The significance of pollination time and frequency and of purity of pollen loads for seed set in Rhinanthus angustifolius (Scrophulariaceae) and Viscaria vulgaris (Caryophyllaceae)

Oecologia ◽  
1986 ◽  
Vol 70 (4) ◽  
pp. 502-507 ◽  
Author(s):  
Manja M. Kwak ◽  
Ola Jennersten
Keyword(s):  
Seed Set ◽  
Pollen Loads ◽  
Rhinanthus Angustifolius

Pollination and reproductive success in the gynodioecious endemic Thymus loscosii (Lamiaceae)

2005 ◽  
Vol 83 (2) ◽  
pp. 183-193 ◽  
Author(s):  
Maria Renée Orellana ◽  
Anna Maria Rovira ◽  
Cèsar Blanché ◽  
Maria Bosch
Keyword(s):  
Reproductive Success ◽  
Seed Quality ◽  
Seed Set ◽  
Pollen Deposition ◽  
Pollinator Visitation ◽  
Heterospecific Pollen ◽  
Pollen Loads ◽  
Visual Attraction ◽  
Insect Exclusion ◽  
Two Populations

Sexual dimorphism can have implications in the reproductive biology of gynodioecious species, affecting sex fitness. We explored the effects of flower sex on pollination visitation rates and pollinator efficiency in terms of stigmatic pollen loads, as well as on quantitative and qualitative aspects of reproductive success in two populations of Thymus loscosii Willk. (Lamiaceae) endemic to the northeastern Iberian Peninsula. We also assessed the dependence of T. loscosii on insect pollination in both hermaphrodite and female plants by performing an insect exclusion test. Apis mellifera and different species of Bombylidae were the most frequent pollinators (68% of approaches to studied plots and 93% of total visited flowers). Hermaphrodite plants received more visits than female ones, possibly as a response to visual attraction, since flowers of the former are larger. Conspecific pollen deposition was higher on stigmas of hermaphrodite flowers than on those of females; in contrast, female stigmas received more heterospecific pollen loads, notably higher in one population. Despite these differences, seed set from open-pollinated flowers was similar in both sexes and in both populations, and relatively low (around 0.5–1 nutlet per fruiting calyx, on average). Thymus loscosii is self-compatible as it was able to produce seeds by spontaneous selfing, but at very low rates, indicating that it is insect-dependent for pollination. In addition, bagged female flowers also set seeds formed by apomitic mechanisms. In general, seeds from females were slightly heavier and began to germinate earlier and at higher rates than those from hermaphrodites, even those formed by apomixis. These results suggest that female plants enjoy a resource allocation advantage that allows increased seed quality and contributes to the maintenance of gynodioecy.Key words: gynodioecy, pollinator visitation, pollen loads, seed set, sex fitness, Thymus loscosii.

Some pollinators are more equal than others: Factors influencing pollen loads and seed set capacity of two actively and passively pollinating fig wasps

2014 ◽  
Vol 57 ◽  
pp. 73-79 ◽  
Author(s):  
Finn Kjellberg ◽  
Nazia Suleman ◽  
Shazia Raja ◽  
Abelouahad Tayou ◽  
Martine Hossaert-McKey ◽  
...  
Keyword(s):  
Seed Set ◽  
Fig Wasps ◽  
Pollen Loads ◽  
Factors Influencing

Disassortative pollination in the distylous plant Jepsonia heterandra

1974 ◽  
Vol 52 (11) ◽  
pp. 2401-2406 ◽  
Author(s):  
Fred R. Ganders
Keyword(s):  
Seed Set ◽  
Adaptive Significance ◽  
Pollen Loads ◽  
Self Pollination

Stigmatic pollen loads were analyzed from naturally pollinated intact and emasculated pin- and thrum-form flowers of Jepsonia heterandra. Observed pollen loads on stigmas of emasculated flowers were compared with expected loads based on random pollination. Observed pollen loads indicated that 13.2% disassortative pollination occurred in the pin form and 43.5% disassortative pollination in the thrum form. Pollen loads from intact flowers indicated that much more self pollination and geitonogamy takes place in the pin form than in the thrum form. In this species, distyly effectively promotes phenotypic disassortative pollination.It is suggested that the adaptive significance of distyly m a diallelic self-incompatible species is that the resultant disassortative pollination increases seed set in the population.

Outcrossing Distance Effects in Delphinium Nelsonii: Pollen Loads, Pollen Tubes, and Seed Set

Ecology ◽  
1991 ◽  
Vol 72 (1) ◽  
pp. 171-179 ◽  
Author(s):  
Nickolas M. Waser ◽  
Mary V. Price
Keyword(s):  
Seed Set ◽  
Pollen Tubes ◽  
Pollen Loads ◽  
Distance Effects

Bumblebee pollination of understorey shrub species in a tropical montane forest in Costa Rica

2000 ◽  
Vol 16 (5) ◽  
pp. 657-672 ◽  
Author(s):  
Renate A. Wesselingh ◽  
Heino C. M. Burgers ◽  
Hans C. M. Den Nijs
Keyword(s):  
Costa Rica ◽  
Seed Set ◽  
Pollen Grains ◽  
Montane Forest ◽  
Shrub Species ◽  
Pollen Loads ◽  
Visitation Rates ◽  
Pollen Types ◽  
Bumblebee Pollination ◽  
Fruit And Seed Set

This study addresses the pollination ecology of shrub species in an upper montane forest in Costa Rica, where the diversity of insect visitors is much below that of the well-studied tropical forests of lower elevations. Data are presented on visitation rates by the tropical bumblebee Bombus ephippiatus to flowers of three species, pollen loads on bumblebee bodies, and pollen loads on stigmas of two of the species. High visitation rates to flowers of Palicourea brenesii were found, a species which produces copious amounts of nectar. Visitation rates to nectarless Leandra subseriata and Deppea grandiflora were much lower. Conspecific pollen comprised on average 90% of the pollen load on stigmas of Leandra, while Palicourea stigmas carried only 26 to 55% conspecific pollen. With only two ovules per flower, fruit and seed set in Palicourea were not limited by a shortage of conspecific pollen. In Leandra, 20–25% of the flowers received too few conspecific pollen grains for maximum seed set among 440 ovules per flower. Individual bumblebees showed no constancy in plant choice, judging from the high number of different pollen types (6–12) on their bodies. Workers returned frequently to the same Palicourea patch without visiting nearby Palicourea plants, which suggests the use of foraging paths.

BEHAVIOUR AND EFFECTIVENESS OF BEES IN POLLINATING LEGUMES

1974 ◽  
pp. 105-110
Author(s):  
I.W. Forster
Keyword(s):  
White Clover ◽  
Seed Set ◽  
Red Clover ◽  
Potential Maximum ◽  
Open Fields

One honeybee or bumblebee working on each square metre of white clover or red clover gave adequate pollination. This could be obtained with one hive of honeybees to each three hectares of flowering clover. Lucerne seeding averaged only 10% of the potential maximum in open fields with honey- or bumblebees. In cages where honeybees were forced to gather pollen, this was raised to 30% but it was not possible to increase seed set significantly in the fields.

Hand-Pollination ofCardamine californicaImproves Seed Set

2006 ◽  
Vol 7 (3) ◽  
pp. 248-252 ◽  
Author(s):  
Kazuki Ariyoshi ◽  
Emily Magnaghi ◽  
Mark Frey
Keyword(s):  
Seed Set ◽  
Hand Pollination

DETERMINATION OF AFTER-RIPENING PERIOD AND HORMONAL RESPONSE OF OROBANCHE SOLMSII C.D. CLARKE SEEDS

1970 ◽  
Vol 11 (1) ◽  
Author(s):  
A. Bista ◽  
G. B. Khattri ◽  
B. D. Acharya ◽  
S. C. Srivastava
Keyword(s):  
Growth Hormone ◽  
Seed Germination ◽  
Key Words ◽  
Incubation Period ◽  
Seed Set ◽  
Summer Season ◽  
Conditioning Period ◽  
Root Parasite ◽  
One Year

To find out the ability of Orobanche seeds to germinate immediately after seed set, seeds were germinated periodically at an interval of three months for one year in GR24. Some Orobanche seeds were capable of germination immediately after seed set but most required about nine months as after ripening or incubation period to be able to germinate. The phenomenon of after ripening in Orobanche seeds could be taken as an ecological measure to dormant over following unfavorable wet summer season. The growth hormone studies on Orobanche seed germination have shown that GA3 at a concentration of 100 ppm substantially enhanced seed germination when applied during pre-conditioning period. NAA showed some stimulatory effect at 0.5 - 1.0 ppm when applied during post-conditioning period but the hormone if applied during pre-conditioning period inhibited the germination. Kinetin failed to stimulate the germination at all the concentrations tested. Key words: Germination, root-parasite, hormone. Ecoprint Vol.11(1) 2004.

Study on floral traits and seed setting in parental lines of hybrid rice during early ahu and kharif seasons

2018 ◽  
Vol 78 (3) ◽  
Author(s):  
Aradhana Phukan ◽  
P. K. Barua ◽  
D. Sarma ◽  
S. D. Deka
Keyword(s):  
Seed Set ◽  
Flag Leaf ◽  
Pollen Dispersal ◽  
Pollen Sterility ◽  
Leaf Length ◽  
Floral Traits ◽  
Opening Angle ◽  
Leaf Angle ◽  
Seed Setting ◽  
Parental Lines

Two CMS lines, IR 58025A and IR 68888A along with their maintainers and two fertility restorers, LuitR and IR 36R, were evaluated for flower and plant characters during early ahu (February-June) and kharif (July-November) seasons. IR 58025A showed longer stigmata and styles, and higher spikelet Length/Breadth (L/B) ratio while IR 68888A showed broader stigmata and wider glume opening angle in both the seasons. IR 68888A also exhibited higher pollen sterility during early ahu. IR 36R was characterized with broad anthers. LuitR showed longer and broader anthers with more pollen than others. Plant height, flag leaf length, flag leaf width and area were higher in IR 36R. Panicle exsertion was complete in pollen parents whereas it was 78-80% in CMS lines. The widest flag leaf angle was found in IR 58025B during early Ahu and in IR 36R during kharif. Kharif season was more favourable for growth of the plants with higher seed set percentage while floral traits of the CMS lines were better expressed in early Ahu. Manipulation of the seeding sequence of the parental lines in early Ahu is warranted for better seed set provided the seed crop escapes heavy premonsoon showers during reproductive stage. IR 68888A/LuitR was a good combination for pollen dispersal and seed setting.

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