Biometrical analysis of resistance to stem rust (Puccinia graminis f. sp. tritici) in the winter wheat genotypes

Stem rust or black rust is one of the most important fungal diseases that widely affect wheat yield and quality in the world. Therefore, the selection of genetic materials resistant to stem rust in the breeding programs is necessary. In this study, 24 winter wheat genotypes including eight varieties and 16 elite lines were evaluated at the adult plant and seedling stages using a randomized complete block design under the influence of local stem rust race TKTTF. Disease indices including the type of infection, the severity of infection, the coefficient of infection, the area under the disease progress curve (AUDPC), the relative area under the disease progress curve (rAUDPC), and genotype reaction were recorded. Significant differences were observed among the genotypes for all disease indices. Based on all indices, MV-17 and C-98-17 were resistant and C-98-14, C-98-9, Bolany, and Morocco were susceptible. Pearson’s correlation coefficients revealed a significant positive correlation between field type of infection, the severity of infection, the coefficient of infection, AUDPC, and rAUDPC at the field, and between greenhouse type of infection and genotype reaction at the greenhouse. Based on cluster analysis by Ward’s method, all the genotypes were classified into four groups (R, MR, MS, and S) in the adult plant stage and into two groups (R and S) at the seedling stage. The resistant genotypes can be used in the breeding programs for improvement of the stem-rust-resistant genotypes.