Explicating drought tolerance of wheat (Triticum aestivum L.) through stress tolerance matrix

Drought has significant effects on the physiological, morphological, biochemical, and molecular processes of the wheat crop. Prediction models have projected increasing episodes of drought across India. Hence, in the present study physiological and biochemical characterizations were done in nine timely sown wheat varieties (WB2, PBW550, DBW17, DPW621-50, HD3086, HD2976, DBW88, PBW343, HD2687) grown in North-western plain zones of India at seedling stage, along with check entries for drought (WL711 as susceptible and NI5439 as a tolerant check). The experiment was conducted under laboratory conditions in a completely randomized design. Watering was withheld for 1 week to a set of 30-day-old seedlings to simulate drought stress, whereas the other set was maintained as control with three replications for each genotype in each treatment and physio-biochemical traits were assessed in both treatments. All studied traits exhibited significant variation among varieties under drought conditions. A significant decrease was seen in all the physiological traits except electrical conductivity and osmotic potential. Whereas, a significant increase was observed in all the biochemical traits of the treated plants under drought stress. A novel stress matrix table was developed based on the tolerance scores of each variety for each trait. Based on the final tolerance scores, genotypes DBW88, NI5439, and PBW343 were classified as tolerant, HD3086, WB2, and WL711 as susceptible, PBW550, DPW621-50 and HD2967 as moderately susceptible, and DBW17 and HD2687 as moderately tolerant to drought stress. Hence, this study is useful in understanding the drought tolerance capacity of wheat varieties released for major wheat growing zones of India and for the wiser selection of varieties under climate change. The identified drought tolerant varieties can also serve as promising source for genome editing and for transgenic studies in wheat.