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

Abstract

Water stress impacts wheat yields and poses a serious threat in stabilizing the global food supply. In the present investigation, 71 diverse bread wheat germplasm accessions were evaluated at Karnal and Hisar locations under normal and water stress (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, K1317, etc., showed higher NDVI values both at heading and grain filling stages under stress conditions. Grain yield (GY) showed positive and significant associations with 1000 grain wt. (r=0.62***) and 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 (DSI), however 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 and WAP91 appeared to be high yielding and drought-tolerant. The traits, such as 1000 grain weight, grains/spike and tillers count can be targeted as on-farm selection criteria under water stress and to train genomic models.