Multivariate analysis of drought stress indices to assess bread wheat (Triticum aestivum L.) germplasm under rainfed conditions

Water stress impacts wheat yields and poses a serious threat to stabilizing the global food supply. In the present investigation, 71 diverse bread wheat germplasm accessions were evaluated at Karnal and Hisar under normal and rainfed (four environments) conditions during rabi, 2022–23. The overall pooled grain yield showed a reduction of 15.6% under water stress, while days to heading, tiller count and plant height were reduced by 8.1, 15.5 and 12.5%, respectively. The genotypes, namely K8027, HI1531, PBW175, UAS375, WH1142, HI1612 and K1317 showed higher NDVI values both at heading and grain filling stages under water stress conditions. Grain yield showed positive and significant associations with 1000-grain wt. (r=0.62***) and no. of tillers/m (r=0.53***). In the principal component biplots, 14 drought stress indices were grouped into three clusters. The genotypes K9465, HD2987 and K8027 were the three top rankers for drought susceptibility index; however, they showed yield reduction of 10.4, 5.5 and 17.4% over the best check NIAW3170. Most of the drought stress indices considered only the grain yield reduction as selection criteria; however, the yield potential coupled with drought tolerance is desired to get favourable gene constellations. The drought resistance index (DRI) was highly successful in identifying high- yielding and drought-tolerant genotypes. The genotypes viz., HD3171, MP1358, 20^th HTWYT-48, 29^th SAWYT-316, WAP91 and K1317, appeared to be high-yielding and water stress-tolerant. The traits, such as 1000 grain weight, no. of grains/spike and tiller count, can be targeted as on-farm selection criteria under water stress and to train genomic models.