Relationship between yield and its components in bread wheat (Triticum aestivum L.) genotypes in drought and non-drought stress conditions

In order to evaluation and determination of the most effective traits in improvement grain yield of bread wheat genotypes, an experiment conducted using 320 genotypes in the research field of agriculture institute of Shahrekord in 2006. Genotypes were cultivated in augmented design along with Karaj1 and Sardari as the check cultivars in both stress and non-stress conditions. Grain yield and 10 related feature of traits were measured in this research. Correlation coefficient analysis showed that in both condition all traits except awn length and in non-stress condition spike weight had positive and significant correlation with grain yield in 1% probability level. By using step-wise regression analysis in stress condition five traits and in non-stress condition three traits entered to the model that verified 97.8% and 96.5% of grain yield variation, respectively. Path analysis for grain yield indicated that in stress condition biological yield, harvest index and grain number per spike and in non-stress condition biological yield and harvest index had the most positive and direct effect on plant kernel yield. Grain number per spike in stress as direct and in non-stress condition as indirect affect positively and significantly on increase grain yield. Therefore, results of research indicate that use of these traits suggest as indirect selection criteria in order to improve grain yield of bread wheat genotypes in both stress and non-stress conditions.