الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Climate change in the form of raising and fluctuating temperatures with heightened competition for scarce natural resources potentially threatens the sustainability of agricultural production, particularly in affected regions like Egypt. However, unpredictable climatic fluctuations greatly affect the productivity and resilience of cotton varieties and consequently should be considered for releasing new varieties. Exploring the sufficient magnitudes of genetic variation of Egyptian cotton segregating populations for agronomical traits under variable environmental conditions is required for the effective selection of promising varieties that may be resilient to climatic changes is a valuable goal of Egyptian cotton breeders.
5. 1. Variation and stability of F2/F3 Egyptian cotton populations and parents.
Fifteen F2/F3 segregating populations along to their parental genotypes/varieties were evaluated under eight field trials during 2019 and 2020 seasons at the Agricultural Experiments and Research Farm of the Faculty of Agriculture, Minia University, El-Minia, Egypt. These populations were stemmed from diallel mating system from M.Sc. study. In each season, four RCBD trials were carried out using two planting dates as early, E (onset of April) and late planting, L (onset of May). In each sowing dates, two trials were conducted using two irrigation intervals as normal, N (each 14 days) and each 28 days (as water stressed, S).
Combined analysis of variance due to 21 cotton genotypes across each four experiments conducted as early or those planted late (irrigated normally and stressed, respectively), normal or stressed watering (planted earlier and late) across both seasons of each type of trials were performed of obtained data of each four trials and across eight environments to detect the influences due to sowing dates and/or irrigation intervals and their interaction. However, genotypes and their components: parents (P), crosses (C) and P vs. C as well as G×E were calculated. The genotypic and phenotypic of variation, broad sense heritability (h2) and the relative expected genetic advance (RGA) to corresponding means from selecting the top 10 % of the investigated genotypes were estimated across investigated environmental combinations.
The stability analyses of performance across the generated eight environments were performed using S2di, bi and Wi as parametric dynamic stability approaches as well as RS and Ysi nonparametric stability parameters.