ABSTRACT Rice grain discolouration (RGD) is an emerging disease that poses a serious threat to rice yield. This study aimed to assess yield loss, genetic variability, heritability and trait associations among diverse rice cultivars under RGD pressure, with the goal of identifying promising genotypes for resistance breeding and yield improvement. A total of 48 rice genotypes were evaluated for yield‐related traits, including discoloured seed weight (DSW), healthy seed weight (HSW), weight of 50 healthy panicles (HPW), difference in grain weight (DGW), reduction in grain weight (RGW), disease incidence (DI) and yield loss. Yield loss across the tested cultivars ranged from 6.0% (cv. Gangavathi Emergency) to 43.5% (cv. CO‐39). Analysis of variance revealed highly significant differences ( p ≤ 0.01) across all traits, particularly for RGW ( F = 1592.62), yield loss ( F = 1207.05) and DI ( F = 531.55). HSW and yield loss exhibited the highest genetic variability, with genotypic coefficient of variation of 35.6% and 37.1%, and heritability of 96.6% and 92.8%, respectively. Correlation and path coefficient analyses showed significant negative associations between DI and yield and quality parameters, confirming the detrimental impact of RGD on agronomic performance. DSW (−0.533) and DI (0.526) had strong effects on yield. Notably, cultivars such as Ajay, Gangavathi Emergency, Gangavathi Sona, GNV‐1108, GNV‐1109, Jaya, Narikela and Siri‐1253 demonstrated superior yield stability and RGD tolerance. These genotypes represent valuable genetic resources for developing RGD‐tolerant, high‐yielding rice varieties through targeted selection and breeding interventions.
Huded et al. (Thu,) studied this question.