Analysis of stability and adaptation of cotton genotypes using GGE biplot method

This research was conducted to study effects of G × E interaction on 38 selected genotypes of cotton with two commercial cultivars Golestan and Sepid (control) in a randomized complete block design with three replications at three locations in Golestan Province in 2014-15. The measured characteristics were included: plant height, sympodial length, sympodial number, boll number, boll weight, seed cotton yield and earliness. Analysis of variance showed that genotype effect is significant in 1 or 5% probability levels on measured traits except for boll number and earliness. A significant interaction effect between genotype × locations in yield showed different variation trends in various locations. So that genotype 29 had the best performance in Hashemabad station but genotypes 24 and 18 showed their best performances in Gonbad and Anbarolum station respectively. Stability parameters were calculated and genotype No. 8 was defined according to regression slope close to 1 as the most stable genotypes among. This genotype had a smaller share in genotype and environment interaction according to Rick ecovalans and Shukla stability variance parameters and 10 and 33 were the most unstable genotypes in terms of performance. GGE biplot method showed that the first two principal components regression model explained 74% of the observed changes. GGE biplot graph plotted by software reflected the superior genotypes TJ82, ER26, DB29, DB19, DB25 and ER36 respectively. Also Hashemabad has been identified as appropriate region for ER26 genotype and TJ82 was identified as the best and most stable genotype