Genetic variability for the leaf rust resistance and its association with morphological yield contributing traits in bread wheat germplasm under field condition

Leaf rust (also called Brown rust) caused by Puccinia triticina Eriks severely reduces the grain yield of bread wheat and causes huge economic losses globally. Identification and development of wheat genotypes having resistance is only durable and ecofriendly solution to combat this devastating disease. Therefore, characterization of the 101 diverse panel of wheat genotypes was done to assess the resistance and diversity against leaf rust based on morphological parameters under natural field conditions. Field trials were conducted under Augmented Design during the two cropping seasons 2020-21 and 2021-22. Out of 101 genotypes, 09 genotypes (G10, G20, G28, G35, G55, G59, G69, G81 and G90) were found to be completely resistant, 63 genotypes were moderately resistant, 17 genotypes were moderately-susceptible to susceptible and 06 genotypes were susceptible to leaf rust. Ninety genotypes had Coefficient of Infection (CI) value between 0 and 20 exhibiting high resistance, 05 genotypes had CI value 21–40 and 06 genotypes had 41–100 CI value indicating moderate and low resistance respectively. Correlation analysis revealed that leaf rust significantly reduced the growth and yield of studied genotypes because the CI showed highly significant negative correlation with Spike Length (SL), Flag Leaf Area (FLA), Chlorophyll content index (CC), Spikelet per Spike (SS), Grain yield per Spike (GYS) and Thousand Grain Weight (TGW). The principal component analysis (PCA) showed that out of ten, three PCs had Eigenvalues greater than 01 which thus being significant contributed 53.84% of variations. Cluster analysis classified 101 genotypes into eight major clusters at Euclidean distance of 0.950.