Evaluation of diversity of bread wheat genotypes based on yield and yield-related traits under yellow rust disease stress condition (Puccinia striiformis)

Yellow rust is one of the most important wheat diseases worldwide. This disease can cause high damage to the plant by affecting the yield and yield components. Also, due to the high recombination of the causative agent of this disease, new breeds appear in it every year, which has forced breeders to constantly study this disease and find resistant genotypes.

In order to evaluate the effect of yellow rust disease on some agronomic characteristics of bread wheat genotypes Includes 297 commercial cultivars and landraces of Iran, a field experiment was conducted in alpha-lattice layout with two replications in the Seed and Plant Improvement Institute (SPII) farm, in 1398-1399 crop season. After sowing the seeds and artificially infecting the plants with the disease, some important agronomic traits including yield and related traits as well as infection type and infection percentage were examined.

The results of analysis of variance showed that wheat genotypes have significant differences in terms of all studied traits. An effective correlation coefficient was observed between single plant yield with all traits. The results of stepwise regression analysis showed that the number of grains per spike, 100-kernel weight, grain width, grain length, spike length, grain thickness and spike width have the highest coefficients of determination, respectively. Based on the results of path analysis, the highest direct effect was observed between the number of grains per spike, 100-kernel weight and grain width with grain yield, respectively. The results of factor analysis showed that there were five factors with a justification of about 70% of the total variance, among which the traits had the highest coefficient of explanation in the first three factors. The first factor was called the yield component factor, the second factor was called the spike features factor, and the third factor was called the grain features factor. Based on the results of cluster analysis, genotypes were divided into three groups. In the first group, 53 genotypes with the highest average of single plant yield, number of single plant seeds and spike length; In the second group there were 110 genotypes with the highest mean of plant height, spike density and 100-kernel weight and in the third group there were 129 genotypes with the highest mean values for other traits. A total of 52 wheat genotypes had resistance reaction to pathotype studied in this study.

The study of wheat genotypes under stress conditions of wheat yellow rust (Puccinia striiformis) based on statistical analysis and multivariate analysis showed a significant difference in yield and yield components. Therefore, as in previous studies, the disease studied on wheat was recognized as one of the most important diseases affecting wheat yield. To evaluate and select cultivars and genotypes with higher grain yield, selection should be done using yield-related traits such as number of seeds per spike and number of single plant seeds. Also, based on infection type and percentage, resistance genes can be identified intermediate resistance to the studied pathotype in this study and used in future breeding programs for resistance to wheat yellow rust.