Role of Exogenous-Applied Salicylic Acid, Zinc And Glycine Betaine To Improve Drought-Tolerance In Wheat During Reproductive Growth Stages

Background: Drought has become a dangerous threat to reduce crop productivity throughout the world. Exogenous application of regulators, micronutrients, or osmoprotectants for inducing drought-tolerance in field crops has been effectively adopted. A controlled pot study was performed to investigate the relative efficacy of salicylic acid (SA), zinc (Zn), and glycine betaine (GB) as foliar applications on the growth, tissues pigments content, relative water content (RWC), leaf gas exchange, antioxidant enzymes activity, reactive oxygen species (ROS) accumulation, osmolytes contents and the yield parameters of wheat plants subjected to two soil water conditions (85% field capacity: well-watered, 50% field capacity: water-deficient) during reproductive growth stages. Results: : Water deficient conditions significantly decreased the growth, yield parameters, RWC, photosynthesis pigment, and gas exchange attributes except for intercellular CO 2 concentration. However, foliar applications remarkably improved the growth parameters under water deficit conditions. Drought stress statistically increased the contents of hydrogen peroxide (H 2 O 2 ), superoxide anion radical (O 2 •− ), and malonaldehyde (MDA), and elevated the harmful oxidation to cell lipids in plants, however, they were considerably reduced by foliar applications. Activities of all antioxidant enzymes, proline content, and soluble sugar were increased in response to foliar applications under water deficit conditions. Conclusions: : Overall, foliar application of GB, SA, and Zn compounds improved the drought-tolerance in wheat by decreasing the ROS accumulation, promoting enzymatic antioxidants, and increasing osmolytes accumulation. Finally, GB treatment was most effective in thoroughly assessed parameters of wheat followed by SA and Zn applications to alleviate the adverse effects of drought stress.