Study on Grain Yield Stability of some Promising Bread Wheat Lines in Northern Warm and Humid Climate of Iran

In order to evaluate grain yield stability of 19 promising lines of bread wheat along with a check cultivar (Tajan) in warm humid climate, an experiment was carried out in four agricultural research stations (Gorgan, Gonbad, Sari and Moghan) during 2004-2006 cropping seasons. The experimental designs in all locations were randomized complete block design with three replications. Combined ANOVA was performed following the Bartelet test (for uniformity of error variances). Year and location effects were considered random while genotypic effect as a fixed variable. Results of combined analysis of variance showed that the effects of genotype×location and genotype×location×year were significant (P<0.01), but effect of genotype×year was not significant. Stability of genotypes were evaluated using different methods including Variance (Si2) and environmental coefficient of variance (CVi), coefficient of regression of mean yield on environmental index (bi), Wricke’s ecovalance, Eberhart and Russell and within location variance (Myy/l and CV). Results of environmental variance and coefficient of variability (CVi) showed that number 19, 18, 11, 12 and 5 with lower values for environmental variance and coefficient of variability (CVi) had the highest stability. In Wricke’s ecovalance stability method number 1, 2, 8, 11and 9 had the highest stability, respectively. On the base of Eberhart and Russell method lines number 2, 1, 19, 8 and 11 had the highest stability, number 12, 14 and 11 were stable on the basis of Myy/l and C V. Result of these methods were different more or less, however, based of all methods, line no.11 with 5230 kgha-1 grain yield was selected as the most stable lines for northern warm and humid zones of Iran.