PRINCIPAL COORDINATE ANALYSIS OF GENOTYPE x ENVIRONMENT INTERACTION FOR GRAIN YIELD OF BREAD WHEAT IN THE SEMI-ARID REGIONS

Multi-environmental trials have significant main effects and significant multiplicative genotype x environment (GE) interaction effect. Principal coordinate analysis (PCOA) offers a more appropriate statistical analysis to deal with such situations, compared to traditional statistical methods. Eighteen bread wheat genotypes were grown in four semi-arid regions over three year seasons to study the GE interaction and yield stability and obtained data on grain yield were analyzed using PCOA. Combined analysis of variance indicated that all of the studied effects including the main effects of genotype and environments as well as the GE interaction were highly significant. According to grand means and total mean yield, test environments were grouped to two main groups as high mean yield (H) and low mean yield (L). There were five H test environments and six L test environments which analyzed in the sequential cycles. For each cycle, both scatter point diagram and minimum spanning tree plot were drawn. The identified most stable genotypes with dynamic stability concept and based on the minimum spanning tree plots and centroid distances were G1 (3310.2 kg ha(-1)) and G5 (3065.6 kg ha(-1)), and therefore could be recommended for unfavorable or poor conditions. Also, genotypes G7 (3047.2 kg ha(-1)) and G16 (3132.3 kg ha(-1)) were located several times in the vertex positions of high cycles according to the principal coordinates analysis. The principal coordinates analysis provided useful and interesting ways of investigating GE interaction of barley genotypes. Finally, the results of principal coordinates analysis in general confirmed the breeding value of the genotypes, obtained on the basis of the yield stability evaluation.