GADDAM TARUN*, KRISHAN PAL, KAVITA RANI AND R. P. SAHARAN
Department of Genetics and Plant Breeding, Guru Kashi University, Talwandi Sabo, Bathinda-151 302 (Punjab), India
*(e-mail: iamtarungaddam@gmail.com; Mobile: 79818 83175)
(Received: May 1, 2025; Accepted: June 13, 2025)
ABSTRACT
Terminal heat stress reduced wheat (Triticum aestivum L.) productivity and quality, threatening global food security, especially in climate-vulnerable places like Ongole, Andhra Pradesh. This study evaluated the impact of heat stress on grain yield and its major contributing morpho-physiological and grain quality traits across 43 diverse wheat genotypes, including three standard checks, over two rabi seasons (2023-24 in Talwandi Sabo as control and 2024-25 in Ongole under terminal heat stress). Analysis of variance indicated significant differences among genotypes for all examined traits in both the environments, confirming notable genetic variability. Terminal heat stress in Ongole led to significant decrease in mean grain yield per plot (from 340.21 to 6.04 g), biological yield per plot (from 868.92 to 38.8 g) and other yield-related traits when compared to the control environment. Traits including grain yield per plot, biological yield per plot, number of grains per spike, and test weight demonstrated high heritability, with values such as 97.41 for grain yield per plot under stress, alongside significant genetic advance as a percentage of mean, exemplified by 119.66 for grain yield per plot under stress. The findings showed that additive gene action had a major impact and that these traits can be selected for even under stress. Heat stress indices (HSI, HTI, YSI, TOL and DI) differentiated genotypes for heat tolerance, demonstrating genotypes with improved stability and performance under terminal heat stress. Terminal heat stress severely impacted wheat yield components, yet genetic promise for heat-resilient types was shown. The found genotypes and features with high heritability and favourable stress indices should inform focused breeding strategies to improve wheat adaptability and productivity in heat-stressed Andhra Pradesh and similar locales.
Key words: Genetic variability, grain yield, heritability, terminal heat stress, wheat