Seed cotton yield is a trait governed by multiple genes that cause changes in the performance of genotypes depending on the cultivation environment; therefore plant breeders always test their genotypes across diverse environments to assess consistency of superior genotypes for wide adaption. Twelve Egyptian cotton genotypes (G) were studied across three various environments (E) representing Middle and Upper Egypt during the three seasons (S) 2016, 2017 and 2018. Genotypes (G) across environments (E) over years (Y) revealed significant differences for seed cotton yield. Significant values of mean squares due to genotypes environment interaction (G × E) and genotypes x year interaction (G × Y) for (SCY K/f).Moreover, the interaction effects due to (Y × E × G) were also significant for seed cotton yield (SCY K/f),indicated that (SCY K/f) of cotton genotypes is mostly affected by environment and years. Environment significance explained by 73.3% (7.2%, 32.3% and 35.9%) for year, environment and their interactions, respectively of the total sum squares due to G, E and (G × E) interaction however partitioning of variance components for environment revealed that both predictable (E) and unpredictable (Y) components were important source of variation. The environment (E), genotype (G) and (G × E) interaction effects explained about 43,9% (32.3%, 4.4% and 7.2%), respectively, of the total sum squares variance components. According to ideal genotype Biplot analysis, genotypes G1, G5 and G7 are more stable and had the high yielding ability compared with the grand mean performance with other genotypes thus genotypes identified as ideal genotypes for seed cotton yield (SCY K/f).
