Full Text Available Observasi tentang tipe dikogami, sistem penyerbukan, dan keterbatasan serbuk sari telah dilakukan pada populasi Aeschynanthus pulcher di Kebun Raya Cibodas. Pengamatan fenologi bunga dilakukan untuk menentukan tipe dikogami. Dalam rangka menentukan sistem perkawinan dan keterbatasan serbuk sari, lima perlakuan penyerbukan telah dilakukan yaitu penyerbukan bebas sebagai kontrol, penyerbukan silang, penyerbukan sendiri, autogami, dan agamospermi. Hasil pengamatan menunjukkan bahwa dikogami pada A. pulcher adalah protandri, tidak sempurna dan durasi tampilan serbuk sari dan stigma reseptif masing-masing yaitu 3-9 hari dan 6-12 hari. A. pulcher merupakan tumbuhan yang dapat membuahi sendiri, sedangkan proses autogami dan agamospermi tidak terjadi. Sindrom keterbatasan serbuk sari pada populasi A. pulcher yang diamati diindikasikan terjadi. Derajat keterbatasan serbuk sari pada A. pulcher mencapai 0.79-0.80. Tiga faktor yang dapat menyebabkan keterbatasan serbuk sari adalah (1 kompetisi antar jenis tumbuhan yang berbunga bersamaan, (2 perilaku berbunga dalam satu periode yang sama, dan (3 kompetisi antara polinator dan pencuri nektar.
Lisa W. Alexander; Keith E. Woeste
We developed a novel scoring system to assess spring phenology in a northern red oak (Quercus rubra L.) clonal seed orchard. The system was used to score from 304 to 364 ramets for three reproductive seasons and to place clones into early, intermediate, and late phenology classes. Although the absolute number of clones in each phenological class...
Jersáková, Jana; Johnson, S.D.
Roč. 21, č. 3 (2007), s. 496-504 ISSN 0269-8463 Institutional research plan: CEZ:AV0Z60870520 Keywords : dichogamy * geitonogamy * inbreeding * Orchidaceae * pollen discounting * self-pollination Subject RIV: EH - Ecology, Behaviour Impact factor: 3.157, year: 2007
Alcaraz Arco, María Librada; Hormaza Urroz, José Ignacio
Avocado has a singular synchronous protogynous dichogamy breeding system that promotes outcrossing. In this work different steps have been optimized to improve controlled pollinations in avocado in order to perform basic studies of reproductive biology and directed crosses in breeding programs. The results show that, in order to achieve successful fruit set, male flowers should be collected when all the anthers have dehisced and the pollen transferred by direct contact of the anthers with the...
Under favourable conditions, the avocado sets more fruits than the tree is able to bring to maturity, so that the plant adjusts, during the early stages of development, its ability to nourish them by modifying their number, that is, causing the fruit drop of those who can not maintain their growth rate. Accordingly, carbohydrate availability could be a key factor in the physiological abscission of these fruits. Since this species presents dichogamy, the abscission of fruits has also been attr...
Hargreaves, Anna L; Harder, Lawrence D; Johnson, Steven D
Many of the diverse animals that consume floral rewards act as efficient pollinators; however, others 'steal' rewards without 'paying' for them by pollinating. In contrast to the extensive studies of the ecological and evolutionary consequences of nectar theft, pollen theft and its implications remain largely neglected, even though it affects plant reproduction more directly. Here we review existing studies of pollen theft and find that: (1) most pollen thieves pollinate other plant species, suggesting that theft generally arises from a mismatch between the flower and thief that precludes pollen deposition, (2) bees are the most commonly documented pollen thieves, and (3) the floral traits that typically facilitate pollen theft involve either spatial or temporal separation of sex function within flowers (herkogamy and dichogamy, respectively). Given that herkogamy and dichogamy occur commonly and that bees are globally the most important floral visitors, pollen theft is likely a greatly under-appreciated component of floral ecology and influence on floral evolution. We identify the mechanisms by which pollen theft can affect plant fitness, and review the evidence for theft-induced ecological effects, including pollen limitation. We then explore the consequences of pollen theft for the evolution of floral traits and sexual systems, and conclude by identifying key directions for future research.
Yan, Juan; Wang, Gang; Sui, Yi; Wang, Menglin; Zhang, Ling
Floral colour change is visual signals for pollinators to avoid old flowers and increase pollination efficiency. Quisqualis indica flowers change colour from white to pink to red may be associated with a shift from moth to butterfly pollination. To test this hypothesis, we investigated Q. indica populations in Southwest China. Flowers secreted nectar continuously from the evening of anthesis until the following morning, then decreased gradually with floral colour change. The scent compounds in the three floral colour stages were similar; however, the scent composition was different, and the scent emission rate decreased from the white to red stage. Dichogamy in Q. indica prevents self-pollination and interference of male and female functions. Controlled pollinations demonstrated that this species is self-incompatible and needs pollinators for seed production. Different pollinators were attracted in each floral colour stage; mainly moths at night and bees and butterflies during the day. Observations of open-pollinated inflorescences showed that white flowers had a higher fruit set than pink or red flowers, indicating the high contribution of moths to reproductive success. We concluded that the nectar and scent secretion are related to floral colour change in Q. indica, in order to attract different pollinators and promote reproductive fitness.
Valentin-Silva, Adriano; Coelho, Victor Peçanha de Miranda; Ventrella, Marília Contin; Vieira, Milene Faria
Dichogamy is a common characteristic among angiosperms, including Piper species. In this genus, the tiny flowers are morphologically similar and have an asynchronous stamen development. However, there is no information on the duration of stigma receptivity and whether it overlaps with pollen release. To better understand mechanisms of floral function in Piper vicosanum, we provide a detailed characterization of the timing of pollen release from the four stamens and the period of stigma receptivity and exposure mode of the receptive areas. We investigated plants of a natural population in a semideciduous seasonal forest (Viçosa, Minas Gerais State, southeastern Brazil), based on chemical tests, light microscopy, and scanning electron microscopy analyses. Incomplete protogyny-a mechanism that favors outcrossing-was recorded. The period of stigma receptivity was long (14 d), and the sequential exposure and senescence of stigmatic papillae occurred gradually and in a basipetal direction. Pollen release began 2-6 d after the beginning of the pistillate phase, with an average pollen viability of 87.7%, during the bisexual flower phase. Pollen was released for up to 6 d and occurred in one stamen at a time. The fruit set observed in tests of self-pollination indicated self-compatibility. The gradual and sequential exposure of stigmatic papillae in P. vicosanum flowers is described here as the mechanism for the long duration of receptivity. Anther development and pollen release were also sequential. These findings are yet unreported reproductive characteristics of the genus and offer new perspectives for future studies on the floral biology of other Piper species. © 2015 Botanical Society of America, Inc.
Full Text Available Although the knowledge of pollination systems of rare and threatened species is one of the principles for development of optimal conservation and management strategies, the data about their pollination requirements are scarce or incomplete. Different problems are listed (xerothermic habitat disappearance, overgrowing of patches, plant biology i.e., slow plant growth, problems with seed germination among the possible causes of Adonis vernalis being threatened, but until now no consideration was given to the flowering biology and pollination. The observations of flowering biology of A. vernalis (Ranunculaceae, a clonal species, were conducted in an out-of-compact-range population, in the Lublin Upland, Poland (51°18'55" N, 22°38'21" E, in 2011–2013. The reproductive potential of A. vernalis is related to the population age structure, pollination syndrome, and breeding system. The flowers exhibit incomplete protogyny. The dichogamy function is supported by different (biological, morphological mechanisms. Stigma receptivity occurred about one day before anthers started shedding self-pollen, and pollen viability was increasing gradually during the flower life-span (66.3% in distal anthers vs. 77.3% in proximal. The decrease in pollen production and in pollen viability coincided with the lowest degree of seed set, irrespective of the pollination treatment. Pollen vectors are necessary for efficient pollination, as the proportion of pistils setting fruits after open pollination (41–82.1% was significantly higher compared to spontaneous self-pollination (only 5.5–12.3%. The pollination requirements together with pollen/ovule ratio (P/O = 501 indicate a facultative xenogamous breeding system in A. vernalis. Therefore, in the conditions of the global lack of pollinators, improper pollination may weaken the population by leading to a decrease in the proportion of recombinants, and in addition to other factors, may accelerate extinction of small A
Fenologia reprodutiva e sistema de polinização de Ziziphus joazeiro Mart. (Rhamnaceae: atuação de Apis mellifera e de visitantes florais autóctones como polinizadores Reproductive phenology and pollination system of Ziziphus joazeiro Mart. (Rhamnaceae: the role of Apis mellifera and autochthonous floral visitors as pollinators
Tarcila de Lima Nadia
Cariri Paraibano, northeastern Brazil. Flowering and fruiting periods occurred at the end of the dry season and beginning of the rainy season, with peaks in December (flowering and February (fruiting. The green, dish-shaped flowers last about 12 hours and have a large yellow nectary surrounding the gynoecium. Protandry occurs associated with heterodichogamy, another type of dichogamy. Ziziphus joazeiro produces little nectar (1 µl but with a high sugar concentration (75%. Floral visitors were wasps, bees and flies. Apis mellifera had the highest frequency of visits (77.5%, followed by wasps (20.4%, both acting as effective pollinators. Flies and other bee species had a lower percentage of visits (2.1% and acted as nectar robbers. The high rate of initial fruit development per inflorescence suggests high pollinator efficiency, since the dichogamic mechanism prevents the occurrence of spontaneous self-pollination and geitonogamy.