JWSS - Journal of Water and Soil Science

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In order to find the high-yielding and adaptable cultivars in different environments, eight cotton genotypes including two early maturity hybrids were studied and compared with the Varamin cultivar as control in a randomized complete block design with four replications in six regions in 1997 and 1998. Using Barttlet test, some of the environments were eliminated from statistical analysis. Therefore, combined analysis of variance and other statistical calculations were carried out based on environment (Year×Location) on the assumption that environment was randomized and cultivars remained constant during the entire study. In combined analysis of variance, genotypic effect (in yield) was significant at 1% probability level. Combined analysis of variance also showed significant differences for the main effect of environment and genotype×environment intreaction at 1% probability level. To select the best genotype with a high and stable yield, parametric statistics of stability including type 1 stability (S²_i,CV_i), type II stability (b_i,σ_i², w²_i), type III stability (Sd²_i) as well as non-parametric statistics such as mean of genotypic rank (R), standard deviation of rank (SDR), and simultaneous selection of parametric and nonparametric statistics for yield and stability (Ys_i) were calculated. Overall, considering the important agronomic and technological characteristics of genotypes such as yield, earliness, span length, fiber strength, percentage of uniformity, and micronariae index, the hybrid Coker×Bulgar was selected as high-yielding and stable cultivar to be substituted for Varamin cultivar across the planting area.