Modest Pollen Limitation of Lifetime Seed Production Is in Good Agreement with Modest Uncertainty in Whole-Plant Pollen Receipt: (A Reply to Burd)

2016 ◽  
Vol 187 (3) ◽  
pp. 397-404 ◽  
Author(s):  
Jay A. Rosenheim ◽  
Neal M. Williams ◽  
Sebastian J. Schreiber ◽  
Joshua M. Rapp
2016 ◽  
Vol 8 (9) ◽  
pp. 95 ◽  
Author(s):  
Min Chen ◽  
Xue-yong Zhao ◽  
Xiao-an Zuo ◽  
Hao Qu ◽  
Wei Mao ◽  
...  

<p>Pollen limitation is considered to be a strong force driving the evolution of reproductive strategies in flowering plants. However, resource reallocation may occur among seeds because of variation in the quantity or quality of pollen received. We performed single-flower and whole-plant pollen supplementation and emasculation of flowers of <em>Apocynum venetum</em> L. to estimate pollen limitation and reproductive assurance. In addition, we calculated the visiting patterns of the pollinators, frequency of pollinators to estimate the effect of pollinator activity and further on the reproductive success of <em>A. venetum</em>. Our results indicated estimates from single-flower manipulations were not biased, closely resembling those from whole-plant manipulations. We found<em> Apis mellifera</em> was the dominant pollinator during the pollination process. In addition, insect pollination played a more important role in the outcrossing system, which could explain the differences in reproductive success. Our results also showed that autonomous self-pollination eliminates pollen limitation and provides reproductive assurance.</p>


Botany ◽  
2012 ◽  
Vol 90 (7) ◽  
pp. 565-573 ◽  
Author(s):  
Wendy E. Van Drunen ◽  
Marcel E. Dorken

Pollination success in dioecious plants is expected to be regulated by the ratio of female:male plants and the distances between plants of each sex. These factors have received considerable attention in studies of dioecious and other gender dimorphic plants, yet their effects have rarely been jointly considered. We documented sex ratios in 26 populations of Cirsium arvense (L.) Scop. (creeping thistle), a widely distributed clonal dioecious plant, and show that population sex ratios are generally female biased (∼60% of shoots were female, and 15 of 26 populations were female biased). We found clear evidence for a negative association between pollen loads and distances between females and males within populations. In contrast, and in spite of broad variation in sex ratios among populations (range: 0.11–0.99 female), we found no relationship between sex ratios and pollen receipt by females. However, both sex ratios and interplant distances were associated with female seed production: seed production declined with distances between females and males and increased with the proportion of male shoots. Our data suggest that female plants of C. arvense might often be pollen limited and that distances between individual females and males drive pollen limitation more strongly than the overall frequency of males within sites.


Plant Ecology ◽  
2014 ◽  
Vol 215 (11) ◽  
pp. 1351-1359 ◽  
Author(s):  
Simon Pierce ◽  
Arianna Bottinelli ◽  
Ilaria Bassani ◽  
Roberta M. Ceriani ◽  
Bruno E. L. Cerabolini

1992 ◽  
Vol 79 (3) ◽  
pp. 288-293 ◽  
Author(s):  
Mark D. Bertness ◽  
Scott W. Shumway

2001 ◽  
Vol 136 (1) ◽  
pp. 75-79 ◽  
Author(s):  
A. T. OMOKANYE ◽  
O. S. ONIFADE ◽  
P. E. OLORUNJU ◽  
A. M. ADAMU ◽  
R. J. TANKO ◽  
...  

At Shika in a subhumid environment of Nigeria, a 3-year study was carried out to select newly developed groundnut varieties for use in crop–livestock production systems. The study examined 11 groundnut varieties. Emergence time, plant stands at full emergence, forage and seed yields and yield components were examined. Whole plant samples were analysed for crude protein (CP) content. Varieties ICGV 87123 gave the lowest forage yield and cultivar M517-80I, the highest, with seven varieties recording forage yields above 5 t/ha. The CP content of forage was lowest (14·8%) for variety M576-80I and highest (21·6%) for variety M554-76. Mean seed yield (over 3 years) varied significantly from 0·73 to 1·68 t/ha. Only two varieties had mean seed yield >1 t/ha. The relationship between seed and forage yields was positive and significant (r = 0·529, P < 0·006). Varieties RMP 12, 88-80I and M517–80 were most promising for both forage and seed production.


2008 ◽  
Vol 275 (1637) ◽  
pp. 907-913 ◽  
Author(s):  
Natacha P Chacoff ◽  
Marcelo A Aizen ◽  
Valeria Aschero

A decline in pollination function has been linked to agriculture expansion and intensification. In northwest Argentina, pollinator visits to grapefruit, a self-compatible but pollinator-dependent crop, decline by approximately 50% at 1 km from forest edges. We evaluated whether this decrease in visitation also reduces the pollination service in this crop. We analysed the quantity and quality of pollen deposited on stigmas, and associated limitation of fruit production at increasing distances (edge: 10, 100, 500 and 1000 m) from the remnants of Yungas forest. We also examined the quantitative and qualitative efficiency of honeybees as pollen vectors. Pollen receipt and pollen tubes in styles decreased with increasing distance from forest edge; however, this decline did not affect fruit production. Supplementation of natural pollen with self- and cross-pollen revealed that both pollen quantity and quality limited fruit production. Despite pollen limitation, honeybees cannot raise fruit production because they often do not deposit sufficient high-quality pollen per visit to elicit fruit development. However, declines in visitation frequency well below seven visits during a flower's lifespan could decrease production beyond current yields. In this context, the preservation of forest remnants, which act as pollinator sources, could contribute to resilience in crop production. Like wild plants, pollen limitation of the yield among animal-pollinated crops may be common and indicative not only of pollinator scarcity, but also of poor pollination quality, whereby pollinator efficiency, rather than just abundance, can play a broader role than previously appreciated.


Botany ◽  
2017 ◽  
Vol 95 (8) ◽  
pp. 809-817 ◽  
Author(s):  
Ashley M. Hembrough ◽  
Victoria A. Borowicz

Baptisia alba (L.) Vent., an herbaceous, perennial legume, produces more flowers than will mature into pods. Single-year experiments on two reconstructed prairies tested the hypothesis that reproductive potential of B. alba depends on nutrients, but pollen limitation and pre-dispersal seed predation by weevils reduce final production. Ramets were assigned one of four treatments that were combinations of fertilizer (none/70 g fertilizer twice) and insect barrier (none/application of Tanglefoot). Within inflorescences, flowers were naturally pollinated or supplemented with pollen. Fertilizer produced no effects, suggesting that B. alba are unresponsive within a season to nutrient supplementation. Pollen supplementation increased pod initiation at the two sites by 6.7% and 2.3%, respectively, but did not affect the proportion of initiated pods that matured or seed number within pods. Where Tychius sordidus occurred, only 67 pods matured on 19 ramets and only four seeds survived. Where only Trichapion rostrum was present, insect barrier increased pod maturation almost three-fold, but did not affect seed number within pods. Barrier treatment increased the reproductive output of entire ramets by increasing seed production, from 3.6 seeds·ramet−1 to 60.5 seeds·ramet−1. Prairie restoration frequently uses fruit collected from other populations. Managers should be careful to avoid the unintended introduction of voracious seed predators.


2004 ◽  
Vol 52 (3) ◽  
pp. 353 ◽  
Author(s):  
A. B. Hingston ◽  
B. M. Potts ◽  
P. B. McQuillan

Flowers of the commercially important tree Eucalyptus globulus Labill. ssp. globulus were visited by a wide variety of insects and birds within its natural distribution. Flowers were visited so frequently that most available nectar was consumed, but seed production within 5 m of the ground was consistently far less than the maximum possible, indicating the presence of large numbers of inefficient pollinators and few efficient pollinators. Pollen limitation was more severe on fully self-incompatible trees than on partially self-compatible trees, demonstrating that pollinator inefficiency resulted from infrequent outcrossing rather than inability to deposit pollen on stigmas. The flower visitors that were responsible for almost all nectar consumption from flowers within 5 m of the ground were insects that were able to permeate cages with 5-mm apertures but not cages with 1-mm apertures, the most abundant of which was the introduced honeybee Apis mellifera L. These insects contributed less than 20% of the maximum possible seed set, indicating that they were inefficient pollinators. Birds and smaller insects made lesser contributions to seed production, but consumed little nectar within 5 m of the ground. However, anthophilous birds appeared to mostly forage higher in the trees and probably consumed more nectar from, and provided more pollination services to, flowers higher in the trees.


2020 ◽  
Vol 99 (1) ◽  
pp. 80-91
Author(s):  
Víctor Parra-Tabla ◽  
Conchita Alonso

Background: Self-compatibility is common on endemic plant species, but pollen limitation and self-pollination could be risk factors. Study species: The endemic Cienfuegosia yucatanensis (Malvaceae), whose distribution is mainly restricted to the north coast of the peninsula of Yucatán, México. Questions: a) Are flowers of C. yucatanensis autonomous for pollination? b) Are C. yucatanensis fruit or seed-set limited by pollen deposition? and, c) Is there evidence of early inbreeding depression in C. yucatanensis? Study sites and dates: Two sites in the north of the peninsula of Yucatán in a seasonally dry scrubland, in the rainy season of 2013 and 2014. Methods: Number of flowers and fruits were weekly recorded. Flowers were collected to count the number of conspecific pollen load and the number of pollen tubes. Autonomous pollination and pollen limitation were evaluated with a hand-pollination experiment. Inbreeding depression on fruit and seed production, and seed weight was evaluated. Results: Flower and fruit production occur simultaneously and last from August to October. Conspecific pollen deposition on stigmas occurred through the whole flowering season and a maximum of pollen tubes was observed in August. Autonomous pollination treatment lead to similar fruit and seed production than cross-pollination, but open pollination produced significantly more seeds. No significant differences among self- and cross-pollination treatments on fruit and seed production or seed weight, were found.  Conclusions: Our results suggest that self-compatibility combined with a relatively efficient autonomous pollination, are suitable mechanisms for the reproductive assurance in C. yucatanensis, with no apparent effects of early inbreeding depression.


2017 ◽  
Author(s):  
Michał Bogdziewicz ◽  
Michael A. Steele ◽  
Shealyn Marino ◽  
Elizabeth E. Crone

Highly variable, synchronized seed production, called masting, is a widespread reproductive strategy in plants. Resource dynamics, pollination success, and, as described here, environmental veto, are possible proximate mechanisms of masting. We extended the resource budget model of masting with correlated and uncorrelated reproductive failure, and ran this model across its parameters space. Next, we parametrized the model based on a 16-year seed production data for red (Quercus rubra) and white (Q. alba) oaks. Simulations showed that resource dynamics and reproduction failure produce masting even in the absence of pollen coupling. In concordance, in both species, among-year variation in resource gain and correlated reproductive failure were necessary and sufficient to produce masting. Environmental variation is a form of reproduction failure caused by environmental veto that may drive large-scale synchronization without density-dependent pollen limitation. Reproductive-inhibiting weather events are prevalent in ecosystems, suggesting that these described mechanisms likely operate in many masting systems.


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