Abstract

Stripe, or yellow rust caused by Puccinia striiformis f. sp. Westend. tritici Eriks is a common disease of wheat in cool and humid climates. Use of genetic resistance is the most economical and environmentally method of disease control. Genetic diversity is the basis of plant breeding and selection depends upon the existence of an appropriate diversity for the trait being selected for. Given that the yield of crops is a function of genotype, environment and their interactions and that to realize a high yield, the selection is more efficient when conducted for the yield components rather than yield itself, the study of the relationship between yield and its components is crucially important in breeding programmes. In the current study, 30 bread wheat genotypes originated from Iran were planted on the basis of a randomized complete block design with two replications under pathogenic and non-pathogenic stressconditions in Khoramabad, Iran. The results of the analysis of variance of the evaluated traits showed that the effects of genotype and the interaction between genotype and environment were significant. Since the interaction between genotype and environment was significant, genetic correlation rather than phenotypic correlation was used for studying the relations among the traits. The results of genetic correlation analysis between yield and the traits remained in ridge regression model showed that spikes number per plant had the highest direct effect on yield, but the highest indirect effect of this trait was applied through plant although 1000-grain weight showed the highest direct effect in phenotypic correlation analysis, too.