Abstract

The present study was aimed to identify heat-tolerant genetic male sterile (GMS) lines of chilli which maintain their yield under heat stress for the development of heat-tolerant hybrids. For this purpose, fifty genetic male sterile lines of chilli were evaluated for various plant growths, fruit quality, and yield parameters under three different temperature regimes. During 1st temperature regime, average day/night temperature during crop growth period was 32/18°C. The second temperature regime had average day/night temperature of 37/22°C, whereas the third temperature regime had average day/night temperature of 40/25°C. Days to 50% flowering, fruit setting percentage, number of fruits per plant, and fresh whole plant weight exhibited consistently high values for genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), broad-sense heritability (H²), and genetic advance (GA), along with significant genotypic correlation with yield per plant across all temperature regimes. These traits were classified as core yield components and corresponded to the first principal component (PC1), explaining 27.7% of the total variation across three temperature regimes. Under heat stress (E2 and E3), stem diameter and plant height became important parameters with significant genotypic correlation with yield per plant, indicating that maintaining vegetative growth is crucial to yield stability under heat stress. Cluster analysis identified seven heat-tolerant GMS lines which gave consistently high yield under all temperature regimes. These lines can be used as female parents to develop heat-tolerant hybrids, while the identified core yield contributing traits can serve as effective selection criteria to accelerate breeding for yield stability under high temperatures. Ten genotypes consistently exhibited stable but low yield across all temperature regimes, highlighting that stability should be coupled with high yield for effective selection in any breeding program.