What determines the number of seed produced in a flowering event? A case study of Calyptrogyne ghiesbreghtiana (Arecaceae)

2000 ◽  
Vol 48 (5) ◽  
pp. 659 ◽  
Author(s):  
Saul A. Cunningham
Keyword(s):  
Resource Allocation ◽  
Seed Production ◽  
Natural Variation ◽  
Seed Set ◽  
Plant Seed ◽  
Flower Production ◽  
Number Of Seeds ◽  
Female Flowers

Calyptrogyne ghiesbreghtiana Linden ex. H. Wendl. is an understorey palm that occurs at La Selva Biological Station, Costa Rica. In this paper I combine analysis of natural variation and results of experimental manipulations to ask (1) what limits seed production? and (2) what processes cause variation in seed production by C. ghiesbreghtiana? The number of seed produced per inflorescence ofC. ghiesbreghtiana was limited substantially by the loss of female flowers to floral herbivores. Much variation in the number of seed produced perinflorescence of C. ghiesbreghtiana was due to losses of developing fruits to predators. Together these phenomena illustrate the influential role of natural enemies in the reproductive success of this plant. Seed-set efficiency (number of seeds/number of female flowers) was highly variable in this species, and such high levels of variation appear to be common in other species. For species with highly variable seed-set efficiency, the role of resource allocation to flower production in determining differences in seed production among individual plants is likely to be relatively small.

scholarly journals The interplay between ovule number, pollination and resources as determinants of seed set in a modular plant

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5384 ◽  
Author(s):  
Marina M. Strelin ◽  
Marcelo A. Aizen
Keyword(s):  
Resource Allocation ◽  
Seed Production ◽  
Seed Set ◽  
Pollen Limitation ◽  
Rubus Idaeus ◽  
Physiological Integration ◽  
Open Pollination ◽  
Plant Resources ◽  
Plant Seed ◽  
Ovule Number

BackgroundA classical dichotomous perspective proposes that either pollination or plant resources limit seed production. However, ovule number could also be limiting when pollination results in complete ovule fertilization and there are more plant resources available than needed to develop seeds. Moreover, this dichotomous view assumes that all flowers of a plant have equal access to a shared pool of resources, although these are frequently compartmentalized within plant modules, for example, inflorescences. How ovule number, pollination and resources affect seed production in physiologically-compartmentalized rather than physiologically-integrated plants has yet to be explored. We used raspberry (Rubus idaeus) to address this question.MethodsWe first assessed if ovule number affected the fraction of ovules that develop into seed (i.e., seed set) and whether this effect related to the extent of physiological integration among flowers within plants. This was achieved by statistically testing predictions on the sign and level of plant organization (i.e., among flowers within inflorescences, among inflorescences within ramets, and among ramets) of the relation between ovule number and seed set given different degrees of physiological integration. We then explored whether the relation between ovule number and seed set was affected by plant age (used here as a surrogate of resource availability) and pollination intensity (open-pollination vs. exclusion).ResultsWithin inflorescences, flowers with more ovules set a larger fraction of seeds. On the other hand, seed set at the inflorescence level was negatively related to the average number of ovules per flower. Seed set increased with ovule number and open-pollination, and decreased with ramet age. However, ovule number explained more variation in seed set than ramet age and pollination treatment. Ramet age affected the strength of the relation of seed set to ovule number, which was stronger in old than young ramets. Pollination did not alter the strength of this relation to any significant extent.DiscussionResults reveal the importance of ovule number as an overriding factor affecting seed set. Within inflorescences, resources appear to be differentially allocated to developing fruits from flowers with many ovules. This is consistent with the fact that in the raspberry a large proportion of the carbon invested in fruit development is fixed by the inflorescence subtending leaf. Differential resource allocation to flowers with many ovules is not affected by pollinator exclusion, being stronger in resource-exhausted ramets. This suggests that the effects of pollen limitation and resource allocation are compartmentalized at the inflorescence level. Consequently, modular plants can be viewed as reproductive mosaics where either ovule number, pollination or resources limit the number of seeds set by different flowers, so that improvements in any of them could increase plant seed production.

scholarly journals Inter-annual variation in seed production has increased over time (1900–2014)

2017 ◽  
Vol 284 (1868) ◽  
pp. 20171666 ◽  
Author(s):  
Ian S. Pearse ◽  
Jalene M. LaMontagne ◽  
Walter D. Koenig
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
Global Climate ◽  
Mast Seeding ◽  
Plant Seed ◽  
Subtle Change ◽  
Animal Populations ◽  
Wide Range ◽  
Seed Crops ◽  
Over Time

Mast seeding, or masting, is the highly variable and spatially synchronous production of seeds by a population of plants. The production of variable seed crops is typically correlated with weather, so it is of considerable interest whether global climate change has altered the variability of masting or the size of masting events. We compiled 1086 datasets of plant seed production spanning 1900–2014 and from around the world, and then analysed whether the coefficient of variation (CV) in seed set, a measure of masting, increased over time. Over this 115-year period, seed set became more variable for plants as a whole and for the particularly well-studied taxa of conifers and oaks. The increase in CV corresponded with a decrease in the long-term mean of seed set of plant species. Seed set CV increased to a greater degree in plant taxa with a tendency towards masting. Seed set is becoming more variable among years, especially for plant taxa whose masting events are known to affect animal populations. Such subtle change in reproduction can have wide-ranging effects on ecosystems because seed crops provide critical resources for a wide range of taxa and have cascading effects throughout food webs.

To disinvest or invest? The role of programme budgeting and marginal analysis (PBMA) for economic evaluation and prioritization between public health interventions

2019 ◽  
pp. 312-340
Author(s):  
Joanna M. Charles ◽  
Rhiannon T. Edwards
Keyword(s):  
Public Health ◽  
Resource Allocation ◽  
Local Population ◽  
Health Improvement ◽  
Evidence Based ◽  
Marginal Analysis ◽  
The Impact ◽  
Allocation Decisions

This chapter describes the application of programme budgeting and marginal analysis (PBMA) as an evidence-based framework to make resource allocation decisions such as whether to invest or disinvest in certain services, products, or interventions. This evidence-based eight-step decision-making process can help decision-makers to maximize the impact of healthcare resources on the health needs of a local population. Programme budgeting is an appraisal of past resource allocation in specified programmes or services with a view to tracking future resource allocation in those same programmes or services. Marginal analysis is the appraisal of the added benefits and added costs of a proposed investment or the lost benefits and lower costs of a proposed disinvestment. This chapter pays particular attention to the use of the PBMA framework to appraise a national health improvement budget as a case study to illustrate the methods practical application in public health.

scholarly journals Towards a deeper understanding of how champions influence the allocation of resources to innovation projects

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Maarten E.J. Rutten ◽  
Andre G. Doree ◽  
Johannes I.M. Halman
Keyword(s):  
Resource Allocation ◽  
Construction Industry ◽  
Allocation Of Resources ◽  
Mediating Role ◽  
Innovation Projects ◽  
Innovation Project

Previous research indicates that the presence of a champion in an innovation project increases the likelihood that firms will allocate resources to the innovation project. Relatively little is, however, known about how champions’ presence exactly influences resource allocation. A case study of two innovation projects in the construction industry was conducted to further explore this question. The findings suggest that it is not so much champions’ presence as such, but one of champions’ prototypical behaviours that influences firms’ willingness to allocate resources. Here we refer to champions’ expression of enthusiasm and confidence about the success of an innovation. Further, the findings suggests that the effect might be explained by the mediating role of firms’ expectations of the rate of adoption. Overall, the case study provides a step towards a deeper understanding of how champions induce firms to allocate resources to innovation projects.

scholarly journals Self-Fertilization, Inbreeding, and Yield in Alfalfa Seed Production

2021 ◽  
Vol 12 ◽  
Author(s):  
Molly E. Dieterich Mabin ◽  
Johanne Brunet ◽  
Heathcliffe Riday ◽  
Lauren Lehmann
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
Inbreeding Depression ◽  
Seed Yield ◽  
Seed Set ◽  
Central Valley ◽  
Selfing Rate ◽  
Alfalfa Seed ◽  
The Impact ◽  
Number Of Seeds

Selfing (self-pollination) is the ultimate form of inbreeding, or mating among close relatives. Selfing can create yield loss when inbreeding depression, defined as a lower survival and reproduction of inbred relative to outbred progeny, is present. To determine the impact of selfing in alfalfa (Medicago sativa L.), we quantified the selfing rate of 32 alfalfa seed production fields located in three regions, namely, the Pacific Northwest (PNW), the Central Valley of California (CEV), and the Imperial Valley of California (IMP). Selfing rates (the proportion of selfed seeds) varied between 5.3 and 30% with an average of 12.2% over the 32 seed production fields. In both the parents and their progeny, we observed an excess of heterozygotes relative to Hardy–Weinberg expectations. We detected notable levels of inbreeding in parents (0.231 ± 0.007 parental inbreeding coefficient) and progeny (0.229 ± 0.005). There were a 15% decrease in the number of seeds per stem (seed set) and a 13% decline in the number of seeds per pod in selfed relative to outcrossed stems, but negligible inbreeding depression for pods per raceme and seed weight. The number of racemes on selfed stems increased significantly in fields with greater selfing rates, supporting the presence of geitonogamous or among flower selfing. Despite the significant level of inbreeding depression, seed set did not decrease in fields with higher selfing rates, where the greater number of racemes on the selfed stems increased the seed set. The effects of the field selfing rate on the seed yield metrics were mostly indirect with direct effects of the number of racemes per stem. Available data indicate that the majority of selfing in alfalfa is pollinator-mediated, and thus, eliminating selfing in alfalfa seed production would require the selection of self-incompatible varieties, which, by eliminating inbreeding depression, would provide a 15% potential increase in seed yield and an increase in future hay yield.

scholarly journals 950 PB 443 DOES WOUNDING BEFORE POLLINATION INCREASE SEED PRODUCTION IN SOLANACEOIJS PLANTS?

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 570a-570
Author(s):  
Ellen K. Muchmor ◽  
Loverine P. Taylor
Keyword(s):  
Natural Product ◽  
Seed Production ◽  
Pollen Germination ◽  
Seed Set ◽  
Pollen Grains ◽  
Inbred Lines ◽  
Nicotiana Tobacum ◽  
Solanaceous Plant ◽  
Number Of Seeds

Seed set is affected by many factors. One of the most important is the number of pollen grains that germinate on the stigma. Our research has shown that kaempferol (a plant natural product) is required for pollen germination. Pollen lacking kaempferol does not germinate, but this defect can be reversed by adding powdered kaempferol to the stigma at pollination. Within 24 hours of wounding the corolla or stamens of V26, a Petunia inbred, high levels of kaempferol accumulate in the stigma. The requirement for kaempferol in pollen germination, and the high levels that can accumulate in the stigma, suggested that seed set might be enhanced by wounding 24 hours before pollination. We tested this hypothesis in two inbred lines of Petunia, a Petunia outcross, and another solanaceous plant Nicotiana tobacum cv. Samsum. The number of seeds per capsule were correlated with the levels of kaempferol in the stigma in wounded and non-wounded flowers.

Resource allocation and service design in local government: a case study

2015 ◽  
Vol 28 (1) ◽  
pp. 29-41
Author(s):  
Manzurul Alam
Keyword(s):  
Resource Allocation ◽  
New Zealand ◽  
Local Government ◽  
Service Design ◽  
City Council ◽  
Reform Process ◽  
Content Type ◽  
Government Organizations

Purpose – Following the introduction of the New Zealand Local Government Amendment Acts (1996, 2002), some significant changes have taken place in resource allocation and service design of local government organizations. The purpose of this paper is to investigate the effect of local government reforms on budgetary processes and service design in a New Zealand local government entity. Design/methodology/approach – The paper adopts a qualitative case study research involving semi-structured interviews with the key informants to understand the evolving role of resource allocation the study investigates the budgetary processes in a metropolitan city council. Findings – The traditional role of budget has changed to a more active and visible instrument in explaining the effectiveness and efficiency in the use and allocation of resources. Budgets have been given a central role in the management of local government finances. The reform process in New Zealand has enabled local government organizations to organize their activities by using the concepts of public and private goods. Research limitations/implications – This is a single local government entity case study. Any generalization of the conclusions from this study should undertaken with care even though there are similarities between New Zealand and other countries even though they operate under different institutional contexts in different countries. Originality/value – This paper makes important contribution by highlighting the implications of resource allocation on service design within New Zealand local government entities.

scholarly journals Honey bee as an effective pollinating agent of pumpkin

2009 ◽  
Vol 66 (4) ◽  
pp. 476-480 ◽  
Author(s):  
Daniel Nicodemo ◽  
Regina Helena Nogueira Couto ◽  
Euclides Braga Malheiros ◽  
David De Jong
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
No Production ◽  
Diabrotica Speciosa ◽  
Number Of Visits ◽  
Male Flowers ◽  
Mean Time ◽  
Number Of Seeds ◽  
Female Flowers

The production of fruits and seeds of many crops is increased when bees visit their flowers pollinating them. The aim of this research was to study the pollination of pumpkins (Cucurbita maxima Duch. var. Exposição), to determine the diversity of insects visiting its flowers, the time and type of provision obtained and the effect of the visits on fruit set, fruit size and weight, and number of seeds. Apis mellifera L. accounted for 73.4% of the visits made by bees, collecting pollen during 34.5 s per flower and nectar in 43.9 s and 29.3 s from female and male flowers, respectively. Trigona spinipes (Fabr.) collected only nectar, during a mean time of 60.5 s per flower, and represented 26.6% of the visits by bees. Diabrotica speciosa (Germ.) only fed on the petals of the flower. When no insect visits occurred, there was no production of fruits. In the flowers with free visitation by insects, fruit set was 40%. The higher the number of visits, up to 16, by A. mellifera to female flowers, the greater was the fruit set, fruit size and weight, and number of seeds. In flowers visited by insects from the onset of anthesis until 9 a.m., fruit set was 35%. After 9 a.m., there was no fruit set, demonstrating the important role of A. mellifera as a pollinating agent of pumpkin, since it was the only insect visiting up to 9 a.m.

Predation by Insects Limits Seed Production in Banksia spinulosa var neoanglica (Proteaceae)

1990 ◽  
Vol 38 (4) ◽  
pp. 335 ◽  
Author(s):  
G Vaughton
Keyword(s):  
Seed Production ◽  
Reproductive Output ◽  
Seed Set ◽  
Control Group ◽  
Insecticide Treatment ◽  
Seed Predators ◽  
Flowering Season ◽  
Number Of Seeds

Application of insecticide to inflorescences of Banksia spinulosa var. neoanglica indicated that damage by flower and seed predators halved the number of seeds produced per plant. Both the proportion of inflorescences that produced fruits and the number of seeds produced per infructescence increased by 45% when insects were excluded. Infructescences in the insecticide treatment produced 28% more follicles than in the control group. Insects damaged the seed in 13% of follicles in the control group whereas there was no damage in the insecticide treatment. The proportion of follicles with aborted seed did not differ between the two groups. The greater seed set occurring when insects were excluded did not affect the weight of individual seeds or reproductive output in the next flowering season. Some inflorescences did not produce fruit even when insects were excluded suggesting that factors besides predation also limit fecundity of B. spinulosa.

Sign in / Sign up

Export Citation Format

Share Document