Estimation of genotype environment interaction in cotton (Gossypium spp. L.)

A multilocation field study was conducted fro three consecutive seasons (1998/1999-2000/2001) at five locations to estimate genotype-environment interactions and to study the associations between yield, yield components and fibre quality traits. Cotton genotypes of Gossypium hirsutum andGossypium barbadense under study were evaluated at all environments in a randomized complete block design with five replications. Highly significant differences for all yield and quality traits under study, except uniformity ratio in few environments, were detected among the tested genotypes. The presence of substantial genotype-season interactions for all evaluated traits indicated that genotypes showed differential responses when grown in different environments. Seed cotton yield and lint yield had significant and positive genotypic and phenotypic correlations with boll weight, seed cotton per plant, seed index, lint index, micronaire value and uniformity ratio but both correlations with plant height were non-significant. On the other hand, seed cotton yield and lint yield had significant and negative genotypic and phenotypic correlations with number of bolls per plant, number of bolls per square meter, 2.5% span length and fibre bundle strength. Genotypes of barbadense cotton particularly OLB (85) 160, B-Pima (85)52 and GS-84 showed a stable performance for number of bolls per plant and number of bolls per square meter, whereas genotypes of hirsutum cotton particularly Shambat B and Barac(67)B were stable in performance for boll weight, seed cotton per plant, seed index, lint index, seed cotton yield, lint yield, micronaire value and uniformity ratio. None of the 12 tested genotypes was stable for fibre bundle strnegth and only Barakat 90 and GS-84 were stable in performance for 2.5% span length