GENOTYPE × ENVIRONMENT INTERACTION AND YIELD STABILITY ANALYSIS OF NEW IMPROVED BREAD WHEAT GENOTYPES

Abstract

Yield stability is an interesting feature of today’s wheat breeding programs, due to the high annual variation in mean yield, particularly in the arid and semi-arid areas. Eighteen bread wheat (Triticum aestivum L.) genotypes sourced from different regions were tested for yield stability and performance in four environments between 2007 and 2009 using various stability statistics. The experiment of each environment was laid out in a randomized complete-block design with four replications. Combined analysis of variance of grain yield revealed highly significant differences among genotypes and environments. Significant genotype × environment interaction indicated differential performance of genotypes across environments. Considering coefficient of several linear regression models, including conventional, adjusted, independent and Tai models as well as deviation variance from these models, genotype G2 was the most stable genotypes. Stability assessment on the basis of parameters like environmental variance, coefficient of variation, stability variance, genotypic stability and Superiority Index, genotypes G2 and G5 were the most stable genotypes. The results of principal component analysis of stability statistics and mean yield indicated that slope of linear regression of both conventional and independent models would be useful for simultaneously selecting for high yield and stability. The plot of the first two principal components also revealed that the stability statistics could be grouped as two distinct classes that corresponded to different static and dynamic concepts of stability. Finally, regarding both mean yield and most of stability characteristics, genotypes G2 and G5 were found to be the most stable genotypes. Such an outcome could be employed in the future to delineate rigorous recommendation strategies as well as to help define stability concepts for other crops.