Is foliar-applied glycinebetaine effective in mitigating the adverse effects of drought stress on wheat (Triticum aestivum L.)?

Drought stress is a serious threat to crop growth and development. Exogenous application of various compatible solutes is an effective means to lessen the adverse drought effects on plants. To explore the effectiveness of exogenously applied GB as foliar spray in mitigating the harmful effect of drought on wheat crop, an experiment was conducted using five wheat cultivars (SARC-I, Inqlab-91, MH-97, Bhakkar and S-24) and three levels (0, 50 and 100 mill) of GB applied as foliar spray under well-watered and water-stressed (60% field capacity) conditions. Growth and yield attributes, gas exchange characteristics, and root and shoot N, P, and K+ were determined in the wheat cultivars. Drought stress significantly reduced shoot and root fresh and dry biomass, shoot length, leaf area, grain yield, photosynthetic (A) and transpiration rates (E), stomatal conductance (g(s)), and shoot and root P and K+ contents. However, foliar-applied GB mitigated the adverse effects of drought stress by enhancing plant biomass, shoot length, transpiration rate, root P, and N contents and in shoot only K+ in both cultivars under stress conditions, while its effect was not prominent on leaf area per plant, water use efficiency (WUE), and shoot P and N, and root K+. The cultivar response to varying GB levels was variable. Overall, foliar-applied GB @ 50 mM showed better performance in reducing the adverse effects of drought stress on wheat crop under water deficit conditions. Cultivars SARC-I and Inglab-91 were better as compared to the others in their response to foliar-applied GB under water deficit conditions.