scholarly journals Propagule pressure and the establishment of emergent polyploid populations

2020 ◽  
Vol 127 (1) ◽  
pp. 1-5
Author(s):  
Donald A Levin
Keyword(s):  
Invasive Species ◽  
Seed Production ◽  
Propagule Pressure ◽  
Prime Factor ◽  
Demographic Stochasticity ◽  
Local Populations ◽  
Population Survival ◽  
Successful Colonization ◽  
Number Of Seeds ◽  
Diploid Populations

Abstract Background Whereas the incidence or rate of polyploid speciation in flowering plants is modest, the production of polyploid individuals within local populations is widespread. Explanations for this disparity primarily have focused on properties or interactions of polyploids that limit their persistence. Hypothesis The emergence of local polyploid populations within diploid populations is similar to the arrival of invasive species at new, suitable sites, with the exception that polyploids suffer interference from their progenitor(s). The most consistent predictor of successful colonization by invasive plants is propagule pressure, i.e. the number of seeds introduced. Therefore, insufficient propagule pressure, i.e. the formation of polyploid seeds within diploid populations, ostensibly is a prime factor limiting the establishment of newly emergent polyploids within local populations. Increasing propagule number reduces the effects of genetic, environmental and demographic stochasticity, which thwart population survival. As with invasive species, insufficient seed production within polyploid populations limits seed export, and thus reduces the chance of polyploid expansion. Conclusion The extent to which propagule pressure limits the establishment of local polyploid populations remains to be determined, because we know so little. The numbers of auto- or allopolyploid seed in diploid populations rarely have been ascertained, as have the numbers of newly emergent polyploid plants within diploid populations. Moreover, seed production by these polyploids has yet to be assessed.

scholarly journals Researches on the Main Characteristics of Red Clover Seedlings and their Influence in

2012 ◽  
Vol 69 (1) ◽  
Author(s):  
Marioara GREBENIȘAN ◽  
Doru PAMFIL ◽  
Dorottya Alice DOMOKOS
Keyword(s):  
Plant Breeding ◽  
Seed Production ◽  
Red Clover ◽  
Production Level ◽  
Seed Crop ◽  
Binding Process ◽  
Lower Variability ◽  
Clover Seed ◽  
Number Of Seeds

Concerning the red clover breeding, it is essential to choose as genitors those varieties that possess good characteristics. In order to identify potential genitors, two red clover varieties were studied at Cluj-Napoca: Roxana, diploid variety and Napoca-tetra, tetraploid variety. The analyzed traits comprised the number of capitula/plant, number of seeds/capitulum and the binding process, under the aspect of their contribution to the seed crop and the interaction between those components, in order to provide important clues about di-and tetraploid red clover seed production, for plant breeding. The highest variability (s%=30) presented regarding the number of flowers/capitulum, diploid variety comparatively with a lower variability (s%=26) regarding the number of flowers number/capitulum, tetraploid varieties. Several traits were compared between di-and tetraploid red clover varieties in order to find genitors which can be used for creating new genotypes with high seed production level.

Seed production in Cardiocrium cordatum: effects of nitrogen and dry mass availability of a plant

2006 ◽  
Vol 84 (5) ◽  
pp. 805-812
Author(s):  
Satoki Sakai ◽  
Akiko Sakai ◽  
Kohta Fujioka
Keyword(s):  
Mass Loss ◽  
Seed Production ◽  
Plant Size ◽  
Dry Mass ◽  
Stem Diameter ◽  
N Content ◽  
N Concentration ◽  
The Mean ◽  
Number Of Seeds

To clarify how seed production depends on the relative N and dry mass availability, we examined the number and size of seeds, and the loss of dry mass in Cardiocrium cordatum (Thunb.) Makaino plants that differed naturally in overall size and stem N content. After adjusting for plant size (basal stem diameter was used as a criterion of plant size), the amount of dry mass lost because of respiration in a plant decreased with an increase in the stem N content of the plant, whereas the total dry mass of seeds of a plant increased with an increase in the stem N content. Plants with a high stem N content relative to dry mass status used dry mass resources more efficiently in seed production by reducing the loss of dry mass. Plants with a higher stem N content produced a greater number of seeds, and the amount of dry mass lost decreased with an increase in the number of seeds of the plant, possibly because the resources allocated to seed production are consumed rapidly, if numerous seeds simultaneously absorb those resources. However, the stem N content of a plant had no influence on the mean seed dry mass, seed N content, and the seed N concentration, and the latter three parameters did not affect respiration loss of dry mass. We concluded that plants undergoing seed production reduce dry mass loss if their relative N to dry mass availability is high, through an increase in the numbers of seeds they produce.

The effect of defoliation on seed production by capeweed (Arctotheca calendula)

1973 ◽  
Vol 13 (65) ◽  
pp. 676 ◽  
Author(s):  
JG McIvor ◽  
DF Smith
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Yield Components ◽  
Seed Weight ◽  
Leaf Removal ◽  
Late Flowering ◽  
Individual Seed ◽  
Number Of Seeds

Two experiments were done in pots to assess the effect of defoliation at different times on the seed yield of capeweed (Arctotheca calendula). Yield components measured were: number of seedheads per plant, number of seeds per seedhead, number of seeds per plant, and weight of individual seeds. Of the components of yield, number of florets per seedhead and individual seed weight were maintained under all treatments; number of seedheads and number of seeds per seedhead were more affected by defoliation. Whether grown as spaced plants or in swards, leaf removal did not significantly reduce the number of seeds produced unless combined with bud and flower removal at late flowering only. The results are discussed in relation to the growth and persistence of capeweed in pastures.

scholarly journals Scale-dependent portfolio effects explain growth inflation and volatility reduction in landscape demography

2017 ◽  
Vol 114 (47) ◽  
pp. 12507-12511 ◽  
Author(s):  
Cang Hui ◽  
Gordon A. Fox ◽  
Jessica Gurevitch
Keyword(s):  
Invasive Species ◽  
Time Series ◽  
Regional Scale ◽  
Scaling Up ◽  
Range Shifts ◽  
Attainable Set ◽  
Local Populations ◽  
Accumulation Curve ◽  
Invasive Organisms ◽  
Regional Population

Population demography is central to fundamental ecology and for predicting range shifts, decline of threatened species, and spread of invasive organisms. There is a mismatch between most demographic work, carried out on few populations and at local scales, and the need to predict dynamics at landscape and regional scales. Inspired by concepts from landscape ecology and Markowitz’s portfolio theory, we develop a landscape portfolio platform to quantify and predict the behavior of multiple populations, scaling up the expectation and variance of the dynamics of an ensemble of populations. We illustrate this framework using a 35-y time series on gypsy moth populations. We demonstrate the demography accumulation curve in which the collective growth of the ensemble depends on the number of local populations included, highlighting a minimum but adequate number of populations for both regional-scale persistence and cross-scale inference. The attainable set of landscape portfolios further suggests tools for regional population management for both threatened and invasive species.

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.

Growth Response of Itchgrass (Rottboellia cochinchinensis) to Water Stress

Weed Science ◽  
2013 ◽  
Vol 61 (1) ◽  
pp. 98-103 ◽  
Author(s):  
Bhagirath S. Chauhan
Keyword(s):  
Water Stress ◽  
Seed Production ◽  
Aboveground Biomass ◽  
Growth Response ◽  
Weight Ratio ◽  
Field Capacity ◽  
Irrigation Regime ◽  
Weed Plants ◽  
Rottboellia Cochinchinensis ◽  
Number Of Seeds

Greenhouse studies were conducted to evaluate the growth response of itchgrass to water stress. Itchgrass plants produced the greatest aboveground biomass and seeds at 75% of field capacity and these parameters at 50 and 100% of field capacity were similar. With further increase in water stress, seed production was sharply reduced, but itchgrass was still able to produce an average of 63 and 9 seeds plant−1at 25 and 12.5% of field capacity, respectively. Itchgrass plants responded to increasing water stress with increased leaf weight ratio; it was 2.5 times greater at 12.5% of field capacity than at 100% of field capacity. In another study, compared with daily irrigation, intervals of 9 d between irrigations reduced aboveground biomass of itchgrass by 27% and 12-d intervals reduced aboveground biomass by 67%. Compared with the daily irrigation regime, itchgrass seed production was reduced by 61% at intervals of 12 d between irrigations; however, the weed plants produced a considerable number of seeds (153 seeds plant−1) at the 12-d intervals. The ability of itchgrass to produce biomass and seeds under water stressed conditions necessitates strategies that minimize weed survival while maximizing irrigation efficiency for the crop at the same time.

scholarly journals LOW DOSES OF FENOXAPROP-P-ETHYL CAUSE HORMESIS IN LITTLESEED CANARYGRASS AND WILD OAT

2016 ◽  
Vol 34 (3) ◽  
pp. 527-533 ◽  
Author(s):  
T. ABBAS ◽  
M.A. NADEEM ◽  
A. TANVEER ◽  
A. ZOHAIB
Keyword(s):  
Seed Production ◽  
Growth Stimulation ◽  
Research Area ◽  
Initial Increase ◽  
Low Doses ◽  
Wild Oat ◽  
Crop Species ◽  
Pot Experiments ◽  
Promotive Effect ◽  
Number Of Seeds

ABSTRACT Hormetic effects of herbicides at ultra-low doses have been proved against range of crop species, although available data of herbicides hormesis about the weeds growth is very limited. This study investigates the promotive effect of low doses of fenoxaprop-Pethyl on growth and seed production of littleseed canarygrass and wild oat. Pot experiments were conducted twice in Wire House at Agronomic Research Area, University of Agriculture, Faisalabad, during 2014-15. Seven different concentrations of fenoxaprop-P-ethyl [0, 1, 3, 6, 9, 12 and 15 g a.i. ha-1] were applied as post emergence herbicide at 3-4 leaves stage of the weeds. Results revealed that increase in growth occurred within first two weeks after spraying at fenoxaprop-P-ethyl doses 1, 3 and 6 g a.i. ha-1. More growth stimulation as compared to all other treatments was observed at fenoxaprop-P-ethyl dose 6 g a.i. ha-1. This initial increase in growth sustains with time up to the maturity of both weeds and positively influences seeds production ability. Up to 28% and 17% increase in number of seeds per plants were occurred in littleseed canarygrass and wild oat, respectively. Doses above 6 g a.i. ha-1 negatively affect the weeds growth and seed production ability.

scholarly journals Prediction Equations for Black Spruce Seed Production and Dispersal in Northern Ontario

1982 ◽  
Vol 58 (2) ◽  
pp. 96-99 ◽  
Author(s):  
B. Payandeh ◽  
V. F. Haavisto
Keyword(s):  
Seed Production ◽  
Nonlinear Regression ◽  
Picea Mariana ◽  
Black Spruce ◽  
Seed Viability ◽  
Original Data ◽  
Regression Equations ◽  
Northern Ontario ◽  
Solution Of Equations ◽  
Number Of Seeds

Nonlinear regression equations were developed to describe seed production and dispersal in black spruce (Picea mariana [Mill.]B.S.P.)in northern Ontario. Solution of the equations can provide useful information beyond the range of the original data, because of the flexibility of the models used. For example, solution of equations 1-3 indicates that cones from intermediate crown class trees initially have about twice as many seeds as those of either the dominant or codominant trees, but disperse their seeds at a much faster rate. Average number of seeds per cone for all three crown classes is about 7 after 10 years. Older cones of the intermediate crown class trees have fewest seeds per cone. Solution of equation 4 indicates that average seed viability is about 53% and decreases only slightly during the first three years. It then decreases very rapidly up to 12 years to about 5%. Similarly, equations 6 and 7 may be solved to determine an optimum strip-cut width for sufficient seedfall across the strip to produce satisfactory regeneration.

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