Characterization of brown rust resistance in bread wheat using yield related morphological indices

Abstract

Current research explores adult plant resistance (APR) to brown rust (leaf rust) in diverse bread wheat genotypes using morphological traits as indicators. Leaf rust disease was induced, and various parameters, including Area Under the Disease Progress Curve (AUDPC), Final Disease Severity % (FDS), and Coefficient of Infection (CI), were assessed, along with yield-related traits like Plant Height (PH), Peduncle Length (PL), Spikelets per Spike (SPS), Number of Grains per Spike (NGPS), Thousand-Grains Weight (TGW) and Grain Yield per Plant (GYP). The study reveals varying levels of resistance among genotypes. Genotypes G3, G5, G6, G7, G12, G15, G16, G19, G21, G22, G25, G26, G27, and G30 demonstrated strong resistance, with low values for FDS, AUDPC and CI. In contrast, Genotypes G1, G8, G18 and G28 were highly susceptible, exhibiting high values for these parameters, categorizing them as “S” (Susceptible). Correlation analysis unveiled strong positive associations between AUDPC and both FDS and CI, indicating increased disease severity with rising AUDPC values. Positive correlations were also found among yield-related traits. Conversely, yield and yield-related traits showed weak, non-significant and negative correlations with disease-related parameters. Principal Component Analysis (PCA) highlighted three significant Principal Components (PCs), with the first two (F1 and F2) explaining 73.74% of data variability. Furthermore, genotype clustering indicated varying genetic similarity levels. These findings offer valuable insights for genotype selection and breeding strategies, contributing to enhanced brown rust resistance in wheat.