The effects of nectar level and flower development on pollen carry-over in inflorescences of fireweed (Epilobium angustifolium) (Onagraceae)

1985 ◽  
Vol 63 (3) ◽  
pp. 488-491 ◽  
Author(s):  
C. Galen ◽  
R. C. Plowright
Keyword(s):  
Plant Species ◽  
Flower Development ◽  
Nearest Neighbor ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Nectar Production ◽  
Epilobium Angustifolium ◽  
Carry Over ◽  
Pollen Receipt ◽  
Female Flowers

Nectar in flowers of Epilobium angustifolium was manipulated experimentally to provide enriched versus depleted reward levels to bumblebee pollinators. Bumblebees visited significantly more flowers on inflorescences with high rewards than low ones and stayed longer on individual flowers with high rewards. The greatest pollen deposition occurred in older female flowers having enriched nectar levels. In older female flowers the stigma lobes coil backward, reducing the distance between their receptive surfaces and the nectary site. Younger female flowers, regardless of reward level, only occasionally received more than a few pollen grains per bee visit. Although higher nectar levels are likely to promote pollen receipt over the course of a flower's lifetime, because of changes in stigma configuration with flower development, the number of pollen grains transferred to the stigma at any given time depends on the flower's age as well as its reward status. In this self-compatible plant species, most of the increase in pollen receipt resulting from high nectar production is likely to lead to self-matings since (i) plants are clonal and bees usually fly to nearest neighbor ramets after rewarding visits, (ii) bees visit more flowers on enriched inflorescences than on depleted ones, and (iii) pollen carry-over declines exponentially over the course of an inflorescence visit.

scholarly journals Sensitivity of commercial pumpkin yield to potential decline among different groups of pollinating bees

2017 ◽  
Vol 4 (5) ◽  
pp. 170102 ◽  
Author(s):  
Sonja C. Pfister ◽  
Philipp W. Eckerter ◽  
Jens Schirmel ◽  
James E. Cresswell ◽  
Martin H. Entling
Keyword(s):  
Crop Yield ◽  
Fruit Set ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Insect Pollination ◽  
Study Region ◽  
Flower Visitation ◽  
Pollen Receipt ◽  
The Relationship ◽  
Pollinator Fauna

The yield of animal-pollinated crops is threatened by bee declines, but its precise sensitivity is poorly known. We therefore determined the yield dependence of Hokkaido pumpkin in Germany on insect pollination by quantifying: (i) the relationship between pollen receipt and fruit set and (ii) the cumulative pollen deposition of each pollinator group. We found that approximately 2500 pollen grains per flower were needed to maximize fruit set. At the measured rates of flower visitation, we estimated that bumblebees (21 visits/flower lifetime, 864 grains/visit) or honeybees (123 visits, 260 grains) could individually achieve maximum crop yield, whereas halictid bees are ineffective (11 visits, 16 grains). The pollinator fauna was capable of delivering 20 times the necessary amount of pollen. We therefore estimate that pumpkin yield was not pollination-limited in our study region and that it is currently fairly resilient to single declines of honeybees or wild bumblebees.

scholarly journals Pollination Is Sufficient, Even with Low Bee Diversity, in Pumpkin and Winter Squash Fields

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1141
Author(s):  
Kimberly A. Stoner
Keyword(s):  
Management Practices ◽  
Fruit Size ◽  
Pollen Grains ◽  
Fruit Production ◽  
Pollen Deposition ◽  
Open Pollination ◽  
Wide Range ◽  
Hand Pollination ◽  
Winter Squash ◽  
Female Flowers

Pumpkins and winter squash require insect pollination to set fruit, but only three bee species are important pollinators of these crops in the Northeastern US. To determine if natural levels of pollen deposition are sufficient for full fruit production, open pollination was measured by counting pollen grains on stigmas, and open pollination was compared to supplemental hand pollination for fruit set, fruit size, and seed number. A threshold of 2300 pollen grains per stigma was sufficient for full pollination and fruit production. This threshold was met in 79 out of 80 combinations of site and sample date over four years on farms across Connecticut with a wide range of field sizes and pest management practices. Along with stigma collection, bees per flower were counted hourly on 100 flowers along a transect. Counts of bumble bees on female flowers were more closely related to the amount of pollen deposited than counts of bees on all flowers or counts of honey bees or squash bees on female flowers. There was tremendous variation in abundance of the three bee species on female flowers across farms within a year and even among years on a single farm.

Resolution of Channels in the Exine by Translocation of Colloidal Iron

1971 ◽  
Vol 29 ◽  
pp. 352-353
Author(s):  
John R. Rowley
Keyword(s):  
Phosphate Buffer ◽  
Pollen Development ◽  
Osmium Tetroxide ◽  
Pollen Grains ◽  
Deionized Water ◽  
Colloidal Iron ◽  
Fixed Material ◽  
Epilobium Angustifolium ◽  
Untreated Material ◽  
Microspore Mitosis

The morphology of the exine of many pollen grains, at the time of flowering, is such that one can suppose that transport of substances through the exine occurred during pollen development. Holes or channels, microscopic to submicroscopic, are described for a large number of grains. An inner part of the exine of Epilobium angustifolium L. and E. montanum L., which may be referred to as the endexine, has irregularly shaped channels early in pollen development although by microspore mitosis there is no indication of such channeling in chemically fixed material. The nucleus in microspores used in the experiment reported here was in prophase of microspore mitosis and the endexine, while lamellated in untreated grains, did not contain irregularly shaped channels. Untreated material from the same part of the inflorescence as iron treated stamens was examined following fixation with 0.1M glutaraldehyde in cacodylate-HCl buffer at pH 6.9 (315 milliosmoles) for 24 hrs, 4% formaldehyde in phosphate buffer at pH 7.2 (1,300 milliosmoles) for 12 hrs, 1% glutaraldehyde mixed with 0.1% osmium tetroxide for 20 min, osmium tetroxide in deionized water for 2 hrs and 1% glutaraldehyde mixed with 4% formaldehyde in 0.1M cacodylate-HCl buffer at pH 6.9 for two hrs.

scholarly journals The Dynamics of Flower Development in Castanea Sativa Mill.

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1538
Author(s):  
Ana Teresa Alhinho ◽  
Miguel Jesus Nunes Ramos ◽  
Sofia Alves ◽  
Margarida Rocheta ◽  
Leonor Morais-Cecílio ◽  
...  
Keyword(s):  
Flower Development ◽  
Molecular Mechanisms ◽  
Castanea Sativa ◽  
Male And Female ◽  
Sweet Chestnut ◽  
Chestnut Tree ◽  
Abcde Model ◽  
Organ Identity ◽  
Castanea Sativa Mill ◽  
Female Flowers

The sweet chestnut tree (Castanea sativa Mill.) is one of the most significant Mediterranean tree species, being an important natural resource for the wood and fruit industries. It is a monoecious species, presenting unisexual male catkins and bisexual catkins, with the latter having distinct male and female flowers. Despite the importance of the sweet chestnut tree, little is known regarding the molecular mechanisms involved in the determination of sexual organ identity. Thus, the study of how the different flowers of C. sativa develop is fundamental to understand the reproductive success of this species and the impact of flower phenology on its productivity. In this study, a C. sativa de novo transcriptome was assembled and the homologous genes to those of the ABCDE model for floral organ identity were identified. Expression analysis showed that the C. sativa B- and C-class genes are differentially expressed in the male flowers and female flowers. Yeast two-hybrid analysis also suggested that changes in the canonical ABCDE protein–protein interactions may underlie the mechanisms necessary to the development of separate male and female flowers, as reported for the monoecious Fagaceae Quercus suber. The results here depicted constitute a step towards the understanding of the molecular mechanisms involved in unisexual flower development in C. sativa, also suggesting that the ABCDE model for flower organ identity may be molecularly conserved in the predominantly monoecious Fagaceae family.

Differential nectar production between male and female flowers in a wild cucurbit: Cucurbita maxima ssp. andreana (Cucurbitaceae)

2002 ◽  
Vol 80 (11) ◽  
pp. 1203-1208 ◽  
Author(s):  
Lorena Ashworth ◽  
Leonardo Galetto
Keyword(s):  
Reproductive Output ◽  
Male Flower ◽  
Female Flower ◽  
Cucurbita Maxima ◽  
Nectar Production ◽  
Male And Female ◽  
Nectar Sugar Composition ◽  
Nectar Sugar ◽  
Male Flowers ◽  
Female Flowers

In dioecious and monoecious plants that depend on animal vectors for reproduction, pollinators have to be attracted to male and female flowers for pollination to be effective. In the monoecious Cucurbita maxima ssp. andreana, male flowers are produced in greater quantity, are spatially more exposed to pollinators and offer pollen in addition to nectar as floral rewards. Nectar traits were compared between male and female flowers to determine any differences in the characteristics of the main reward offered to pollinators. Nectar chemical composition and sugar proportions were similar between flower types. Total nectar sugar production per female flower was threefold higher than per male flower, and nectar removal did not have any effect on total nectar production in both flower morphs. Pollinators reduced nectar standing crops to similar and very scarce amounts in both flower types. Results indicate indirectly that pollinators are consuming more nectar from female flowers, suggesting that the higher nectar production in female flowers may be a reward-based strategy to achieve the high female reproductive output observed in this species.Key words: Cucurbitaceae, Cucurbita maxima ssp. andreana, nectar production, nectar sugar composition, removal effects, standing crop.

scholarly journals Pollinator importance networks illustrate the crucial value of bees in a highly speciose plant community

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Gavin Ballantyne ◽  
Katherine C. R. Baldock ◽  
Luke Rendell ◽  
P. G. Willmer
Keyword(s):  
Plant Species ◽  
Community Level ◽  
Taxonomic Resolution ◽  
Pollen Deposition ◽  
Pollinator Effectiveness ◽  
Flower Visitors ◽  
Pollinator Importance ◽  
Visitation Frequency ◽  
Pollinator Performance ◽  
Number Of Plant Species

AbstractAccurate predictions of pollination service delivery require a comprehensive understanding of the interactions between plants and flower visitors. To improve measurements of pollinator performance underlying such predictions, we surveyed visitation frequency, pollinator effectiveness (pollen deposition ability) and pollinator importance (the product of visitation frequency and effectiveness) of flower visitors in a diverse Mediterranean flower meadow. With these data we constructed the largest pollinator importance network to date and compared it with the corresponding visitation network to estimate the specialisation of the community with greater precision. Visitation frequencies at the community level were positively correlated with the amount of pollen deposited during individual visits, though rarely correlated at lower taxonomic resolution. Bees had the highest levels of pollinator effectiveness, with Apis, Andrena, Lasioglossum and Osmiini bees being the most effective visitors to a number of plant species. Bomblyiid flies were the most effective non-bee flower visitors. Predictions of community specialisation (H2′) were higher in the pollinator importance network than the visitation network, mirroring previous studies. Our results increase confidence in existing measures of pollinator redundancy at the community level using visitation data, while also providing detailed information on interaction quality at the plant species level.

scholarly journals Pollen morphology and availability of pollen and stigma in Syzygium (Myrtaceae)

2019 ◽  
Vol 41 (6) ◽  
Author(s):  
Guilherme Nacata ◽  
Talita Kely Belonsi ◽  
Eduardo Custódio Gasparino ◽  
Renata Aparecida de Andrade
Keyword(s):  
Flower Development ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Scanning Microscopy ◽  
Stigma Receptivity ◽  
Equatorial View ◽  
Equatorial Diameter ◽  
Species Overlap ◽  
Polar Diameter

Abstract The present study aimed to describe the pollen morphology in three species of Syzygium, to test pollen availability and stigma receptivity. The pollen was analyzed by light and scanning microscopy to show the detailed ornamentation of the pollen grains. Pollen availability was measured according to two protocols. Stigmatic receptivity was tested at different stages of flower development. There are differences among the pollen morphology for the species studied; when the polar and equatorial diameters are measured in the equatorial view of the pollen grains, it is observed that S. jambos is the largest species concerning the two values of the diameters, S. malaccense is the smallest species and S. aqueum, the largest species in relation to the polar diameter in the equatorial view. For the equatorial diameter in equatorial view, S. aqueum showed the smallest diameters and S. malaccense, the major diameters, but the two species overlap in the values of the measured diameters. There are variations in the number of apertures in the pollen grains. Alexander’s stain is more sensitive to estimate pollen availability and the species S. aqueum and S. jambos have the same schedules of pollen availability and stigma receptivity.

scholarly journals Breeding biology and distyly in Palicourea rigida H. B. & K. (Rubiaceae) in the Cerrados of Central Brazil

2010 ◽  
Vol 24 (3) ◽  
pp. 686-696 ◽  
Author(s):  
Adriana de Oliveira Machado ◽  
Ana Palmira Silva ◽  
Helder Consolaro ◽  
Mariluza A. Granja e Barros ◽  
Paulo Eugênio Oliveira
Keyword(s):  
Reproductive Success ◽  
Fruit Set ◽  
Pollen Grains ◽  
Floral Biology ◽  
Nectar Production ◽  
Central Brazil ◽  
Palicourea Rigida ◽  
Floral Visitors ◽  
Compatible Pollen ◽  
Incompatibility Reactions

Distyly is a floral polymorphism more common among the Rubiaceae than in any other angiosperm group. Palicourea rigida is a typically distylous species of the Rubiaceae widely distributed in the Brazilian Cerrados. This work aimed to study the floral biology and breeding system of P. rigida in order to verify if there wasasymmetry between floral morphs. The work was carried out at Fazenda Água Limpa, Brasília-DF, from 1993 to 1995; and at Serra Caldas Novas State Park-Goias and in Clube Caça e Pesca Itororó de Uberlândia-Minas Gerais in 2005 and 2006. Density, height and pin/thrum ratio were assessed for flowering individuals in all areas. Plants were investigated for differences in floral morphology, nectar production, reproductive success and site of self incompatibility reactions. Blooming period was long and concentrated during the rains. Flowers were clearly distylous and with reciprocal herkogamy. They produced nectar and lasted for a single day. In spite of differences in density and height, populations were mostly isoplethic. Nectar production varied in volume and concentration but the differences could not be associated with floral morphs. The species is self-incompatible but reproductive success was always high and independent of floral morphs. There were differences in the site of incompatibility barriers between floral morphs, which were similar to those observed for other Rubiaceae. The main floral visitors and pollinators were the hummingbirds Colibri serrirostris and Eupetomena macroura. High fruit-set indicates that the pollinators transported enough compatible pollen grains between floral morphs, despite their territorial behavior.

Flowering and fruit set in lychee (Litchi chinensis Sonn.) in subtropical Queensland

1992 ◽  
Vol 32 (1) ◽  
pp. 105 ◽  
Author(s):  
CM Menzel ◽  
DR Simpson
Keyword(s):  
Flower Development ◽  
Fruit Set ◽  
The Other ◽  
Litchi Chinensis ◽  
Panicle Development ◽  
Maximum Temperatures ◽  
The Times ◽  
Female Flowers

The pattern of panicle and flower development of lychee (Litchi chinensis Sonn.) trees was studied in subtropical Queensland (lat. 27�S.). The cultivars studied were Tai So at 3 sites, Bengal at 4 sites, Kwai May Pink at 2 sites, Salathiel at 3 sites, and Wai Chee at 2 sites. Tai So was the earliest cultivar, with panicle emergence in late May and flower anthesis in mid September. The other cultivars were 5-7 weeks later. Tai So had a longer period of flower anthesis than the other cultivars (4 weeks v. 1-3 weeks). Cultivars Tai So and Bengal generally had longer panicles than cvv. Kwai May Pink, Salathiel and Wai Chee (17-32 v. 10-14 cm), and more flowers per panicle (1800-3400 v. 400-900). Similarly, the number of fruit per panicle ranged from 7-33/panicle 2-3 weeks after the end of flowering, to 4-22/panicle at harvest. The proportion of female flowers setting fruit ranged from 2.1 to 19.5%. Similar estimates for fruit carried to harvest ranged from 0.8 to 6.8%. Variations in the times of panicle emergence, panicle development, and anthesis among the cultivars in relation to seasonal progressions in temperature affected the number of fruit set. The number of fruit set per panicle increased as the number of female flowers per panicle increased. Higher numbers of female flowers were associated with maximum temperatures during flower development of 18�C, with lower numbers at 23�C. Higher maximum temperatures during anthesis (30�C v. 24�C) increased the proportion of female flowers setting fruit.

scholarly journals Pollination effectiveness of European honeybee, Apis mellifera (Hymenoptera: Apidae), in an Oriental persimmon, Diospyros kaki (Ericales: Ebenaceae), orchard

2020 ◽  
Vol 55 (4) ◽  
pp. 405-412
Author(s):  
Shoko Nakamura ◽  
Shunsuke Yamamoto ◽  
Nobuo Sawamura ◽  
Aoi Nikkeshi ◽  
Shigeki Kishi ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Trifolium Pratense ◽  
Pollen Grains ◽  
Red Clover ◽  
Diospyros Kaki ◽  
Japanese Persimmon ◽  
Pollination Effectiveness ◽  
Mature Seeds ◽  
European Honeybee ◽  
Female Flowers

Abstract Most common cultivars of Oriental (or Japanese) persimmon, Diospyros kaki Thunb. (Ericales: Ebenaceae), set mostly female flowers and require pollen from male flowers of other cultivars for pollination. Growers often introduce the European honeybee, Apis mellifera L. (Hymenoptera: Apidae), into their orchards to promote pollination. Here, we investigated the pollination effectiveness of A. mellifera for D. kaki ‘Saijo,’ by monitoring flower visitors, analyzing pollen grains on bees’ body surfaces, and comparing the number of mature seeds in fruits among years with different pollinator availabilities. Apis mellifera and the bumblebee Bombus ardens ardens Smith (Hymenoptera: Apidae) were the major visitors for 3 years, although their dominance varied among years. The number of mature seeds was positively correlated with the number of B. ardens ​ardens visiting D. kaki flowers, but not with that of A. mellifera. Apis mellifera might be less efficient because visitors to female flowers carried significantly fewer pollen grains on their body surfaces than those of B. ardens ​ardens. Analysis of pollen loads of honeybees captured at their nest entrance suggested their preference for red clover, Trifolium pratense L. (Fabales: Fabaceae), and Toxicodendron spp. (Sapindales: Anacardiaceae), over D. kaki as a pollen source in our study site. The effectiveness of A. mellifera on D. kaki pollination should be carefully evaluated considering the effects of coexisting floral and pollinator species.

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