Combining ability, heterosis and variability studies of bread wheat (Triticum aestivum L.) for grain yield and its attributes under moisture stress conditions

The study was conducted to identify promising parents and hybrids of bread wheat (Triticum aestivum L.) for grain yield and its related traits under moisture stress conditions, given the increasing need for wheat to tolerate limited water due to climate change patterns. In rabi 2023–24, six genotypes (RAJ3765, WH730, NIAW3170, MP1378, MACS6768 and UAS375) were crossed in a 6 × 6 half-diallel mating design, resulting in 15 F₁ hybrids. During rabi 2024–25, these hybrids, along with two check varieties (UAS347 and HD3090), were evaluated using a Randomised Complete Block Design (RCBD) with three replications under restricted irrigation given at 25 and 45 DAS. Analysis of variance (ANOVA) indicated significant differences among genotypes (p < 0.05), demonstrating the presence of considerable genetic variability. WH730, RAJ3765 and NIAW3170 were identified as good general combiners, while NIAW3170 × MACS6768 and RAJ3765 × MP1378 showed high specific combining ability, superior heterosis and better yield performance. High heritability and genetic advance for test weight and grain yield, suggesting scope for direct selection. Grain yield showed positive correlations with spike length, NDVI, SPAD, grains per spike and test weight, while a negative correlation with flowering time suggests early flowering is beneficial under moisture stress. Path analysis highlighted test weight, NDVI and SPAD as the key direct contributors. PCA identified NIAW3170 × MACS6768 as the most promising hybrid. Hybrids like NIAW3170 × MACS6768 and RAJ3765 × MP1378 show strong potential for developing high-yielding and moisture-stress-tolerant wheat varieties.