scholarly journals SEX RATIO, SEED PRODUCTION, BIOMASS ALLOCATION, AND THE COST OF MALE FUNCTION IN CUCURBITA FOETIDISSIMA HBK (CUCURBITACEAE)

Evolution ◽  
1989 ◽  
Vol 43 (7) ◽  
pp. 1424-1434 ◽  
Author(s):  
Joshua R. Kohn
Keyword(s):  
Sex Ratio ◽  
Seed Production ◽  
Biomass Allocation ◽  
Male Function ◽  
The Cost

Marginal analysis and cost effectiveness in seed orchard management

1987 ◽  
Vol 17 (6) ◽  
pp. 510-515 ◽  
Author(s):  
Thomas A. Thomson ◽  
Donald T. Lester ◽  
Jeanne A. Martin
Keyword(s):  
Seed Production ◽  
Analytical Techniques ◽  
Cost Effective ◽  
Seed Orchard ◽  
Induction Treatment ◽  
Marginal Analysis ◽  
Orchard Management ◽  
Improvement Programs ◽  
Four Quadrant ◽  
The Cost

We use marginal analysis for three seed orchard management decisions. First we consider the roguing of a seed orchard established with many untested trees. We show that inferior parents should be rogued to the point where the number of orchard trees times the average expected volume gain of trees from seed produced by that orchard is maximized. Marginal analysis also is useful where one must choose the number of trees to establish in an orchard planted after progeny tests have identified superior parents. The cost of establishing many ramets to meet early seed production goals can be balanced with the projected value of seed. For the example presented, an additional orchard tree is cost effective if its seed is needed at an orchard age of 12 to 15 years. Finally, we use marginal analysis to determine whether to induce a seed orchard to increase its seed production when there is an excess demand for seed. This decision is guided by balancing the cost of the induction treatment with the combined effect of expected increase in seed harvest, the amount of genetic gain, and the discount rate. We present a four-quadrant decision diagram for estimating this balance. In designing tree improvement programs, these analytical techniques can be applied to proposed alternatives as one way to structure decision making and to provide comparable economic assessments from which cost-effective choices can be made.

Female-biased mortality induced by male sexual harassment in a feral sheep population

1996 ◽  
Vol 74 (10) ◽  
pp. 1812-1818 ◽  
Author(s):  
Denis Réale ◽  
Patrick Boussès ◽  
Jean-Louis Chapuis
Keyword(s):  
Sex Ratio ◽  
Bimodal Distribution ◽  
Ovis Aries ◽  
Operational Sex Ratio ◽  
High Survival ◽  
Sexually Dimorphic ◽  
Female Mortality ◽  
Male Mortality ◽  
Sheep Population ◽  
The Cost

In contrast to most populations of sexually dimorphic ungulates, a 3-year study revealed a tertiary sex ratio (the number of males per female at sexual maturity) strongly biased towards males in the Île Longue feral sheep (Ovis aries) population (Kerguelen subantarctic archipelago). This population presents a main winter lambing season and a secondary summer lambing period. The sex ratios of lambs and lamb carcasses were even. The skewed sex ratio of adults was therefore attributed to shorter longevity of females. We showed that (i) male monthly mortality followed a bimodal distribution with peaks corresponding to the two rutting periods. Male mortality was, however, highest during the winter even though less rutting occurred in this season than in the summer, suggesting that harsher winter conditions enhance the cost of mating competition; (ii) female mortality was related to the rutting activity of males but not to lambing. Female mortality peaked in the summer despite plentiful food resources. This period corresponds to the main rutting peak, suggesting a high survival cost of mating for females. Female mortality due to male harassment was confirmed by direct observations and examination of females injured during rutting periods. This situation may be due to a strongly male-biased operational sex ratio in the population, associated with an inability of males to establish a stable dominance hierarchy within a large flock.

Nutrient sensitivity of the cost of male function in gynodioecious Phacelia linearis (Hydrophyllaceae)

1997 ◽  
Vol 84 (8) ◽  
pp. 1092-1098 ◽  
Author(s):  
Vincent M. Eckhart ◽  
F. Stuart Chapin
Keyword(s):  
Male Function ◽  
The Cost

scholarly journals EVALUATION OF THE MATERNAL FORMS OF CUCUMBER HYBRIDS FOR OPEN GROUND IN TERMS OF THE DEGREE OF EXPRESSION OF THE FEMALE SEX

2018 ◽  
pp. 40-42
Author(s):  
I. B. Korottseva ◽  
S. N. Belov
Keyword(s):  
Seed Production ◽  
Hybrid Seed ◽  
Hybrid Seed Production ◽  
Labor Costs ◽  
Single Male ◽  
Female Type ◽  
Female Sex ◽  
Open Ground ◽  
Male Flowers ◽  
The Cost

Growing heterotic hybrids of cucumber on large areas is possible only if the production of their seeds does not require large additional labor costs in comparison with conventional varieties. Cleaning of maternal forms by flowering type – removal of plants of intermediate type of flowering and single male flowers on plants of predominantly female type requires considerable labor costs. Significantly simplifies and reduces the cost of hybrid seed production using maternal forms of female type that do not have male flowers. It is very important to create maternal forms with a consistently high female expression that do not respond to changing environmental conditions. This will allow hybrid seed production of cucumber not only in protected, but also in the open ground, which will significantly reduce the cost of production of seeds. The objective was to assess the maternal forms of the cucumber hybrids F1 Krepish (L-100), F1 Brunet (L-105), F1 Frant (L-290), F1 Krasotka (L-25) according to the female expression in the conditions of spring film greenhouses and open ground near Moscow. The open ground served as a provocative background for identifying the most stable in terms of the severity of the female sex lines. It was determined that the bee-polluted hybrids of the cucumber F1 Krepish and F1 Brunet are most suitable for conducting hybrid seed production in the open field, since their maternal forms need to be cleaned according to the blooming type less than others.

scholarly journals Male Fertility Genes in Bread Wheat (Triticum aestivum L.) and Their Utilization for Hybrid Seed Production

2021 ◽  
Vol 22 (15) ◽  
pp. 8157
Author(s):  
Manjit Singh ◽  
Marc C. Albertsen ◽  
A. Mark Cigan
Keyword(s):  
Male Sterility ◽  
Seed Production ◽  
Male Fertility ◽  
Production Systems ◽  
Triticum Aestivum L ◽  
Hybrid Seed ◽  
Addition Line ◽  
Hybrid Seed Production ◽  
Wheat Varieties ◽  
The Cost

Hybrid varieties can provide the boost needed to increase stagnant wheat yields through heterosis. The lack of an efficient hybridization system, which can lower the cost of goods of hybrid seed production, has been a major impediment to commercialization of hybrid wheat varieties. In this review, we discuss the progress made in characterization of nuclear genetic male sterility (NGMS) in wheat and its advantages over two widely referenced hybridization systems, i.e., chemical hybridizing agents (CHAs) and cytoplasmic male sterility (CMS). We have characterized four wheat genes, i.e., Ms1, Ms5, TaMs26 and TaMs45, that sporophytically contribute to male fertility and yield recessive male sterility when mutated. While Ms1 and Ms5 are Triticeae specific genes, analysis of TaMs26 and TaMs45 demonstrated conservation of function across plant species. The main features of each of these genes is discussed with respect to the functional contribution of three sub-genomes and requirements for complementation of their respective mutants. Three seed production systems based on three genes, MS1, TaMS26 and TaMS45, were developed and a proof of concept was demonstrated for each system. The Tams26 and ms1 mutants were maintained through a TDNA cassette in a Seed Production Technology-like system, whereas Tams45 male sterility was maintained through creation of a telosome addition line. These genes represent different options for hybridization systems utilizing NGMS in wheat, which can potentially be utilized for commercial-scale hybrid seed production.

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