeding volatiles, as a form of plant-plant communications, in pest management programs is necessary.

Seed Bank Variation under Contrasting Site Quality Conditions in Mixed Oak Forests of Southeastern Ohio, USA

International Nuclear Information System (INIS)

Small, Ch.J.; McCarthy, B.C.

2010-01-01

Seed bank composition was sampled in 192-2.5 m 2 quadrats, established in six regenerating clearcut (∼7 years) and six second-growth ((∼125 years) mixed-oak forest stands in southeastern Ohio. Seed bank and aboveground composition diverged markedly (Sorensen's coefficient <10%), emphasizing the importance of fast-growing, early-successional germinants to early ecosystem recovery. Seed richness was significantly (ρ<.01) higher in clearcut stands, suggesting declining richness with stand age. Richness estimations 28%-60% higher than observed values demonstrated high seed bank heterogeneity, emphasizing the need for intensive sampling to assess temperate forest seed bank variation. Site quality (topographic aspect) strongly influenced seed bank composition, with greater importance of early-successional trees, thicket-forming shrubs, and nonnative species on mesic sites. Thus, forest seed banks are likely to play an important, site-dependent role in shaping competitive environments for commercially important timber species after harvesting and soil disturbance and have the potential for marked influence on post harvest forest development.

Analysis of plant soil seed banks and seed dispersal vectors: Its potential and limits for forensic investigations.

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Šumberová, Kateřina; Ducháček, Michal

2017-01-01

Plant seeds exhibit many species-specific traits, thus potentially being especially helpful for forensic investigations. Seeds of a broad range of plant species occur in soil seed banks of various habitats and may become attached in large quantities to moving objects. Although plant seeds are now routinely used as trace evidence in forensic practice, only scant information has been published on this topic in the scientific literature. Thus, the standard methods remain unknown to specialists in such botanical subjects as plant ecology and plant geography. These specialists, if made aware of the forensic uses of seeds, could help in development of new, more sophisticated approaches. We aim to bridge the gap between forensic analysts and botanists. Therefore, we explore the available literature and compare it with our own experiences to reveal both the potential and limits of soil seed bank and seed dispersal analysis in forensic investigations. We demonstrate that habitat-specific and thus relatively rare species are of the greatest forensic value. Overall species composition, in terms of species presence/absence and relative abundance can also provide important information. In particular, the ecological profiles of seeds found on any moving object can help us identify the types of environments through which the object had travelled. We discuss the applicability of this approach to various European environments, with the ability to compare seed samples with georeferenced vegetation databases being particularly promising for forensic investigations. We also explore the forensic limitations of soil seed bank and seed dispersal vector analyses. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Weed management through herbicide application in direct-seeded rice and yield modeling by artificial neural network

Energy Technology Data Exchange (ETDEWEB)

Ghosh, D.; Singh, U.P.; Ray, K.; Das, A.

2016-11-01

In direct seeded rice (DSR) cultivation, weed is the major constraint mainly due to absence of puddling in field. The yield loss due to weed interference is huge, may be up to 100%. In this perspective, the present experiment was conducted to study the efficacy of selected herbicides, and to predict the rice yield using artificial neural network (ANN) models. The dry weight and density of weeds were recorded at different growth stages and consequently herbicidal efficacy was evaluated. Experimental results revealed that pre-emergence (PRE) herbicide effectively controlled the germination of grassy weeds. Application bispyribac-sodium as post-emergence (POST) following PRE herbicides (clomazone or pendimethalin) or as tank-mixture with clomazone effectively reduced the density and biomass accumulation of diverse weed flora in DSR. Herbicidal treatments improved the plant height, yield attributes and grain yield (2.7 to 5.5 times) over weedy check. The sensitivity of the best ANN model clearly depicts that the weed control index (WCI) of herbicides was most important than their weed control efficiency (WCE). Besides, the early control of weeds is a better prescription to improve rice yield. Differences in sensitivity values of WCI and WCE across the crop growth stages also suggest that at 15, 30 and 60 days after sowing, herbicides most effectively controlled sedges, broad leaves and grasses, respectively. Based on the grain yield and herbicidal WCE, it can be concluded that the combined application of pendimethalin or clomazone as PRE followed by bispyribac-sodium as POST or tank-mixture of clomazone + bispyribac sodium can effectively control different weed flushes throughout the crop growth period in DSR. (Author)

Stochastic and deterministic processes regulate spatio-temporal variation in seed bank diversity

Science.gov (United States)

Alejandro A. Royo; Todd E. Ristau

2013-01-01

Seed banks often serve as reservoirs of taxonomic and genetic diversity that buffer plant populations and influence post-disturbance vegetation trajectories; yet evaluating their importance requires understanding how their composition varies within and across spatial and temporal scales (α- and β-diversity). Shifts in seed bank diversity are strongly...

Effects of 10-Year Management Regimes on the Soil Seed Bank in Saline-Alkaline Grassland

Science.gov (United States)

Ma, Hongyuan; Yang, Haoyu; Liang, Zhengwei; Ooi, Mark K. J.

2015-01-01

Background Management regimes for vegetation restoration of degraded grasslands can significantly affect the process of ecological succession. However, few studies have focused on variation in the soil seed bank during vegetation restoration under different management regimes, especially in saline-alkaline grassland habitats. Our aim was to provide insights into the ecological effects of grassland management regimes on soil seed bank composition and vegetation establishment in mown, fenced, transplanted and natural grassland sites, all dominated by the perennial rhizomatous grass Leymus chinensis. Methodology We studied species composition and diversity in both the soil seed bank and aboveground vegetation in differently managed grasslands in Northeast China. An NMDS (nonmetric multidimensional scaling) was used to evaluate the relationship between species composition, soil seed banks, aboveground vegetation and soil properties. Principal Findings Fenced and mown grassland sites had high density and species richness in both the soil seed bank and aboveground vegetation. The Transplanted treatment exhibited the highest vegetation growth and seed production of the target species L. chinensis. Seeds of L. chinensis in the soil occurred only in transplanted and natural grassland. Based on the NMDS analysis, the number of species in both the soil seed bank and aboveground vegetation were significantly related to soil Na+, Cl-, RSC (residual sodium carbonate), alkalinity, ESP (exchangeable sodium percentage) and AP (available phosphorus). Conclusions Soil seed bank composition and diversity in the saline-alkaline grassland were significantly affected by the management regimes implemented, and were also significantly related to the aboveground vegetation and several soil properties. Based on vegetative growth, reproductive output and maintenance of soil seed bank, the transplanting was identified as the most effective method for relatively rapid restoration of the target

SEEDS BANK OF BOTANICAL GARDEN OF CHECHEN STATE UNIVERSITY

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R. S. Erzhapova

2013-01-01

Full Text Available Abstract. One of priorities of seed laboratory is creation of collection of seeds of wild plants, conservation of flora gene pool of the Chechen Republic, neighboring areas and biological diversity of flora of the Caucasus. Inventory data of seed bank of "Seed Laboratory" of Department of Botany of Chechen State University (seeds from botanical gardens, natural habitat of the Chechen Republic and adjacent areas is the basis of this work. Currently, there are more than 350 species, representatives of more than 70 families in the collection.

Seed Bank Variation under Contrasting Site Quality Conditions in Mixed Oak Forests of Southeastern Ohio, USA

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Christine J. Small

2010-01-01

Full Text Available Seed bank composition was sampled in 192–2.5 m2 quadrats, established in six regenerating clearcut (∼7 years and six second-growth (∼125 years mixed-oak forest stands in southeastern Ohio. Seed bank and aboveground composition diverged markedly (Sørensen's coefficient <10%, emphasizing the importance of fast-growing, early-successional germinants to early ecosystem recovery. Seed richness was significantly (P<.01 higher in clearcut stands, suggesting declining richness with stand age. Richness estimations 28%–60% higher than observed values demonstrated high seed bank heterogeneity, emphasizing the need for intensive sampling to assess temperate forest seed bank variation. Site quality (topographic aspect strongly influenced seed bank composition, with greater importance of early-successional trees, thicket-forming shrubs, and nonnative species on mesic sites. Thus, forest seed banks are likely to play an important, site-dependent role in shaping competitive environments for commercially important timber species after harvesting and soil disturbance and have the potential for marked influence on postharvest forest development.

Composition of soil seed bank over cholistan desert microhabitats at dingarh for area, pakistan

International Nuclear Information System (INIS)

Hamid, A.; Arshad, M.; Ghazali, H.M.Z.

2016-01-01

Soil seed banks were assessed in three soil layers (L1, from 0 to 2 cm, L2, 2 to 4 cm and L3, 4 to 6 cm depth ) from five microhabitats i.e., Lee-ward side of sand dune (S1), Wind-ward side of sand dune (S2), Clayey area covered with sand (S3), Interdunal sandy area (S4) and Shifting sand dune of site Dingarh Fort area (S5) in Cholistan desert of Pakistan to analyse differences of soil seed bank among these habitats. Ten soil samples were collected from each microhabitat and from each layer i.e., 0-2 cm depth (L1), 2-4 cm depth (L2) and 4-6 cm depth (L3) by using 15*15*6 cm metallic sampler. Consistent differences in seed composition were observed among these microhabitats. Seedling emergence approach was used to assess the soil seed bank of Cholistan desert. Canonical correspondence analysis (CCA) was used for the soil seed bank and the plant species analysis. The microhabitats S3 (Clayey area covered with sand) and S4 (Interdunal sandy area) contributed prominently to the total variance in the species and had maximum density of seed bank and soil layer L1 contained maximum number of seeds. (author)

Dynamics of the weed infestation with Senecio vulgaris after a single entry from seeds

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Söchting, Hans-Peter

2014-02-01

Full Text Available Due to a short generation time associated with a high seed production and a quick germination, which is possible throughout the year, Senecio vulgaris is especially in horticultural crops one of the most important weed species. Like all ragwort species, also Senecio vulgaris contains pyrrolizidine alkaloids which are converted in the liver to harmful substances. For this reason an accidental consumption of this species should be avoided completely. Belonging to the Compositae, chemical control of this weed species in vegetable crops, particularly in lettuce, is difficult. Based on a field-grown model experiment the emergence behavior and growth of Senecio vulgaris in leafy lettuce was studied. The first step was the contamination of the trial plots with Senecio seeds. For this purpose Senecio plants were planted at three different densities (1, 2 and 10 plants m2 in the designated plots. All plots were covered with fleece in order to prevent an unregulated dispersal of seeds. After seed maturity the fleece was removed, plants were cut into small pieces and the plant material including the seeds was incorporated into the soil. Then different leafy lettuces crops (rocket, asia green, spinach, lamb´s lettuce were cultivated in a six-crop sequence over two years (three crop sopecies per year. The development of Senecio vulgaris and the resulting possible contamination of the lettuces with Senecio leaves was recorded. From the date of removing the fleece on seed-production a shedding of Senecio plants was prevented to avoid further contamination. Also the entry from outside the plots was excluded. Depending on the initial plant density, the 71, 55 and 216 Senecio plants m2 which emerged after the first sowing of lettuce dropped to 7, 9 and 16 plants m2 after the sixth sowing. Thus, the density of S. vulgaris plants rapidly decreased but there was still a significant potential of emerging seedlings potentially contaminating the lettuce crops after

EFFECT OF SOWING DATE AND WEED CONTROL METHOD ON THE GROWTH AND YIELD OF SOYBEAN

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Nasrin Akter

2016-06-01

Full Text Available Sowing date and weed management play a significant role in determining soybean growth, development and seed yield. Results showed that different sowing date and weed control methods had significant effect on relative weed density, weed biomass, weed control efficiency, plant height, dry weight plant-1 and seed yield of soybean. Among the infested weed species in the experimental field the dominant weeds were Lindernia procumbens (44.78%, Echinochloa colonum (26.39% and Cynodon dactylon (16.30%. The results also revealed that early sowing (2 January brought about the highest seed yield (2.17 t ha-1 and sowing delay (1 February resulted in the lowest yield (1.64 t ha-1. Two times hand weeding (20 and 40 DAS controlled the weeds most effectively and led to highest seed yield (2.23 t ha-1 which was statistically similar (2.19 t ha-1 with herbicide application. Combination effect showed that the highest seed yield (2.50 t ha-1 was obtained from 2 January sowing when the crop was weeded by hand at 20 and 40 DAS.

Host-parasite coevolution can promote the evolution of seed banking as a bet-hedging strategy.

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Verin, Mélissa; Tellier, Aurélien

2018-04-20

Seed (egg) banking is a common bet-hedging strategy maximizing the fitness of organisms facing environmental unpredictability by the delayed emergence of offspring. Yet, this condition often requires fast and drastic stochastic shifts between good and bad years. We hypothesize that the host seed banking strategy can evolve in response to coevolution with parasites because the coevolutionary cycles promote a gradually changing environment over longer times than seed persistence. We study the evolution of host germination fraction as a quantitative trait using both pairwise competition and multiple mutant competition methods, while the germination locus can be genetically linked or unlinked with the host locus under coevolution. In a gene-for-gene model of coevolution, hosts evolve a seed bank strategy under unstable coevolutionary cycles promoted by moderate to high costs of resistance or strong disease severity. Moreover, when assuming genetic linkage between coevolving and germination loci, the resistant genotype always evolves seed banking in contrast to susceptible hosts. Under a matching-allele interaction, both hosts' genotypes exhibit the same seed banking strategy irrespective of the genetic linkage between loci. We suggest host-parasite coevolution as an additional hypothesis for the evolution of seed banking as a temporal bet-hedging strategy. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Soil Seed Bank and Plant Community Development in Passive Restoration of Degraded Sandy Grasslands

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Renhui Miao

2016-06-01

Full Text Available To evaluate the efficacy of passive restoration on soil seed bank and vegetation recovery, we measured the species composition and density of the soil seed bank, as well as the species composition, density, coverage, and height of the extant vegetation in sites passively restored for 0, 4, 7, and 12 years (S0, S4, S7, and S12 in a degraded grassland in desert land. Compared with S0, three more species in the soil seed bank at depths of 0–30 cm and one more plant species in the community was detected in S12. Seed density within the topsoil (0–5 cm was five times higher in S12 than that in S0. Plant densities in S7 and S12 were triple and quadruple than that in S0. Plant coverage was increased by 1.5 times (S4, double (S7, and triple (S12 compared with S0. Sørensen’s index of similarity in species composition between the soil seed bank and the plant community were high (0.43–0.63, but it was lower in short-term restoration sites (S4 and S7 than that in no and long-term restoration sites (S0 and S12. The soil seed bank recovered more slowly than the plant community under passive restoration. Passive restoration is a useful method to recover the soil seed bank and vegetation in degraded grasslands.

SEEDBANK AND SEEDLING EMERGENCE CHARACTERISTICS OF WEEDS IN RICEFIELD SOILS OF THE MUDA GRANARY AREA IN NORTH-WEST PENINSULAR MALAYSIA

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2006-01-01

Full Text Available Tlie experiment was conducted in the glasshouse of UPM from March 2003 to June 2004 to determine the soil seedbank in the ricefields ot'Muda rice granary area in Peninsular Malaysia. Six soil cores of 5 cm in diameter and 10 cm depth were sampled from each of 24 fields. All samples from each individual field were bulked and placed in plastic trays of 38 x 25 x 10 cm. Soil was moistened as required and emergence of weed seedlings were recorded over period of one year. After one year, remaining seeds were separated, removed and identified. The total seed bank was estimated at 1136.48 million/ha of whic h 62.35% (708.60 million seedlings ha"1 germinated within 12 months and 37.65% (427.88 million seeds ha"1 remained ungerminated. Total of 20 taxa were recognized. Based on importance value (I.V. the five most dominant species in terms of emerged seedling were Fimbristylis miliacea, Leplochloa chinensis, LitJwigia hyssopifolia, Cyperus difformii and C. iria. Of the remaining seeds the five dominant species with decreasing trend in ranking were F. miliacea, Scirpus lateriflonis, Monochoria vagina/is, L. hyssopifolia and L. chinensis. Ranking of total seed reserves (seedlings+ remaining seeds were similar to emerged seedling indi cating that emerged seedlings reflect the actual weed flora in the Muda area. Among the dominant species F. miliacea accounted for 58.07% of emerged seedlings, 79.31% of remaining seeds and 66.07% of total seed bank. Total seedling emergence of all species was higher in the first observation in April 2003 and cumulative seedling emergence showed no clear peaks.

Evolution with a seed bank: The population genetic consequences of microbial dormancy.

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Shoemaker, William R; Lennon, Jay T

2018-01-01

Dormancy is a bet-hedging strategy that allows organisms to persist through conditions that are suboptimal for growth and reproduction by entering a reversible state of reduced metabolic activity. Dormancy allows a population to maintain a reservoir of genetic and phenotypic diversity (i.e., a seed bank) that can contribute to the long-term survival of a population. This strategy can be potentially adaptive and has long been of interest to ecologists and evolutionary biologists. However, comparatively little is known about how dormancy influences the fundamental evolutionary forces of genetic drift, mutation, selection, recombination, and gene flow. Here, we investigate how seed banks affect the processes underpinning evolution by reviewing existing theory, implementing novel simulations, and determining how and when dormancy can influence evolution as a population genetic process. We extend our analysis to examine how seed banks can alter macroevolutionary processes, including rates of speciation and extinction. Through the lens of population genetic theory, we can understand the extent that seed banks influence the evolutionary dynamics of microorganisms as well as other taxa.

Integration of Agronomic Practices with Herbicides for Sustainable Weed Management in Aerobic Rice

Science.gov (United States)

Anwar, M. P.; Juraimi, A. S.; Mohamed, M. T. M.; Uddin, M. K.; Samedani, B.; Puteh, A.; Man, Azmi

2013-01-01

Till now, herbicide seems to be a cost effective tool from an agronomic view point to control weeds. But long term efficacy and sustainability issues are the driving forces behind the reconsideration of herbicide dependent weed management strategy in rice. This demands reappearance of physical and cultural management options combined with judicious herbicide application in a more comprehensive and integrated way. Keeping those in mind, some agronomic tools along with different manual weeding and herbicides combinations were evaluated for their weed control efficacy in rice under aerobic soil conditions. Combination of competitive variety, higher seeding rate, and seed priming resulted in more competitive cropping system in favor of rice, which was reflected in lower weed pressure, higher weed control efficiency, and better yield. Most of the herbicides exhibited excellent weed control efficiency. Treatments comprising only herbicides required less cost involvement but produced higher net benefit. On the contrary, treatments comprising both herbicide and manual weeding required high cost involvement and thus produced lower net benefit. Therefore, adoption of competitive rice variety, higher seed rate, and seed priming along with spraying different early-postemergence herbicides in rotation at 10 days after seeding (DAS) followed by a manual weeding at 30 DAS may be recommended from sustainability view point. PMID:24223513

Strip Tillage and Early-Season Broadleaf Weed Control in Seeded Onion (Allium cepa)

OpenAIRE

Sarah Gegner-Kazmierczak; Harlene Hatterman-Valenti

2016-01-01

Field experiments were conducted in 2007 and 2008 near Oakes, North Dakota (ND), USA, to evaluate if strip tillage could be incorporated into a production system of seeded onion (Allium cepa) to eliminate the standard use of a barley (Hordeum vulgare) companion crop with conventional, full width tillage, yet support common early-season weed control programs. A split-factor design was used with tillage (conventional and strip tillage) as the main plot and herbicide treatments (bromoxynil, DCPA...

Seed germination response to high temperature and water stress in three invasive Asteraceae weeds from Xishuangbanna, SW China.

Science.gov (United States)

Yuan, Xia; Wen, Bin

2018-01-01

Crassocephalum crepidioides, Conyza canadensis, and Ageratum conyzoides are alien annuals naturalized in China, which produce a large number of viable seeds every year. They widely grow in Xishuangbanna, becoming troublesome weeds that compete with crops for water and nutrients. As seed germination is among the most important life-stages which contribute to plant distribution and invasiveness, its adaptation to temperature and water stress were investigated in these three species. Results showed that: (1) These three species have wide temperature ranges to allow seed germination, i.e., high germination and seedling percentages were achieved between 15°C and 30°C, but germination was seriously inhibited at 35°C; only A. conyzoides demonstrated relative preference for warmer temperatures with approximately 25% germination and seedling percentage at 35°C; (2) light was a vital germination prerequisite for C. crepidioides and A. conyzoides, whereas most C. canadensis seeds germinated in full darkness; (3) Although all three species have good adaptation to bare ground habitat characterized by high temperatures and water stress, including their tolerance to soil surface temperatures of 70°C in air-dried seeds, A. conyzoides seeds exhibited higher tolerance to both continuous and daily periodic high-temperature treatment at 40°C, and to water restriction (e.g., ca. 65% seeds germinated to -0.8 MPa created by NaCl), which is consistent with their field behavior in Xishuangbanna. This study suggests that seed high-temperature tolerance contributes to the weed attributes of these three species, and that adaptation to local micro-habitats is a critical determinant for invasiveness of an alien plant.

Flavonoids from leaves of Derris urucu: assessment of potential effects on seed germination and development of weeds

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EWERTON A.S. DA SILVA

2013-09-01

Full Text Available In some previous studies, we described the isolation of nine compounds from leaves of Derris urucu, a species found widely in the Amazon rainforest, identified as five stilbenes and four dihydroflavonols. In this work, three of these dihydroflavonols [urucuol A (1, urucuol B (2 and isotirumalin (3] were evaluated to identify their potential as allelochemicals, and we are also reporting the isolation and structural determination of a new flavonoid [5,3′-dihydroxy-4′-methoxy-(7,6:5″,6″-2″,2″-dimethylpyranoflavanone (4]. We investigated the effects of the dihydroflavonols 1-3 on seed germination and radicle and hypocotyl growth of the weed Mimosa pudica, using solutions at 150 mg.L–1. Urucuol B, alone, was the substance with the greatest potential to inhibit seed germination (26%, while isotirumalin showed greater ability to reduce the development of the hypocotyl (25%, but none of the three substances showed the potential to inhibit radicle. When combined in pairs, the substances showed synergism for the development of root and hypocotyl and effects on seed germination that could be attributed to antagonism. When tested separately, the trend has become more intense effects on seed germination, while for the substances tested in pairs, the intensity of the effect was greater on development of weed.

Effect of Different Methods of Chemical Weed Control Irrigation Regimes on Weed Biomass and Safflower Yield

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M. Matinfar

2011-06-01

Full Text Available In order to investigate the effects of different weed control methods and moisture regimes on safflower (Carthamus tinctorius, a field split plot experiment based on randomized complete block design with 4 replications was conducted in Takestan Iran, during growing seasons of 2007-8. Three irrigations regimes (normal irrigation, restricted irrigation at stem elongation and restricted irrigation at  flowering stage were assigned to the main plots and nine chemical weed control method (complete hand weeding, treflan with 2 L/ha as pre plant herbicide, sonalan with 3 L/ha ad pre plant herbicide, estomp with 3 L/ha as pre plant herbicide, gallant super with 0/75 L/ha as post emergence herbicide, treflan with 2 L/ha as pre plant herbicide+ gallant super with 0/75 L/ha as post emergence herbicide, sonalan with 3 L/ha as pre plant herbicide + gallant super with 0/75 L/ha as post emergence herbicide estomp with 3 L/ha as pre plant herbicide + gallant super with 0/75 L/ha as post emergence herbicide and without hand weeding to sub- plots. At the end of growing period traits like number of head   per plant, number of seed per head, 1000 grain weight, percent of seed oil, yield of seed oil and grain yield were measured. Results indicated that treflan + gallant super treatment in restricted irrigation at stem elongation stage had the lowest dry weight of weeds. In this study maximum grain yield (2927 Kg/ha was achieved from hand weeding + usual irrigation treatments. In general treflan + gallant super treatment was the most effective treatment on safflower yield and weed control.

Banking on the Future. Seed Bank Investigations Teach Biodiversity and Biocomplexity

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Clary, Renee; Wandersee, James

2013-01-01

People depend on plants to fulfill many of their basic needs, such as food, clothing, and shelter. Although plants are all around us, people are often afflicted with "plant blindness," paying more attention to animals (Wandersee and Clary 2006; Wandersee and Schussler 2001). Studying seed banks and building one in the classroom can…

Flora, life form and chorological study of soil seed bank in Sisangan box tree (Buxus hyrcanus Pojark Forest Reserve

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Moslem Akbarinia

2014-08-01

Full Text Available The present study involves the soil seed bank flora of the Sisangan Box tree (Buxus hyrcanus Pojark reserve by using seedling emergence method. 150 soil samples were collected during late June and early November by hammering a hollow metal frame 400 cm2 to a depth of 5 cm. Results showed 67 species, representing 63 genera and 38 families germinated from soil seed bank. 45 species belonging to 28 families and 59 species belonging to 32 families were recorded in June and November soil seed bank respectively. The largest families were Asteraceae (7 species, 10.5%, Lamiaceae (6 species, 9%, Poaceae (5 species, 7.5% and Rosaceae (4 species, 6% which compromised 32.8% percent of the total species in the soil seed bank. Results also showed that Hemicrptophytes (28.4% and Euro-Sibria elements (23/9% were the most important biological spectrum and phytochorion respectivly in the soil seed bank of Sisangan forest. From the total number of species recorded in seed bank, 30 species (44.6 % were found only in the seed bank and never observed in above-ground vegetation. In this regard, seeds of 10 woody species including Albizia julibrissin, Ficus carica, Morus alba, Diospyrus lotus, Celtis australis, Gleditsia caspica, Buxus hyrcana, Ulmus minor, Zelkova carpinifolia and Carpinus betulus were found in the soil seed bank, from which only 6 species were able to produce persistent soil seed bank. This condition confirmed low similarity between above-ground vegetation and persistent soil seed bank and it also reiterated the importance of soil seed bank study for introducing more accurate capacity of plant biodiversity.

Invasive Australian Acacia seed banks: Size and relationship with stem diameter in the presence of gall-forming biological control agents.

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Matthys Strydom

Full Text Available Australian Acacia are invasive in many parts of the world. Despite significant mechanical and biological efforts to control their invasion and spread, soil-stored seed banks prevent their effective and sustained removal. In response South Africa has had a strong focus on employing seed reducing biological control agents to deal with Australian Acacia invasion, a programme that is considered as being successful. To provide a predictive understanding for their management, seed banks of four invasive Australian acacia species (Acacia longifolia, A. mearnsii, A. pycnantha and A. saligna were studied in the Western Cape of South Africa. Across six to seven sites for each species, seed bank sizes were estimated from dense, monospecific stands by collecting 30 litter and soil samples. Average estimated seed bank size was large (1017 to 17261 seed m-2 as was annual input into the seed bank, suggesting that these seed banks are not residual but are replenished in size annually. A clear relationship between seed bank size and stem diameter was established indicating that mechanical clearing should be conducted shortly after fire-stimulated recruitment events or within old populations when seed banks are small. In dense, monospecific stands seed-feeding biological control agents are not effective in reducing seed bank size.

Long-term persistence of pioneer species in tropical forest soil seed banks

Energy Technology Data Exchange (ETDEWEB)

Dalling, J W; Brown, T A

2008-10-05

In tropical forests, pioneer species regenerate from seeds dispersed directly into canopy gaps, and from seeds that persisted in soil seed banks before gap formation. However, life-history models suggest that selection for long-term persistence of seeds in soil should be weak, as persistence incurs a fitness cost resulting from prolonged generation time. We use a carbon dating technique to provide the first direct measurements of seed persistence in undisturbed tropical forest seed banks. We show that seeds germinate successfully from surface soil microsites up to 38 years after dispersal. Decades-long persistence may be common in pioneers with relatively large mass, and appears to be unrelated to specific regeneration requirements. In Croton billbergianus, a sub-canopy tree that recruits in abundant small gaps, long-term persistence is associated with short-distance ballistic seed dispersal. In Trema micrantha, a canopy tree with widespread dispersal, persistence is associated with a requirement for large gaps that form infrequently in old-growth forest.

Repeated drought alters resistance of seed bank regeneration in baldcypress swamps of North America

Science.gov (United States)

Lei, Ting; Middleton, Beth A.

2018-01-01

Recurring drying and wetting events are likely to increase in frequency and intensity in predicted future droughts in the central USA and alter the regeneration potential of species. We explored the resistance of seed banks to successive droughts in 53 sites across the nine locations in baldcypress swamps in the southeastern USA. Along the Mississippi River Alluvial Valley and northern Gulf of Mexico, we investigated the capacity of seed banks to retain viable seeds after successive periods of drying and wetting in a greenhouse study. Mean differences in species richness and seed density were compared to examine the interactions of successive droughts, geographical location and water regime. The results showed that both species richness and total density of germinating seedlings decreased over repeated drought trials. These responses were more pronounced in geographical areas with higher annual mean temperature. In seed banks across the southeastern swamp region, most species were exhausted after Trial 2 or 3, except for semiaquatic species in Illinois and Tennessee, and aquatic species in Texas. Distinct geographical trends in seed bank resistance to drought demonstrate that climate-induced drying of baldcypress swamps could influence the regeneration of species differently across their ranges. Despite the health of adult individuals, lack of regeneration may push ecosystems into a relict status. Seed bank depletion by germination without replenishment may be a major conservation threat in a future with recurring droughts far less severe than megadrought. Nevertheless, the protection of moist refugia might aid conservation.

El Niño effects on soil seed bank dynamics in north-central Chile.

Science.gov (United States)

Gutiérrez, Julio R; Meserve, Peter L

2003-03-01

The soil seed bank was monitored in four 75x75 m plots over 6 years (1990-1995) in an arid thorn scrub community in north-central Chile. Sixty-six species were identified. Total seed densities ranged from 2,000 to 42,000/m(2). Average mass of shrub seeds was significantly greater than that of other growth-forms. Between 70 and 90% of the seeds were less than 1 mg, with those in the 0.51-1.00 mg size class being most numerous. Seed densities were highly variable between years as well as within years, but were also closely associated with plant cover patterns and rainfall regime. Higher seed densities were found in wet years, and in samples taken in early summer and early autumn (i.e., after seed set); the lowest seed densities were in late winter (i.e., after annual plant germination). The annual plant species with the highest cover were also the most abundant in the soil seed bank and exhibited the largest seed density fluctuations. In general, seed densities were 5- to 10-fold higher during the 1991-1992 El Niño/southern oscillation (ENSO) years than non-ENSO years, showing the importance of this phenomenon for seed bank replenishment in the arid region of Chile.

Conservation implications of weed management of lake reservoirs ...

African Journals Online (AJOL)

Management of weeds around lake reservoirs is often implemented to reduce any possibility of siltation. However, machineries used in weed management have resulted in habitat degradation and geometrical multiplication of weeds by chopping rhizomes and scattering seeds. In general, the removal offers some feedbacks ...

Predação de sementes de plantas daninhas em áreas cultivadas Weed seeds predation in cultivaded fields

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Alvadi Antonio Balbinot Jr.

2002-08-01

Full Text Available Na investigação das relações ecológicas entre as espécies, observou-se que certos animais, principalmente insetos, alimentavam-se de sementes de plantas daninhas antes e depois da sua deiscência, reduzindo a entrada de sementes no banco de sementes do solo e, portanto, a quantidade total de propágulos disponíveis à germinação. Em situações favoráveis à atividade dos predadores, o consumo de sementes pode ser significativo, chegando a 90% do total de sementes produzidas. Esse processo depende, basicamente, das condições de ambiente e das práticas de manejo adotadas, como: método de preparo do solo, espécie cultivada, densidade e espaçamento da cultura e também do tamanho da lavoura. Deste modo, a predação de sementes pode ser uma ferramenta natural importante para o manejo integrado de plantas daninhas. Todavia são necessários estudos com maior consistência dos fatores envolvidos na regulação do processo de consumo de sementes para elucidação e orientação de práticas culturais que maximizem a intensidade de ocorrência desta forma biológica de manejo de infestantes.In investigating ecological relations among species, it has been observed that various animals, mainly insects, feed on weed seeds before and after their dehiscence, reducing seed replenishment in the soil and total amount of propagules available for future germination. Under favorable conditions for predation activity, consumption of seeds can be quite high, reaching as much as 90% of total seeds produced. This process depends, basically, on environmental conditions and on management practices adopted, as soil preparation method, crop species, crop density and spacing, and on the size of cultivated area. Therefore, seed predation is an important natural tool to be used in integrated weed management. Nevertheless, seed predation requires additional studies in order to elucidate more consintently the factors involved in the regulation of seed

Crop characteristics and weed Interactions of diverse Rrecurrent Inbred Lines (RILs) from a weed-suppressive x non-suppressive rice mapping population

Science.gov (United States)

ndica rice genotypes with enhanced weed suppression traits have been previously identified as potentially useful in supplementing weed control efforts in drill-seeded systems in the southern USA. A particularly weed-suppressive indica genotype (PI 312777) that was also high tillering and high yield...

The Art and the Science of Cultivation for Weed Control in Organic Peanut

Science.gov (United States)

Cultural weed control is the basis on which an integrated system of weed management in organic peanut is based. The cultural practices evaluated for weed control were row patterns and seeding rates, integrated with cultivation intensity. Results showed that peanut seeded in wide rows (two rows, 91...

Broomrape weeds. Underground mechanisms of parasitism and associated strategies for their control: a review.

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Monica eFernandez-Aparicio

2016-02-01

Full Text Available Broomrapes are plant-parasitic weeds which constitute one of the most difficult-to-control of all biotic constraints that affect crops in Mediterranean, central and eastern Europe, and Asia. Due to their physical and metabolic overlap with the crop, their underground parasitism, their achlorophyllous nature, and hardly destructible seed bank, broomrape weeds are usually not controlled by management strategies designed for non-parasitic weeds. Instead, broomrape are in a current state of intensification and spread due to lack of broomrape-specific control programs, unconscious introduction to new areas and may be decline of herbicide use and global warming to a lesser degree. We reviewed relevant facts about the biology and physiology of broomrape weeds and the major feasible control strategies. The points of vulnerability of some underground events, key for their parasitism such as crop-induced germination or haustorial development are reviewed as inhibition targets of the broomrape-crop association. Among the reviewed strategies are those aimed 1 to reduce broomrape seed bank viability, such as fumigation, herbigation, solarization and use of broomrape-specific pathogens; 2 diversion strategies to reduce the broomrape ability to timely detect the host such as those based on promotion of suicidal germination, on introduction of allelochemical interference, or on down-regulating host exudation of germination-inducing factors; 3 strategies to inhibit the capacity of the broomrape seedling to penetrate the crop and connect with the vascular system, such as biotic or abiotic inhibition of broomrape radicle growth, crop resistance to broomrape penetration either natural, genetically engineered or elicited by biotic- or abiotic-resistance-inducing agents and 4 strategies acting once broomrape seedling has bridged its vascular system with that of the host, aimed to impede or to endure the parasitic sink such as those based on the delivery of herbicides

Broomrape Weeds. Underground Mechanisms of Parasitism and Associated Strategies for their Control: A Review

Science.gov (United States)

Fernández-Aparicio, Mónica; Reboud, Xavier; Gibot-Leclerc, Stephanie

2016-01-01

Broomrapes are plant-parasitic weeds which constitute one of the most difficult-to-control of all biotic constraints that affect crops in Mediterranean, central and eastern Europe, and Asia. Due to their physical and metabolic overlap with the crop, their underground parasitism, their achlorophyllous nature, and hardly destructible seed bank, broomrape weeds are usually not controlled by management strategies designed for non-parasitic weeds. Instead, broomrapes are in current state of intensification and spread due to lack of broomrape-specific control programs, unconscious introduction to new areas and may be decline of herbicide use and global warming to a lesser degree. We reviewed relevant facts about the biology and physiology of broomrape weeds and the major feasible control strategies. The points of vulnerability of some underground events, key for their parasitism such as crop-induced germination or haustorial development are reviewed as inhibition targets of the broomrape-crop association. Among the reviewed strategies are those aimed (1) to reduce broomrape seed bank viability, such as fumigation, herbigation, solarization and use of broomrape-specific pathogens; (2) diversion strategies to reduce the broomrape ability to timely detect the host such as those based on promotion of suicidal germination, on introduction of allelochemical interference, or on down-regulating host exudation of germination-inducing factors; (3) strategies to inhibit the capacity of the broomrape seedling to penetrate the crop and connect with the vascular system, such as biotic or abiotic inhibition of broomrape radicle growth and crop resistance to broomrape penetration either natural, genetically engineered or elicited by biotic- or abiotic-resistance-inducing agents; and (4) strategies acting once broomrape seedling has bridged its vascular system with that of the host, aimed to impede or to endure the parasitic sink such as those based on the delivery of herbicides via

Temporal patterns of genetic variation across a 9-year-old aerial seed bank of the shrub Banksia hookeriana (Proteaceae).

Science.gov (United States)

Barrett, Luke G; He, Tianhua; Lamont, Byron B; Krauss, Siegfried L

2005-11-01

The pattern of accumulation of genetic variation over time in seed banks is poorly understood. We examined the genetic structure of the aerial seed bank of Banksia hookeriana within a single 15-year-old population in fire-prone southwestern Australia, and compared genetic variation between adults and each year of a 9-year-old seed bank using amplified fragment length polymorphism (AFLP). B. hookeriana is well suited to the study of seed bank dynamics due to the canopy storage of its seeds, and because each annual crop can be identified. A total of 304 seeds from nine crop years and five maternal plants were genotyped, along with 113 plants from the adult population. Genetic variation, as assessed by the proportion of polymorphic markers (P(p)) and Shannon's index (I), increased slightly within the seed bank over time, while gene diversity (H(j)), did not change. P(p), I, and H(j) all indicated that genetic variation within the seed bank quickly approached the maximal level detected. Analysis of molecular variance revealed that less than 4% of variation could be accounted for by variation among seeds produced in different years, whereas there was greater differentiation among maternal plants (12.7%), and among individual seeds produced by different maternal plants (83.4%). With increasing population age, offspring generated each year were slightly more outbred, as indicated by an increase in the mean number of nonmaternal markers per offspring. There were no significant differences for H(j) or I between adults and the seed bank. Viability of seeds decreased with age, such that the viability of 9-year-old seeds was half that of 2-year-old seeds. These results suggest that variable fire frequencies have only limited potential to influence the amount of genetic variation stored within the seed bank of B. hookeriana.

Evaluating the Competitive Ability of Different Common Bean Genotypes Against The Weeds

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R Amini

2014-12-01

Full Text Available In order to investigate the effects of weeds interference on yield and yield components of different genotypes of common bean, an experiment was conducted as split plot based on randomized complete block design with three replications at Agricultural Research Station of Tabriz University, in 2011. The main plots were eight genotypes of different types of common bean including red bean, (cv. Gholi, Sayad, Derakhshan and Akhtar; pinto bean, (cv. Khomein and Sadri and white bean (cv. Shokufa and Pak and the sub-plots were two levels of weed including weed-free and weed-infested. Results indicated that the effect of bean genotype was significant on yield and yield components. The effect of weed treatment was significant on all traits of common bean, except 100-seeds weight. The pod number per plant of all common bean genotypes reduced significantly under weed-infested treatment. The interaction effect of weed treatment× genotype was significant on bean seed number per pod, grain and biological yield. Among the genotype, the cv. Gholi had the highest pod number per plant and the cultivars Gholi and Shokufa had the highest seed number per pod. The cultivars of Gholi and Khomein produced the highest and lowest seed yield, respectively in both weed-free and weed-infested treatment. The common bean genotype showed different competitive ability as the genotypes Gholi and Pak had the higher competitive ability against the weeds than other genotypes. Therefore by cultivating the bean genotypes with high competitive ability against the weeds, the yield loss of common bean could be reduced as well as the growth of weed species will be suppressed.

Germination and Seed Bank Studies of Macbridea alba (Lamiaceae), a Federally Theatened Plant

Science.gov (United States)

Dana Madsen Schulze; John L. Walker; Timothy P. Spira

2002-01-01

Macbridea alba (Lamiaceae) is a Federally threatened plant endemic to Florida. Seedlings are rarely observed in natural populations, but seed production has been documented. We assessed the germinability of dry-stored seeds and of experimentally buried seeds, and sampled soil to detect a persistent seed bank.More than 20% of recorded seeds...

Disentangling the role of seed bank and dispersal in plant metapopulation dynamics using patch occupancy surveys.

Science.gov (United States)

Manna, F; Pradel, R; Choquet, R; Fréville, H; Cheptou, P-O

2017-10-01

In plants, the presence of a seed bank challenges the application of classical metapopulation models to aboveground presence surveys; ignoring seed bank leads to overestimated extinction and colonization rates. In this article, we explore the possibility to detect seed bank using hidden Markov models in the analysis of aboveground patch occupancy surveys of an annual plant with limited dispersal. Patch occupancy data were generated by simulation under two metapopulation sizes (N = 200 and N = 1,000 patches) and different metapopulation scenarios, each scenario being a combination of the presence/absence of a 1-yr seed bank and the presence/absence of limited dispersal in a circular 1-dimension configuration of patches. In addition, because local conditions often vary among patches in natural metapopulations, we simulated patch occupancy data with heterogeneous germination rate and patch disturbance. Seed bank is not observable from aboveground patch occupancy surveys, hence hidden Markov models were designed to account for uncertainty in patch occupancy. We explored their ability to retrieve the correct scenario. For 10 yr surveys and metapopulation sizes of N = 200 or 1,000 patches, the correct metapopulation scenario was detected at a rate close to 100%, whatever the underlying scenario considered. For smaller, more realistic, survey duration, the length for a reliable detection of the correct scenario depends on the metapopulation size: 3 yr for N = 1,000 and 6 yr for N = 200 are enough. Our method remained powerful to disentangle seed bank from dispersal in the presence of patch heterogeneity affecting either seed germination or patch extinction. Our work shows that seed bank and limited dispersal generate different signatures on aboveground patch occupancy surveys. Therefore, our method provides a powerful tool to infer metapopulation dynamics in a wide range of species with an undetectable life form. © 2017 by the Ecological Society of America.

Soil Seed Bank Responses to Postfire Herbicide and Native Seeding Treatments Designed to Control Bromus tectorum in a Pinyon–Juniper Woodland at Zion National Park, USA

Science.gov (United States)

Brooks, Matthew L.; Hondo Brisbin, graduate student; Andrea Thode, Associate Professor; Karen Weber, graduate student

2013-01-01

The continued threat of an invasive, annual brome (Bromus) species in the western United States has created the need for integrated approaches to postfire restoration. Additionally, the high germination rate, high seed production, and seed bank carryover of annual bromes points to the need to assay soil seed banks as part of monitoring programs. We sampled the soil seed bank to help assess the effectiveness of treatments utilizing the herbicide Plateau® (imazapic) and a perennial native seed mix to control annual Bromus species and enhance perennial native plant establishment following a wildfire in Zion National Park, Utah. This study is one of few that have monitored the effects of imazapic and native seeding on a soil seed bank community and the only one that we know of that has done so in a pinyon–juniper woodland. The study made use of untreated, replicated controls, which is not common for seed bank studies. One year posttreatment, Bromus was significantly reduced in plots sprayed with herbicide. By the second year posttreatment, the effects of imazapic were less evident and convergence with the controls was evident. Emergence of seeded species was low for the duration of the study. Dry conditions and possible interactions with imazapic probably contributed to the lack of emergence of seeded native species. The perennial grass sand dropseed outperformed the other species included in the seed mix. We also examined how the treatments affected the soil seed bank community as a whole. We found evidence that the herbicide was reducing several native annual forbs and one nonnative annual forb. However, overall effects on the community were not significant. The results of our study were similar to what others have found in that imazapic is effective in providing a short-term reduction in Bromus density, although it can impact emergence of nontarget species.

Seasonal variation in soil seed bank size and species composition of selected habitat types in Maputaland, South Africa

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M. J. S. Kellerman

2007-08-01

Full Text Available Seasonal variation in seed bank size and species composition of five selected habitat types within the Tembe Elephant Park. South Africa, was investigated. At three-month intervals, soil samples were randomly collected from five different habitat types: a, Licuati forest; b, Licuati thicket; c, a bare or sparsely vegetated zone surrounding the forest edge, referred to as the forest/grassland ecotone; d, grassland; and e, open woodland. Most species in the seed bank flora were either grasses, sedges, or forbs, with hardly any evidence of woody species. The Licuati forest and thicket soils produced the lowest seed densities in all seasons.  Licuati forest and grassland seed banks showed a two-fold seasonal variation in size, those of the Licuati thicket and woodland a three-fold variation in size, whereas the forest/grassland ecotone maintained a relatively large seed bank all year round. The woodland seed bank had the highest species richness, whereas the Licuati forest and thicket soils were poor in species. Generally, it was found that the greatest correspondence in species composition was between the Licuati forest and thicket, as well as the forest/grassland ecotone and grassland seed bank floras.

Effects of amount and timing of nitrogen application and weed density on wild mustard (Sinapis arvensis seed production in winter wheat

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mehdi rastgoo

2009-06-01

Full Text Available In order to study the effects of amount and timing of nitrogen application and weed density on wild mustard (Sinapis arvensis seed production in winter wheat, an experiment was conducted in 2001 at Research station of college of agriculture, Ferdowsi University of Mashhad. A Split plot design with three replications were used with factorial combination of weed density (0, 8, 16, and 32 plant/m2 and nitrogen (low=100, optimum= 150, and high= 225 Kg/ha as main plots.The sub plot factor included nitrogen splitting pattern (P1=1/3 at planting time+2/3 at tillering, P2= 1/3 at planting time + 1/3 at tillering + 1/3 at shooting. According to the results, wild mustard seed production increased with increasing wild mustard density and nitrogen rates, due to high wild mustard biomass production. Seed production of wild mustard was 161, 311, and 488 million/ha in low, optimum and high nitrogen rates, respectively. In the other hand, density and nitrogen rates had a significant effect on wild mustard fecundity. However, nitrogen splitting pattern showed no significant effect on wild mustard seed production.

Effect of Cultural Practices in Night on Weed Density and Weed Dry Matter

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M.H Rashed Mohasel

2011-01-01

Full Text Available Abstract In order to evaluate the response of weed seeds to light, two experiments, at two different locations were conducted at Ferdowsi university of Mashhad in 2009. At the first experiment, field was ploughed in day and night. Weed density was evaluated 70 d after plough, with 1×1 quadrate. At the second experiment, at night treatment, ploughing, potato planting and weeding with cultivator were done at night. Weed sampling was done twice at 43 and 130 days after planting with 1×1 quadrate and weeds were identified and counted. Result showed pigweed (Amaranthus retroflexus L., sowthistle (Sonchus oleraceus L., crabgrass (Digitaria sanguinalis (L. scop, jimsonweed (Datura stramonium L. and mallow (Hibiscus trionum L. did not observed at night plough, in contrast, night plough has no significance influence on common lambsquarters (Chenopodium album L., and black nightshade (Solanum nigrum L.. Only common lambsquarters had similar appearance in two treatments, indicating insusceptibility of this weed to time of plough. Interestingly, at the second experiment, result was very similar. Potato yield was higher at night treatment, but not significant. This research showed that some cultural practice like plough, planting and weeding with cultivator in night can reduce weed density and weed dry matter. Keywords: Germination, Time of plough, Sustainable weeds management, Light

Diversity in soil seed bank of Sinai and implications for conservation ...

African Journals Online (AJOL)

Understanding the diversity level of seed bank is important for designing conservation and restoration programs especially in arid ecosystems. A diverse of diversity indices has been used in evaluating seed communities regardless of its suitability to measure the ecological quality of the targeted biological community.

The long-term persistence of phytoplankton resting stages in aquatic "seed banks"

DEFF Research Database (Denmark)

Ellegaard, Marianne; Ribeiro, Sofia

2018-01-01

to terrestrial seed beds of vascular plants, but are much less studied. It is therefore timely to review the phenomenon of long-term persistence of aquatic resting stages in sediment seed banks. Herein we compare function, morphology and physiology of phytoplankton resting stages to factors central...... for persistence of terrestrial seeds. We review the types of resting stages found in different groups of phytoplankton and focus on the groups for which long-term (multi-decadal) persistence has been shown: dinoflagellates, diatoms, green algae and cyanobacteria. We discuss the metabolism of long-term dormancy......In the past decade, research on long-term persistence of phytoplankton resting stages has intensified. Simultaneously, insight into life-cycle variability in the diverse groups of phytoplankton has also increased. Aquatic 'seed banks' have tremendous significance and show many interesting parallels...

Sexual production in SE Asian seagrasses: the absence of a seed bank in Thalassia hemprichii (Bolinao, NW Philippines)

NARCIS (Netherlands)

Rollon, R.N.; Nacorda, H.M.E.; Vermaat, J.E.

2003-01-01

We report the absence of a persistent seed bank in Thalassia hemprichii in NW Philippine seagrass beds. The survival of buried seeds was assessed experimentally since such a capacity is a prerequisite for the formation of seed bank. We found a rapid germination of non-dormant seeds and development

Seed banks in a degraded desert shrubland: Influence of soil surface condition and harvester ant activity on seed abundance

Science.gov (United States)

DeFalco, L.A.; Esque, T.C.; Kane, J.M.; Nicklas, M.B.

2009-01-01

We compared seed banks between two contrasting anthropogenic surface disturbances (compacted, trenched) and adjacent undisturbed controls to determine whether site condition influences viable seed densities of perennial and annual Mojave Desert species. Viable seeds of perennials were rare in undisturbed areas (3-4 seeds/m2) and declined to importance of litter as an indicator of site degradation and recovery potential in arid lands.

Phytotoxic Effects of Nepeta meyeri Benth. Extracts and Essential Oil on Seed Germinations and Seedling Growths of Four Weed Species

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Saban Kordali

2015-05-01

Full Text Available Essential oil isolated from the aerial parts of Nepeta meyeri Benth. by hydrodistilation was analysed by GC and GC-MS methods. A total 18 components were identified in the oil representing 100.0% of the oil. Main components were 4aα,7α,7aβ-nepetalactone (80.3%, 4aα,7α,7aα–nepetalactone (10.3%, trans-pulegol (3.1%, 1, 8-cineole (3.0% and β-bourbonene (2.0%. In addition, n-hexane extract of N. meyeri was analysed by using GC and GC-MS methods and 18 components were identified. Likewise, nepetalactones, 4aα,7α,7aβ-nepetalactone (83.7%, 4aα,7α,7aα–nepetalactone (3.6%, 1, 8-cineole (1.9% and α-terpinene (1.5% were the predominat compounds in the hexane extract. Three concentrations (0.5, 1.0 and 2.0 mg/mL of the essential oil and n-hexane, chloroform, acetone and methanol extracts isolated from the aerial partsand roots were tested for the herbicidal effects on the germination of the seeds of four weed species including Amaranthus retroflexus L., Chenopodium album L., Cirsium arvense L. and Sinapsis arvensis L. The essential oil of N. meyeri completely inhibited the germination of all weed seeds whereas the extracts showed various inhibition effects on the germination of the weed species. Herbicidal effect was increased with the increasing application concentrations of the extracts. In general, the acetone extract was found to be more effective as compared to the other extracts. All extracts also exhibited various inhibition effects on the seedling growths of the weed species. All extracts also tested for their phytotoxic effects on the weeds at greenhouse condition and the results showed that the oil and extracts caused mortality with 22.00-66.00% 48h after the treatments. These findings suggest that the essential oil and the extracts of N. meyeri have potentials for use as herbicides against those weed species.

Seed bank and established vegetation in the last remnants of the Mexican Central Plateau wetlands: the Lerma marshes.

Science.gov (United States)

Zepeda, Carmen; Lot, Antonio; Nemiga, Xanat Antonio; Manjarrez, Javier

2014-06-01

Seed banks play a central role in vegetation dynamics of many wetlands. Therefore, knowledge of seed reservoirs in the soils of aquatic communities should provide useful tools for conservation and restoration efforts. This study was conducted in the Lerma marshes, one of the last remnants of the vast wetlands that were once in the Mexican Central Plateau. The main objective was to determine the composition and abundance of seed bank and its relationship with established vegetation of the three Lerma marshes. In each marsh, we systematically selected 18 to 40 sampling sites. In each site, the composition of vascular plant vegetation was evaluated in two 10m lines perpendicular to the shore. Every 0.5m, we determined the coverage of species by measuring the intercepted length for each plant or group of plants. At each sampling site where we had evaluated the established vegetation, we collected a sample of the top 10cm of sediment; the soil cores were divided into an upper layer (0-5cm) and a lower layer (5-10cm). These samples were used to evaluate the seed bank by the seedling emergence method. All samples were placed in a greenhouse at 20-25 degrees C and remained flooded for 15 weeks. Forty-nine species were recorded in the vegetation. Chiconahuapan had the richest and most diverse flora and the greatest number of perennial species. A life-forms analysis showed that perennial herbs, especially rooted-emergent hydrophytes, dominated in the three wetlands. Sixty-one species were identified in the total seed bank; Chimaliapan had the most diverse total seed bank, whereas the mean seedling density was higher in Chignahuapan. Only two species of the total seed bank of each marsh had a density greater than 10% of the total, and more than half were uncommon. The upper layer of sediment (0-5cm) contained two times more seeds/m2 and species per sample than the lower layer (5-10cm), and there was a significant decrease of seed density with depth. The detrended

Effect of Plant Density and Weed Interference on Yield and Yied Components of Grain Sorghum

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S. Sarani

2018-01-01

Full Text Available Introduction Weed control is an essential part of all crop production systems. Weeds reduce yields by competing with crops for water, nutrients, and sunlight. Weeds also directly reduce profits by hindering harvest operations, lowering crop quality, and producing chemicals which are harmful to crop plants. Plant density is an efficient management tool for maximizing grain yield by increasing the capture of solar radiation within the canopy, which can significantly affect development of crop-weed association. The response of yield and yield components to weed competition varies by crop and weeds species and weeds interference duration. The objective of the present study was to evaluate the effect of weed interference periods and plant density on the yield and yield components of sorghum. Materials and Methods In order to study the effect of plant density and weeds interference on weeds traits, yield and yield components of sorghum (Var. Saravan, an experiment was conducted as in factorial based on a randomized complete block design with three replications at the research field of Islamic Azad University, Birjand Branch in South Khorasan province during year of 2013. Experimental treatments consisted of three plant density (10, 20 and 30 plants m-2 and four weeds interference (weed free until end of growth season, interference until 6-8 leaf stage, interference until stage of panicle emergence, interference until end of growth season. Measuring traits included the panicle length, number of panicle per plant, number of panicle per m2, number of seed per panicle, 1000-seed weight, seed yield, biological yield, number and weight of weeds per m2. Weed sampling in each plot have done manually from a square meter and different weed species counted and oven dried at 72 °C for 48 hours. MSTAT-C statistical software used for data analysis and means compared with Duncan multiple range test at 5% probability level. Results and Discussion Results showed that

Mathematical modeling of seed bank dynamics in population genetics

OpenAIRE

Martin, Anna

2017-01-01

We study the genealogical structure of samples from a population for which any givengeneration is made up of direct descendants from one randomly chosen previousgeneration. These occur in nature when there are seed banks or egg banks allowingan individual to leave offspring several generations in the future. Kaj et al. studied in2001 the case where any given generation is made up of descendants from severalprevious generations and showed how this temporal structure in the reproductionmechanis...

Evolução do banco de sementes de arroz vermelho em diferentes sistemas de utilização do solo de várzeas Red rice seed bank evolution under different systems of lowland utilization

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Luis A. de Avila

2000-08-01

Full Text Available Num ecossistema agrícola, a redução do banco de sementes é um dos aspectos mais importantes no manejo de plantas daninhas; e em solos de várzeas, o arroz vermelho (Oryza sativa L. é atualmente considerado a principal planta daninha. Nesse sentido, conduziu-se um experimento com o objetivo de avaliar a evolução do banco de sementes de arroz vermelho no solo em diferentes sistemas de semeadura de arroz irrigado e em alternativas de manejo do solo de várzea. O experimento foi instalado em campo por dois anos consecutivos na mesma área (safras agrícolas 1996/97 e 1997/98 em Santa Maria, RS, em solo classificado como Planossolo, com infestação média de 516 sementes viáveis de arroz vermelho/m². A estimativa do banco de sementes de arroz vermelho foi realizada através de 10 coletas de solo, utilizando um cilindro com 0,10m de diâmetro a 0,10m de profundidade. Após a coleta, os grãos foram separados do solo e realizado teste de tetrazólio para determinar a quantidade de sementes viáveis na amostra. As coletas foram realizadas antes da instalação do experimento (set/1996, após a colheita do primeiro ano (mai/1997 e após a colheita do segundo ano (mai/1998. Os resultados mostraram que o cultivo do arroz no sistema convencional promove aumento no banco de sementes de arroz vermelho, enquanto que a semeadura de arroz em solo inundado (mix de pré-germinado, prégerminado ou transplante de mudas é tão eficiente na redução do banco de sementes de arroz vermelho quanto a rotação com o sorgo, o pousio do solo sem a presença de animais e também o preparo de verão.In an agricultural ecosystem, the redution of weed seed bank is of utmost importance. In lowland areas, red rice (Oryza sativa is the most important weed. Therefore, an experiment was conducted to evaluate the evolution of the red rice seed bank under different seeding systems and alternatives of soil management. The experiment was conducted during two years (1996

[Soil seed bank and its correlations with aboveground vegetation and environmental factors in water level fluctuating zone of Danjiangkou Reservoir, Central China].

Science.gov (United States)

Liu, Rui-Xue; Zhan, Juan; Shi, Zhi-Hua; Chen, Long-qing

2013-03-01

Taking the water level fluctuating zone of the Danjiangkou Reservoir as a case, and by the method of hierarchical cluster analysis, the soil seed banks at 37 sampling plots within the areas of 140-145 m elevation were divided into 6 groups, and the species composition, density, and diversity of the soil seed banks among the groups were compared. The differences between the soil seed banks and the aboveground vegetations were analyzed by S0rensen similarity coefficient, and the correlations among the soil seed banks, aboveground vegetations, and environmental factors were explored by principal component analysis (PCA) and multivariable regression analysis. At the same altitudes of the water level fluctuating zone, the species composition of the soil seed banks had obvious heterogeneity, and the density and diversity indices of the soil seed banks among different groups were great. The similarity coefficient between the soil seed banks and aboveground vegetations was low, and the species number in the soil seed banks was obviously lesser than that in the aboveground vegetations. The density of the soil seed banks was highly positively correlated with the aboveground vegetations coverage and species number and the soil texture, but highly negatively correlated with the soil water-holding capacity and soil porosity.

Seed loss and volunteer seedling establishment of rapeseed in the northernmost European conditions: potential for weed infestation and GM risks

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Pirjo Peltonen-Sainio

2014-11-01

Full Text Available Rapeseed soil seed bank development and volunteer plant establishment represent substantial risk for crop infestation and GM contamination. This study was designed to complement such investigations with novel understanding from high latitude conditions. Four experiments were designed to characterise seed loss at harvest, persistence, viability and capacity for volunteer seedling establishment, as well as impact of management measures on soil seed bank dynamics. Oilseed rape was the primary crop investigated due to the availability of GM cultivars and because of the increasing importance. Harvest losses and soil seed bank development were significant. Volunteer seedlings emerged at reasonably high rates, especially in the first autumn after harvest, but about 10% of buried seeds maintained their viability for at least three years. Soil incorporation methods had no major effect on numbers of volunteer seedlings, but herbicide treatments controlled volunteer seedlings efficiently, though not completely, due to irregular timing of seedling emergence.

Effect of straw mulch residues of previous crop oats on the weed population in direct seeded faba bean in Organic Farming

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Massucati, Luiz Felipe Perrone

2014-02-01

Full Text Available Under conditions of Organic Farming, we investigated whether direct seeding of faba bean (Vicia faba L. into straw mulch from residues of precrop oats used for weed control enables at least occasional/opportunistic direct seeding in Organic Agriculture. Eight field trials were carried out at different study sites in North Rhine-Westphalia, Germany, in 2008-2009 and 2009-2010. Direct seeding (DS was performed into mulch layers of 0,4 and 6 t ha-1 of straw residues applied to the remaining stubble, simulating different yield levels of the precrop oats. LBS was used as a reference treatment, where straw was harvested, stubble tillage performed and seedbed prepared in fall and oil radish (Raphanus sativus grown as winter cover crop. Mouldboard ploughing combined with conventional seedbed preparation was performed in early spring to V. faba. Compared with LBS, straw mulch with subsequent direct seeding suppressed especially dicotyledonous annuals significantly. DS treatments with straw reduced the abundance of this group by 81 and 85% compared with LBS. Straw mulch resulted in effective suppression of photosensitive weeds such as Matricaria spp. and late germinating Chenopodium album. Grasses and perennial species occurred independent of the amount of straw. Compared with DS, the abundance of these weeds was reduced by 64 and 82% in LBS treatment. The shoot dry matter production of faba bean was retarded by DS compared with LBS, but significant yield losses could be avoided with straw residues of at least 4 t ha-1. Sufficient amount of straw of from the previous crop is a key criterion to facilitate organic no-till farming of faba bean in a suitable crop sequence when pressure of perennials and grasses is low.

Germination and soil seed bank traits of Podocarpus angustifolius (Podocarpaceae): an endemic tree species from Cuban rain forests.

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Ferrandis, Pablo; Bonilla, Marta; Osorio, Licet del Carmen

2011-09-01

Podocarpus angustifolius is an endangered recalcitrant-seeded small tree, endemic to mountain rain forests in the central and Pinar del Río regions in Cuba. In this study, the germination patterns of P. angustifolius seeds were evaluated and the nature of the soil seed bank was determined. Using a weighted two-factor design, we analyzed the combined germination response to seed source (i.e. freshly matured seeds directly collected from trees versus seeds extracted from soil samples) and pretreatment (i.e. seed water-immersion for 48h at room temperature). Germination was delayed for four weeks (= 30 days) in all cases, regardless of both factors analyzed. Moreover, nine additional days were necessary to achieve high germination values (in the case of fresh, pretreated seeds). These results overall may indicate the existence of a non-deep simple morphophysiological dormancy in P. angustifolius seeds. The water-immersion significantly enhanced seed germination, probably as a result of the hydration of recalcitrant seeds. Although germination of seeds extracted from soil samples was low, probably due to aging and pathogen effects throughout the time of burial, the study revealed the existence of a persistent soil seed bank (at least short-termed) of approximately 42 viable seeds per m2 in the upper 10cm of soil. Such a record is noteworthy since references to persistent soil seed banks in recalcitrant-seeded species are scarce in the literature. The population consequences derived from the formation of persistent soil seed banks in this endangered species are discussed.

Weed clearance in Hudiara Nallah by chemical weed control

International Nuclear Information System (INIS)

Dhillon, G.S.

1981-01-01

Hudiara Nallah is a flood stream in West Punjab. It has a length of about 45km and breadth of nearly 25 metres. About 20 subsidiary drains join with the Nallah. These drains have a length of about 270km. The Nallah has a discharge capacity of 1248 cusecs. Most of the subsidiary drains start from ponds which are generally infected with Eichhornia plants. These plants enter into the subsidiary drains and finally into Hudiara Nallah. The plants float freely on the surface of water and multiply at a high rate. One plant of the weed propagates to 24 plants in a period of one month. The plants thus cover the whole drain in a few months. The weed also originates from seeds. Their heavy growth forms a mat-like surface. The weeds also choke bridges and sometimes cause damage to their structures. These obstruct the flow of water and decrease the carrying capacity of the drain. Their infestation thus causes floods and the very purpose of the drains gets lost. Thus the Nallah is heavily infested with Eichhornia crassipes (water hyacinth weed). Due to its fast propagation and heavy infestation it was not possible to clear the weed manually. The problem was, therefore, referred to the Chemistry Division of the Irrigation and Power Research Institute, Amritsar, by the Drainage Circle of the Irrigation Department in June 1978 when weed propagation was in full swing. A chemical treatment method of eradication was attempted

Relationship between seed bank expression, adult longevity and aridity in species of Chaetanthera (Asteraceae) in central Chile.

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Arroyo, M T K; Chacon, P; Cavieres, L A

2006-09-01

Broad surveys have detected inverse relationships between seed and adult longevity and between seed size and adult longevity. However, low and unpredictable precipitation is also associated with seed bank (SB) expression in semi-arid and arid areas. The relationship between adult longevity, SB formation, seed mass and aridity is examined in annual and perennial herbs of Chaetanthera (Asteraceae) from the Chilean Mediterranean-type climate and winter-rainfall desert areas over a precipitation range of one order of magnitude. Seeds of 18 species and subtaxa (32 populations) were buried in field locations, and exhumed after two successive germination periods. Seeds not germinating in the field were tested in a growth chamber, and remnant intact seed tested for viability. Seed banks were classed as transient or persistent. The effect of life form, species, population and burial time on persistent SB size was assessed with factorial ANOVA. Persistent seed bank size was compared with the Martonne aridity index (shown to be a surrogate for inter-annual variation in precipitation) and seed size using linear regression. ANCOVA assessed the effect of life-form on SB size with aridity as covariate. Three species had a transient SB and 15 a persistent SB. ANOVA revealed a significant effect of life-form on SB size with annuals having larger SB size and greater capacity to form a persistent SB than perennials. Significant inter-population variation in SB size was found in 64% of cases. Seed mass was negatively correlated with persistent SB size. Persistent seed bank size was significantly correlated with the Martonne aridity index in the perennial and annual species, with species from more arid areas having larger persistent SBs. However, when aridity was considered as a covariate, ANCOVA revealed no significant differences between the annual and perennial herbs. Persistent seed bank size in Chaetanthera appears to reflect environmental selection rather than any trade-off with

Germination and soil seed bank traits of Podocarpus angustifolius (Podocarpaceae: an endemic tree species from Cuban rain forests

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Pablo Ferrandis

2011-09-01

Full Text Available Podocarpus angustifolius is an endangered recalcitrant-seeded small tree, endemic to mountain rain forests in the central and Pinar del Río regions in Cuba. In this study, the germination patterns of P. angustifolius seeds were evaluated and the nature of the soil seed bank was determined. Using a weighted two-factor design, we analyzed the combined germination response to seed source (i.e. freshly matured seeds directly collected from trees versus seeds extracted from soil samples and pretreatment (i.e. seed water-immersion for 48h at room temperature. Germination was delayed for four weeks (≈30 days in all cases, regardless of both factors analyzed. Moreover, nine additional days were necessary to achieve high germination values (in the case of fresh, pretreated seeds. These results overall may indicate the existence of a non-deep simple morphophysiological dormancy in P. angustifolius seeds. The water-immersion significantly enhanced seed germination, probably as a result of the hydration of recalcitrant seeds. Although germination of seeds extracted from soil samples was low, probably due to aging and pathogen effects throughout the time of burial, the study revealed the existence of a persistent soil seed bank (at least short-termed of ≈42 viable seeds per m² in the upper 10cm of soil. Such a record is noteworthy since references to persistent soil seed banks in recalcitrant-seeded species are scarce in the literature. The population consequences derived from the formation of persistent soil seed banks in this endangered species are discussed. Rev. Biol. Trop. 59 (3: 1061-1069. Epub 2011 September 01.

Stimulating a Great Lakes coastal wetland seed bank using portable cofferdams: implications for habitat rehabilitation

Science.gov (United States)

Kowalski, K.P.; Wilcox, D.A.; Wiley, M.J.

2009-01-01

Coastal wetland seed banks exposed by low lake levels or through management actions fuel the reestablishment of emergent plant assemblages (i.e., wetland habitat) critical to Great Lakes aquatic biota. This project explored the effectiveness of using portable, water-filled cofferdams as a management tool to promote the natural growth of emergent vegetation from the seed bank in a Lake Erie coastal wetland. A series of dams stretching approximately 450??m was installed temporarily to isolate hydrologically a 10-ha corner of the Crane Creek wetland complex from Lake Erie. The test area was dewatered in 2004 to mimic a low-water year, and vegetation sampling characterized the wetland seed bank response at low, middle, and high elevations in areas open to and protected from bird and mammal herbivory. The nearly two-month drawdown stimulated a rapid seed-bank-driven response by 45 plant taxa. Herbivory had little effect on plant species richness, regardless of the location along an elevation gradient. Inundation contributed to the replacement of immature emergent plant species with submersed aquatic species after the dams failed and were removed prematurely. This study revealed a number of important issues that must be considered for effective long-term implementation of portable cofferdam technology to stimulate wetland seed banks, including duration of dewatering, product size, source of clean water, replacement of damaged dams, and regular maintenance. This technology is a potentially important tool in the arsenal used by resource managers seeking to rehabilitate the functions and values of Great Lakes coastal wetland habitats.

Analysis of seed quality in NS sunflower hybrid seed processed between 2010 and 2014

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Jokić Goran

2015-01-01

Full Text Available This paper analyzed the processed seed of five sunflower hybrid seed developed at the Institute of Field and Vegetable Crops in Novi Sad. The cultivars were Rimi PR, Duško, NS Dukat, Sumo 1 PR and Sremac. The analysis was conducted on seed lots processed between 2010 and 2014 and involved the following parameters: seed purity percentage, 1000-seed weight, germination energy, germination, seed moisture, number of weed seeds per 1000 grams of seed. The results of the study produced the following average values: seed purity - 99.72%, 1000-seed weight - 67.59g, germination energy - 88.2%, germination - 91.8%, seed moisture - 8.3%. There were not found weeds seeds as well as pathogens on the seed samples, these values are all within the legally prescribed limits.

[Viability of 7 kinds of medicinal plant seeds stored in medium-term gene bank of the National Medicinal Plant Gene Bank].

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Jin, Yue; Yang, Cheng-Min; Wei, Jian-He

2016-05-01

In order to evaluate seed viability of Platycodon grandiflorum, Schizonepeta tenuifolia, Andrographis paniculat, Codonopsis pilosula, Scutellaria baicalensis, Leonurus japonicus, Rabdosia rubescens, stored in the medium-term gene bank of the National Medicinal Plant Gene Bank for 4 years, we tested seed germination rate of 7 species of medicinal plant and analyzed the change of significance of levels of the germination rate in pre and post store. Seed germination rates of 7 species of medicinal plants were all decreased after 4 years, and the decrease of S. tenuifolia and S. baicalensis germination rates were much smaller than other species. The higher initial germination rate of P. grandiflorum, C. pilosula, R. rubescens seed has the smaller decline of germination rate, but the data of A. paniculata showed the opposite trend. The rate decline of the germination of S. tenuifolia and S. baicalensis was roughly the same in different germination rate interval. The results showed that low temperature storage could effectively prolong the seed longevity, and maintain the seed vigor. Moreover, it is necessary to study on the storage characteristics of the main medicinal plant seeds, and establish the monitoring plan and regeneration standard. Copyright© by the Chinese Pharmaceutical Association.

Effect of sunn hemp (Crotalaria juncea L.) cutting date and planting density on weed suppression in Georgia, USA.

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Morris, J Bradley; Chase, Carlene; Treadwell, Danielle; Koenig, Rosie; Cho, Alyssa; Morales-Payan, Jose Pable; Murphy, Tim; Antonious, George F

2015-01-01

A field study was conducted in 2008 and 2009 at the USDA, ARS, Plant Genetic Resources Conservation Unit in Griffin, GA, to investigate weed suppression by sunn hemp (Crotalaria juncea L). The objectives were to (1) evaluate the effects of apical meristem removal (AMR) at three dates [5, 6, and 7 wks after planting (WAP) on May 14, 2008 and May 21, 2009] and (2) assess the impact of seeding rates (11, 28, and 45 kg ha(-1)) on weed biomass reduction. Weed species were identified at 4, 8, and 12 wks after sunn hemp planting. Sunn hemp cutting date had no significant effect on weed suppression in 2008 but significant differences for grass weeds at 4, 8, and 12 WAP and for yellow nutsedge at 8 and 12 WAP did occur when compared to the control in 2009. In comparison to the sunn hemp-free control plot in 2009, all three seeding rates had reduced grass weed dry weights at 4, 8, and 12 WAP. The total mass of yellow nutsedge when grown with sunn hemp was reduced compared to the total mass of yellow nutsedge grown in the weedy check for all seeding rates at 8 and 12 WAP. Lower grass weed biomass was observed by 12 WAP for cutting dates and seeding rates during 2008 and 2009. Sunn hemp cutting date and seeding rate reduced branch numbers in both years. The reduction in sunn hemp seeding rates revealed a decrease in weed populations.

Seasonal dynamics of the plant community and soil seed bank along a successional gradient in a subalpine meadow on the Tibetan Plateau.

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Miaojun Ma

Full Text Available BACKGROUND: Knowledge about how change the importance of soil seed bank and relationship between seed mass and abundance during vegetation succession is crucial for understanding vegetation dynamics. Many studies have been conducted, but their ecological mechanisms of community assembly are not fully understood. METHODOLOGY: We examined the seasonal dynamics of the vegetation and soil seed bank as well as seed size distribution along a successional gradient. We also explored the potential role of the soil seed bank in plant community regeneration, the relationship between seed mass and species abundance, and the relative importance of deterministic and stochastic processes along a successional gradient. PRINCIPAL FINDINGS: Species richness of seed bank increased (shallow layer and the total and seed density decreased (each layer and the total significantly with succession. Species richness and seed density differed significantly between different seasons and among soil depths. Seed mass showed a significant negative relationship with relative abundance in the earliest successional stage, but the relationships were not significant in later stages. Seed mass showed no relationship with relative abundance in the whole successional series in seed bank. Results were similar for both July 2005 and April 2006. CONCLUSIONS: The seed mass and abundance relationship was determined by a complex interaction between small and larger seeded species and environmental factors. Both stochastic processes and deterministic processes were important determinants of the structure of the earliest stage. The importance of seed bank decreased with succession. The restoration of abandoned farmed and grazed meadows to the species-rich subalpine meadow in Tibetan Plateau can be successfully achieved from the soil seed bank. However, at least 20 years are required to fully restore an abandoned agricultural meadow to a natural mature subalpine meadow.

Bet hedging via seed banking in desert evening primroses (Oenothera, Onagraceae): demographic evidence from natural populations.

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Evans, Margaret E K; Ferrière, Régis; Kane, Michael J; Venable, D Lawrence

2007-02-01

Bet hedging is one solution to the problem of an unpredictably variable environment: fitness in the average environment is sacrificed in favor of lower variation in fitness if this leads to higher long-run stochastic mean fitness. While bet hedging is an important concept in evolutionary ecology, empirical evidence that it occurs is scant. Here we evaluate whether bet hedging occurs via seed banking in natural populations of two species of desert evening primroses (Oenothera, Onagraceae), one annual and one perennial. Four years of data on plants and 3 years of data on seeds yielded two transitions for the entire life cycle. One year was exceptionally dry, leading to reproductive failure in the sample areas, and the other was above average in precipitation, leading to reproductive success in four of five populations. Stochastic simulations of population growth revealed patterns indicative of bet hedging via seed banking, particularly in the annual populations: variance in fitness and fitness in the average environment were lower with seed banking than without, whereas long-run stochastic mean fitness was higher with seed banking than without across a wide range of probabilities of the wet year. This represents a novel, unusually rigorous demonstration of bet hedging from field data.

Effects of nitrogen application method and weed control on corn yield and yield components.

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Sepahvand, Pariya; Sajedi, Nurali; Mousavi, Seyed Karim; Ghiasvand, Mohsen

2014-04-01

The effects of nitrogen fertilizer application and different methods for weed control on yield and yield components of corn was evaluated in Khorramabad in 2011. The experiment was conducted as a split plot based on randomized complete block design in 3 replications. Nitrogen application was as main plot in 4 levels (no nitrogen, broadcasting nitrogen, banding nitrogen and sprayed nitrogen) and methods of weed control were in 4 levels (non-control weeds, application Equip herbicide, once hand control of weeds and application Equip herbicide+once time weeding) was as subplots. Result illustrated that effects of nitrogen fertilizer application were significant on grain and forage yield, 100 seeds weight, harvest index, grain number per row and cob weight per plant. Grain yield increased by 91.4 and 3.9% in application banding and broadcasting for nitrogen fertilizer, respectively, compared to the no fertilizer treatment. The results show improved efficiency of nitrogen utilization by banding application. Grain yield, harvest index, seed rows per cob, seeds per row and cob weight were increased by weed control. In the application of Equip herbicide+ hand weeding treatment corn grain yield was increased 126% in comparison to weedy control. It represents of the intense affects of weed competition with corn. The highest corn grain yield (6758 kg h(-1)) was related to the application banding of nitrogen fertilizer and Equip herbicide+once hand weeding.

The effects of Fusarium oxysporum on broomrape (Orobanche egyptiaca) seed germination.

Science.gov (United States)

Hasannejad, S; Zad, S Javad; Alizade, H Mohamad; Rahymian, H

2006-01-01

Broomrape (Orobanche aegyptiaca L.), one of the most important parasitic weeds in Iran, is a root parasitic plant that can attack several crops such as tobacco, sunflower, tomato and etc. Several methods were used for Orobanche control, however these methods are inefficient and very costly. Biological control is an additional recent tool for the control of parasitic weeds. In order to study of the fungus Fusarium oxysporum (biocontrol agent) effects on broomrape seed germination, two laboratory studies were conducted in Tehran University. In the first experiment, different concentration of GR60 (0, 1, 2 and 5 ppm) as stimulation factor for Orobanche seeds germination were experimented. Results showed that concentrations of GR60 had a significant effect on seed germination. The highest seed germination percent was obtained in 1 ppm. In the second experiment, the effect of Fusarium oxysporum was tested on O. aegyptiaca seeds germination. The fungus Fusarium oxysporum were isolated from infested and juvenile O. aegyptiaca ower stalks in tomato field in karaj. Fungus spores suspension in different concentrations (0 (Control), 10(5) (T1), 10(6) (T2), 10(7) (T3) and 3 x 10(7) (T4)) from potato dextrose agar (PDA) prepared and together with 1ppm of GR60 concentration were tested on O. aegyptiaca seeds. Results show that the highest inhibition of seed germination obtained in 10(5) spores/ml. With increasing of suspension concentrations, inhibition percent was reduced and mortality of seeds germ tube was increased. In this investigation, Fusarium oxysporum can be used to inhibit seed germination, stimulate the "suicidal germination" of seeds and reduce the Orobanche seed bank.

Upper limit for context-based crop classification in robotic weeding applications

DEFF Research Database (Denmark)

Midtiby, Henrik Skov; Åstrand, Björn; Jørgensen, Ole

2016-01-01

Knowledge of the precise position of crop plants is a prerequisite for effective mechanical weed control in robotic weeding application such as in crops like sugar beets which are sensitive to mechanical stress. Visual detection and recognition of crop plants based on their shapes has been...... described many times in the literature. In this paper the potential of using knowledge about the crop seed pattern is investigated based on simulated output from a perception system. The reliability of position–based crop plant detection is shown to depend on the weed density (ρ, measured in weed plants per...... square metre) and the crop plant pattern position uncertainty (σx and σy, measured in metres along and perpendicular to the crop row, respectively). The recognition reliability can be described with the positive predictive value (PPV), which is limited by the seeding pattern uncertainty and the weed...

Variability of the soil seed banks in the natural deciduous forest in the Białowieża National Park

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Małgorzata Jankowska-Błaszczuk

2014-01-01

Full Text Available Using the germination method, the species diversity, density of the soil seed bank and its relation to cover vegetation in a natural deciduous forest with primary and secondary tree stand were compared. It was found that the mean density and species composition of the soil seed bank in the forest with secondary tree stand that has spontaneously been overgrown over the last 90 years after clear-cutting does not differ from the soil seed bank derived from primeval forest (3167M-2 vs. 3827m-2. In both stands there were 46 species altogether and 36 were common and seed banks were dominated by herbs. The most abundant in this group were: Urtica dioica, Chrysosplenium alternifolium, Geranium robertianum, Oxalis acetosella. In both cases it was found that the species structure of the herb layer was similar to that of the seed bank in about 70%. The seed banks of species absent from the herb layer or present there only sporadically were much more abundant. The seedlings of these species constituted more than one third of all seedlings that emerged in the samples from the secondary tree stand and only 5% those from the primary one. The analysis of seed bank in heavily rooted places under primary and secondary tree stands showed that in places with a totally distroyed herb layer the density of the soil seed bank in primeval forest was three times lower than in places with fully developed herb layer structure (102.60±22.61 vs. 307.0±206.5 per sample. This difference under secondary tree stand turned out to be much lower (415.8±137.8 vs. 358.2±126.0 per sample.

The Effect of Different Treatments on Seed Dormancy Breaking of Weed Stalked Bur Grass Tragus racemosus (L. AlI.

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Gholam reza doraki

2017-01-01

Full Text Available Introduction: Stalked Bur Grass (Tragus racemosus L. is an angiosperm annual plant with C4 photosynthesis pathway and stolon. It grows in hot and dry summers. This plant spreaded throughout the world from hot regions of Africa. It is regularly seen in barren lands or in between the generations with sequential initial stages with light-texture soils. Seed dormancy is in fact a physiological phenomenon which is observed in the seeds of most crops, pasture plants, medicinal herbs and weeds. Dormancy allows the plant to guarantee its germination and survival for long years and to survive through adverse environmental conditions through its spatial and temporal spread. Materials and Methods: In order to evaluation dormancy break of Tragus racemosus L. seeds, an experiment was carried out based a Randomized Complete Block Design with four replications in research laboratory of Department of Agriculture, Birjand University during 2013. The initial experiments showed that the seeds of Stalked Bur Grass had initial dormancy and were unable to germinate at normal conditions, so that less than 5% of the seeds germinated. The studied treatments for breaking seeds dormancy included control (seeds disinfection by distilled water, wet chilling at 4°C for 1, 2, 3 and 4 weeds, treatment with H2SO4 at 97% for 20, 40, 60 and 80 seconds, treatment with KNO3 at 0.2, 0.4, 0.6 and 0.8% for 24 hours and treatment with Gibberellic acid (GA3 at 50, 100, 200 and 400 ppm. In this study, 25 seeds of Stalked Bur Grass were uniformly placed in petri dishes with the diameters of 9 cm on Watmann filter papers and were applied with 5 mL distilled water. The number of germinated seeds was counted on a daily basis for 21 days. In the end, germination percentage and rate was determined. Results and Discussion: The results revealed that the effect of all studied levels of all treatments were significant on germination percentage and rate. The highest germination percentage (76% was

Cruciferous weeds in oil seed rape – appearance and control

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Klingenhagen, Günter

2014-02-01

Full Text Available Different cruciferous weeds were drilled in autumn 2011 and 2012 in a field near Münster. Beside common species like hedge mustard (Sisymbrium officinale Scop., shepherd`s purse (Capsella bursa-pastoris, pennycress (Thlaspiarvense, tall hedge mustard (Sisymbrium loeselii and flixweed (Descurainia sophia, we tried to establish weeds that are not common on arable land in Germany until now. These were: Yellow rocket (Barbarea vulgaris, hoary cress (Lepidium draba and Turkish rocket (Bunias orientalis. In autumn 2011 emergence of the sown weeds was poor. In the second year of experiment we got good emergence of the named weeds excluding hoary cress (Lepidium draba. In autumn 2011 and 2012 different herbicidecombinations were applied across the stripes. The best results were achieved with Colzor Trio (clomazone + dimethachlor + napropamid which was applied in pre-emergence state, a spray sequence Butisan Gold (metazachlor + quinmerac + dimethenamid-P applied in pre-emergence followed by Salsa (ethametsulfuronmethyl + Trend (adjuvant in post-emergence and Clearfield-Vantiga (metazachlor + quinmerac + imazamox + Dash (adjuvant, also applied in post-emergence state of the weeds.

Behind the Public Face of Kew: Education and Conservation in the Millennium Seed Bank

Science.gov (United States)

McFarlane, Angela

2010-01-01

At its Wakehurst Place garden in West Sussex, the Royal Botanic Gardens, Kew, has established the UK home of one of the world's largest conservation projects, the Millennium Seed Bank (MSB) partnership, a global project to conserve biodiversity by collecting and preserving seeds. This article describes what the MSB partnership does, how seeds are…

The seasonal dormancy pattern and germination of Matricaria maritima subsp. inodora (L. Dostal seeds in hydrotime model terms

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Anna Bochenek

2011-01-01

Full Text Available Changes in hydrotime model parameters were determined in Matricaria maritima L. subsp. inodora seeds during burial in a field in order to describe the seasonal dormancy pattern. Seeds were exhumed at regular intervals over a year and incubated at different water potentials at 19°C. Germination time courses were analyzed to determine hydrotime population parameters. Values of ѱb(50, ѲH and σѱb varied each month. Mean base water potential values in seeds exhumed each month were related to precipitation over 20 days before their exhumation. Soil temperature could be a trend-controlling factor of this relationship. The seeds were in deep dormancy after remaining 80-90 days in soil below or above limit temperature 15°C. The application of the hydrotime model to describe and predict seasonal dormancy patterns of weed seed is promising, especially for species with a considerable diversification of life strategies and ecophysiological flexibility of diaspores. It could also suggest mechanisms of seasonal dormancy changes of seeds in natural conditions and provide a basis for their examination. One of advantages of the dormancy pattern description of weed seeds remaining in a soil bank by means of threshold models is its simplicity.

Combining a weed traits database with a population dynamics model predicts shifts in weed communities.

Science.gov (United States)

Storkey, J; Holst, N; Bøjer, O Q; Bigongiali, F; Bocci, G; Colbach, N; Dorner, Z; Riemens, M M; Sartorato, I; Sønderskov, M; Verschwele, A

2015-04-01

A functional approach to predicting shifts in weed floras in response to management or environmental change requires the combination of data on weed traits with analytical frameworks that capture the filtering effect of selection pressures on traits. A weed traits database (WTDB) was designed, populated and analysed, initially using data for 19 common European weeds, to begin to consolidate trait data in a single repository. The initial choice of traits was driven by the requirements of empirical models of weed population dynamics to identify correlations between traits and model parameters. These relationships were used to build a generic model, operating at the level of functional traits, to simulate the impact of increasing herbicide and fertiliser use on virtual weeds along gradients of seed weight and maximum height. The model generated 'fitness contours' (defined as population growth rates) within this trait space in different scenarios, onto which two sets of weed species, defined as common or declining in the UK, were mapped. The effect of increasing inputs on the weed flora was successfully simulated; 77% of common species were predicted to have stable or increasing populations under high fertiliser and herbicide use, in contrast with only 29% of the species that have declined. Future development of the WTDB will aim to increase the number of species covered, incorporate a wider range of traits and analyse intraspecific variability under contrasting management and environments.

Seed bank response to prescribed fire in the central Appalachians.

Science.gov (United States)

Thomas M. Schuler; Melissa Thomas Van-Gundy; Mary B. Adams; W. Mark. Ford

2010-01-01

Pre- and post-treatment seed-bank characteristics of woody species were compared after two prescribed fires in a mesic mixed-oak forest in the central Appalachians. Nineteen woody species were identified from soil samples. Mean species richness declined but evenness did not after prescribed burning. The...

Predicting Emergence of the Most Important Weed Species in Soybean (Glycine max L. under Different Management Operation

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R. Khakzad

2017-12-01

Full Text Available Introduction: Summer annual weeds typically germinate in spring and early summer, grow throughout the summer, and set seeds by fall. Summer annual weeds are a persistent problem in summer annual row crops, competing directly for water, light, and nutrients, causing yield losses in quantity and quality. Although agriculture is increasingly relying on modern technology, knowledge of the biological systems in which these technologies are used is still critical for implementation of management strategies. Biological information about weeds is valuable and necessary for developing management strategies to minimize their impact. Scouting fields for pest problems are essential in any cropping system and knowledge of the timing and sequence of weed species emergence could increase the effectiveness of weed scouting trips and subsequent management practices. The success of any annual plant is directly correlated to its time of seedling emergence because it determines the ability of a plant to compete with its neighbors, survive biotic and abiotic stresses, and reproduce. The period and pattern of emergence of the weed community depend on the species present in the seed bank and their interaction with the environment. Therefore, knowledge of the weed species present in the soil seed bank and when these species are most likely to emerge is important in planning effective weed control programs. Temperature has been reported to be the main environmental factor regulating germination and emergence of weed species. Scientists have developed TT models to predict the emergence of weed species based on a daily accumulation of heat units or growing degree days (GDD above a minimum base threshold value (Tbase. The predictive models for weed emergence based on the accumulation of TT appear to be accurate enough for projections of weed emergence time (Grundy 2003. Moreover, soil temperature data are easily accessible, making this type of model practical and useful to

Resilience of (seed bank) aerobic methanotrophs and methanotrophic activity to desiccation and heat stress.

NARCIS (Netherlands)

Ho, A.; Lueke, C.; Reim, A.; Frenzel, P.

2016-01-01

In seasonally changing environments, aerobic methanotrophs are exposed to elevated temperatures and drought. Prior exposure to adverse conditions (site history) may leave an imprint on the methanotrophic community composition in the form of a seed bank. While the significance of a microbial seed

Seed banks as a source of vegetation regeneration to support the recovery of degraded rivers: A comparison of river reaches of varying condition.

Science.gov (United States)

O'Donnell, Jessica; Fryirs, Kirstie A; Leishman, Michelle R

2016-01-15

Anthropogenic disturbance has contributed to widespread geomorphic adjustment and the degradation of many rivers. This research compares for river reaches of varying condition, the potential for seed banks to support geomorphic river recovery through vegetation regeneration. Seven river reaches in the lower Hunter catchment of south-eastern Australia were assessed as being in poor, moderate, or good condition, based on geomorphic and ecological indicators. Seed bank composition within the channel and floodplain (determined in a seedling emergence study) was compared to standing vegetation. Seed bank potential for supporting geomorphic recovery was assessed by measuring native species richness, and the abundance of different plant growth forms, with consideration of the roles played by different growth forms in geomorphic adjustment. The exotic seed bank was considered a limiting factor for achieving ecological restoration goals, and similarly analysed. Seed bank native species richness was comparable between the reaches, and regardless of condition, early successional and pioneer herbs, sedges, grasses and rushes dominated the seed bank. The capacity for these growth forms to colonise and stabilise non-cohesive sediments and initiate biogeomorphic succession, indicates high potential for the seed banks of even highly degraded reaches to contribute to geomorphic river recovery. However, exotic propagules increasingly dominated the seed banks of moderate and poor condition reaches and reflected increasing encroachment by terrestrial exotic vegetation associated with riparian degradation. As the degree of riparian degradation increases, the resources required to control the regeneration of exotic species will similarly increase, if seed bank-based regeneration is to contribute to both geomorphic and ecological restoration goals. Copyright © 2015 Elsevier B.V. All rights reserved.

The Effect of Temperature and Water Potential on Seed Germination of Asian spiderflower (Cleome viscose L.: As Invasive Weed in Soybean Fields in Golestan Province

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M. Shirdel

2016-09-01

Full Text Available Introduction: Cleome viscose Linn. with a common name as “Asian spiderflower”, belongs to the Capparidacea family. It is an annual, sticky herb found as a common weed all over the tropical regions of the world. It is a very competitive weed of annual crops. This plant is currently introduced as an invasive plant in soybean fields of Golestan province. There is no management recommendation to control Asian spider flower. Thus large quantities of soybean destroyed by this weed every year. Germination and emergence are the two most important stages in the life cycle of plants. Environmental factors such as temperature, light, pH, planting depth and soil moisture are known to affect seed germination and emergence of weeds. An understanding of the germination biology of Asian spider flower would facilitate the development of better management strategies for this weed. Therefore, the purposes of this research were to study the effects of temperature and water potential on Asian spider flower seed germination. Material and Methods: To evaluate the effect of temperature and water potential on seed germination and determination of seed germination cardinal temperatures of Asian spider flower, an experiment was conducted as Factorial Experiment in Completely Randomized Design with 4 replications in Agricultural Research and Natural Resources Center of Golestan Province during 2013. Treatments were included temperatures with seven levels (15, 20, 25, 30, 35, 38 and 400C and water potentials with six levels (0, -2, -4, -6, -8 and -10 bar. Germination was monitored daily until germination discontinued and the number of the germinated seeds was recorded. Seeds were observed twice daily and considered germinated when the radical was approximately >2mm long. To quantify the response of germination rate to temperature and to determine the cardinal temperatures for germination original beta, and modified beta, segmented and dent models were used. Water

Weed control technology for environmentally, economically and socially sustainable agriculture

International Nuclear Information System (INIS)

Khan, A.R.; Srivastava, R.C.; Ghorai, A.K.; Singh, S.R.

2001-04-01

Studies were conducted through a series of experiments for five consecutive wet seasons with a variety of alternative biological weed control techniques by means of soil solarization. This is a method of heating soil surface by using transparent polyethylene sheets placed on soil surface to trap solar radiation. This raises soil temperature to a level lethal for many soil borne pathogens and weed seeds, thus killing weeds before crop emergence. The use of black low density polyethylene sheets reduces weed growth and increases rice yield

Weed control technology for environmentally, economically and socially sustainable agriculture

Energy Technology Data Exchange (ETDEWEB)

Khan, A R [Directorate of Water Management Research, Indian Council of Agricultural Research (ICAR), Walmi Complex, Phulwari Sharif, Patna, Bihar (India); [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy); Srivastava, R C [Water Technology Centre for Eastern Region (ICAR), Bhubaneswar (India); Ghorai, A K [CRIJAF (ICAR), Barrackpore, West Bengal (India); Singh, S R [Directorate of Water Management Research, Indian Council of Agricultural Research (ICAR), Walmi Complex, Phulwari Sharif, Patna, Bihar (India)

2001-04-01

Studies were conducted through a series of experiments for five consecutive wet seasons with a variety of alternative biological weed control techniques by means of soil solarization. This is a method of heating soil surface by using transparent polyethylene sheets placed on soil surface to trap solar radiation. This raises soil temperature to a level lethal for many soil borne pathogens and weed seeds, thus killing weeds before crop emergence. The use of black low density polyethylene sheets reduces weed growth and increases rice yield.

Supplementing seed banks to rehabilitate disturbed Mojave Desert shrublands: where do all the seeds go?

Science.gov (United States)

DeFalco, Lesley A.; Esque, Todd C.; Nicklas, Melissa B.; Kane, Jeffrey M.

2012-01-01

Revegetation of degraded arid lands often involves supplementing impoverished seed banks and improving the seedbed, yet these approaches frequently fail. To understand these failures, we tracked the fates of seeds for six shrub species that were broadcast across two contrasting surface disturbances common to the Mojave Desert—sites compacted by concentrated vehicle use and trenched sites where topsoil and subsurface soils were mixed. We evaluated seedbed treatments that enhance soil-seed contact (tackifier) and create surface roughness while reducing soil bulk density (harrowing). We also explored whether seed harvesting by granivores and seedling suppression by non-native annuals influence the success of broadcast seeding in revegetating degraded shrublands. Ten weeks after treatments, seeds readily moved off of experimental plots in untreated compacted sites, but seed movements were reduced 32% by tackifier and 55% through harrowing. Harrowing promoted seedling emergence in compacted sites, particularly for the early-colonizing species Encelia farinosa, but tackifier was largely ineffective. The inherent surface roughness of trenched sites retained three times the number of seeds than compacted sites, but soil mixing during trench development likely altered the suitability of the seedbed thus resulting in poor seedling emergence. Non-native annuals had little influence on seed fates during our study. In contrast, the prevalence of harvester ants increased seed removal on compacted sites, whereas rodent activity influenced removal on trenched sites. Future success of broadcast seeding in arid lands depends on evaluating disturbance characteristics prior to seeding and selecting appropriate species and seasons for application.

Canopy seed banks as time capsules of biodiversity in pasture-remnant tree crowns.

Science.gov (United States)

Nadkarni, Nalini M; Haber, Willam A

2009-10-01

Tropical pastures present multiple barriers to tree regeneration and restoration. Relict trees serve as "regeneration foci" because they ameliorate the soil microclimate and serve as safe spots for dispersers. Here, we describe another mechanism by which remnant trees may facilitate pasture regeneration: the presence of seed banks in the canopy soil that accumulates from decomposing epiphytes within the crowns of mature remnant trees in tropical cloud forest pastures. We compared seed banks of canopy soils (histosols derived from fallen leaves, fruits, flower, and twigs of host trees and epiphytes, dead bryophytes, bark, detritus, dead animals, and microorganisms, and dust that accumulate on trunks and the upper surfaces of large branches) in pastures, canopy soils in primary forest trees, and soil on the forest floor in Monteverde, Costa Rica. There were 5211 epiphytic and terrestrial plant seeds in the three habitats. All habitats were dominated by seeds in a relatively small number of plant families, most of which were primarily woody, animal pollinated, and animal dispersed. The density of seeds on the forest floor was greater than seed density in either pasture-canopy or forest-canopy soils; the latter two did not differ. Eight species in 44 families and 61 genera from all of the habitats were tallied. There were 37 species in the pasture-canopy soil, 33 in the forest-canopy soil, and 57 on the forest floor. Eleven species were common to all habitats. The mean species richness in the pasture canopy was significantly higher than the forest canopy (F =83.38; p banks of pasture trees can function as time capsules by providing propagules that are removed in both space and time from the primary forest. Their presence may enhance the ability of pastures to regenerate more quickly, reinforcing the importance of trees in agricultural settings.

Host Status of Seven Weed Species and Their Effects on Ditylenchus destructor Infestation of Peanut.

Science.gov (United States)

De Waele, D; Jordaan, E M; Basson, S

1990-07-01

The host suitability to Ditylenchus destructor of seven common weed species in peanut (Arachis hypogaea) fields in South Africa was determined. Based on the number of nematodes per root unit, white goosefoot (Chenopodium album), feathertop chloris (Chloris virgata), purple nutsedge (Cyperus rotundus), jimson weed (Datura stramonium), goose grass (Eleusine indica), khaki weed (Tagetes minuta), and cocklebur (Xanthium strumarium) were poor hosts. Ditylenchus destructor survived on all weed species; population densities increased in peanut hulls and caused severe damage to seeds of peanut grown after weeds. Roots of purple nutsedge left in the soil suppressed populations of D. destructor and root and pod development in peanut grown after the weed. However, nematode populations in peanut hulls and seeds were not suppressed. Some weed species, especially purple nutsedge which is common in peanut fields, can be used to indicate the presence of D. destructor in the absence of peanut.

Contributions of seed bank and vegetative propagules to vegetation composition on prairie dog colonies in western South Dakota

Science.gov (United States)

Emily R. Helms; Lan Xu; Jack L. Butler

2012-01-01

Characterizing the contributions of the seed bank and vegetative propagules will enhance our understanding of community resiliency associated with prairie dog disturbances. Our objective was to determine the effects of ecological condition (EC) and distance from burrows on the soil seed bank and vegetative propagules. Based on species composition of the extant...

Interaction Effects of Planting Date and Weed Competition on Yield and Yield Components of Three white Bean Cultivars in Semirom

Directory of Open Access Journals (Sweden)

A. Yadavi

2012-06-01

Full Text Available Unsuitable planting and weed competition are the most important factors that greatly reduce the yield of bean. In order to study the effect of planting date on yield and yield components of three white bean cultivars in weed infest and weed free condition a factorial experiment with randomized complete block design and three replications was carried out at Semirom in 2009. The treatments were planting date (May10, May 25 and June 9 and white bean cultivars (Shekofa, Pak and Daneshkade and two levels of weed infestation (weedy and weed free. Results showed that planting date, weed competition and cultivars had significant effects on yield and yield components of white bean. The 30-day delay in planting date reduced the number of pods per plant, seeds per pod, 100 seed weight and biological yield of white bean cultivars, 22.5, 18, 20.1 and 22.5 percent respectively. Also weed competition, reduced the number of seeds per pod, 100 seed weight and biological yield respectively by 13.5, 5.7 and 27.1 percent. Result of planting date and weed competition interaction effects indicated that the weed competition decreased grain yield (53% in third planting date more than others and delay in planting date was companion with increasing weed density and dry weight in flowering stage of bean. Also Shekofa cultivar had highest grain yield (3379 kg/ha at the first planting date and weed free condition.

Seed Detection and Discrimination by Ground Beetles (Coleoptera: Carabidae) Are Associated with Olfactory Cues.

Science.gov (United States)

Kulkarni, Sharavari S; Dosdall, Lloyd M; Spence, John R; Willenborg, Christian J

2017-01-01

Olfactory ability is an element of fitness in many animals, guiding choices among alternatives such as mating partners or food. Ground beetles (Coleoptera; Carabidae), exhibit preferences for prey, and some species are well-known weed seed predators. We used olfactometer-based bioassays to determine if olfactory stimuli are associated with detection of Brassica napus L., Sinapis arvensis L., and Thlaspi arvense L. seeds by ground beetles characteristic of agroecosystems, and whether behavioural responses to seed odors depended on seed physiological state (imbibed or unimbibed). Imbibed B.napus seeds were preferred over other weed species by two of the three carabid species tested. Only A. littoralis responded significantly to unimbibed seeds of B. napus. Sensitivity to olfactory cues appeared to be highly specific as all carabid species discriminated between the olfactory cues of imbibed brassicaceous weed seeds, but did not discriminate between weed seeds that were unimbibed. Overall, our data suggest that depending on seed physiological state, odours can play an important role in the ability of carabids to find and recognize seeds of particular weed species.

[Soil seed bank formation during early revegetation of areas affected by mining in a tropical rain forest of Chocó, Colombia].

Science.gov (United States)

Valois-Cuesta, Hamleth; Martínez-Ruiz, Carolina; Urrutia-Rivas, Yorley

2017-03-01

Mining is one of the main economic activities in many tropical regions and is the cause of devastation of large areas of natural tropical forests. The knowledge of the regenerative potential of mining disturbed areas provides valuable information for their ecological restoration. The aim of this study was to evaluate the effect of age of abandonment of mines and their distance from the adjacent forest, on the formation of soil seed bank in abandoned mines in the San Juan, Chocó, Colombia. To do this, we determined the abundance and species composition of the soil seed bank, and the dynamics of seed rain in mines of different cessation period of mining activity (6 and 15 years), and at different distances from the adjacent forest matrix (50 and 100 m). Seed rain was composed by five species of plants with anemocorous dispersion, and was more abundant in the mine of 6 years than in the mine of 15 years. There were no significant differences in the number of seeds collected at 50 m and 100 m from the adjacent forest. The soil seed bank was represented by eight species: two with anemocorous dispersion (common among the seed rain species) and the rest with zoochorous dispersion. The abundance of seeds in the soil did not vary with the age of the mine, but was higher at close distances to the forest edge than far away. During the early revegetation, the formation of the soil seed bank in the mines seems to be related to their proximity to other disturbed areas, rather than their proximity to the adjacent forest or the cessation activity period of mines. Therefore, the establishment of artificial perches or the maintenance of isolated trees in the abandoned mines could favour the arrival of bird-dispersed seeds at mines. However, since the soil seed bank can be significantly affected by the high rainfall in the study area, more studies are needed to evaluate management actions to encourage soil seed bank formation in mines of high-rainfall environments in the Choc

Changes in vegetation and soil seed bank of meadow after waterlogging caused by Castor fiber

Directory of Open Access Journals (Sweden)

Magdalena Franczak

2015-07-01

Full Text Available Soil waterlogging is among abiotic stresses that influence species composition and productivity in numerous plant communities. The aim of the study was to find answer to the question of how waterlogging caused by beavers’ activity induces quantitative and qualitative changes of vegetation and soil seed bank levels of variable-moist meadows. An immediate effect of the waterlogging at the level of vegetation was the decline in species richness and a decrease in the values of the biodiversity index. Water stress inhibited growth and development of plants already present and, primarily, impeded recruitment of new individuals of species characteristic of variable-moist meadows, e.g. Cirsium rivulare, Filipendula ulmaria and Lythrum salicaria, which were replaced by Carex acutiformis. Prolonged waterlogging did not induce equally substantial changes in the soil seed bank as in the vegetation. Both in the waterlogged and control patches, slightly decreased species richness and biodiversity index were recorded. After waterlogging withdrawal, the reserves of the soil seed bank were slightly higher than the initial values. The differences were not statistically significant. In the waterlogged patch, the qualitative floristic similarity between taxa identified in the soil seed bank and vegetation cover declined, which was evidenced by the value of Jaccard’s index decreasing from 0.46 to 0.36. A reverse relationship was found in control patch, where the value of the similarity index slightly increased from 0.41 to 0.48.

The Short Term Effects of Fire Severity on Composition and Diversity of Soil Seed Bank in Zagros Forest Ecosystem, Servan County

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M. Heydari

2014-12-01

Full Text Available In most ecosystems, disturbance is an important agent of variation in community structure and composition. Determining the diversity and composition of soil seed bank is essential for designing conservation and restoration programs because it can markedly contribute to future plant communities. Despite the important role of soil seed banks in the composition of different plant communities, and thus in their conservation, the floristic studies in Zagros forests have only focused on aboveground vegetation. In this study, the characteristics of soil seed banks were examined in three conditions after one year of fire high severity burned, low severity burned and control (not burned in Shirvanchardavol city in northeast of Ilam Province. The result of DCA showed that different fire severities and their effects on site conditions have been reflected clearly in the composition of the soil seed bank. The results also indicated that soil seed bank composition between control and high severity burned spots was specifically different. The shanon diversity, Margalef richness and evenness indices differed significantly between three treatments and the highest diversity was observed at low severity. In this regard the proportion of annual forbs tended to decrease with increasing severity of fire. In soil seed bank, Therophytes were the dominant life form of low severity burned and control spots and Hemichryptophytes were dominant in high severity burned spots.

Effects of pollination timing and distance on seed production in a dioecious weed Silene latifolia

Science.gov (United States)

Anderson, Jay F.; Duddu, Hema S. N.; Shirtliffe, Steven J.; Benaragama, Dilshan; Syrovy, Lena D.; Stanley, Katherine A.; Haile, Teketel A.

2015-11-01

Silene latifolia Poir. (white cockle or white campion) is an important invasive weed in North American agriculture. It exhibits dioecy, therefore, both male and female plants are required in order for seed production to occur. However, dioecious species being invasive is not common because of their limitations in pollination and subsequent seed production. The objective of this study is to determine the effect of pollination timing and distance on seed production of Silene latifolia. A series of experiments including pollination exclusion, timing and pollination distance were conducted in 2009 and 2010 at or around Saskatoon, Saskatchewan. For pollination exclusion, exclosures were built around the natural female plants for exclosure, sham-exclosure, and male and female combined treatments. Pollination timing was studied by applying exclosure, non-exclosure, night-exclosure, and day-exclosure treatments to individual female plants. Female plants were transplanted along a linear interval at six different distances from the pollen source to study the effect of pollination distance. S. latifolia was exclusively insect-pollinated and pollination occurred both day and night; however, in one year, pollination occurred mainly at night. Female plants that were in the range of 0-4 m from a compatible pollen source experienced no limitation to pollination. However, when the distance was increased further up to 128 m, pollination levels and subsequent seed production were declined. Moreover, there were differences in seed production between years suggesting that pollination was affected by the environmental conditions during pollination and the crop that white cockle was grown in. These experiments indicate that seed production in S. latifolia is limited by insect-pollination. Although there was pollination limitation for seed production at greater distances from a pollen source, the high fecundity rate (3000-18000 seeds per plant) resulted in a large seed output. Thus, we

Mapping the Distribution and Flora of the Weeds in Canola Fields of Gorgan Township by Geographic Information System (GIS

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sahar jannati ataie

2018-02-01

. Conclusion: In general, weed distribution maps showed that Phalaris minor, Melilotus officinalis, Rapistrum rugosum, Avena ludoviciana, Veronica persica and Sinapis arvensis are present in the most of canola fields in Gorgan region. Therefore, we can be conclude that, observation of high diversity and high dominance of weeds in these fields, may because of similar cropping management by farmers. So, it is recommended as a first step to produce the weed and seed banks maps. On the other hand, we should institutionalize strategies based on sustainable management of weeds.

The Essential Oil of Monarda didyma L. (Lamiaceae Exerts Phytotoxic Activity in Vitro against Various Weed Seed

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Donata Ricci

2017-02-01

Full Text Available The chemical composition of the essential oil of the flowering aerial parts of Monarda didyma L. cultivated in central Italy was analyzed by Gas Chromatography/Mass Spectrometry (GC/MS. The major compounds of the oil were thymol (59.3%, p-cymene (10.3%, terpinolene (9.2%, δ-3-carene (4.4%, myrcene (3.7%, and camphene (3.4%. The essential oil was tested in vitro for its anti-germination activity against Papaver rhoeas L., Taraxacum officinale F. H. Wigg., Avena fatua L., Raphanus sativus L. and Lepidium sativum L. seeds, demonstrating good inhibitory activity in a dose-dependent way. The exposure of the employed weed seeds to M. didyma essential oil and thymol solution (59.3% increased the level of hydrogen peroxide (H2O2 and malondialdehyde (MDA, markers of oxidative stress, in emerging 5-day-old rootlets.

Soil seed banks and growth rates of an invasive species, Piper aduncum, in the lowlands of Papua New Guinea

NARCIS (Netherlands)

Rogers, H.R.; Hartemink, A.E.

2000-01-01

Secondary fallow vegetation in parts of the Papua New Guinea lowlands is dominated by the shrub Piper aduncum L. that originates from South America. Here we report on its seed bank, growth rate and biomass accumulation. P. aduncum accounted for 69 % (408 m[minus sign]2) of the seed bank in the

Germination traits of three weed species in Kosovo

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A. Mehmeti

2010-02-01

Full Text Available Amaranthus retroflexus, Echinochloa crus-galli and Datura stramonium are the most important weed species in Kosovo. They cause severe yield depression, contaminate fodder and negatively affect growth and reproduction of other weed species. To counteract these problems, specific strategies need to be developed. Such strategies should consider information on species germination traits. In this context, our study provides information on temperature requirements for germination. Seeds of A. retroflexus, E. crus-galli and D. stramonium were harvested in two sub-regions of Kosovo (western and eastern parts differing in climate and land use. They were set for germination experiments in growth chambers at temperatures ranging from 3 to 35 °C and under field conditions. In both experiments, the germination rate differed between species and provenances. In the growth chamber experiment, germination of all three species was negligible below 15 °C and reached the highest rates between 24 and 30 °C. Seeds originating from the western part of Kosovo had higher germination rates and required a lower temperature for germination than seeds originating from the eastern part. In the field experiment, the time-dependent germination behaviour of D. stramonium differed between provenances. In general, germination started when soil temperature was above 18 °C and continued as long as the soil was moist. The results are discussed in the context of the need to develop weed management strategies against these weeds in Kosovo.

Tree seed rain and seed removal, but not the seed bank, impede forest recovery in bracken (Pteridium aquilinum (L.) Kuhn)-dominated clearings in the African highlands.

Science.gov (United States)

Ssali, Fredrick; Moe, Stein R; Sheil, Douglas

2018-04-01

Considerable areas dominated by bracken Pteridium aquilinum (L.) Kuhn occur worldwide and are associated with arrested forest recovery. How forest recovery is impeded in these areas remains poorly understood, especially in the African highlands. The component processes that can lead to recruitment limitation-including low seed arrival, availability and persistence-are important determinants of plant communities and offer a potential explanation for bracken persistence. We investigated key processes that can contribute to recruitment limitation in bracken-dominated clearings in the Bwindi Impenetrable National Park, Uganda. We examined if differences in seed rain (dispersal limitation), soil seed bank, or seed removal (seed viability and persistence) can, individually or in combination, explain the differences in tree regeneration found between bracken-dominated areas and the neighboring forest. These processes were assessed along ten 50-m transects crossing the forest-bracken boundary. When compared to the neighboring forest, bracken clearings had fewer seedlings (bracken 11,557 ± 5482 vs. forest 34,515 ± 6066 seedlings/ha), lower seed rain (949 ± 582 vs. 1605 ± 335 tree seeds m -2  year -1 ), comparable but sparse soil seed bank (304 ± 236 vs. 264 ± 99 viable tree seeds/m 2 ), higher seed removal (70.1% ± 2.4% vs. 40.6% ± 2.4% over a 3-day interval), and markedly higher rodent densities (25.7 ± 5.4 vs. 5.0 ± 1.6 rodents per 100 trapping sessions). Camera traps revealed that rodents were the dominant animals visiting the seeds in our seed removal study. Synthesis : Recruitment limitation contributes to both the slow recovery of forest in bracken-dominated areas, and to the composition of the tree species that occur. Low seed arrival and low persistence of unburied seeds can both explain the reduced density of seedlings found in bracken versus neighboring forest. Seed removal, likely due to rodents, in particular appears sufficient to

Critical Period of Weed Control in Aerobic Rice

Science.gov (United States)

Anwar, M. P.; Juraimi, A. S.; Samedani, B.; Puteh, A.; Man, A.

2012-01-01

Critical period of weed control is the foundation of integrated weed management and, hence, can be considered the first step to design weed control strategy. To determine critical period of weed control of aerobic rice, field trials were conducted during 2010/2011 at Universiti Putra Malaysia. A quantitative series of treatments comprising two components, (a) increasing duration of weed interference and (b) increasing length of weed-free period, were imposed. Critical period was determined through Logistic and Gompertz equations. Critical period varied between seasons; in main season, it started earlier and lasted longer, as compared to off-season. The onset of the critical period was found relatively stable between seasons, while the end was more variable. Critical period was determined as 7–49 days after seeding in off-season and 7–53 days in main season to achieve 95% of weed-free yield, and 23–40 days in off-season and 21–43 days in main season to achieve 90% of weed-free yield. Since 5% yield loss level is not practical from economic view point, a 10% yield loss may be considered excellent from economic view point. Therefore, aerobic rice should be kept weed-free during 21–43 days for better yield and higher economic return. PMID:22778701

Assessment of soil seed bank from six different vegetation types in ...

African Journals Online (AJOL)

Kakamega forest, the only rainforest in Kenya, has faced extensive fragmentation and degradation over the last decades. Slow recovery of degraded areas is due to slow or no natural regeneration. An assessment was conducted to ascertain the contribution of soil seed bank in forest regeneration within six sites in ...

Fruit dispersal and seed banks in Atriplex sagittata: the role of heterocarpy

Czech Academy of Sciences Publication Activity Database

Mandák, Bohumil; Pyšek, Petr

2001-01-01

Roč. 89, - (2001), s. 159-165 ISSN 0022-0477 R&D Projects: GA AV ČR KSK2005601 Institutional research plan: CEZ:AV0Z6005908 Keywords : Atriplex sagittata * Chenopodiaceae * seed bank Subject RIV: EF - Botanics Impact factor: 2.291, year: 2001

Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions

DEFF Research Database (Denmark)

Johansen, Anders; Bangsø Nielsen, Henrik; Hansen, Christian M.

2013-01-01

did not affect egg survival during the first 48h and it took up to 10days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites......, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37°C) and thermophilic (55°C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55°C...

Narrow rows reduce biomass and seed production of weeds and increase maize yield

NARCIS (Netherlands)

Mashingaidze, A.B.; Werf, van der W.; Lotz, L.A.P.; Chipomho, J.; Kropff, M.J.

2009-01-01

Smallholder farmers in southern African countries rely primarily on cultural control and hoe weeding to combat weeds, but often times, they are unable to keep up with the weeding requirements of the crop because of its laboriousness, causing them to incur major yield losses. Optimisation of crop

Seed germination behavior of swallow wort

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amir hosein pahlavani

2009-06-01

Full Text Available The exotic plant, Swallow- wort, a twining perennial of the Milkweed family, has become increasingly invasive in some place of Iran, especially orchards. Increased knowledge of wort germination biology would facilitate development of an optimum control program. Germination of Swallow wort seeds as affected by environmental factors was studied under controlled-environment growth chamber conditions. The following studies were conducted in plant Pests & Diseases Research Institute during the years 2003-4: 1- Effect of constant temperature on germination that including 10, 15, 18, 20, 25, 30, 35 and 40˚C; 2- Effect of light on constant germination; 3- Effect of temperature fluctuations on seed germination: 15/7, 20/12, 25/17 and 30/22˚C. All experiments were conducted with 8 replications. Swallow wort seeds showed no dormancy when detachment from mother plant. Seed germination was strongly influenced by temperature. Light did not play a crucial role on seed germination of this weed. Therefore Swallow wort seeds were not photoblastic and temperature fluctuations did not increase seed germination of Swallow wort. The above characteristics are very important in making swallowwort an invasive weed. Having precise information of these traits enables us to a better management and control of this troublesome weed.

THE EFFECT OF WINTER CATCH CROPS ON WEED INFESTATION IN SWEET CORN DEPENDING ON THE WEED CONTROL METHODS

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Robert Rosa

2015-02-01

Full Text Available An experiment was carried out in east-central Poland (52°06’ N, 22°55’ E over 2008–2011 to study the effect of winter catch crops on the weed infestation, number, and fresh matter of weeds in sweet corn (Zea mays L. var. saccharata. The following winter catch crops were grown: hairy vetch (Vicia villosa Roth., white clover (Trifolium repens L., winter rye (Secale cereale L., Italian ryegrass (Lolium multiflorum L. and winter turnip rape (Brassica rapa var. typica Posp.. The catch crops were sown in early September and incorporated in early May. The effect of the catch crops was compared to the effect of FYM (30 t·ha-1 and control without organic manuring (NOM. Three methods of weed control were used: HW – hand weeding, twice during the growing period, GCM – the herbicide Guardian Complete Mix 664 SE, immediately after sowing of corn seeds, Z+T – a mixture of the herbicides Zeagran 340 SE and Titus 25 WG applied at the 3–4-leaf stage of sweet corn growth. Rye and turnip rape catch crops had least weeds in their fresh matter. Sweet corn following winter catch crops was less infested by weeds than corn following farmyard manure and non-manured corn. Least weeds and their lowest weight were found after SC, BRT and VV. LM and BRT reduced weed species numbers compared with FYM and NOM. The greatest weed species diversity, determined at the corn flowering stage, was determined after SC and FYM. The number and weight of weeds were significantly lower when chemically controlled compared with hand weeding. The best results were observed after a post-emergent application of the mixture Z+T. The weed species diversity on Z+T-treated plots was clearly lower compared with GCM and HW.

Dinamica y manejo de poblaciones de malas hierbas Dynamics and management of weed populations

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Milagros S. Saavedra

1994-01-01

Full Text Available El presente trabajo es una revisión de la modelización de estudios de dinámica de poblaciones de malas hierbas, que fue presentada como ponencia en el XVIII Congresso Brasile iro de Herbicida s e Plant as Daninh as en 1991, Brasília. Partiendo de la población, como unidad básica de los ecosistemas agrarios, se relacionan diferentes modelos de dinámica incluyendo el fenómeno de competencia intra específica, la evolución del banco de semillas y aplicaciones a la asociación cultivo y mala hierba. A través de los diagramas de ciclos vitales, que relacionan los estados funcionales y los procesos demográficos, se llega al establecimiento del modelo matricial.This literature review is a report about the study model of weed population dynamics, which was presented at the XVIII Congress of the Brazilian Weed Science Society, held in Brasilia, Brazil, 1991. Starting from population as the basic block of farm ecosystems, different models of dynamics are related, including the phenomenon of intraspecific competition, the evolution of seed banks, and applications to the weed/crop asso ciation. Through life cycle diagrams, which relates the functional status and the demographic processes, it is possible to achieve a matricial model.

Evaluation of Wheat (Triticum aestivum, L. Seed Quality of Certified Seed and Farm-Saved Seed in Three Provinces of Iran

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Khazaei Fardin

2016-06-01

Full Text Available The objective of this study was to study the seed quality aspects of wheat (Triticum aestivum L. and the extent of weed seed contamination present in wheat seeds produced in different regions of Iran. Four districts (cities, each including 12 fields (six certified seed fields and six farm-saved seed fields, were selected in each regions (provinces. One kilogram of the wheat seed sample was collected from each field for analysis in the laboratory. Wheat seeding was commonly done by farm-saved seed sourced from within the farm due to the high costs of certified seeds purchased from outside sources, followed by the low seed quality. The use of a farm-saved seed resulted in a higher germination rate and a lower mean time to germination compared with another system. The more positive temperatures experienced by mother plants could decrease the number of normal seedling and seedling length vigor index. Generally there was virtually no difference about physiological quality between certified seed and farm-saved seed sector that is related to lower quality of certified seed. The certified produced seeds had the lower number of weed seed, species and genus before and after cleaning. The highest seed purity and 1000 seed weight was obtained from the certified seed production system. The need for cleaning the farm-saved seed samples before sowing is one of the important findings of this survey.

Microwave Technologies as Part of an Integrated Weed Management Strategy: A Review

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Graham Brodie

2012-01-01

Full Text Available Interest in controlling weed plants using radio frequency or microwave energy has been growing in recent years because of the growing concerns about herbicide resistance and chemical residues in the environment. This paper reviews the prospects of using microwave energy to manage weeds. Microwave energy effectively kills weed plants and their seeds; however, most studies have focused on applying the microwave energy over a sizable area, which requires about ten times the energy that is embodied in conventional chemical treatments to achieve effective weed control. A closer analysis of the microwave heating phenomenon suggests that thermal runaway can reduce microwave weed treatment time by at least one order of magnitude. If thermal runaway can be induced in weed plants, the energy costs associated with microwave weed management would be comparable with chemical weed control.

Sementes nocivas que ocorreram em amostras de sementes de azevém (Lolium multiflorum, analisadas no Rio Grande do Sul nos anos de 1978 e 1979 Weed seeds in ryegrass seeds, analysed in Rio Grande do Sul, during 1978 and 1979

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H. Giaretta

1984-06-01

Full Text Available Foram levantadas informações sobre a qualidade da semente de azevém utilizadas no Rio Grande do Sul e produzida no próprio Estado ou em outras uni dades da Federação e mesmo em outros Países, nos anos de 1978 e 1979. Estas informações foram obtidas através de fichas e Boletins de Análise de Sementes dos Laboratórios de Análise de Sementes (LAS do Rio Grande do Sul. Em 1978 analisou-se 2.319 t de azevém sendo 74% da semente oriunda do Rio Grande do Sul e 26% introduzida, enquanto que das 4.772 t analisadas em 1979 99,6% são do Rio Grande do Sul e 0,4% são introduzidas. O percentual de sementes de azevém, produzidas no Estado, contaminadas com sementes nocivas foi de 61,5% em 1978 e de 60,0% em 1979; e o de sementes int roduzidas no Estado foi de 45,6% em 1978 e de 29,4%em 1979. Foi observado que ent re as sementes originárias do RS destacaram -se com maior ocorrênci a em 1978 as espécies nocivas de Silene gallica, Setaria geniculata, Anthemis cotula, Digitaria adscendens e Echinochloa spp, enquanto que nas sementes int roduzidas desta caram-se Sida spp e Rumex spp; em 1979, na semente oriunda do Estado desta caram-se Amaranthus spp, Silene gallica e Setaria geniculata, enquanto que nas sementes introduzidas a maior ocorrência foi de Setaria geniculata, Echinochloa spp e Solanum spp.This paper presents a quality record of rye-grass seeds produced in Rio Grande do Sul or imported from other countries. It refers to the presence of weeds in ryegrass during 1978 and 1979. These record were obtained in the Analysis Bulletins at the Seed Analysis Laboratory of the Instituto de Pesquisas Agronômicas (IPAGRO Rio Grande do Sul°Brasil and in those from other institutions. This State produced 74% of 2.319 t analysed seeds and 26% come from other places in 1978. In 1979 4.772 t were registred, 99,6% from here and 0,4% from outside. The percentage of ryegrass seeds contaminated with weed seeds produced in the State, in 1978, were 61

Influence of grazing on soil seed banks determines the restoration potential of aboveground vegetation in a semi-arid savanna in Ethiopia

NARCIS (Netherlands)

Tessema, Z.K.; Boer, de W.F.; Baars, R.M.T.; Prins, H.H.T.

2012-01-01

Species composition, number of emerging seedlings, species diversity and functional group of the soil seed banks, and the influence of grazing on the similarity between the soil seed banks and aboveground vegetation, were studied in 2008 and 2009 in a semi-arid savanna of Ethiopia. We tested whether

Weed Control Strategies for Organic Peanut Production and Transition: A Lesson in Basic Agronomy

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Weed control in organic peanut production is difficult and costly. The only production inputs that consistently improved weed management in organic peanut production were modified production practices and intense cultivation with a tine weeder. Research trials evaluated row patterns, seeding rates...

Parthenium weed (Parthenium hysterophorus L.) and climate change: the effect of CO2 concentration, temperature, and water deficit on growth and reproduction of two biotypes.

Science.gov (United States)

Nguyen, Thi; Bajwa, Ali Ahsan; Navie, Sheldon; O'Donnell, Chris; Adkins, Steve

2017-04-01

Climate change will have a considerable impact upon the processes that moderate weed invasion, in particular to that of parthenium weed (Parthenium hysterophorus L.). This study evaluated the performance of two Australian biotypes of parthenium weed under a range of environmental conditions including soil moisture (100 and 50% of field capacity), atmospheric carbon dioxide (CO 2 ) concentration (390 and 550 ppm), and temperature (35/20 and 30/15 °C/day/night). Measurements were taken upon growth, reproductive output, seed biology (fill, viability and dormancy) and soil seed longevity. Parthenium weed growth and seed output were significantly increased under the elevated CO 2 concentration (550 ppm) and in the cooler (30/15 °C) and wetter (field capacity) conditions. However, elevated CO 2 concentration could not promote growth or seed output when the plants were grown under the warmer (35/20 °C) and wetter conditions. Warm temperatures accelerated the growth of parthenium weed, producing plants with greater height biomass but with a shorter life span. Warm temperatures also affected the reproductive output by promoting both seed production and fill, and promoting seed longevity. Dryer soil conditions (50% of field capacity) also promoted the reproductive output, but did not retain high seed fill or promote seed longevity. Therefore, the rising temperatures, the increased atmospheric CO 2 concentration and the longer periods of drought predicted under climate change scenarios are likely to substantially enhance the growth and reproductive output of these two Australian parthenium weed biotypes. This may facilitate the further invasion of this noxious weed in tropical and sub-tropical natural and agro-ecosystems.

Soil solarization for weed control in carrot

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MARENCO RICARDO ANTONIO

2000-01-01

Full Text Available Soil solarization is a technique used for weed and plant disease control in regions with high levels of solar radiation. The effect of solarization (0, 3, 6, and 9 weeks upon weed populations, carrot (Daucus carota L. cv. Brasília yield and nematode infestation in carrot roots was studied in São Luís (2º35' S; 44º10' W, MA, Brazil, using transparent polyethylene films (100 and 150 mm of thickness. The maximum temperature at 5 cm of depth was about 10ºC warmer in solarized soil than in control plots. In the study 20 weed types were recorded. Solarization reduced weed biomass and density in about 50% of weed species, including Cyperus spp., Chamaecrista nictans var. paraguariensis (Chod & Hassl. Irwin & Barneby, Marsypianthes chamaedrys (Vahl O. Kuntze, Mitracarpus sp., Mollugo verticillata L., Sebastiania corniculata M. Arg., and Spigelia anthelmia L. Approximately 40% of species in the weed flora were not affected by soil mulching. Furthermore, seed germination of Commelina benghalensis L. was increased by soil solarization. Marketable yield of carrots was greater in solarized soil than in the unsolarized one. It was concluded that solarization for nine weeks increases carrot yield and is effective for controlling more than half of the weed species recorded. Mulching was not effective for controlling root-knot nematodes in carrot.

Germination of some important weeds influenced by red light and nitrogenous compounds

International Nuclear Information System (INIS)

Tanfg, Dong-Seng; Hamayun, M.; Khan, A.L.; Shinwari, Z.K.; Kim, H.A.; Yoon-Ha; Kang, Sang-Mo; Lee, Joon-Hee; Chae-In; Nawaz, Y.; Kang, Kee-Kyung; Lee, In-Jung

2010-01-01

Seed dormancy is a major constraint in the eradication of weeds from agriculture fields. Seeds of Amaranthus retroflexus, Echinocloa crus-galli and Digitaria adscendens were collected from cultivated fields, dried and then treated with different nitrogen containing compounds i.e., potassium nitrate, ammonium chloride, ammonium nitrate and sodium nitrite. Some seeds were kept under dark while others were irradiated with red light for 10 min., after 12 hr of inhibition. The N-compounds were applied at the rate of 1, 5, 10, 25 and 50 mM, while the strength of red light pulse was maintained at 80 mu mols/sup -2/m/sup -1/. It was observed that red light significantly improved germination rates of A. retroflexus, E. crus-galli and D. adscendens. Nitrogenous compounds significantly improved germination of weeds and maximum germination was induced by ammonium nitrate. However, exposure of seeds to both red light and N-compounds provided significantly higher germination as compared to singular application of either of them. E. crusgalli recorded highest germination rates in response to red light and N-compounds, while D. adscendens provided least values for the same treatments. Application of N-compounds in conjunction with red light significantly improves germination rates of selected weed species by breaking their dormancy. (author)

Isolation and characterization of deleterious Pseudomonas aeruginosa KC1 from rhizospheric soils and its interaction with weed seedlings

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Vijaya Lakshmi

2015-04-01

Full Text Available The bacterial isolate KC1 was screened from the rhizosphere of castor plants (Ricinus communis indigenous to agricultural fields of Bihar. The isolate was Gram negative, non-spore forming, and exhibited fluorescence under UV light. Its molecular characterization is based on the sequencing of 16S rDNA (1450 bp and alignment at GeneBank (NCBI, MaryLand. The strain has been validated as Pseudomonas aeruginosa (HM195190. The bacterium grew at 4–42 °C, with a temperature optima of 30 °C. The strain KC1 was found to produce cyanide (4.78 nmol l−1 over a period of 36 h. Data revealed enhanced cyanogenesis (6.98 nmol l−1, when glycine was provided in the King’s B medium. Seed bacterization exhibited reduction in root length, shoot length of weed seedlings (Amaranthus spinosus, Portulaca oleracea, which was significant (p < 0.05 in both laboratory and glasshouse experiments. Biomass was significantly reduced (p < 0.05 for the weed seedlings in glasshouse experiments. However, KC1 inoculated crop seedlings (Triticum aestivum were found to be less inhibitory as compared to weed seedlings. The observations are significant to establish, that the secondary metabolites producing KC1 rhizobacterium, P. aeruginosa KC1 could be exploited as a weed biocontrol agent. The innate potential of KC1 could be further formulated and utilized in field applications for agricultural sustainability.

Suicidal germination for parasitic weed control.

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Zwanenburg, Binne; Mwakaboko, Alinanuswe S; Kannan, Chinnaswamy

2016-11-01

Parasitic weeds of the genera Striga and Orobanche spp. cause severe yield losses in agriculture, especially in developing countries and the Mediterranean. Seeds of these weeds germinate by a chemical signal exuded by the roots of host plants. The radicle thus produced attaches to the root of the host plant, which can then supply nutrients to the parasite. There is an urgent need to control these weeds to ensure better agricultural production. The naturally occurring chemical signals are strigolactones (SLs), e.g. strigol and orobanchol. One option to control these weeds involves the use of SLs as suicidal germination agents, where germination takes place in the absence of a host. Owing to the lack of nutrients, the germinated seeds will die. The structure of natural SLs is too complex to allow multigram synthesis. Therefore, SL analogues are developed for this purpose. Examples are GR24 and Nijmegen-1. In this paper, the SL analogues Nijmegen-1 and Nijmegen-1 Me were applied in the field as suicidal germination agents. Both SL analogues were formulated using an appropriate EC-approved emulsifier (polyoxyethylene sorbitol hexaoleate) and applied to tobacco (Nicotiana tabacum L.) fields infested by Orobanche ramosa L. (hemp broomrape), following a strict protocol. Four out of 12 trials showed a reduction in broomrape of ≥95%, two trials were negative, two showed a moderate result, one was unclear and in three cases there was no Orobanche problem in the year of the trials. The trial plots were ca 2000 m 2 ; half of that area was treated with stimulant emulsion, the other half was not treated. The optimal amount of stimulant was 6.25 g ha -1 . A preconditioning prior to the treatment was a prerequisite for a successful trial. In conclusion, the suicidal germination approach to reducing O. ramosa in tobacco fields using formulated SL analogues was successful. Two other options for weed control are discussed: deactivation of stimulants prior to action and

Comparison of some Vegetative and Reproductive Traits of Dominant Weeds in Cultivated Tomato as Influence by Metribuzin and Non-living Mulches

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R. Zangoueinejad

2016-03-01

Full Text Available Introduction: Tomato production, similar to other important crops, is affected by weed competition in the early season. Weed infestation can affect tomato yield significantly. So weed control can be one of the most important factors in improving of crop production. Nowadays pre-plant, post-plant and post-emergence herbicides are widely used for controlling weeds in tomato fields, but it can lead to increasing environmental hazards, making weed resistant to herbicides and injuring tomato plants. Therefore, the use of non-living mulch (organic mulch and inorganic mulch could be a suitable substitutional way to weed control. Material and method: In this study, in order to investigating the time of emergence, flowering, seed shattering, length of vegetative and reproductive growth period of weeds under six types of non-living mulches (black plastic mulch, clear plastic mulch, wheat straw, sawdust, coco peat and peat moss and mtribuzin in tomato, research was conducted in a randomized complete block design with three replications at College of Agriculture, Shiraz University in 2012. The plots were fertilized with 20:20:20 (N, P2O5 and K2O with concentration of 166 kg ha-1. In this study, the appearance of plumule (for narrow leaf weeds and hypocotyl (for broad leaf weeds from weed seeds in soil medium was considered as the time of emergence. The weeds were visited once a week since transplanting tomato seedlings to the farm and the related date was recorded. Flowering time recording for each weed species was carried out after flowering. Plots without mulch (weedy and weed free were used as control. Statistical analysis of the collected data was performed by using SAS 9.1 software and comparing of the mean of characteristics was done by Tukey's test at 5 % significant level. Result and discussion: The longest and shortest time of weed emergence respectively belonged to the clear plastic mulch (28 days after transplanting and organic mulches and

Effect of Non-chemical Procedures of Weed Management on Growth Characteristics and Yield of Cumin (Cuminnum cyminum L.

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Surur Khorramdel

2018-02-01

Full Text Available Introduction Medicinal and aromatic plants are major crops of domestic and industrial interest. The essential oil yield, seed yield and biomass of medicinal and aromatic plants are seriously affected by interspecific competition, meaning proper weed management becomes crucial. Competition with weeds is detrimental for medicinal and aromatic plants production for two main reasons. The first reason is that, in acting as an important stress factor, the interference of weeds is supposed to generate variations in photosynthesis rate and direction, pushing plants to allocate more carbon to roots (competition for nutrients or water or shoots (competition for light. These plants are increasingly organically grown to improve profitability. However, the presence of weeds may lead to a decline in both yield and quality. Therefore, nonchemical methods of weed management are needed. More attention has been paid worldwide about the technical means for weeding, generally addressed to a removal of weeds as complete as possible, and sometimes to the effects of weeds on medicinal and aromatic plants yields and quality.Cumin (Cuminum cyminum L. is an herbaceous and annual plant belonging to Apiaceae family which is planted in arid and semi-arid regions of Iran as medicinal plant. About 26% of the total area under cultivation of medicinal plants in Iran is allocated to cumin cultivation. This paper studied the methods of non-chemical weed control on yield components and quantitative and qualitative yield of cumin. Materials and Methods In order to study weed management methods, an experiment was conducted based on a randomized complete block design with nine treatments and three replications at the Agricultural Research Station, Ferdowsi University of Mashhad during growing season 2012-2013. Treatments included tillage at night, false seed bed, three cover crops such as hairy vetch, chuckling vetch and fenugreek, crop residues of sunflower, barley and garlic and

Soil seed bank during succession at an abandoned pasture in the upper Paraná river-floodplain, Brazil - doi: 10.4025/actascibiolsci.v33i1.6391 Soil seed bank during succession at an abandoned pasture in the upper Paraná river-floodplain, Brazil - doi: 10.4025/actascibiolsci.v33i1.6391

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João Batista Campos

2011-02-01

Full Text Available We evaluated density and species composition of the soil seed bank in active pasture and in secondary forest on a 10 year-old abandoned pasture to identify changes in density, richness, diversity and species composition during secondary succession of abandoned pastures. The implications of those changes for the forest recovery process were also considered. Soil samples were collected at Porto Rico island, state of Paraná, in 2007. The seedling emergence method was used. Data on active pasture collected in 1996, published by Campos and Souza (2003 were used for comparative analysis. No evidence was found of a pattern of changes in density of the soil seed bank during succession of abandoned pastures. We observed increases in richness and diversity, in the contribution of tree and shrub species and dominance of herb species for the seed bank during the first 10 years of abandonment of pastures in riparian forests. At the end of succession, the soil used as pasture can result in systems that are different from the original environment, due to seed bank impoverishment and presence of exotic species.We evaluated density and species composition of the soil seed bank in active pasture and in secondary forest on a 10 year-old abandoned pasture to identify changes in density, richness, diversity and species composition during secondary succession of abandoned pastures. The implications of those changes for the forest recovery process were also considered. Soil samples were collected at Porto Rico island, state of Paraná, in 2007. The seedling emergence method was used. Data on active pasture collected in 1996, published by Campos and Souza (2003 were used for comparative analysis. No evidence was found of a pattern of changes in density of the soil seed bank during succession of abandoned pastures. We observed increases in richness and diversity, in the contribution of tree and shrub species and dominance of herb species for the seed bank during the

Impacts of Mastication: Soil Seed Bank Responses to a Forest Thinning Treatment in Three Colorado (USA Conifer Forest Types

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Akasha M. Faist

2015-08-01

Full Text Available Mastication is a forest fuel thinning treatment that involves chipping or shredding small trees and shrubs and depositing the material across the forest floor. By decreasing forest density mastication has been shown to lessen crown fire hazard, yet other impacts have only recently started to be studied. Our study evaluates how mastication treatments alter the density and composition of soil seed banks in three Colorado conifer forest types. The three forest types were (1 lodgepole pine, (2 ponderosa pine and (3 pinyon pine-juniper. Results showed that masticated sites contained higher seed bank densities than untreated sites: a pattern primarily driven by treatment effects in ponderosa pine forests. The seed bank was dominated by forbs regardless of forest type or treatment. This pattern of forb dominance was not observed in the aboveground vegetation cover as it demonstrated more even proportions of the functional groups. Graminoids showed a higher seed density in treated sites than untreated and, similarly, the identified non-native species only occurred in the treated ponderosa pine sites suggesting a potential belowground invasion for this forest type. These results suggest that presence of masticated material might not be creating a physical barrier hindering the transfer of seeds as predicted.

EASTERN DODDER (CUSCUTA MONOGYNA VAHL.) SEED GERMINATION AFFECTED BY SOME HERBACEOUS DISTILLATES.

Science.gov (United States)

Movassaghi, M; Hassannejad, S

2015-01-01

Eastern dodder (Cuscuta monogyna Vahl.) is one of the noxious parasitic weeds that infected many ornamental trees in green spaces and gardens. Our purpose is to find natural inhibitors for prevention of its seed germination. In order to reach this aim, laboratory studies were conducted by using of herbaceous distillates of Dracocephalum moldavica, Nasturtium officinalis, Malva neglecta, Mentha piperita, Mentha pulegium, Rosa damascene, Ziziphora tenuior, and Urtica dioica on seed germination of C. monogyna. Z. tenuior distillate stimulated C. monogyna seed germination, whereas others reduced this parasitic weed's seed germination. D. moldavica caused maximum inhibition on weed seed germination. Seedling growth of C. monogyna was more affected than its seed germination. All of these herbaceous distillates reduced C. monogyna seedling length so that the latter decreased from 28.2 mm in distilled water to 4.5, 3.97, 3.85, 3.67, 3.1, 2.87, 2.57, 1.9, and 1.17 in M. pulegium, M. piperita, F. officinalis, Z. tenuior, N. officinalis, M. neglecta, R. damascene, U. dioica and D. moldavica, respectively. By using these medicinal plants distillates instead of herbicides, the parasitic weed seedling length and host plant infection will reduce.

Influence of Afforestation on the Species Diversity of the Soil Seed Bank and Understory Vegetation in the Hill-Gullied Loess Plateau, China.

Science.gov (United States)

Wang, Ning; Jiao, Juying; Jia, Yanfeng; Wang, Dongli

2017-10-24

The Chinese Loess Plateau region has long been suffering from serious soil erosion. Thus, large-scale afforestation has continued during the past decades in order to control soil erosion. Afforestation can dramatically alter nutrient cycles, affect soil-carbon storage, and change hydrology. However, it is unknown how afforestation influences species diversity of the soil seed bank and understory vegetation compared with spontaneous restoration of abandoned land. Forest land with trees planted 30 years ago, abandoned slope land restored spontaneously for 30 years, and the corresponding slopes with remnant natural vegetation were selected as sampling sites. The species richness both in the soil seed bank and vegetation was significantly higher on the afforested slope compared to the spontaneously restored abandoned land. The species similarity between the afforested slope and the remnant slope land was high both in the soil seed bank and standing vegetation compared to the abandoned land. The soil seed bank density varied from 1778 ± 187 to 3896 ± 221 seeds/m², and more than half of it was constituted by annual and biennial species, with no significant difference among sampling habitats. However, the afforested slope had higher seed density of grass and shrub/subshrubs compared to the abandoned slope. The present study indicates that in the study region, characterized by serious soil erosion, afforestation can better facilitate vegetation succession compared to spontaneously restoration of abandoned slope land.

Fluridone: a combination germination stimulant and herbicide for problem fields?

Science.gov (United States)

Goggin, Danica E; Powles, Stephen B

2014-09-01

Problem weeds in agriculture, such as Lolium rigidum Gaud., owe some of their success to their large and dormant seed banks, which permit germination throughout a crop-growing season. Dormant weed seed banks could be greatly depleted by application of a chemical that stimulates early-season germination and then kills the young seedlings. Fluridone, a phytoene desaturase-inhibiting herbicide that can also break seed dormancy, was assessed for its efficacy in this regard. The germination of fluridone-treated Lolium rigidum seeds was stimulated on soils with low organic matter, and almost 100% seedling mortality was observed, while the treatment was only moderately effective on a high-organic-matter potting mix. Seedlings from wheat, canola, common bean and chickpea seeds sown on fluridone-treated sandy loam were bleached and did not survive, but lupins and field peas grew normally. This proof-of-concept study with fluridone suggests that it may be possible to design safe and effective molecules that act as germination stimulants plus herbicides in a range of crop and soil types: a potentially novel way of utilising herbicides to stimulate seed bank germination and a valuable addition to an integrated weed management system. © 2014 Society of Chemical Industry.

Control of ALS resistant volunteer oil seed rape and other dicotyledonous weeds with GF-145, a new cereal herbicide product containing isoxaben and florasulam

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Becker, Jörg

2014-02-01

Full Text Available GF-145 contains the active ingredients isoxaben (610 g ai/kg and florasulam (40 g ai/kg and is formulated as a Wettable Granule (WG. The active ingredients are found in commercial products such as Primus™2 (florasulam, Starane XL™ (fluroxypyr + florasulam, Ariane C™ (fluroxypyr + florasulam + clopyralid or Flexidor™ (isoxaben. While florasulam has been widely used in cereal crops in recent years, isoxaben offers a new mode of action (MOA for use in German cereal herbicides even when considering that Flexidor™ has had regulatory approval in 1988 to 1991. The MOA of isoxaben is inhibition of cellulose synthesis (HRAC class L, while florasulam inhibits Acetolactate Synthase (ALS and is a representative of the HRAC class B. It is known that florasulam works through uptake by green leaves. Isoxaben is a herbicide with soil activity and with a very low activity when foliar applied, except on some species in the cruciferae family. GF-145 is intended to be applied in the autumn in cereals (wheat, barley, rye, triticale for the control of ALS resistant volunteer oil seed rape and annual dicotyledonous weeds including Matricaria spp., Stellaria media, Papaver rhoeas, Capsella bursa-pastoris, Myosotis arvensis, Lamium spp., Galium aparine, Veronica spp. and others when applied at early post-emergence from BBCH 10 to 13 of the crop. The use rate in winter cereals is 95 g product/ha (58 g ai/ha isoxaben plus 3.75 g ai/ha florasulam. Field trials conducted in previous years confirmed excellent selectivity in all cereal crops and efficacy trials initiated in autumn 2012 show that GF-145 provides excellent and superior control to ALS resistant oil seed rape that was better than straight florasulam and other ALS active ingredients. GF-145 adds a new MOA to the cereal herbicide portfolio and controls volunteer oil seed rape, cruciferous weeds and broad-leaved weeds and is more robust than florasulam based products that do not contain isoxaben.

Impact of municipal wastewater effluent on seed bank response and soils excavated from a wetland impoundment

Science.gov (United States)

Finocchiaro, R.G.; Kremer, R.J.; Fredrickson, L.H.

2009-01-01

Intensive management of wetlands to improve wildlife habitat typically includes the manipulation of water depth, duration, and timing to promote desired vegetation communities. Increased societal, industrial, and agricultural demands for water may encourage the use of alternative sources such as wastewater effluents in managed wetlands. However, water quality is commonly overlooked as an influence on wetland soil seed banks and soils. In four separate greenhouse trials conducted over a 2-yr period, we examined the effects of municipal wastewater effluent (WWE) on vegetation of wetland seed banks and soils excavated from a wildlife management area in Missouri, USA. We used microcosms filled with one of two soil materials and irrigated with WWE, Missouri River water, or deionized water to simulate moist-soil conditions. Vegetation that germinated from the soil seed bank was allowed to grow in microcosms for approximately 100 d. Vegetative taxa richness, plant density, and biomass were significantly reduced in WWE-irrigated soil materials compared with other water sources. Salinity and sodicity rapidly increased in WWE-irrigated microcosms and probably was responsible for inhibiting germination or interfering with seedling development. Our results indicate that irrigation with WWE promoted saline-sodic soil conditions, which alters the vegetation community by inhibiting germination or seedling development. ?? 2009, The Society of Wetland Scientists.

Effect of Planting Methods and Seeding Rates on Yield of Alfalfa (Medicago sativa L. CV. Hamedani in Bajgah, Fars Province

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A. Yazdani

2015-06-01

ha-1, respectively. Seeding rates also had a significant effect on number of weeds so that maximum and minimum weed numbers were obtained in 20 kg and 5 kg seed ha-1. Our results showed that 20 kg seed ha-1 and furrow planting method was the best treatment to gain maximum forage yield and minimum weed's detrimental impact.

Weed competitiveness and yielding ability of aerobic rice genotypes

NARCIS (Netherlands)

Zhao, D.L.

2006-01-01

Keywords:    Broad-sense heritability; Crop vigour; Genetic correlation; Indirect selection index; Plant erectness; Rice germplasm; Seeding rate; Vegetative growth; Weed-suppressive ability.

Impact of invasions by alien plants on soil seed bank communities: emerging patterns

Czech Academy of Sciences Publication Activity Database

Gioria, Margherita; Jarošík, Vojtěch; Pyšek, Petr

2014-01-01

Roč. 16, č. 3 (2014), s. 132-142 ISSN 1433-8319 R&D Projects: GA ČR(CZ) GAP504/11/1028; GA ČR GB14-36079G Institutional support: RVO:67985939 Keywords : plant invasions * impact * soil seed bank Subject RIV: EF - Botanics Impact factor: 3.606, year: 2014

The effect of environmental conditions on the seasonal dormancy pattern and germination of weed seeds

NARCIS (Netherlands)

Bouwmeester, H.J.

1990-01-01

Weeds cause considerable losses in horticultural and agricultural crops. Weeds are still predominantly controlled with herbicides. To reduce the use of chemicals, a better understanding of the biology of weeds is required. In this thesis the effect of environmental conditions on dormancy

Effect of long-term fertilisation on the weed community of a winter wheat field.

Science.gov (United States)

Jiang, Min; Liu, Tao; Huang, Niansheng; Shen, Xinping; Shen, Mingxing; Dai, Qigen

2018-03-05

Effects of fertilisation and other management techniques on a weed community were evaluated during wheat growth in a rice-wheat cropping system. Fertiliser treatments were C0 (C means chemical, C0 means zero chemical fertiliser.), CN (N fertiliser), CNK (N plus K fertiliser), CNPK (N plus P and K fertiliser), CNP (N plus P fertiliser), and CPK (P plus K fertiliser). Weed density, biomass, and bio-diversity were determined. Redundancy analysis (RDA) was used to investigate the relationship between fertiliser management, weed species, and weed density. The overall weed densities in the C0 and CPK treatments were the greatest during wheat seeding and ripening periods and were significantly greater than densities in the other treatments. N, P and organic matter in soil were highly correlated with weed species and density, whereas K in soil was not significantly correlated with weed species and weed density. N fertiliser significantly reduced weed density. Balanced fertilisation maintained weed species richness and resulting in a high yield of wheat. CNPK application reduced weed damage and improved the productivity and stability of the farmland ecosystem.

Germination biology of Hibiscus tridactylites in Australia and the implications for weed management

Science.gov (United States)

Chauhan, Bhagirath Singh

2016-05-01

Hibiscus tridactylites is a problematic broadleaf weed in many crops in Australia; however, very limited information is available on seed germination biology of Australian populations. Experiments were conducted to evaluate the effect of environmental factors on germination and emergence of H. tridactylites. Germination was stimulated by seed scarification, suggesting the inhibition of germination in this species is mainly due to the hard seed coat. Germination was not affected by light conditions, suggesting that seeds of this species are not photoblastic. Germination was higher at alternating day/night temperatures of 30/20 °C (74%) and 35/25 °C (69%) than at 25/15 °C (63%). Moderate salinity and water stress did not inhibit germination of H. tridactylites. Seedling emergence of H. tridactylites was highest (57%) for the seeds buried at a 2 cm depth in the soil; 18% of seedlings emerged from seeds buried at 8 cm but no seedlings emerged below this depth. Soil inversion by tillage to bury weed seeds below their maximum depth of emergence could serve an important tool for managing H. tridactylites.

Optical Sensing of Weed Infestations at Harvest.

Science.gov (United States)

Barroso, Judit; McCallum, John; Long, Dan

2017-10-19

Kochia ( Kochia scoparia L.), Russian thistle ( Salsola tragus L.), and prickly lettuce ( Lactuca serriola L.) are economically important weeds infesting dryland wheat ( Triticum aestivum L.) production systems in the western United States. Those weeds produce most of their seeds post-harvest. The objectives of this study were to determine the ability of an optical sensor, installed for on-the-go measurement of grain protein concentration, to detect the presence of green plant matter in flowing grain and assess the potential usefulness of this information for mapping weeds at harvest. Spectra of the grain stream were recorded continuously at a rate of 0.33 Hz during harvest of two spring wheat fields of 1.9 and 5.4 ha. All readings were georeferenced using a Global Positioning System (GPS) receiver with 1 m positional accuracy. Chlorophyll of green plant matter was detectable in the red (638-710 nm) waveband. Maps of the chlorophyll signal from both fields showed an overall agreement of 78.1% with reference maps, one constructed prior to harvest and the other at harvest time, both based on visual evaluations of the three green weed species conducted by experts. Information on weed distributions at harvest may be useful for controlling post-harvest using variable rate technology for herbicide applications.

Determination of Cardinal Temperatures for Cool Season Turfgrass and Two Common Weed Species

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Marjan Diayanat

2018-02-01

Full Text Available Introduction The presence of broadleaf weeds not only reduces the aesthetic quality of the turfgrass, but more importantly they compete with desired turfgrass for water, nutrients, and light. Weed management after seeding is an important component to successfully establishing a healthy stand of cool season turfgrass. Weed seed germination is a key process because determines both the number of weeds that could potentially emerge and the timing of their appearance in the turfgrass. Temperature is of the most important factor regulating germination of non-dormant seeds in irrigated, annual agroecosystems at the beginning of the growth season where light, nutrients, and moisture are typically not growth limiting. Also prostrate knotweed (Polygonum aviculare L. and annual sowthistle (Sonchus oleraceus L. are two annual common broad leaf weeds in cool season turfgrass. Prostrate knotweed is very competitive in infertile and compacted soils and often invades turfgrasses along driveways, sidewalks, and beaten paths across lawns. Annual sowthistle is found in open habitats that include waste areas, turf, and roadsides. The aim of this study was to evaluate different nonlinear regression models to describe response of germination rate to different temperatures in perennial ryegrass (Lolium perenne L., fescue (Festuca rubra L., prostrate knotweed and annual sowthistle. Materials and Methods This experiment was based on completely randomized design with 4 replications at Islamic Azad University in the laboratory of Science Research Branch in 2015. The seeds were treated with different temperatures (2, 5, 10, 15, 20, 25, 30, 35, 40 and 45oC Twenty five seeds were placed in each petri dish for each species in per replication. Ten milliliters of distilled water were added to each petri dish and the filter papers were regularly moistened to ensure saturation throughout the germination tests. Petri dishes were placed in germinator with 16 hour day, 8 hour night

Problems and achievements of cotton (Gossypium Hirsutum L. weeds control

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T. Barakova

2017-09-01

Full Text Available Abstract. Weed control in the cultivation of cotton is critical to the yield and quality of production. The influence of economically important weeds was studied. Chemical control is the most effective method of weed control in cotton but much of the information on it relates to primary weed infestation. Problems with primary weed infestation in cotton have been solved to a significant extent. The question of secondary weed infestation with annual and perennial graminaceous weeds during the period of cotton vegetation is also determined largely by the use of antigraminaceous herbicides. The data related to herbicides to effectively control secondary germinated broadleaf weeds in conventional technology for cotton growing are quite scarce, even globally. We are still seeking effective herbicides for control of these weeds in cotton crops. Studies on their influence on the sowing characteristics of cotton seed and the quality of cotton fiber are still insufficient. In the scientific literature there is not enough information on these questions. The combinations of herbicides, as well as their tank mixtures with fertilizers or plant growth regulators are more efficient than autonomous application. Often during their combined application higher synergistic effect on yield is produced. There is information about cotton cultivars resistant to glyphosate. These cultivars are GMO and they are banned within the European Union, including Bulgaria.

Effects of vermicompost and nitrogen fertilizers on growth of Jimson weed (Datura stramonium L. as a medicinal plant

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Ramin Abbaspour

2016-05-01

Full Text Available An experiment was conducted in order to evaluate the effect of organic (3 and 6 ton/ha vermicompost and chemical (150 and 300 kg/ha nitrogen fertilizers on growth, seed dispersal and heteroblasty of jimson weed at green house of Shiraz University in 2012. The results showed that the highest and the lowest plant growth, seed production and seed dispersal was in 300 kg/ha N and 6 ton/ha vermicompost, respectively. Position of the seeds on maternal plant had an important influence on the emergence percentage. Seeds on the middle and lowest parts of the plants had less emergence percentage compared with those on the higher parts. In general, application of 300 kg/ha nitrogen accelerated the growth of jimson weed and increase dispersal and heteroblasty of the jimson seed.

Influence of Afforestation on the Species Diversity of the Soil Seed Bank and Understory Vegetation in the Hill-Gullied Loess Plateau, China

Science.gov (United States)

Wang, Ning; Jiao, Juying; Jia, Yanfeng; Wang, Dongli

2017-01-01

The Chinese Loess Plateau region has long been suffering from serious soil erosion. Thus, large-scale afforestation has continued during the past decades in order to control soil erosion. Afforestation can dramatically alter nutrient cycles, affect soil-carbon storage, and change hydrology. However, it is unknown how afforestation influences species diversity of the soil seed bank and understory vegetation compared with spontaneous restoration of abandoned land. Forest land with trees planted 30 years ago, abandoned slope land restored spontaneously for 30 years, and the corresponding slopes with remnant natural vegetation were selected as sampling sites. The species richness both in the soil seed bank and vegetation was significantly higher on the afforested slope compared to the spontaneously restored abandoned land. The species similarity between the afforested slope and the remnant slope land was high both in the soil seed bank and standing vegetation compared to the abandoned land. The soil seed bank density varied from 1778 ± 187 to 3896 ± 221 seeds/m2, and more than half of it was constituted by annual and biennial species, with no significant difference among sampling habitats. However, the afforested slope had higher seed density of grass and shrub/subshrubs compared to the abandoned slope. The present study indicates that in the study region, characterized by serious soil erosion, afforestation can better facilitate vegetation succession compared to spontaneously restoration of abandoned slope land. PMID:29064405

Using soil seed banks to assess temporal patterns of genetic variation in invasive plant populations.

Science.gov (United States)

Fennell, Mark; Gallagher, Tommy; Vintro, Luis Leon; Osborne, Bruce

2014-05-01

Most research on the genetics of invasive plant species has focused on analyzing spatial differences among existing populations. Using a long-established Gunnera tinctoria population from Ireland, we evaluated the potential of using plants derived from seeds associated with different soil layers to track genetic variation through time. This species and site were chosen because (1) G. tinctoria produces a large and persistent seed bank; (2) it has been present in this locality, Sraheens, for ∼90 years; (3) the soil is largely undisturbed; and (4) the soil's age can be reliably determined radiometrically at different depths. Amplified fragment length polymorphic markers (AFLPs) were used to assess differences in the genetic structure of 75 individuals sampled from both the standing population and from four soil layers, which spanned 18 cm (estimated at ∼90 years based on (210)Pb and (137)Cs dating). While there are difficulties in interpreting such data, including accounting for the effects of selection, seed loss, and seed migration, a clear pattern of lower total allele counts, percentage polymorphic loci, and genetic diversity was observed in deeper soils. The greatest percentage increase in the measured genetic variables occurred prior to the shift from the lag to the exponential range expansion phases and may be of adaptive significance. These findings highlight that seed banks in areas with long-established invasive populations can contain valuable genetic information relating to invasion processes and as such, should not be overlooked.

Germination Ecology of Johnsongrass Seeds (Sorghum halepense (L. PERS.

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Mehdi Mojab

2018-01-01

day/night (5, 10, 15, 20, 25, 30, 35, 40 and 45 C in both light/dark and dark regimes. The salt and osmotic potentials were applied in -1, -3, -5, -7, -9, -11 levels and control treatment in order to survey the stress of salt, drought on seed germination and to compare both stress on it. NaCl was applied in the Vant Hoff method to influence salt stress and also PEG 6000 was applied in the Michel methods to affect osmotic potential. In the burial depth experiment, a number of 30 seeds, for 30 days, were laid in the depth of 0, 0.5, 1, 2, 3, 4, 6, 8 cm in plastic vases with 15 cm diameters. All experiments were conducted twice in the form of randomized complete-block design with four replications. Each replication was arranged on a different shelf of growth chamber and considered as a single block in the laboratory experiments. The data of the replicated experiments were pooled for analysis, as the time interaction and treatment was absolutely meaningless. A functional three-parameter logistic model Was fitted to the germination values (% obtained at different concentrations of NaCl or osmotic potential. Also, a sigmoidal decay curve was fitted to show the seedling emergence (% values at different burial depths. Results and Discussion Seed germination was influenced significantly on different treatments of breaking dormancy (Fig 1. Sulfuric acid treatments showed significant difference rather than control treatment. In 30 and 45 min sulfuric acid scarification, germination was recorded more than 95 %. Based on the achieved results it is very probable that the hard seed prevents germination and this issue causes the weed remains stable in seed bank. Germination percentage was not affected by light regime and temperature interaction (both in constant and alternative (Fig 2a and 2b, the influence of different temperatures on the feature was significant (Fig 2a. The same germination has been seen in all temperatures (both light and light/ dark regime in all temperature, The

Seed biometric parameters in oil palm accessions from a Brazilian germplasm bank

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Julcéia Camillo

2014-08-01

Full Text Available The objective of this work was to evaluate the morphological diversity of oil palm seeds and to cluster the accessions according to their morphological characteristics. Forty-one accessions from the oil palm germplasm bank of Embrapa Amazônia Ocidental were evaluated - 18 of Elaeis oleifera and 23 of E. guineensis. The groups were formed based on morphological characteristics, by principal component analysis. In E. oleifera, four groups were formed, tied to their region of origin, but with significant morphological differences between accessions from the same population. For tenera-type E. guineensis seeds, three widely divergent groups were formed, especially as to external parameters, which differentiated them from the other ones. The parameter endocarp thickness stood out in intra- and inter-population differentiation. For dura-type E. guineensis, three groups were formed, with larger seeds and thicker endocarps, which differed from all the other ones. The variability observed for seed characteristics in the analyzed accessions allows the establishment of different groups, to define strategies for genetic improvement.

Phytotoxic effects of Calotropis procera (Ait. R. Br. extract on three weed plants

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Gulzar, A.

2014-11-01

Full Text Available A study was conducted to determine the potential and nature of allelopathic interference of Calotropis procera on seed germination and seedling growth of three weed species (Ageratum conyzoides L., Cannabis sativa L. and Trifolium repens L. Aqueous extracts of Calotropis procera at 0.5, 1.0, 2.0 and 4.0% concentrations were applied to determine their effect on seed germination and seedling growth of test plants under laboratory conditions. The aqueous extracts had retardary effect on seed germination, root length and shoot length. Germination percentage, root length and shoot length of weed species decreased progressively when treated with increasing extract concentration (0.5, 1, 2 and 4%. The pH values did not increase at all extract concentrations. Therefore, the change in pH values in this experiment is not responsible for the inhibition of test species growth.The phenolic content analysed show more pronounced increase in its contents at 4% concentrations. The study concludes that C. procera releases phenolics into the extract and these are probably involved in the growth inhibitory effect, which causes allelopathy operative in the community dominated by C. procera and provide an advantage to the weed.

Using soil seed banks to assess temporal patterns of genetic variation in invasive plant populations

OpenAIRE

Fennell, Mark; Gallagher, Tommy; Vintro, Luis Leon; Osborne, Bruce

2014-01-01

Most research on the genetics of invasive plant species has focused on analyzing spatial differences among existing populations. Using a long-established Gunnera tinctoria population from Ireland, we evaluated the potential of using plants derived from seeds associated with different soil layers to track genetic variation through time. This species and site were chosen because (1) G. tinctoria produces a large and persistent seed bank; (2) it has been present in this locality, Sraheens, for ∼...

Robotic weeding and automated weed measurements

DEFF Research Database (Denmark)

Christensen, S.; Søgaard, H.T.; Jørgensen, R.N.

2003-01-01

The goal of decreasing herbicide usage has so far focused on reducing the herbicide dosage or replacing chemical weed control by hoeing and harrowing. The conventional weed control strategy is to apply the same dose of herbicide or the same intensity of hoeing and harrowing in the whole field. Th...... the state-of-the-art of automated weed measurement methods and the research projects concerning autonomous platform and information system for crop and weed monitoring and robotic weeding....

Soil Seed Bank Dynamics in Tithonia diversifolia Dominated Fallowland Vegetation in Ile-Ife Area of Southwestern Nigeria

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Samson Olajide OKE

2009-12-01

Full Text Available The soil seedbank of Tithonia diversifolia, an invasive species which dominates open waste fallowland vegetation was studied. Two different roadside sites which vary in extent of open waste land were selected.The species composition of the established vegetation was assessed in the two diferent sites. Twenty top soil samples were collected at five different distances (15 cm, 30 cm, 45 cm, 60 cm, and 75 cm inwards away from each main road in dry and rainy seasons and the seed bank composition was determined by greenhouse germination over a 6 month period. The similarity between the composition of the seed bank flora and that of the established vegetation was low. The least and the highest emerged seedlings density was recorded in the 15 metres and 75 metres respectively inwards away from the main road in both seasons. The results of the seedlings emergence is a reflection of the extent of open waste land dominated by the invasive species due to human disturbance (road construction on both sites. Overall results suggest that the emergence of the species from the soil seed bank may be due to the impact of the invasive species Tithonia diversifolia on other plant species in the study environment.

Germination and soil seed bank traits of Podocarpus angustifolius (Podocarpaceae: an endemic tree species from Cuban rain forests

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Pablo Ferrandis

2011-09-01

Full Text Available Podocarpus angustifolius is an endangered recalcitrant-seeded small tree, endemic to mountain rain forests in the central and Pinar del Río regions in Cuba. In this study, the germination patterns of P. angustifolius seeds were evaluated and the nature of the soil seed bank was determined. Using a weighted two-factor design, we analyzed the combined germination response to seed source (i.e. freshly matured seeds directly collected from trees versus seeds extracted from soil samples and pretreatment (i.e. seed water-immersion for 48h at room temperature. Germination was delayed for four weeks (≈30 days in all cases, regardless of both factors analyzed. Moreover, nine additional days were necessary to achieve high germination values (in the case of fresh, pretreated seeds. These results overall may indicate the existence of a non-deep simple morphophysiological dormancy in P. angustifolius seeds. The water-immersion significantly enhanced seed germination, probably as a result of the hydration of recalcitrant seeds. Although germination of seeds extracted from soil samples was low, probably due to aging and pathogen effects throughout the time of burial, the study revealed the existence of a persistent soil seed bank (at least short-termed of ≈42 viable seeds per m² in the upper 10cm of soil. Such a record is noteworthy since references to persistent soil seed banks in recalcitrant-seeded species are scarce in the literature. The population consequences derived from the formation of persistent soil seed banks in this endangered species are discussed. Rev. Biol. Trop. 59 (3: 1061-1069. Epub 2011 September 01.Podocarpus angustifolius es un árbol endémico de los bosques lluviosos de la región de Pinar del Río y la parte central de Cuba, que se encuentra en peligro de extinción. En este estudio se evaluó la germinación de sus semillas y la naturaleza del banco de semillas del suelo. Específicamente, se analizó la respuesta germinativa

Effects of simulated acid rain on germination, seedling growth and oxidative metabolism of recalcitrant-seeded Trichilia dregeana grown in its natural seed bank.

Science.gov (United States)

Ramlall, Chandika; Varghese, Boby; Ramdhani, Syd; Pammenter, Norman W; Bhatt, Arvind; Berjak, Patricia; Sershen

2015-01-01

Increased air pollution in a number of developing African countries, together with the reports of vegetation damage typically associated with acid precipitation in commercial forests in South Africa, has raised concerns over the potential impacts of acid rain on natural vegetation in these countries. Recalcitrant (i.e. desiccation sensitive) seeds of many indigenous African species, e.g. must germinate shortly after shedding and hence, may not be able to avoid exposure to acid rain in polluted areas. This study investigated the effects of simulated acid rain (rainwater with pH adjusted to pH 3.0 and 4.5 with 70:30, H2 SO4 :HNO3 ) on germination, seedling growth and oxidative metabolism in a recalcitrant-seeded African tree species Trichilia dregeana Sond., growing in its natural seed bank. The results suggest that acid rain did not compromise T. dregeana seed germination and seedling establishment significantly, relative to the control (non-acidified rainwater). However, pH 3.0 treated seedlings exhibited signs of stress typically associated with acid rain: leaf tip necrosis, abnormal bilobed leaf tips, leaf necrotic spots and chlorosis, reduced leaf chlorophyll concentration, increased stomatal density and indications of oxidative stress. This may explain why total and root biomass of pH 3.0 treated seedlings were significantly lower than the control. Acid rain also induced changes in the species composition and relative abundance of the different life forms emerging from T. dregeana's natural seed bank and in this way could indirectly impact on T. dregeana seedling establishment success. © 2014 Scandinavian Plant Physiology Society.

Exotic, native and seeded species and soil biotic community response to post-fire seedings in northern Utah

Science.gov (United States)

Megan Taylor

2013-01-01

Post-fire seeding of native species is intended to reduce weed entry, yet few studies have addressed the impacts of seeding methods on the establishment and persistence of exotic annuals. In summers of 2010 and 2011, we investigated productivity of exotic annuals across rehabilitation seedings that were established on the Scooby Wildfire site in northern Utah. The site...

Seed-bank structure and plant-recruitment conditions regulate the dynamics of a grassland-shrubland Chihuahuan ecotone.

Science.gov (United States)

Moreno-de Las Heras, Mariano; Turnbull, Laura; Wainwright, John

2016-09-01

Large areas of desert grasslands in the southwestern United States have shifted to sparse shrublands dominated by drought-tolerant woody species over the last 150 yr, accompanied by accelerated soil erosion. An important step toward the understanding of patterns in species dominance and vegetation change at desert grassland-shrubland transitions is the study of environmental limitations imposed by the shrub-encroachment phenomenon on plant establishment. Here, we analyze the structure of soil seed banks, environmental limitations for seed germination (i.e., soil-water availability and temperature), and simulated seedling emergence and early establishment of dominant species (black grama, Bouteloua eriopoda, and creosotebush, Larrea tridentata) across a Chihuahuan grassland-shrubland ecotone (Sevilleta National Wildlife Refuge, New Mexico, USA). Average viable seed density in soils across the ecotone is generally low (200-400 seeds/m 2 ), although is largely concentrated in densely vegetated areas (with peaks up to 800-1,200 seeds/m 2 in vegetated patches). Species composition in the seed bank is strongly affected by shrub encroachment, with seed densities of grass species sharply decreasing in shrub-dominated sites. Environmental conditions for seed germination and seedling emergence are synchronized with the summer monsoon. Soil-moisture conditions for seedling establishment of B. eriopoda take place with a recurrence interval ranging between 5 and 8 yr for grassland and shrubland sites, respectively, and are favored by strong monsoonal precipitation. Limited L. tridentata seed dispersal and a narrow range of rainfall conditions for early seedling establishment (50-100 mm for five to six consecutive weeks) constrain shrub-recruitment pulses to localized and episodic decadal events (9-25 yr recurrence intervals) generally associated with late-summer rainfall. Re-establishment of B. eriopoda in areas now dominated by L. tridentata is strongly limited by the

Use of Essential Oils of Cinnamon, Lavender and Peppermint for Weed Control

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Enio Campiglia

Full Text Available The indiscriminate use of synthetic chemical compounds for weed control has been often responsible of damage to both the environment and the human health. To challenge these problems, in the last years research has increased its effort to find out alternative farming strategies. A feasible alternative could be the identification of natural substances with allelopathic effects for the realization of natural herbicides. Some research has already highlighted the possibility of using essential oils, extracted from aromatic plants, for weed control. The advantage in the utilization of such natural compounds is the quickly breaking down process into the environment and so the possible application in sustainable agriculture like organic farming. Objective of this research was the evaluation of the inhibition effect exerted by the essential oils of cinnamon, peppermint and lavender on seeds germination of some of the most common weeds species of the Mediterranean environment (pigweed, wild mustard and ryegrass. The results have highlighted a control in the weeds germination. Among the essential oils tested, cinnamon oil has exerted the highest inhibition effect compared with lavender and peppermint ones. The dicotyledonous species have been more susceptible compared with the monocotyledonous, even if it has been recorded only for redroot pigweed a dose able to inhibit totally the seed germination.

The role of plant-microbiome interactions in weed establishment and control.

Science.gov (United States)

Trognitz, Friederike; Hackl, Evelyn; Widhalm, Siegrid; Sessitsch, Angela

2016-10-01

The soil microbiome plays an important role in the establishment of weeds and invasive plants. They associate with microorganisms supporting their growth and health. Weed management strategies, like tillage and herbicide treatments, to control weeds generally alter soil structure going alongside with changes in the microbial community. Once a weed population establishes in the field, the plants build up a close relationship with the available microorganisms. Seeds or vegetative organs overwinter in soil and select early in the season their own microbiome before crop plants start to vegetate. Weed and crop plants compete for light, nutrition and water, but may differently interact with soil microorganisms. The development of new sequencing technologies for analyzing soil microbiomes has opened up the possibility for in depth analysis of the interaction between 'undesired' plants and crop plants under different management systems. These findings will help us to understand the functions of microorganisms involved in crop productivity and plant health, weed establishment and weed prevention. Exploitation of the knowledge offers the possibility to search for new biocontrol methods against weeds based on soil and plant-associated microorganisms. This review discusses the recent advances in understanding the functions of microbial communities for weed/invasive plant establishment and shows new ways to use plant-associated microorganisms to control weeds and invasive plants in different land management systems. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effects of Corn Canopy on Seedling Emergence of Seven Weed Species

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F Kordbacheh

2012-02-01

Full Text Available In this research corn were planted in 3 densities (8, 12, 16 plant/m2 in two planting patterns (single and double-row with seven summer weed species, including redroot pigweed, green foxtail, annual bluegrass, common lambsquarter, jimsonweed, black nightshade and johnsongrass were planted. Temperature, quality and quantity of light reaching to soil surface were measured and the number of emerged seedlings for each weed species was countered in three sampling dates. Temperature fluctuation wasn't affected by density and planting patterns and was reduced with canopy formation. In all weed species 3 seedling emergence patterns were observed. In small seed species, redroot pigweed had one germination flush, so it was not respond to crop canopy. The number of emerged weed seedlings of annual bluegrass, common lambsquarter and green foxtail were significantly higher in bareground than under corn canopy. In double-row planting pattern was higher compared to the single-row and had three germination flushes. The number of emerged seedlings in the species with relatively large seeds had no significant difference between bareground and under corn canopy in jimsonweed and black nightshade. But it increased in johnsongrass under corn canopy compare to the bare ground. In all three species it was higher in double-row compare to single-row pattern. Jimsonweed had three germination flushes but blacknightshade and johnsongrass had 1 germination flush.

Soil seed banks and their germination responses to cadmium and salinity stresses in coastal wetlands affected by reclamation and urbanization based on indoor and outdoor experiments

Energy Technology Data Exchange (ETDEWEB)

Bai, Junhong, E-mail: junhongbai@163.com; Huang, Laibin, E-mail: seahuanglaibin@gmail.com; Gao, Zhaoqin; Lu, Qiongqiong; Wang, Junjing; Zhao, Qingqing

2014-09-15

Highlights: • A higher germination rate of soil seed bank was observed in the indoor experiment. • The outdoor experiment showed larger number and destiny of germinated seedlings. • Urbanization had greater impacts on soil seed banks than wetland reclamation. • Soil seed banks for wetland restoration were more suitable in the reclaimed region. • Suitable salt or Cd levels could activate seedling emergence in the soil seed bank. - Abstract: Indoor and outdoor seedling emergence experiments were conducted to thoroughly investigate germination patterns as affected by reclamation and urbanization, the ecological characteristics of soil seed banks, and their relationships with environmental factors in both urbanized and reclaimed regions of the Pearl River Delta in coastal wetlands. The germination rate of the soil seed bank was higher in the indoor experiment compared with that in the outdoor experiment, whereas the number and destiny of the germinated seedlings were greater in the outdoor experiment. The species diversity and number, as well as the richness and evenness indices, were higher in the urbanized region compared with the reclaimed region. However, the dominance and Sørensen similarity indices were greater in the reclaimed region compared with those indices in the urbanized region. Higher salinity and Cadmium (Cd) levels could inhibit seed germination; however, their suitable ranges (i.e. [0–2000 mg kg{sup −1}] for salinity and [0–4.0 mg kg{sup −1}] for available Cd) can activate seedling emergence, and more seedlings germinated under the intersectional levels at 0.34 mg kg{sup −1} available Cd and 778.6 mg kg{sup −1} salinity. Seawater intrusion caused by the sea level rise will possibly result in the salt-tolerant community in this area due to increasing salinity.

Soil seed banks and their germination responses to cadmium and salinity stresses in coastal wetlands affected by reclamation and urbanization based on indoor and outdoor experiments

International Nuclear Information System (INIS)

Bai, Junhong; Huang, Laibin; Gao, Zhaoqin; Lu, Qiongqiong; Wang, Junjing; Zhao, Qingqing

2014-01-01

Highlights: • A higher germination rate of soil seed bank was observed in the indoor experiment. • The outdoor experiment showed larger number and destiny of germinated seedlings. • Urbanization had greater impacts on soil seed banks than wetland reclamation. • Soil seed banks for wetland restoration were more suitable in the reclaimed region. • Suitable salt or Cd levels could activate seedling emergence in the soil seed bank. - Abstract: Indoor and outdoor seedling emergence experiments were conducted to thoroughly investigate germination patterns as affected by reclamation and urbanization, the ecological characteristics of soil seed banks, and their relationships with environmental factors in both urbanized and reclaimed regions of the Pearl River Delta in coastal wetlands. The germination rate of the soil seed bank was higher in the indoor experiment compared with that in the outdoor experiment, whereas the number and destiny of the germinated seedlings were greater in the outdoor experiment. The species diversity and number, as well as the richness and evenness indices, were higher in the urbanized region compared with the reclaimed region. However, the dominance and Sørensen similarity indices were greater in the reclaimed region compared with those indices in the urbanized region. Higher salinity and Cadmium (Cd) levels could inhibit seed germination; however, their suitable ranges (i.e. [0–2000 mg kg −1 ] for salinity and [0–4.0 mg kg −1 ] for available Cd) can activate seedling emergence, and more seedlings germinated under the intersectional levels at 0.34 mg kg −1 available Cd and 778.6 mg kg −1 salinity. Seawater intrusion caused by the sea level rise will possibly result in the salt-tolerant community in this area due to increasing salinity

Seed banks of managed and degraded grasslands in the Krkonoše Mts., Czech Republic

Czech Academy of Sciences Publication Activity Database

Handlová, Viola; Münzbergová, Zuzana

2006-01-01

Roč. 41, - (2006), s. 275-288 ISSN 1211-9520 R&D Projects: GA ČR GA526/05/0430 Institutional research plan: CEZ:AV0Z60050516 Keywords : degradation * mountain grasslands * seed bank Subject RIV: EF - Botanics Impact factor: 1.196, year: 2006

Mechanical pre-planting weed control in short rotation coppice using deep forestry ploughing techniques

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

This report describes a trial by Border biofuels to investigate the deep forestry plough as a mechanical pre-planting weed control method to reduce weed infestations in willow coppice and thus contribute to improved establishment and eventual yield. The results suggest that there was a considerable increase in biomass productivity from the deep ploughed area compared to the conventionally cultivated area at all three SRC sites tested. This technique also suggests that the deep forestry ploughing provides the benefit of much reduced levels of seed germination of many annual weed species and a reduction in levels of perennial weed infestation. It is not possible at this stage to predict the longer term benefits in terms of harvestable biomass productivity but it may be considered that the improved establishment and lack of weed competition would consistently produce higher yields of biomass than plantations which suffer from persistent and invasive weed competition. (author)

Puncturevine seed response to postemergence herbicides

Science.gov (United States)

Puncturevine (Tribulus terrestris) continues to plague growers, vegetation managers, and home gardeners. Puncturevine is a summer annual weed with spiny fruits that split into five segments, each containing one to four seeds. The seed nearest the pointed end of the bur is the largest and usually ge...

Seed dormancy, seedling establishment and dynamics of the soil seed bank of Stipa bungeana (Poaceae on the Loess Plateau of northwestern China.

Directory of Open Access Journals (Sweden)

Xiao Wen Hu

Full Text Available Studying seed dormancy and its consequent effect can provide important information for vegetation restoration and management. The present study investigated seed dormancy, seedling emergence and seed survival in the soil seed bank of Stipa bungeana, a grass species used in restoration of degraded land on the Loess Plateau in northwest China. Dormancy of fresh seeds was determined by incubation of seeds over a range of temperatures in both light and dark. Seed germination was evaluated after mechanical removal of palea and lemma (hulls, chemical scarification and dry storage. Fresh and one-year-stored seeds were sown in the field, and seedling emergence was monitored weekly for 8 weeks. Furthermore, seeds were buried at different soil depths, and then retrieved every 1 or 2 months to determine seed dormancy and seed viability in the laboratory. Fresh seeds (caryopses enclosed by palea and lemma had non-deep physiological dormancy. Removal of palea and lemma, chemical scarification, dry storage (afterripening, gibberellin (GA3 and potassium nitrate (KNO3 significantly improved germination. Dormancy was completely released by removal of the hulls, but seeds on which hulls were put back to their original position germinated to only 46%. Pretreatment of seeds with a 30% NaOH solution for 60 min increased germination from 25% to 82%. Speed of seedling emergence from fresh seeds was significantly lower than that of seeds stored for 1 year. However, final percentage of seedling emergence did not differ significantly for seeds sown at depths of 0 and 1 cm. Most fresh seeds of S. bungeana buried in the field in early July either had germinated or lost viability by September. All seeds buried at a depth of 5 cm had lost viability after 5 months, whereas 12% and 4% seeds of those sown on the soil surface were viable after 5 and 12 months, respectively.

Effect of three mound-building ant species on the formation of soil seed bank in mountain grassland

Czech Academy of Sciences Publication Activity Database

Dostál, Petr

2005-01-01

Roč. 200, - (2005), s. 148-158 ISSN 0367-2530 Institutional research plan: CEZ:AV0Z60050516 Keywords : myrmecochory * Lasius * soil seed bank Subject RIV: EF - Botanics Impact factor: 1.086, year: 2005

Distinct germination response of endangered and common arable weeds to reduced water potential.

Science.gov (United States)

Rühl, A T; Eckstein, R L; Otte, A; Donath, T W

2016-01-01

Arable weeds are one of the most endangered species groups in Europe. Modern agriculture and intensive land-use management are the main causes of their dramatic decline. However, besides the changes in land use, climate change may further challenge the adaptability of arable weeds. Therefore, we investigated the response pattern of arable weeds to different water potential and temperature regimes during the phase of germination. We expected that endangered arable weeds would be more sensitive to differences in water availability and temperature than common arable weeds. To this end, we set up a climate chamber experiment where we exposed seeds of five familial pairs of common and endangered arable weed species to different temperatures (5/15, 10/20 °C) and water potentials (0.0 to -1.2 MPa). The results revealed a significant relationship between the reaction of arable weed species to water availability and their Red List status. The effects of reduced water availability on total germination, mean germination time and synchrony were significantly stronger in endangered than in common arable weeds. Therefore, global climate change may present a further threat to the survival of endangered arable weed species. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

Closing oil palm yield gaps among Indonesian smallholders through industry schemes, pruning, weeding and improved seeds.

Science.gov (United States)

Soliman, T; Lim, F K S; Lee, J S H; Carrasco, L R

2016-08-01

Oil palm production has led to large losses of valuable habitats for tropical biodiversity. Sparing of land for nature could in theory be attained if oil palm yields increased. The efficiency of oil palm smallholders is below its potential capacity, but the factors determining efficiency are poorly understood. We employed a two-stage data envelopment analysis approach to assess the influence of agronomic, supply chain and management factors on oil palm production efficiency in 190 smallholders in six villages in Indonesia. The results show that, on average, yield increases of 65% were possible and that fertilizer and herbicide use was excessive and inefficient. Adopting industry-supported scheme management practices, use of high-quality seeds and higher pruning and weeding rates were found to improve efficiency. Smallholder oil palm production intensification in Indonesia has the capacity to increase production by 26%, an equivalent of 1.75 million hectares of land.

Effects of carbaryl-bran bait on trap catch and seed predation by ground beetles (Coleoptera: Carabidae).

Science.gov (United States)

Fielding, Dennis J; DeFoliart, Linda S; Hagerty, Aaron M

2013-04-01

Carbaryl-bran bait is effective against grasshoppers without many impacts on nontarget organisms, but ground beetles (Coleoptera: Carabidae) may be susceptible to these baits. Carabids are beneficial in agricultural settings as predators of insect pests and weed seeds. Carabid species and their consumption of weed seeds have not been previously studied in agricultural settings in Alaska. This study examined the effect of grasshopper bran bait on carabid activity-density, as measured by pitfall trap catches, and subsequent predation by invertebrates of seeds of three species of weed. Data were collected in fallow fields in agricultural landscape in the interior of Alaska, near Delta Junction, in 2008 and 2010. Bait applications reduced ground beetle activity-density by over half in each of 2 yr of bait applications. Seed predation was generally low overall (1-10%/wk) and not strongly affected by the bait application, but predation of lambsquarters (Chenopodium album L.) seed was lower on treated plots in 1 yr (340 seeds recovered versus 317 seeds, on treated versus untreated plots, respectively). Predation of dandelion (Taraxacum officinale G. H. Weber ex Wiggers) seeds was correlated with ground beetle activity-density in 1 yr, and predation of dragonhead mint (Dracocephalum parvifolium Nutt.) seed in the other year. We conclude that applications of carbaryl-bran bait for control of grasshoppers will have only a small, temporary effect on weed seed populations in high-latitude agricultural ecosystems.

Optimization of Inter-Row Spacing and Nitrogen Rate for the Application of Vision Guided Inter-Row weeding in Organic Spring Cereals

DEFF Research Database (Denmark)

Melander, Bo; Green, O.; Znova, L.

2016-01-01

-row spacing and nitrogen rate on weed and crop growth. Results are reported from two years field experiments with spring barley and spring wheat. It was aimed to maintain a constant seed rate for all five row spacing studied (12.5, 15, 20, 25 and 30 cm), which gave a higher crop density in the rows...... with increasing row spacing. A denser intra-row crop stand would improve the suppression of surviving intra-row weeds and partly compensate for the more weed growth that wider row spacing would cause by allowing more light penetration into the crop canopy. It was found that maintaining the seed rate when...

The effect of species, planting date, and management of cover crops on weed community in hybrid sunflower (Helianthus annuus

Directory of Open Access Journals (Sweden)

M. Bolandi Amoughein

2016-02-01

Full Text Available Introduction: Studies showed that if mixed populations of annual weeds grow with the sunflower, for every 10% increase in weed biomass, seed yield would decrease by 13% (Van Gessel & Renner, 2000. In addition to control weeds using herbicides multi-stage spraying is required. In organic farming systems mulch is used to control weeds, protection, fertility and improve soil quality (Glab & Kulig, 2008; Kuchaki et al., 2001. Surface mulches from cover crops suppress weed growth by reducing light levels at the soil surface, thereby slowing photosynthesis. In return, these conditions reduce seed germination and act as a physical barrier to seedling emergence and growth (Teasdale et al., 2007. Materials and Methods: The experiment was carried out in Ardabil Agricultural Research Station, as a factorial experiment based on randomized complete block design with three replications during 1390-1391. The first factor was considered four types of cover crops including winter rye (Secale cereal, spring barley (Hordeum vulgare, winter wheat (Triticum aestivum and control (no cover crop, no weeding.The second factor was mulch management at two levels (living mulch and dead mulch and the third factor was two planting dates for cover crops (synchronous with sunflower planting and 45 days after sunflower planting. Sunflower seeding performed manually on 23 May on the ridges with 50 cm row distance and spacing between plants was 25 cm in depth of 5 cm. Cover crops seeds, rye, barley and wheat, were planted between rows of sunflower. Due to the low density of weeds in study field, complete weeding and sampling of weeds in one session was performed (60 days after planting date sunflower. Statistical analysis of data performed using SAS software and mean comparison performed using Duncan's test with probability level of 5% and 1%. Diagrams drawn using Excel (Version 8.2. Results and Discussion\t: Density and dry weight of Field bindweed (Convolvulus arvensis L

Soil, Vegetation, and Seed Bank of a Sonoran Desert Ecosystem Along an Exotic Plant ( Pennisetum ciliare) Treatment Gradient

Science.gov (United States)

Abella, Scott R.; Chiquoine, Lindsay P.; Backer, Dana M.

2013-10-01

Ecological conditions following removal of exotic plants are a key part of comprehensive environmental management strategies to combat exotic plant invasions. We examined ecological conditions following removal of the management-priority buffelgrass ( Pennisetum ciliare) in Saguaro National Park of the North American Sonoran Desert. We assessed soil, vegetation, and soil seed banks on seven buffelgrass site types: five different frequencies of buffelgrass herbicide plus hand removal treatments (ranging from 5 years of annual treatment to a single year of treatment), untreated sites, and non-invaded sites, with three replicates for each of the seven site types. The 22 measured soil properties (e.g., pH) differed little among sites. Regarding vegetation, buffelgrass cover was low (≤1 % median cover), or absent, across all treated sites but was high (10-70 %) in untreated sites. Native vegetation cover, diversity, and composition were indistinguishable across site types. Species composition was dominated by native species (>93 % relative cover) across all sites except untreated buffelgrass sites. Most (38 species, 93 %) of the 41 species detected in soil seed banks were native, and native seed density did not differ significantly across sites. Results suggest that: (1) buffelgrass cover was minimal across treated sites; (2) aside from high buffelgrass cover in untreated sites, ecological conditions were largely indistinguishable across sites; (3) soil seed banks harbored ≥12 species that were frequent in the aboveground vegetation; and (4) native species dominated post-treatment vegetation composition, and removing buffelgrass did not result in replacement by other exotic species.

How much genetic variation is stored in the seed bank? A study of Atriplex tatarica (Chenopodiaceae)

Czech Academy of Sciences Publication Activity Database

Mandák, Bohumil; Bímová, Kateřina; Mahelka, Václav; Plačková, Ivana

2006-01-01

Roč. 15, - (2006), s. 2653-2663 ISSN 0962-1083 R&D Projects: GA AV ČR IAA6005206 Institutional research plan: CEZ:AV0Z60050516 Keywords : seed bank * population genetic structure * competition Subject RIV: EF - Botanics Impact factor: 4.825, year: 2006

An improved method for seed-bank analysis : Seedling emergence after removing the soil by sieving

NARCIS (Netherlands)

ter Heerdt, G.N.J.; Bekker, R.M.; Bakker, J.P.; Verweij, G.L.

1. The seedling emergence method for assessing the size of the seed bank is improved by washing soil samples on a fine sieve and spreading the thus concentrated samples in a 3-5 mm thick layer on sterilized potting compost. 2. The method largely increases the number of seedlings that emerge as

Effects of seeding rate and poultry litter on weed suppression from a rolled cereal rye cover crop

Science.gov (United States)

Growing enough cover crop biomass to adequately suppress weeds is one of the primary challenges in reduced-tillage systems that rely on mulch-based weed suppression. We investigated two approaches to increasing cereal rye biomass for improved weed suppression: (1) increasing soil fertility and (2) i...

To be or not to be - common and endangered arable weed species in the face of Global Climate Change

Directory of Open Access Journals (Sweden)

Rühl, Anna Theresa

2014-02-01

Full Text Available Arable weeds are one of the most endangered species groups in Europe. Modern agriculture and intensive land use management with the application of herbicides and fertilisers, enhanced seed cleaning, simplified crop rotations and abandonment of marginal arable sites are the main causes for the continuous decline of arable weeds. However, besides these changes in land use also global climate change may challenge the adaptability of arable weeds. Most scientists agree that the frequency of extreme meteorological conditions will increase in the future. As a consequence, plants of Central Europe will be subject to higher temperatures and reduced water supply due to longer intervals without precipitation during the growing season. We exposed seeds of five common and five endangered arable weed species to different temperatures and water potentials to study i how this plant group responds to higher temperatures and lower moisture during germination in general and ii whether there is a significant difference between common and endangered species in this respect.

INVASIVE WEEDS IN BOGOR BOTANIC GARDENS, INDONESIA AND ITS IMPLICATION ON SURROUNDING LANDSCAPES

Directory of Open Access Journals (Sweden)

Edi Santosa

2014-07-01

Full Text Available Conservation areas with the objective for collection and exchange plant materials have been speculated as weed bank for surrounding areas. Objective of this study was to identify and characterize ruderal invasive weeds in the Bogor Botanic Gardens (BBG. Observations were conducted in all vak (collection blocks in the BBG in order to identify the weeds species, determine their invasiveness, dominance and distribution. Weeds associations with host plants were observed. Current weed control program and data of dead trees collection were analyzed in relevant to weed. Distribution of weeds outside BBG was observed by transects method following river and road directions. Results showed that there were seven invasive weeds, i.e., Cecropia adenopus (Cecropiaceae, Cissus nodosa Blume (Vitaceae, Cissus sicyoides Blume (Vitaceae, Dioscorea bulbifera L. (Dioscoreaceae, Ficus elastica Roxb. (Moraceae, Mikania micrantha H.B.K. (Asteraceae and Paraserianthes falcataria (L. Nielsen (Fabaceae. These seven weeds species invaded 41 out of 215 plant families in BBG. Six species of weeds, i.e., C. adenopus, C. nodosa Blume., C. sicyoides Blume., D. bulbifera L., M. micrantha H.B.K. and P. falcataria (L. Nielsen, were introduced as BBG collections for the first time while the F. elastica Roxb was considered as native. It is most likely that the weeds dispersal agents are the wind, birds, bats, visitors, and waters. All of these weeds existed in surrounding areas outside BBG. Given the detrimental impact of invasive weeds on the plant collection in BBG, it is necessary to develop long–term comprehensive control measures both inside and neighboring areas by involving other government authorities beyond BBG.

Weeds and Wildlife: Perceptions and Practices of Weed Managers

Directory of Open Access Journals (Sweden)

Emma H Carlos

2014-01-01

Full Text Available Negative impacts of invasive plants or weeds on biodiversity have been well established yet their role in providing key habitats and resources for wildlife has been little understood. Weed removal thus has the potential to adversely affect wildlife but whether this is considered during weed management is poorly known. To determine the extent of this knowledge, we examined the perceptions of weed managers regarding wildlife and weed management in Victoria, Australia. We surveyed 81 weed managers of varying levels of experience from different types of organisations, including state and local government, community groups and private companies. We found 90% of managers had observed wildlife-weed interactions and that most (70% adjusted management programmes to accommodate wildlife. Despite this, few (19% had adopted the recommended practice of combining gradual weed removal with re-vegetation. While management programmes included monitoring of native vegetation, consideration of wildlife monitoring in weed management was rare. This highlights the need for management to better understand and respond to wildlife-weed relationships. If the improvement of wildlife habitat is included in the objectives of weed programmes, as it should be, then wildlife should also be incorporated in project monitoring. This would lead to a greater understanding of the role weeds and their management have in each situation and, ultimately, more informed decision making.

Spatial variation in seed bank dynamics of two annual brome species in the northern Great Plains

Science.gov (United States)

Annual bromes decrease forage production in northern central plains rangelands of North America. Early life history stages are when plants are most failure-prone, yet studying death post-germination and prior to emergence is difficult. In seed bank collections conducted over the course of two growin...

Mechanical weed control in organic winter wheat

Directory of Open Access Journals (Sweden)

Euro Pannacci

2017-12-01

Full Text Available Three field experiments were carried out in organic winter wheat in three consecutive years (exp. 1, 2005-06; exp. 2, 2006- 07; exp. 3, 2007-08 in central Italy (42°57’ N - 12°22’ E, 165 m a.s.l. in order to evaluate the efficacy against weeds and the effects on winter wheat of two main mechanical weed control strategies: i spring tine harrowing used at three different application times (1 passage at T1, 2 passages at the time T1, 1 passage at T1 followed by 1 passage at T1 + 14 days in the crop sowed at narrow (traditional row spacing (0.15 m; and ii split-hoeing and finger-weeder, alone and combined at T1, in the crop sowed at wider row spacing (0.30 m. At the time T1 winter wheat was at tillering and weeds were at the cotyledons-2 true leaves growth stage. The experimental design was a randomized block with four replicates. Six weeks after mechanical treatments, weed ground cover (% was rated visually using the Braun-Blanquet coverabundance scale; weeds on three squares (0.6×0.5 m each one per plot were collected, counted, weighed, dried in oven at 105°C to determine weed density and weed above-ground dry biomass. At harvest, wheat ears density, grain yield, weight of 1000 seeds and hectolitre weight were recorded. Total weed flora was quite different in the three experiments. The main weed species were: Polygonum aviculare L. (exp. 1 and 2, Fallopia convolvulus (L. Á. Löve (exp. 1 and 3, Stachys annua (L. L. (exp. 1, Anagallis arvensis L. (exp. 2, Papaver rhoeas L. (exp.3, Veronica hederifolia L. (exp. 3. In the winter wheat sowed at narrow rows, 2 passages with spring-tine harrowing at the same time seems to be the best option in order to reconcile a good efficacy with the feasibility of treatment. In wider rows spacing the best weed control was obtained by split hoeing alone or combined with finger-weeder. The grain yield, on average 10% higher in narrow rows, the lower costs and the good selectivity of spring-tine harrowing

Effect of Dose and Oxadiargyl Application Time at the Different Growth Stages on Weed Biomass and Tuber Yield of Potato (Solanum tuberosum L.

Directory of Open Access Journals (Sweden)

E. Samadi Kalkhoran

2016-01-01

Full Text Available To evaluate the effects of dose and application time of oxadiargyl, as a postemergence herbicide, on weed biomass and tuber yield of potato, a factorial experiment based on randomized complete block design with 3 replications was conducted at Alaroog Research Station at the University of Mohaghegh-Ardabili in 2013. Treatments consisted of oxadiargyl dosages (0, 0.05, 0.1, 0.2, 0.4, 0.6 and 0.8 lit a.i /ha, and its time of applications at different potato growth stages (potato emergence, stolon initiation and potato tuber bulking, weed free treatment was considered as control. Statistical analysis showed that 0.8 lit a.i/ha of oxadiargyl reduced biomass of weed by 66.16 percent. Oxadiargyl application at emergence time resulted in highest percent reduction of weed biomass. Results, also, showed that application 0.8 lit a.i/ha of oxadiargyl, after weed free condition, increased number of seed tuber and total tuber yield by 82.16 and 51.59 percent respectively, but it reduced number of non seed tuber by 43.17 percent. Application of oxadiargyl at emergence time, as compared with the other application times, resulted in highest increase in the number of seed tuber and total tuber yield, but it did not affected number of non seed tubers. Interaction effect of dose by time of oxadiargyl application revealed that using 0.8 lit a.i/ha dose at potato emergence time increased number of edible tubers by 100%. It may be conducted that application of this dose at potato emergence time was highly efficient in controlling weeds and increasing potato tuber yield.

Identification of the infection route of a Fusarium seed pathogen into nondormant Bromus tectorum seeds

Science.gov (United States)

JanaLynn Franke; Brad Geary; Susan E. Meyer

2014-01-01

The genus Fusarium has a wide host range and causes many different forms of plant disease. These include seed rot and seedling blight diseases of cultivated plants. The diseases caused by Fusarium on wild plants are less well-known. In this study, we examined disease development caused by Fusarium sp. n on nondormant seeds of the important rangeland weed Bromus...

WEED INTERFERENCE IN COTTON PLANTS GROWN WITH REDUCED SPACING IN THE SECOND HARVEST SEASON

Directory of Open Access Journals (Sweden)

MICHEL ALEX RAIMONDI

2017-01-01

Full Text Available Changes in row spacing may result in changes in crop and weed behavior and crop-weed competition. A study was performed to determine the periods of weed presence and weed control in cotton sown with 0.76 m spacing between planting rows. Cotton cultivar FM 993 was sown on 01/08/2010 with the aim of reaching a density of 190,000 seeds ha-1. Treatments with either weed presence or weed control during the first 0, 5, 10, 15, 22, 29, 36, 43, 50, 57, 64, 71, and 190 days of cultivation were established to determine the period prior to weed interference (PPI, total period of interference prevention (TPIP and critical period of weed control (CPWC. The weed species with high relative importance were Amaranthus retroflexus, Bidens pilosa, Eleusine indica, Digitaria horizontalis, Alternanthera tenella, and Commelina benghalensis. Considering a maximum yield loss of 5%, the PPI was established 11 days after cotton emergence (DAE, the TPWC at 46 DAE, and the CPWC between 11 and 46 DAE, for a total duration of 35 days. Considering a maximum acceptable yield loss equal to the standard deviation for the weed-free treatment, the PPI was established at 6 DAE, the TPWC at 55 DAE, and the CPWC between 6 and 55 DAE for a total duration of 49 days.

Complex foraging ecology of the red harvester ant and its effect on the soil seed bank

Science.gov (United States)

Luna, Pedro; García-Chávez, Juan Héctor; Dáttilo, Wesley

2018-01-01

Granivory is an important interaction in the arid and semi-arid zones of the world, since seeds form an abundant and nutritious resource in these areas. While species of the genus Pogonomyrmex have been studied in detail as seed predators, their impact on seed abundance in the soil has not yet been explored in sufficient depth. We studied the impact of the harvesting activities of the ant Pogonomyrmex barbatus on seed abundance in the soil of the Zapotitlán valley, Mexico. We found that P. barbatus activity significantly impacts the abundance of seeds in the soil, which is lower in the sites where P. barbatus forages than it is in sites with no recorded foraging. We also found that P. barbatus distributes intact seeds of three tree species, two of which are nurse plants, and could consequently be promoting the establishment of these species. Using tools derived from graph theory, we observed that the ant-seed interactions exhibit a nested pattern; where more depredated seed species seem to be the more spatially abundant in the environment. This study illustrates the complex foraging ecology of the harvester ant P. barbatus and elucidates its effect on the soil seed bank in a semi-arid environment.

Seed dormancy and seed longevity: from genetic variation to gene identification

NARCIS (Netherlands)

Nguyen, T.P.

2014-01-01

Seed dormancy and seed longevity are the most important survival traits in the soil seed bank. Both traits are induced during seed maturation and evolved to assure seed survival during environmental conditions that cannot support the regular course of life. Seed dormancy is related to the timing of

Efeito do condicionamento osmótico de sementes de soja sobre a habilidade competitiva da cultura com as plantas daninhas Soybean seed osmoconditioning effect on the crop competitive ability against weeds

Directory of Open Access Journals (Sweden)

U.R. Nunes

2003-04-01

weeds. Soybean seeds, variety UFV 16, were harvested at the phenological stages R8 and R8 + 15 days and submitted to osmotic conditioning in a polyethylene glycol (PEG 6000 solution, at -0.8 Mpa, and 20ºC, for 96 hours. Seeds without pre-hydration treatment harvested at the same phenological stage were used as control. Seed germination and vigor were analyzed under laboratory conditions through the standard germination test, using a randomized complete design, 2x2 factorial, with 4 repetitions. Two experiments were conducted under field conditions, using seeds with and without osmotic conditioning, also harvested at the phenological stages R8 and R8 + 15 days, respectively. In both the experiments using randomized blocks with four repetitions, the effects of different weed coexistence periods (0, 15, 30, 45, 60 and 125 days after soybean emergence with the soybean crop were evaluated. The highest germination and vigor values related to initial and final stands and to grain yield were found in the treatments of seeds conditioned and harvested at the phenological stage R8. Other characteristics evaluated (plant height, number of nodes, number of pods per plant, number of seeds per plant, number of seeds per pod and 100-seed weight were not altered by conditioning. The competitive effect between weed and crop was verified by the lowest dry biomass values of the weeds, in the treatments in which seeds were harvested at the phenological stage R8 and were osmotically conditioned.

Soil seed banks in plant invasions: promoting species invasiveness and long-term impakt on plant community dynamics

Czech Academy of Sciences Publication Activity Database

Gioria, M.; Pyšek, Petr; Moravcová, Lenka

2012-01-01

Roč. 84, č. 2 (2012), s. 327-350 ISSN 0032-7786 R&D Projects: GA ČR GA206/09/0563 Institutional support: RVO:67985939 Keywords : soil seed bank * plant invasions * species invasive ness Subject RIV: EF - Botanics Impact factor: 2.833, year: 2012

Controle de plantas daninhas na cultura da soja através do herbicida acetochlor em sistemas de semeadura direta e preparo convencional Weed control in soybean crop using the herbicide acetochlor under direct seeding and conventional system

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M.V.W. Ferri

2002-08-01

Full Text Available O manejo do solo altera a bioatividade dos herbicidas residuais e influi na persistência, na eficácia de controle das plantas daninhas e na fitotoxicidade para as culturas. Um experimento foi conduzido na Faculdade de Agronomia da Universidade Federal do Rio Grande do Sul, com objetivo de avaliar a eficácia de controle das plantas daninhas pelo herbicida acetochlor aplicado em solo Argissolo Vermelho sob semeadura direta e preparo convencional. O delineamento experimental foi o de blocos casualizados com quatro repetições em parcelas subsubdivididas. O acetochlor foi utilizado nas doses de 0, 1.680, 2.520, 3.360 e 4.200 g ha¹. Foi avaliado o controle das plantas daninhas aos 15, 30 e 45 dias após aplicação do acetochlor (DAT. Foram avaliados também a injúria na cultura da soja aos 14, 21 e 28 DAT e a matéria seca das plantas daninhas aos 40 e 60 DAT. O herbicida acetochlor foi mais eficiente no controle das plantas daninhas no solo sob preparo convencional que sob semeadura direta. A produção de matéria seca dessas plantas foi menor no preparo convencional comparado à semeadura direta. Não ocorreu injúria à cultura da soja.Soil management affects herbicide bioactivity and changes persistence, weed control and crop selectivity. An experiment was carried out at the Federal University of Rio Grande do Sul - Brazil, to evaluate the efficacy of the herbicide acetochlor in controling weeds in a Paleudult soil under direct seeding and conventional system. The following treatments were tested: acetochlor at 0, 1,680, 2,520, 3,360 and 4,200 g ha-1, applied under tillage and no-till systems. Assessments included crop injury at 14, 21 and 28 days after acetochlor aplication, weed dry matter at 40 and 60 days after herbicide aplication and weed control at 15, 30 and 45 days after acetochlor aplication. Acetochlor was more efficient under conventional than direct seeding system. Weed dry biomass was lower under conventional than direct

Impurities in alfalfa seed and their impact on processing technology

OpenAIRE

Đokić, Dragoslav; Stanisavljević, Rade; Marković, Jordan; Terzić, Dragan; Anđelković, Bojan

2012-01-01

The aim of this research was to determine relevant parameters and optimal alfalfa seed processing technology by a comparative analysis of two systems of machinery for processing natural alfalfa seed of different purity (59.0% and 71.0%) and with different content of impurities. The relevant parameters monitored during the test were: pure seed (%), weed seeds and seeds of other crops (%), inert matter (%), amount of processed seed (kg), seed processing time (min), consumption of steel powder (...

Heliolactone, a non-sesquiterpene lactone germination stimulant for root parasitic weeds from sunflower.

Science.gov (United States)

Ueno, Kotomi; Furumoto, Toshio; Umeda, Shuhei; Mizutani, Masaharu; Takikawa, Hirosato; Batchvarova, Rossitza; Sugimoto, Yukihiro

2014-12-01

Root exudates of sunflower (Helianthus annuus L.) line 2607A induced germination of seeds of root parasitic weeds Striga hermonthica, Orobanche cumana, Orobanche minor, Orobanche crenata, and Phelipanche aegyptiaca. Bioassay-guided purification led to the isolation of a germination stimulant designated as heliolactone. FT-MS analysis indicated a molecular formula of C20H24O6. Detailed NMR spectroscopic studies established a methylfuranone group, a common structural component of strigolactones connected to a methyl ester of a C14 carboxylic acid via an enol ether bridge. The cyclohexenone ring is identical to that of 3-oxo-α-ionol and the other part of the molecule corresponds to an oxidized carlactone at C-19. It is a carlactone-type molecule and functions as a germination stimulant for seeds of root parasitic weeds. Heliolactone induced seed germination of the above mentioned root parasitic weeds, while dehydrocostus lactone and costunolide, sesquiterpene lactones isolated from sunflower root exudates, were effective only on O. cumana and O. minor. Heliolactone production in aquacultures increased when sunflower seedlings were grown hydroponically in tap water and decreased on supplementation of the culture with either phosphorus or nitrogen. Costunolide, on the other hand, was detected at a higher concentration in well-nourished medium as opposed to nutrient-deficient media, thus suggesting a contrasting contribution of heliolactone and the sesquiterpene lactone to the germination of O. cumana under different soil fertility levels. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study of allelopathic effects of Eucalyptus erythrocorys L. crude extracts against germination and seedling growth of weeds and wheat.

Science.gov (United States)

Ben Ghnaya, Asma; Hamrouni, Lamia; Amri, Ismail; Ahoues, Haifa; Hanana, Mohsen; Romane, Abderrahmane

2016-09-01

Allelopathic materials inside a tree can produce positive or negative change in the survival, growth, reproduction and behaviour of other organisms if they escape into the environment. To assess these effects, this work was carried out to evaluate the allelopathic impact of Eucalyptus erythrocorys L. on seed germination and seedling growth of two weeds: Sinapis arvensis L. and Phalaris canariensis L.; on one cultivated crop: Triticum durum L. Aqueous; and on ethanolic leaf extracts of E. erythrocorys L. The study was effected using four concentrations (10, 20, 25 and 30 μL/mL) while distilled water was used as a control. The results showed that the E. erythrocorys L. crude extracts had an inhibitory effect on seed germination and seedling growth of both studied weeds and wheat. The inhibition rate was increased by the increase in extract concentration. Only ethanolic extracts of E. erythrocorys L. induced a significant inhibition of seed germination of durum wheat. The effect of E. erythrocorys L. crude extracts was more severe on weeds than on durum wheat. These results indicate that the seedling growth, especially radicle elongation, was the more sensitive indicator to evaluate the effects of extracts than was the seed germination.

Processing scale-up of sicklepod (Senna obtusifolia L.) seed.

Science.gov (United States)

Harry-O'Kuru, Rogers E; Mohamed, Abdellatif

2009-04-08

Sicklepod (Senna obtusifolia L.) is an invasive weed species especially of soybean and other field crops in the southeastern United States. The seeds contain a small amount (5-7%) of a highly colored fat as well as various phenolics, proteins, and galactomannans. The color of sicklepod seed oil is such that the presence of a small amount of the weed seed in a soybean crush lowers the quality of the soybean oil. Sicklepod is very prolific, and even volunteer stands yield >1000 lb of seed per acre, and prudence calls for tapping the potential of this weed as an alternative economic crop in the affected region. Pursuant to this, we have shown in laboratory-scale work the feasibility of separating the components of sicklepod seed. However, at kilogram and higher processing quantities, difficulties arise leading to modification of the earlier approach in order to efficiently separate components of the defatted seed meal. In a version for cleanly separating the proteins, the defatted meal was extracted with 0.5 M NaCl solution to remove globular proteins. Prolamins were extracted from the pellet left after salt extraction using 80% ethanol, and glutelins were then obtained in 0.1 N alkali from the residual solids left from ethanol treatment. In a pilot-scale version for water-soluble polysaccharides, the defatted meal was stirred with deionized water (DI) and centrifuged. The pooled centrifugates were heated to 92 degrees C (20-25 min), filtered, cooled to room temperature, and passed through a column of Amberlite XAD-4 to separate the polysaccharides from the anthraquinones. Senna obtusifolia L. is a one-stop-shop of a seed (from food components to medicinals).

Leucaena allelopathy on weeds and soybean seed germination / Alelopatia de Leucena sobre soja e plantas invasoras

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Raquel Leszczynski

2009-07-01

Full Text Available With the advance of agriculture, there was consequent rising in environment degradation. Therefore, It is interesting the use of plants which have in their chemical composition substances capable of helping in the control of weeds to minimize the use of pesticides. Hence, the objective of this paper was to evaluate solutions of leucena extract on weeds that are frequent on soybean crop. The treatments were leucena extracts at 0, 20, 40, 60, 80 and 100% at room temperature water and water heated to 80°C. The extracts were obtained by crushing 200g of leucena leaves and mixing them with one liter of distilled water with the help of a blender. Seeds were kept in B.O.D. at a temperature of 25°C, with a photoperiod of 12 hours of light. Evaluations were done on a daily basis, from the first to the last day of the experiment, varying according to the species. Results show a negative interference of the extracts, both hot and cold, in the root length of Ipomoea grandifolia, in the percentage of germination and in the root length of Arrowleaf sida and Hair beggarticks. There was no negative interference in the analyzed parameters for soybean seeds. Thus, the results indicate allelopatic potential of Leucaena leuucocephala as an alternative for the management of weeds without interfering on the development of the soybean crop.Com o desenvolvimento da agricultura surgiram os conseqüentes aumentos na degradação ambiental. Assim, estuda-se a utilização de plantas que possuam em sua composição química substâncias capazes de auxiliar no controle de plantas invasoras, amenizando o uso de agrotóxicos. Desta forma, o objetivo do trabalho foi avaliar soluções de extratos de leucena sobre plantas invasoras que freqüentemente ocorrem na cultura da soja. Foram utilizados como tratamentos os seguintes extratos de leucena nas proporções de: 0, 20, 40, 60, 80 e 100% com água à temperatura ambiente e com água aquecida à 80°C. Os extratos foram

Competitive Ability of Lentil (Lens culinaris L. Cultivars to Weed Interference under Rain-fed Conditions

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Javad Hamzei

2016-07-01

Full Text Available Introduction The lentil or masoor (Lens culinaris L. is a brushy annual plant of the legume family, grown for its lens-shaped seeds. Lentil has been one of the first crops domesticated in the Near East. With 26% protein, lentil is the vegetable with the highest level of protein other than soybeans, and it is an important part of people’s diet in many parts of the world. It is reported that the average yield of lentil is considerably low compared to its potential yield of 1500-2000 kg ha-1, obtained in the research field. Such lower yield may be attributed to the poor management of the crop among which poor weed management is an important one. Lentil crop is not very competitive against weeds due to small and weak canopy. Weed reduces yield through competition with crop plants for space, moisture, light and plant nutrients. Generally 20 to 30% losses of grain yield are quite usual and may increase even 50%, if the crop management practices are not properly followed (Deihimfard et al., 2007. The modern lentil varieties give good yield if the land remains weed free for the first one month. However, most of the farmers are reluctant to control weeds in lentil field timely and finally, loses yield. Inadequate weed control was found to reduce the yield 40-66% in lentil (Erman et al., 2008; McDonald et al., 2007. A major component of integrated weed management is the use of more competitive crops, although the selection of better crop competitiveness is a difficult task. The use of competitive plants for weed control could be considered cost-effective and less labour-intensive, and thus reduces the amount of herbicides required. Therefore, the aim of this research was to evaluate lentil competitive ability and to compare the effects of cultivar selection. Materials and methods An experiment was carried out as a factorial based on a randomized complete block design (RCBD with 10 treatments and three replications. Experimental treatments included hand

Factors affecting the population density of weeds and yield loss of them in wheat: a case study in Golestan province – Bandargaz

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Mohamad Zaman Nekahi

2016-05-01

Full Text Available To investigate the factors affecting the population density of weeds and yield loss of them in wheat, a non systematic survey experiment was conducted in 45 fields in the township of Bandar-gaz (Sarmahaleh village in 2012. Sampling of wheat and weeds were taken in two stages (Heading and Harvest maturity by randomized to the five points of each field using quadrate size 1m*1m. In this study all information about crop management including Land area , farmers experience , the seed bed preparation, sowing date , cultivar and site preparation of them, sowing ways , seed rate , weeds control ways , kind , amount and time of herbicide , fungicide use and wheat harvest time were collected during a growing season by preparing questionnaire and complete them with farmers. At the end of the growing season, the actual yield harvested by farmers’ ‬ recorded. Among the various parameters, Wheat plant and raceme density, farmer experience, Kind of variety and use of Tapic+Geranestar herbicide had significant effects on weed population. With increased wheat plant density, weed density decreased. Also there was less weed density in field of high experience farmer. Weed density was lesser in N8118 variety than N8019 variety and not use Tapic+granestar herbicide due to increased of weeds density. Among weed different species, Avena sp, Phalaris minor and Sinapis arvense had highest negative effect on wheat yield. Model study showed if wheat plant density was optimum and there were weeds, yield will be 2713kg/ha and if weeds remove yield will increase to 2877kg/ha (yield gap equal164kg/ha. Amaong weed, Phalaris minor (12 plant per m-2, Sinapis arvensis (3plant per m-2 and Avena sp (2 plant per m-2 with 65, 18 and 17% yield loss respectively, were the strongest competitor with wheat.

Efficacy of Maister OD (Foramsulfuron + Idosulfuron a New Herbicide in Controlling Weeds of Corn Fields

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J. Abdi

2012-07-01

Full Text Available To evaluate the efficacy of a new herbicide Foramsulfuron +Idosulfuron (Maister OD against other herbicides in corn fields, this experiment was fulfielld in 2010 at Mahidasht, Research Center of Agriculture and Natural Resources of Kermanshah, Iran. It was concucted in randomized complete block design with four replications and 11 treatments. In this experiment, three doses of herbicides (38.75, 46.5 and 54.25 g/ha including foramsulfuron + idosulfuron along with Nicusulfuron, ForamSulfuron, Rimsulfuron, Foramsulfuron + Rimsulfuron , Bromicid + hand weeding narrow leaf weeds, Bromicid + Nicusulfuron and U46 + hand weeding of narrow leaf weeds and a complete weeding as the control treatments were investigated. Weeds present in the field were Xanthium stromarium,Chenopedium album, Portulaca oleracea, Sorgum halepense and Setaria virdis. The results of this study showed that doses 38.75 and 46.5 g/ha of herbicide foramsulfuron + idosulfuron after treatments of Bromicid + Nicusulfuron and, Bromicid + narrow leaf weed, hand weeding respectively could control 90 and 86 % of weeds in corn field and increase its yields significantly. Because there are presently few registered herbicide available in Iran, necessity of finding proper herbicides to control weeds in corn field and based on the results oblained from this experiment it seems using 46.5 and 38-75 grams per hectare respectively of foramsulfuron + idosulfuron could be a better option than other herbicides to control weeds in corn fields and increase its seed yield.

Biology and management of Avena fatua and Avena ludoviciana: two noxious weed species of agro-ecosystems.

Science.gov (United States)

Bajwa, Ali Ahsan; Akhter, Muhammad Javaid; Iqbal, Nadeem; Peerzada, Arslan Masood; Hanif, Zarka; Manalil, Sudheesh; Hashim, Saima; Ali, Hafiz Haider; Kebaso, Lynda; Frimpong, David; Namubiru, Halima; Chauhan, Bhagirath Singh

2017-08-01

Avena fatua and Avena ludoviciana are closely related grass weed species infesting a large number of crops around the world. These species are widely distributed in diverse agro-ecosystems from temperate to sub-tropical regions due to their unique seed traits, successful germination ecology, high competitive ability, and allelopathic potential. A. fatua is more widespread, adaptable, and problematic than A. ludoviciana. Both these species infest major winter and spring crops, including wheat, oat, barley, canola, maize, alfalfa, and sunflower, causing up to 70% yield losses depending on crop species and weed density. Chemical control has been challenged by large-scale herbicide resistance evolution in these weed species. A. fatua is the most widespread herbicide-resistant weed in the world, infesting about 5 million hectares in 13 countries. The use of alternative herbicides with different modes of action has proved effective. Several cultural practices, including diverse crop rotations, cover crops, improved crop competition (using competitive cultivars, high seed rates, narrow row spacing, altered crop geometry), and allelopathic suppression, have shown promise for controlling A. fatua and A. ludoviciana. The integrated use of these cultural methods can reduce the herbicide dose required, and lower dependency on herbicides to control these grasses. Moreover, integrated management may successfully control herbicide-resistant populations of these weed species. The use of integrated approaches based on the knowledge of biology and ecology of A. fatua and A. ludoviciana may help to manage them sustainably in the future.

Effect of fungal and plant metabolites on broomrapes (Orobanche and Phelipanche spp.) seed germination and radicle growth.

Science.gov (United States)

Cimmino, Alessio; Fernández-Aparicio, Mónica; Andolfi, Anna; Basso, Sara; Rubiales, Diego; Evidente, Antonio

2014-10-29

Orobanche and Phelipanche species (the broomrapes) are root parasitic plants, some of which cause heavy yield losses on important crops. The development of herbicides based on natural metabolites from microbial and plant origin, targeting early stages on parasitic plant development, might contribute to the reduction of broomrape seed bank in agricultural soils. Therefore, the effect of metabolites belonging to different classes of natural compounds on broomrape seed germination and radicle development was assayed in vitro. Among the metabolites tested, epi-sphaeropsidone, cyclopaldic acid, and those belonging to the sesquiterpene class induced broomrape germination in a species-specific manner. epi-Epoformin, sphaeropsidin A, and cytochalasans inhibited germination of GR24-treated broomrape seeds. The growth of broomrape radicle was strongly inhibited by sphaeropsidin A and compounds belonging to cyclohexene epoxide and cytochalasan classes. Broomrape radicles treated with epi-sphaeropsidone developed a layer of papillae while radicles treated with cytochalasans or with sphaeropsidin A turned necrotic. These findings allow new lead natural herbicides for the management of parasitic weeds to be identified.

Dicotyledon Weed Quantification Algorithm for Selective Herbicide Application in Maize Crops.

Science.gov (United States)

Laursen, Morten Stigaard; Jørgensen, Rasmus Nyholm; Midtiby, Henrik Skov; Jensen, Kjeld; Christiansen, Martin Peter; Giselsson, Thomas Mosgaard; Mortensen, Anders Krogh; Jensen, Peter Kryger

2016-11-04

The stricter legislation within the European Union for the regulation of herbicides that are prone to leaching causes a greater economic burden on the agricultural industry through taxation. Owing to the increased economic burden, research in reducing herbicide usage has been prompted. High-resolution images from digital cameras support the studying of plant characteristics. These images can also be utilized to analyze shape and texture characteristics for weed identification. Instead of detecting weed patches, weed density can be estimated at a sub-patch level, through which even the identification of a single plant is possible. The aim of this study is to adapt the monocot and dicot coverage ratio vision (MoDiCoVi) algorithm to estimate dicotyledon leaf cover, perform grid spraying in real time, and present initial results in terms of potential herbicide savings in maize. The authors designed and executed an automated, large-scale field trial supported by the Armadillo autonomous tool carrier robot. The field trial consisted of 299 maize plots. Half of the plots (parcels) were planned with additional seeded weeds; the other half were planned with naturally occurring weeds. The in-situ evaluation showed that, compared to conventional broadcast spraying, the proposed method can reduce herbicide usage by 65% without measurable loss in biological effect.

Dormancy in Plant Seeds

NARCIS (Netherlands)

Hilhorst, H.W.M.; Finch-Savage, W.E.; Buitink, J.; Bolingue, W.; Leubner-Metzger, G.

2010-01-01

Seed dormancy has been studied intensely over the past decades and, at present, knowledge of this plant trait is at the forefront of plant biology. The main model species is Arabidopsis thaliana, an annual weed, possessing nondeep physiological dormancy. This overview presents the state-of-the-art

The legacy of plant invasions: changes in the soil seed bank of invaded plant communities

Czech Academy of Sciences Publication Activity Database

Gioria, Margherita; Pyšek, Petr

2016-01-01

Roč. 66, č. 1 (2016), s. 40-53 ISSN 0006-3568 R&D Projects: GA ČR GA15-13491S; GA ČR GB14-36079G Grant - others:AV ČR(CZ) AP1002 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:67985939 Keywords : plant invasions * soil seed bank * impact Subject RIV: EH - Ecology, Behaviour Impact factor: 5.378, year: 2016

Impact of crop residues on seed germination of native desert plants ...

African Journals Online (AJOL)

Crop residues produce allelochemicals that may inhibit seed germination of many weeds. In this study, I assessed the effect of aqueous extracts of three crop residues (radish, rocket and rhodes) on final germination percentage and germination rate of four desert plants recorded as weeds in the United Arab Emirates farms ...

How does population genetic diversity change over time? An experimental seed bank study of Atriplex tatarica (Chenopodiaceae)

Czech Academy of Sciences Publication Activity Database

Mandák, Bohumil; Plačková, Ivana

2009-01-01

Roč. 204, č. 2 (2009), s. 423-433 ISSN 0367-2530 R&D Projects: GA AV ČR IAA6005206; GA AV ČR IAA600050707 Institutional research plan: CEZ:AV0Z60050516 Keywords : seed banks * succession * competition Subject RIV: EF - Botanics Impact factor: 1.439, year: 2009

Simplified strigolactams as potent analogues of strigolactones for the seed germination induction of Orobanche cumana Wallr.

Science.gov (United States)

Lumbroso, Alexandre; Villedieu-Percheron, Emmanuelle; Zurwerra, Didier; Screpanti, Claudio; Lachia, Mathilde; Dakas, Pierre-Yves; Castelli, Laure; Paul, Verity; Wolf, Hanno Christian; Sayer, Danielle; Beck, Andreas; Rendine, Stefano; Fonné-Pfister, Raymonde; De Mesmaeker, Alain

2016-11-01

Strigolactones play an important role in the rhizosphere as signalling molecules stimulating the seed germination of parasitic weed seeds and hyphal branching of arbuscular micorrhiza, and also act as hormones in plant roots and shoots. Strigolactone derivatives, e.g. strigolactams, could be used as suicidal germination inducers in the absence of a host crop for the decontamination of land infested with parasitic weed seeds. We report the stereoselective synthesis of novel strigolactams, together with some of their critical physicochemical properties, such as water solubility, hydrolytic stability, as well as their short soil persistence. In addition, we show that such strigolactams are potent germination stimulants of O. cumana parasitic weed seeds and do not affect the seed germination and the root growth of sunflower. The novel strigolactam derivatives described here compare favourably with the corresponding GR-28 strigolactones in terms of biological activity and physicochemical properties. However, we believe strigolactone and strigolactam derivatives require further structural optimisation to improve their soil persistence to demonstrate a potential for agronomical applications. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Effect of Planting Date and Weed Control Methods on Yield and Agronomic Traits of Sunflower (Helianthus annuus L. in Khoy Region

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M. Akbari

2010-12-01

Full Text Available Effects of planting dates and weed control methods on yield and agronomic traits of sunflower was investigated. A factorial experiment based on a complete randomized blocks design with four replications was conducted in 2009. Treatments consisted of three planting date (April 4th, May5th and Juns5th and five weed control methods, Trifluralin (2 Lit/ha + Fokus (1.5 Lit/ha, Trifluralin+Nabu-s (3Lit/ha, Trifluralin, Hand weeding and without control. Results indicated that planting dates and weed control methods significantly affected head diameter, 100 grain weight, seed number per head and grain yield. Harvest index and oil percent was affected only by planting dates. The highest grain yield (630.1 g/m2, was produced in the second planting date (May 5 by using Trifluralin+Fokus. Delaying sowing date (after May 5 significantly decreased grain yield. The most important weeds in the experimental site were common lambsquarter (Chenopodium album, field bind weed (Convolvulus arvensis, bastard cabbage (Rapistrum rugosum, flower-of-an-hour (Hibiscus trionum, cockspur grass (Echinochloa colorum and green bristle grass (Setaria verticillata. It was observed that the dry matter weight sharply varied in all weed species in different planting dates, that is, in the 4th April the dry matter production of common lambsquarter and bastard cabbage, in June 5th planting date were maximum. Dry matter of broad leaf and narrow leaf weeds in the date of May 5th was lower than the other two planting dates. The interaction of planting date ×control methods on head diameter, seed number per head, grain yield and weeds dry matter was significant.

Weed flora, yield losses and weed control in cotton crop

OpenAIRE

Jabran, Khawar

2016-01-01

Cotton (Gossypium spp.) is the most important fiber crop of world and provides fiber, oil, and animals meals. Weeds interfere with the growth activities of cotton plants and compete with it for resources. All kinds of weeds (grasses, sedges, and broadleaves) have been noted to infest cotton crop. Weeds can cause more than 30% decrease in cotton productivity. Several methods are available for weed control in cotton. Cultural control carries significance for weed control up to a certain extent....

Seed predation in a Mediterranean pasture: can ants modify the floristic composition of soil seed banks? Depredación de semillas en un pastizal mediterráneo: ¿pueden las hormigas modificar la composición florística de los bancos de semillas?

Directory of Open Access Journals (Sweden)

TÍSCAR ESPIGARES

2005-12-01

Full Text Available Ants may play an important role on vegetation dynamics, especially in arid and semiarid environments, where they can consume a high proportion of the produced seeds. Although some works have analysed the influence of seed predation by ants on the density of vegetation in Mediterranean pastures, there are no studies on the influence of ant activity upon the floristic composition of the vegetation and the soil seed banks in this kind of ecosystem. We have studied the effect of ant exclusion on the floristic composition of the vegetation and the soil seed bank in a Mediterranean pasture of central Spain. We sampled the floristic composition of the pasture during 2002 and 2003 springs and also we collected soil seed bank samples in autumn 2002. Floristic composition of soil seed banks was estimated by means of greenhouse germination. Cerastium semidecandrum seeds were almost four times more abundant in the plots subjected to ant exclusion than in those with ant activity. Due to the high spatial heterogeneity shown by soil seed banks, we have corrected the differences found between the autumn soil seed banks subjected to different ant treatments by using the floristic composition of the pasture community in the previous spring, as it was the primary source of the seeds collected in autumn. We found significant differences between the floristic composition of the soil seed banks subjected to ant exclusion and control treatments. However, no effects where found when the same procedure was used to detect ant effects on the spring adult community, highlighting the necessity of longer time spans for these pastures to manifest changes taking place at the soil seed bank stageLa mirmecofauna juega un papel fundamental sobre la dinámica de la vegetación, especialmente en zonas de carácter árido o semiárido, donde puede llegar a consumir una elevada proporción de las semillas producidas, condicionando la composición florística de la vegetación. Aunque

Biologia e manejo de plantas daninhas em áreas de plantio direto Weed biology and management in no-tillage areas

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F.G. Gomes JR.

2008-01-01

light incidence on the soil surface influence dormancy of some weed species. Adequate strategy for weed control under the no tillage system requires knowledge on weed seed bank dynamics and must integrate methods of weed control in order to reduce the use of herbicides. The release of alellopathic compounds by some of the cover crops and the suppressive effects of crop residue cover are important measures in order to integrate the chemical control of weeds. However, it is important to be aware of the negative impacts over certain cultivated species of plants. Studies on weed biology and alellopathy of cover crops, associated to herbicide application technology and precision agriculture may contribute to weed control optimization in areas under no tillage system.

Special aspects of seed reproduction of the Liriodendron tulipifera L. in the context of plant introduction in the Ukraine’s Right-Bank forest steppe

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Sulyga Nadezhda Vladimirovna

2015-12-01

Full Text Available It was confirmed that in order to overcome seed dormancy and to improve the seed germination of Liriodendron tulipifera L. need stratification. Seed germination of L. tulipifera is 5,2–7,4%, the execution of seeds in one fruit is 5,3–16,0%. The depth of seeding L. tulipifera affects their germination. The seedlings of L. tulipifera are characterized by successful growth and development in the conditions of introduction to the Right Bank Forest-Steppe zone of Ukraine.

Persistent Soil Seed Banks for Natural Rehabilitation of Dry Tropical Forests in Northern Ethiopia

OpenAIRE

Gebrehiwot, K.; Heyn, M.; Reubens, B.; Hermy, M.; Muys, B.

2007-01-01

Dry tropical forests are threatened world-wide by conversion to grazing land, secondary forest, savannah or arable land. In Ethiopia, natural dry forest cover has been decreasing at an alarming rate over the last decennia and has reached a critical level. Efforts like the rehabilitation of dry forests to curb this ecological degradation, need a stronger scientific basis than currently available. The aim of the present research was to test the hypothesis whether soil seed banks can contribute ...

Development of a testing system for the documentation and evaluation of the weed-suppressing ability of blue lupins

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Böhm, Herwart

2016-02-01

Full Text Available Within the framework of a joint research project for breeding advancement of blue and yellow lupins, which is being conducted in cooperation with the Julius Kühn-Institute, Institute for Breeding Research on Agricultural Crops (coordinator, Saatzucht Steinach and the IPK Gatersleben, in a sub-project at the Thünen-Institute of Organic Farming 1. a test system for detection and assessment of weed-suppressing effect of blue lupins will be developed, and 2. this test system will be tested to pre-breeding lines of blue lupin. In the first year of the project, plot trials were conducted in 3-fold field repetition with two phenological widely differing varieties (cv. Boruta [terminated type], cv. Boregine [branched type] in combination with selected partners with four different seed rates. As partners, monocotyledonous species (e.g., cereals and dicotyledonous species (false flax or resp., a mixture of oil seed rape, phacelia and buckwheat, are used. Twice during the growing season and at harvest, the aboveground biomass, separated by lupin, partners and weeds, were recorded. The results of the first project year show that all the partner plants which should serve as artificial weeds were successfully established. False flax leads to the strongest effect on the development of lupins, which showed the lowest biomass production in these variants. In comparison to the sown partners, the false flax variants also showed the highest biomass production, while the lowest biomass production was recorded for the natural weeds occurring at the site. The species mixture of oil seed rape, phacelia and buckwheat, however, led to the lowest biomass production; contemporaneously the biomass production of lupins in these variants was only affected slightly. Comparing the two cultivated lupin varieties, Boruta showed a better weed suppressive effect.

An early-killed rye cover crop has potential for weed management in edamame

Science.gov (United States)

The potential role of fall-seeded cover crops for weed management in edamame is unknown. Field experiments were conducted over three edamame growing seasons to test the following objectives: 1) determine the extent to which cover crop residue management systems influence edamame emergence while sele...

SPATIAL CORRELATION BETWEEN PHYSICAL PROPERTIES OF SOIL AND WEEDS IN TWO MANAGEMENT SYSTEMS

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Valter Roberto Schaffrath

2015-02-01

Full Text Available The spatial correlation between soil properties and weeds is relevant in agronomic and environmental terms. The analysis of this correlation is crucial for the interpretation of its meaning, for influencing factors such as dispersal mechanisms, seed production and survival, and the range of influence of soil management techniques. This study aimed to evaluate the spatial correlation between the physical properties of soil and weeds in no-tillage (NT and conventional tillage (CT systems. The following physical properties of soil and weeds were analyzed: soil bulk density, macroporosity, microporosity, total porosity, aeration capacity of soil matrix, soil water content at field capacity, weed shoot biomass, weed density, Commelina benghalensis density, and Bidens pilosa density. Generally, the ranges of the spatial correlations were higher in NT than in CT. The cross-variograms showed that many variables have a structure of combined spatial variation and can therefore be mapped from one another by co-kriging. This combined variation also allows inferences about the physical and biological meanings of the study variables. Results also showed that soil management systems influence the spatial dependence structure significantly.

7 CFR 361.6 - Noxious weed seeds.

Science.gov (United States)

2010-01-01

... aciculatus (Retzius) Trinius Commelina benghalensis L. Crupina vulgaris Cassini Cuscuta spp. Digitaria...), nightshade (Solanaceae), and sunflower (Asteraceae). (5) Dodder (Cuscuta spp.) seeds devoid of embryos and...

Banking Wyoming big sagebrush seeds

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Robert P. Karrfalt; Nancy Shaw

2013-01-01

Five commercially produced seed lots of Wyoming big sagebrush (Artemisia tridentata Nutt. var. wyomingensis (Beetle & Young) S.L. Welsh [Asteraceae]) were stored under various conditions for 5 y. Purity, moisture content as measured by equilibrium relative humidity, and storage temperature were all important factors to successful seed storage. Our results indicate...

Weed Control Efficiency of wild Safflower (Carthamus oxyacanthus M. Bieb in Replacement Series Technique of Barley (Hordeum vulgare L. and Common Vetch (Vicia sativa L.

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abdolreza ahmadi

2017-08-01

significant 1% and 5%. Results and discussion There was significant difference between minimum and maximum dry weight of weeds, the results showed that barley have important role in weed control wild safflower. Therefore, weed control efficiency in 15 plant in m2 was higher than two 10 and 20 plant in m2. The lowest WCE (161.27% was found at 15-35-65 treatment, but, the highest WCE (51.99 was obtained from 15-65-35 (Wild safflower-common vetch-barley treatment. Computes showed that WCE, in 15 plants of wild safflower/m2, was more than 10 and 20 p/m2. The reduction in weed population and biomass in intercropping systems with barley may be attributed to shading effect and competition stress created by the canopy. Thus, result showed that reduction rate of common vetch in intercropping, with bearing compatibility power to weeds reduced LER. CR for common vetch intercropping component in comparison with barley in total treatments was>1. The highest CR, for vetch obtained from treatment 45-55-control (2.64 and for barley from seed ratio 65-35-control (1.83. Conclusion The results in this study showed various seed rate had noticeable effect on forage yield, LER and weed control. In this experiment changing seed rate in two tested plants (barly- commen vetch changed the number and weed species, as a result noticeable changing was created in their competitive power. Result showed that seed rate (35% barley-65% common vetch was better than other treatment, not only in use efficiency of environment, but also it had more dry forage yield. Also, former seed rate had effective role in decreasing the weed biomass. This important result was related to reduced light penetrate at the bottom of cover crop and probably lack of competition in access to environmental resources was also affected. So using this seed density for mentioned area is recommended for reducing weed competition and improving the quality and quantity of dry forage. Acknowledgments The authors gratefully acknowledge the

Sistema de classificação fuzzy para o risco de infestação por plantas daninhas considerando a sua variabilidade espacial Fuzzy classification system for risk of weed infestation considering spatial variability

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G.M. Bressan

2006-06-01

Full Text Available Este artigo trata do problema de classificação do risco de infestação por plantas daninhas usando técnicas geoestatísticas, análise de imagens e modelos de classificação fuzzy. Os principais atributos utilizados para descrever a infestação incluem a densidade de sementes, bem como a sua extensão, a cobertura foliar e a agressividade das plantas daninhas em cada região. A densidade de sementes reflete a produção de sementes por unidade de área, e a sua extensão, a influência das sementes vizinhas; a cobertura foliar indica a extensão dos agrupamentos das plantas daninhas emergentes; e a agressividade descreve a porcentagem de ocupação de espécies com alta capacidade de produção de sementes. Os dados da densidade de sementes, da cobertura foliar e da agressividade para as diferentes regiões são obtidos a partir de simulação com modelos matemáticos de populações. Neste artigo propõe-se um sistema de classificação fuzzy utilizando os atributos descritos para inferir os riscos de infestação de regiões da cultura por plantas daninhas. Resultados de simulação são apresentados para ilustrar o uso desse sistema na aplicação localizada de herbicida.This paper deals with the problem of classifying the risk of infestation by weeds in a field using geoestatistics techniques, image analysis and fuzzy classification models. The main attributes used to describe the infestation include seed density, seed density patch, weed cover and aggressivity to produce seeds in each region. Seed density reflects seed production per area unit; seed density patch reflects the influence of the neighbouring seeds in a clustering; weed cover indicates the extension of the emergent weed plant clusterings; and, finally, aggressivity describes the percentage of occupation of species with high weed seed production capacity. Data for seed density, weed cover and aggressivity for the different regions are obtained from mathematical models. In

Applying the seedling-emergence method under waterlogged conditions to detect the seed bank of aquatic plants in submerged sediments

NARCIS (Netherlands)

Boedeltje, G; ter Heerdt, GNJ; Bakker, JP

Seed bank studies focused on submerged aquatic plants are generally performed under submerged conditions, using the seedling-emergence method. However, if a study targets at both submerged species and helophytes, submerged conditions are generally not suitable. We tested the emergence of seedlings

Effect of Soybean and Wheat as Cover Crops on Corn Yield and Weed Control using Different Fertilizer Sources

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F. Dadashi

2016-02-01

Full Text Available Introduction: According to the importance of corn in supplying the human food directly and indirectly, it is one of the most important plants among crops. One of the major problems in corn production systems, is competition with weeds that reduce corn yield significantly. Weeds not only reduce crop yields but also decrease the commercial quality and the feeding palatability of main crops. They enhance the soil seed bank of weeds, which may cause continuous weed infestation of field crops as well. Herbicide application is a reliable and highly effective method for weed control. However, demand for safe food products that have been produced with a minimum application of chemical inputs is increasing. Therefore, farmers interested in weed management have to rely on other control approaches. An alternative weed control method is the use of cover crops, which can suppress the growth of weeds by preventing them from light and by producing allelopathic compounds. Cover crops successfully have been integrated into conservational agriculture systems in many areas of the world. Legumes are used as cover crop because of their rapid growth, in addition their potential to provide further nitrogen,along with high ability to compete with weeds. Materials and Methods: In order to study the effect of cover crops (soybean and wheat and different fertilizers sources on yield of corn and weed control, a filed experiment was conducted in randomized complete block design with three replications in 2012. Treatments included two cover crop (wheat and soybean and three fertilizer (no fertilizer, chemical fertilizer and compost..Fertilizer treatments was used according to soil analysis and requirement of corn (as a main plant. Weed-infestation and weed-free plots were used as controls. Study cultivars of corn, wheat and soybean were NS-640, Milan and Sari, respectively. Planting of corn was in June and cover crop was planted with corn simultaneously and between corn rows

Downy brome seed ecology: From flower to emergence

Science.gov (United States)

Downy brome (Bromus tectorum) seed is very common in seed banks throughout Great Basin rangelands. Previously, using a soil bioassay method, we tested 100 separate sites within the Great Basin (1000 samples) to measure downy brome seed bank densities. The locations differed greatly by precipitation,...

Allelopathic potential of a noxious weed on mung bean

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Parthapratim Maiti

2013-10-01

Full Text Available Eupatorium odoratum have invaded the waste lands of South West Bengal, India. A field study indicated a gradual and also significant increase in Eupatorium odoratum accompanied with significant decrease in other coexisting species. Considering the above in mind, a study was undertaken to evaluate the existence of inhibitory effect of leaf extracts and leaf leachates noxious weed Eupatorium odoratum using fully viable seeds of mung bean (Vigna radiata as the bioassay material. The study showed the reduced the percentage germination and TTC stainability along with extended T50 values of mung bean seeds. The levels of protein, DNA and RNA, activities of dehydrogenase and catalase enzymes were significantly retarded in pretreated seed samples. Amino acid and sugar levels were increased in the leachates of seeds pretreated with leaf extracts and leaf leachates. Thus, from the overall results it can be concluded that various inhibitors present in E. odoratum can impart strong inhibitory effect on mung bean. The study suggests that the leaves of E. odoratum possess phytotoxic or allelopathic chemicals which potentially rendered the inhibitory action on mung bean seeds.

About the value of species diversity in arable weeds for weed management

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Gerowitt, Bärbel

2016-02-01

Full Text Available Arable weeds accompany arable land use – we define them based on their affiliation to ar able systems. They are adapted to such a degree that most of them cannot exist without arable land use. Weeds are part of the total biodiversity on arable fields, as primary producers they are basic for important functions within the ecosystem. This paper elaborates the relevance of species diversity in arable weeds for their management. Arable systems can be regarded for the number of different methods for preventive and direct weed control which are realized. Historical arable land use is roughly divided into three periods, which differ concerning the diversity of weed management and the occurring diversity in weed species. Obviously divers weed management in arable systems and diversity in weed species depend on each other, this is illustrated with a simple abstract picture. Arable systems, which are characterised by simpleness, favor the domination of few species which ensure an effective use of the resources within the ecosystem. One consequence under continuous pressure of an overused tool in weed management is that the genetic diversity within a dominating weed population is exploited to ensure this resource use. Current herbicides represent this tool – the results are herbicide resistant biotypes within the weed populations. Species diversity in arable weeds as a rationale within arable production can assist to prevent this development.

Weed Control in White Bean with Various Halosulfuron Tankmixes

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Nader Soltani

2014-01-01

Full Text Available Four field trials were conducted over a three-year period (2011–2013 in southwestern Ontario to evaluate the level of weed control provided by various halosulfuron tankmixes applied preplant incorporated (PPI in white bean. Trifluralin, s-metolachlor, halosulfuron, and imazethapyr applied alone or in combination caused 4% or less visible injury 1 and 4 weeks after emergence (WAE in white bean. Trifluralin, s-metolachlor, halosulfuron, and imazethapyr applied PPI provided 80–96%, 84–95%, 83–100%, and 75–92% control of redroot pigweed; 19–28%, 30–40%, 97–99%, and 73–84% control of common ragweed; 94–96%, 63–82%, 96–100%, and 96–100% control of common lambsquarters; 14-15%, 12–35%, 100%, and 96–97% control of wild mustard; and 96–97%, 95–97%, 53–56%, and 80–82% control of green foxtail, respectively. The two- and three-way tankmixes of halosulfuron with trifluralin, s-metolachlor, or imazethapyr provided 85–100% control of redroot pigweed, 90–98% control of common ragweed, 97–100% control of common lambsquarters, 100% control of wild mustard, and 93–98% control of green foxtail. Weed density, weed biomass and white bean seed yields reflected the level of visible weed control.

Space distribution of a weed seedbank in a bean cultivation area

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Jefferson Luis Meirelles Coimbra

2009-12-01

Full Text Available The objective of this work was to elucidate the characteristics of space distribution of a weed seedbank in order to assist in decision-making for the adoption of management techniques applied to an area under bean monoculture. Agricultural precision tools, as well as techniques of geostatistic analysis, were utilized. The samples were composed of 24 soil samples from georeferenced points, within a quadratic mesh consisting of 20x20 meter cells. The samples of soil were conditioned in plastic trays to provide ideal conditions for seed germination. Some samples presented a potential weed infestation of about 8000 plants m-2 constituting a problem for bean cultivation, disfavoring its development and grain yield.

Weeds in a Changing Climate: Vulnerabilities, Consequences, and Implications for Future Weed Management.

Science.gov (United States)

Ramesh, Kulasekaran; Matloob, Amar; Aslam, Farhena; Florentine, Singarayer K; Chauhan, Bhagirath S

2017-01-01

Whilst it is agreed that climate change will impact on the long-term interactions between crops and weeds, the results of this impact are far from clear. We suggest that a thorough understanding of weed dominance and weed interactions, depending on crop and weed ecosystems and crop sequences in the ecosystem, will be the key determining factor for successful weed management. Indeed, we claim that recent changes observed throughout the world within the weed spectrum in different cropping systems which were ostensibly related to climate change, warrant a deeper examination of weed vulnerabilities before a full understanding is reached. For example, the uncontrolled establishment of weeds in crops leads to a mixed population, in terms of C 3 and C 4 pathways, and this poses a considerable level of complexity for weed management. There is a need to include all possible combinations of crops and weeds while studying the impact of climate change on crop-weed competitive interactions, since, from a weed management perspective, C 4 weeds would flourish in the increased temperature scenario and pose serious yield penalties. This is particularly alarming as a majority of the most competitive weeds are C 4 plants. Although CO 2 is considered as a main contributing factor for climate change, a few Australian studies have also predicted differing responses of weed species due to shifts in rainfall patterns. Reduced water availability, due to recurrent and unforeseen droughts, would alter the competitive balance between crops and some weed species, intensifying the crop-weed competition pressure. Although it is recognized that the weed pressure associated with climate change is a significant threat to crop production, either through increased temperatures, rainfall shift, and elevated CO 2 levels, the current knowledge of this effect is very sparse. A few models that have attempted to predict these interactions are discussed in this paper, since these models could play an

Latencia y banco de semillas en plantas de la región mediterránea de Chile central Seed bank and dormancy in plants of the Mediterranean region of central Chile

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JAVIER A. FIGUEROA

2004-03-01

un modelo estructural y funcional del banco de semillas para el matorral de Chile central, que debería ser enriquecido con futuras investigacionesSeed banks on Mediterranean regions display characteristics that distinguish them from the seed banks of other regions. A seed bank is the concentration of viable propagules buried in the soil for variable periods of time. Seed banks in the Chilean matorral are chiefly transient and functionally similar to seed banks in other Mediterranean ecosystems not disturbed by fire, except for those of Australia. A transient seed bank is that composed of seeds that cannot survive in the upper levels of the soil for more than 1 year. The density of herb seeds in the Chilean matorral soil is one of the highest among Mediterranean ecosystems anywhere in the world, and a large proportion of these seeds is made up of seeds without dormancy that germinate easily, particularly annual grasses. With respect to the dormancy mechanisms that may be responsible for the behavior of these seeds stored in the transient bank, our analysis revealed the following germination syndromes: (1 species whose seeds must be stratified in cold due to the presence of physiological dormancy (particularly introduced herbs, (2 species whose seeds must be scarified with acids or mechanical means due to the presence of physical dormancy (mainly native woody species and, (3 species that present physiological dormancy and need heat stratification to activate germination (both native and introduced species. These syndromes determine that the timing of germination in central Chile has an autumn and an early spring phase. Besides, there is absence of sporadic germination syndromes for the components of a persistent seed bank. We propose a structural and functional model of the seed bank for the matorral of central Chile that should be enriched with future research

Allelopathic cover crop prior to seeding is more important than subsequent grazing/mowing in grassland establishment

Science.gov (United States)

Milchunas, Daniel G.; Vandever, Mark W.; Ball, Leonard O.; Hyberg, Skip

2011-01-01

The effects of grazing, mowing, and type of cover crop were evaluated in a previous winter wheat–fallow cropland seeded to grassland under the Conservation Reserve Program in eastern Colorado. Prior to seeding, the fallow strips were planted to forage sorghum or wheat in alternating strips (cover crops), with no grazing, moderate to heavy grazing, and mowing (grazing treatments) superimposed 4 yr after planting and studied for 3 yr. Plots previously in wheat had more annual and exotic species than sorghum plots. Concomitantly, there were much greater abundances of perennial native grass and all native species in sorghum than wheat cropped areas. The competitive advantage gained by seeded species in sorghum plots resulted in large increases in rhizomatous western wheatgrass. Sorghum is known to be allelopathic and is used in crop agriculture rotations to suppress weeds and increase crop yields, consistent with the responses of weed and desired native species in this study. Grazing treatment had relatively minor effects on basal and canopy cover composition of annual or exotic species versus perennial native grass or native species. Although grazing treatment never was a significant main effect, it occasionally modified cover crop or year effects. Opportunistic grazing reduced exotic cheatgrass by year 3 but also decreased the native palatable western wheatgrass. Mowing was a less effective weed control practice than grazing. Vegetative basal cover and aboveground primary production varied primarily with year. Common management practices for revegetation/restoration currently use herbicides and mowing as weed control practices and restrict grazing in all stages of development. Results suggest that allelopathic cover crop selection and opportunistic grazing can be effective alternative grass establishment and weed control practices. Susceptibility, resistance, and interactions of weed and seeded species to allelopathic cover species/cultivars may be a fruitful area

Burial increases seed longevity of two Artemisia tridentata (Asteraceae) subspecies

Science.gov (United States)

Wijayratne, Upekala C.; Pyke, David A.

2012-01-01

Premise of the study: Seed longevity and persistence in soil seed banks may be especially important for population persistence in ecosystems where opportunities for seedling establishment and disturbance are unpredictable. The fire regime, an important driver of population dynamics in sagebrush steppe ecosystems, has been altered by exotic annual grass invasion. Soil seed banks may play an active role in postfire recovery of the foundation shrub Artemisia tridentata, yet conditions under which seeds persist are largely unknown. Methods: We investigated seed longevity of two Artemisia tridentata subspecies in situ by retrieving seed bags that were placed at varying depths over a 2 yr period. We also sampled naturally dispersed seeds in litter and soil immediately after seed dispersal and before flowering in subsequent seasons to estimate seed persistence. Key results: After 24 mo, seeds buried at least 3 cm below the soil surface retained 30–40% viability whereas viability of seeds on the surface and under litter declined to 0 and Artemisia tridentata has the potential to form a short-term soil seed bank that persists longer than has been commonly assumed, and that burial is necessary for seed longevity. Use of seeding techniques that promote burial of some seeds to aid in formation of a soil seed bank may increase restoration potential.

Allelopathic potential of Hyptis suaveolens on physio-biochemical changes of mung bean seeds

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Parthapratim Maiti

2015-10-01

Full Text Available Hyptis suaveolens is an exotic invasive weed in many areas of West Bengal, India. The allelopathic potential of leaf extracts and leachates of H. suaveolens was investigated on germination and metabolism of mung bean seeds (Vigna radiata cv. K851. The extracts and leachates reduced the germination and seed viability. The insoluble carbohydrates, proteins, and the activities of dehydrogenase and catalase enzymes were significantly reduced. Amino acid and soluble carbohydrate levels were increased in seeds pretreated with leaf extracts and leachates. The overall biochemical results indicate that various inhibitors present in H. suaveolens impart strong inhibitory effect on mung bean. The leaves of H. suaveolens possess phytotoxic chemicals, which potentially rendered the inhibitory action on mung bean seeds and provided key information for the proper management of H. suaveolens and other invasive weeds showing similar behavior.

The effects of the coexistence of weed communities on table beet yield during early crop development = Efeitos de convivência da comunidade de plantas daninhas na produção de beterraba durante o desenvolvimento inicial da cultura

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Leonardo Bianco Carvalho

2010-10-01

Full Text Available The objective was to evaluate the effects of initial weedy periods on the weed community and on the productivity of direct seeded and transplanted table beet cropping systems. A field trial was conducted at São Paulo State University, Brazil, in a randomized complete block design using a 2 x 13 factorial scheme. Direct seeding and seedling transplanting methods were evaluated within thirteen increasing weekly weedy periods. Weed relative importance was calculated and weed density and weed dry matter accumulation data were analyzed by nonlinear regression as well as beet yield and stand, which were submitted to analysis of variance. Amaranthus viridis, Coronopus didymus, Cyperus rotundus, Digitaria nuda, Galinsoga parviflora and Nicandra physaloides were the most important weeds found, with special reference to C. didymus. Weed dry matter accumulation was greater in the direct seeded crop, although weed density was higher in the transplanted crop. Transplanted beet yield was greater than of direct seeded beet in the weed-free treatment during the whole crop cycle. Crop-weed coexistence could remain for four and seven weeks after seeding/transplanting in direct seeded and in transplanted beet, respectively, before reducing yield economically. Thus, direct seeded crop was more susceptible to weed interference than the transplanted one.Objetivando avaliar efeitos de períodos de infestação inicial na comunidade infestante e na produtividade da beterraba em sistema de semeadura direta e transplantio, conduziu-se um experimento em delineamento de blocos casualizados, esquema fatorial 2 x 13. Métodos de semeadura direta e transplante de mudas foram avaliados dentro de 13 períodos semanais crescentes de infestação. Importância relativa, densidade e matéria seca acumulada pelas plantas daninhas foram analisadas por regressão não-linear, assim como produtividade e estande da cultura de beterraba, que foram submetidos à análise de vari

Spatial and temporal distribution of weeds in no-tillage system

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Eduardo L. Bottega

Full Text Available ABSTRACT Brazil is one of the largest grain producers in the world, due to its extensive arable land and favorable climate for the cultivation of any species. The production could be higher, but problems such as competition between crops and weeds reduces crop yields. This study aimed to analyze the spatial distribution of weeds, especially milkweed (Sonchus oleraceus, horse weed (Conyza spp. and ‘maria-mole’ (Senecio brasiliensis in an area under no-tillage system for two harvests. The work was carried out during the 2013/14 and 2014/15 crop years in an area of 22.5 ha, where soybean is grown in the summer and oat in the winter. The weeds were mapped using a sampling grid of 85 points. The number of plants present in 0.25 m2 was recorded at each sampling point. The data collected in the field composed the information bank and were used for geostatistical analysis and production of maps. Using geostatistical analysis, it was possible to map the horseweed infestation in the studied area for the 2013/14 season. The species ‘maria-mole’ and milkweed did not show spatial dependence. During the 2014/2015 season, because of the management carried out in the off season, none of the studied species showed spatial dependence.

URJC GB dataset: Community-based seed bank of Mediterranean high-mountain and semi-arid plant species at Universidad Rey Juan Carlos (Spain).

Science.gov (United States)

Alonso, Patricia; Iriondo, José María

2014-01-01

The Germplasm Bank of Universidad Rey Juan Carlos was created in 2008 and currently holds 235 accessions and 96 species. This bank focuses on the conservation of wild-plant communities and aims to conserve ex situ a representative sample of the plant biodiversity present in a habitat, emphasizing priority ecosystems identified by the Habitats Directive. It is also used to store plant material for research and teaching purposes. The collection consists of three subcollections, two representative of typical habitats in the center of the Iberian Peninsula: high-mountain pastures (psicroxerophylous pastures) and semi-arid habitats (gypsophylic steppes), and a third representative of the genus Lupinus. The high-mountain subcollection currently holds 153 accessions (63 species), the semi-arid subcollection has 76 accessions (29 species,) and the Lupinus subcollection has 6 accessions (4 species). All accessions are stored in a freezer at -18 °C in Kilner jars with silica gel. The Germplasm Bank of Universidad Rey Juan Carlos follows a quality control protocol which describes the workflow performed with seeds from seed collection to storage. All collectors are members of research groups with great experience in species identification. Herbarium specimens associated with seed accessions are preserved and 63% of the records have been georreferenced with GPS and radio points. The dataset provides unique information concerning the location of populations of plant species that form part of the psicroxerophylous pastures and gypsophylic steppes of Central Spain as well as populations of genus Lupinus in the Iberian Peninsula. It also provides relevant information concerning mean seed weight and seed germination values under specific incubation conditions. This dataset has already been used by researchers of the Area of Biodiversity and Conservation of URJC as a source of information for the design and implementation of experimental designs in these plant communities. Since

URJC GB dataset: Community-based seed bank of Mediterranean high-mountain and semi-arid plant species at Universidad Rey Juan Carlos (Spain

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Patricia Alonso

2014-03-01

Full Text Available The Germplasm Bank of Universidad Rey Juan Carlos was created in 2008 and currently holds 235 accessions and 96 species. This bank focuses on the conservation of wild-plant communities and aims to conserve ex situ a representative sample of the plant biodiversity present in a habitat, emphasizing priority ecosystems identified by the Habitats Directive. It is also used to store plant material for research and teaching purposes. The collection consists of three subcollections, two representative of typical habitats in the center of the Iberian Peninsula: high-mountain pastures (psicroxerophylous pastures and semi-arid habitats (gypsophylic steppes, and a third representative of the genus Lupinus. The high-mountain subcollection currently holds 153 accessions (63 species, the semi-arid subcollection has 76 accessions (29 species, and the Lupinus subcollection has 6 accessions (4 species. All accessions are stored in a freezer at -18 °C in Kilner jars with silica gel. The Germplasm Bank of Universidad Rey Juan Carlos follows a quality control protocol which describes the workflow performed with seeds from seed collection to storage. All collectors are members of research groups with great experience in species identification. Herbarium specimens associated with seed accessions are preserved and 63% of the records have been georreferenced with GPS and radio points. The dataset provides unique information concerning the location of populations of plant species that form part of the psicroxerophylous pastures and gypsophylic steppes of Central Spain as well as populations of genus Lupinus in the Iberian Peninsula. It also provides relevant information concerning mean seed weight and seed germination values under specific incubation conditions. This dataset has already been used by researchers of the Area of Biodiversity and Conservation of URJC as a source of information for the design and implementation of experimental designs in these plant

Integrated weed management for sustainable rice production: concepts, perspectives and options

International Nuclear Information System (INIS)

Amartalingam Rajan

2002-01-01

Weed management has always been in some way integrated with cultural and biological methods, probably occurring more fortuitously than purposefully. Experience has shown that repeated use of any weed control technique especially in monocultures production systems results in rapid emergence of weeds more adapted to the new practice. In intensive high input farming systems, heavy selection pressure for herbicide tolerant weeds and the environmental impacts of these inputs are important tissues that require a good understanding of agroecosystem for successful integration of available options. Rice culture, in particular flooded rice culture has always employed integration through an evolution of management practices over the generations. However, a vast majority office farmers in Asia have yet to achieve the high returns realised by farmers elsewhere, where a near optimum combination of high inputs are being effectively integrated for maximum productivity. In addition to technological and management limitations, farmers in developing countries are faced with social, economic and policy constraints. On the other hand, farmers who had achieved considerable increases in productivity through labour replacing technologies, in particular direct seeding with the aid of herbicides, are now faced with issues related to environmental concerns due to high levels of these inputs. The issues facing weed scientists and farmers alike in managing weeds effectively and in a manner to ensure sustainability have become more challenging than ever before. In the last two decades, no issue has been discussed so. intensively as Sustainable Farming, Sustainable Agriculture or Alternative Agriculture within the broader global concept of Sustainable Development. To address these challenges a clear perspective of sustainable farming is essential. This paper addresses these concepts, perspectives and options for choices in weed management for sustainable rice production. (Author)

Ecological Weed Management by Cover Cropping: Effect on Winter Weeds and Summer Weeds Establishment in Potato

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M Ghaffari

2012-07-01

Full Text Available Now a day winter cover crops planting has been attended to reduce herbicide application. An experiment was carried out at the Research Farm of Agriculture Faculty, Bu- Ali Sina, University, in 2009. The experiment was a randomized complete block design with three replications. The trial included of five treatments consists of no cover crop, rye, winter oilseed rape, barley and triticale. The results showed that winter cereals were produced more biomass than winter oilseed rape. living mulch of rye, barley, oilseed rape and triticale reduced winter weeds biomass 89, 86, 82 and 70 percent respectively, in compare to control. Cover crop treatments showed significant different weeds control of potato at 3 time (15, 45 and 75 DAPG compare to control treatment. Residues mixed to soil of oilseed rape and rye had the most inhibition affects on summer weeds. These treatments, average weeds biomass decreased 61 and 57 percent respectively, in compare to control. Oilseed rape and rye in compare to control reduced weeds density in potato 36 and 35 percent, respectively. Significant negation correlations of weeds plant population, weeds dry matter with average tuber weight and potato yield. The treatments, oilseed rape and rye in compare to control increased tuber yield of potato 54 and 50 percent, respectively. These treatments, the average tuber weight increased 74 and 38 percent in compare with control, respectively.

Shrub seed banks in mixed conifer forests of northern California and the role of fire in regulating abundance

Science.gov (United States)

Eric E. Knapp; Phillip C. Weatherspoon; Carl N. Skinner

2012-01-01

Understory shrubs play important ecological roles in forests of the western US, but they can also impede early tree growth and lead to fire hazard concerns when very dense. Some of the more common genera (Ceanothus, Arctostaphylos, and Prunus) persist for long periods in the seed bank, even in areas where plants have been...

Characterizing and valuing of regeneration potential of the seed germination bank at the Carpatos forest reserve (Guasca, Cundinamarca)

International Nuclear Information System (INIS)

Cantillo Higuera Edgard Ernesto; Castiblanco Gutierrez Viviana; Pinilla Mondragon David Fernando; Alvarado Claudia Liliana

2008-01-01

In the Carpatos Forest Reserve the bank seed germinate (BSG) was marked and valued and the dispersion mechanisms and strategies of there serve defined. They subsequently determined the spatial, dinamogenetic and temporary structures of the seral states and their populations. For the vegetation on foot 61 species were recorded, represented by 53 genera and 36 families, alongside the BSG were 55 species, represented by 50 genera and 27 families. The minimum volume was 1.500 cm 3, for a total of 13.150 germinating seeds; the total density for BSG was 1.553 seeds per m2. The species emerged in the BSG were mostly herbaceous and flush - approximately 70% of all individuals and species -; Phytolacca bogotensis, Digitalis purpurea and Ageratina sp. were the dominant species in the three trials Bank, other important species were Carex sp., Poa annua, Rubus floribundum, Bulbostylis sp.and Borreria sp. The species of woody habit usually varied in each trial according to the phenophase of each species, the most representative species were Cestrum Mutisia, Clusia ducu, Myrsine coriacea, Axinaea macrophylla and Miconia denticulata. As for phenology and dispersal, it was found that vegetation stands submitted to the zoocoria as the dominant scattering strategy in all fields; the maximum flowering occurred during the dry season, from December to March, though the greatest fruiting records correspond to the longest rainy season, from June to August.

Non-chemical weed management

DEFF Research Database (Denmark)