Abstract
BackgroundDrought has become a dangerous threat to reduce crop productivity throughout the world. Exogenous applications of regulators, micronutrients, and/or osmoprotectants for inducing drought-tolerance in field crops have 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.ResultsWater deficient conditions significantly decreased the growth, yield parameters, RWC, photosynthesis pigment, and gas-exchange attributes except for intercellular CO2 concentration. However, foliar applications remarkably improved the growth and yield parameters under water deficit conditions. Under drought condition, exogenous applications of SA, Zn, and GB increased the grain yield pot− 1 by 27.99, 15.23 and 37.36%, respectively, as compared to the control treatment. Drought stress statistically increased the contents of hydrogen peroxide (H2O2), superoxide anion radical (O2•−), and malonaldehyde (MDA), and elevated the harmful oxidation to cell lipids in plants, however, they were considerably reduced by foliar applications. Foliar applications of SA, Zn, and GB decreased MDA content by 29.09, 16.64 and 26.51% under drought stress, respectively, as compared to the control treatment. Activities of all antioxidant enzymes, proline content, and soluble sugar were increased in response to foliar applications under water deficit conditions.ConclusionsOverall, 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.
Highlights
Drought has become a dangerous threat to reduce crop productivity throughout the world
Our results indicated that Chl. a, Chl. b, and total Chl. contents, and relative water content (RWC) were severely decreased in wheat plants by drought stress (Fig. 1)
The present study showed that MDA content in wheat leaves was statistically increased under the water-deficient condition and it was well associated with H 2O2 and O 2− contents, while respective foliar applications decreased MDA, Hydrogen peroxide (H2O2), and O2− contents (Figs. 3 and 4)
Summary
Drought has become a dangerous threat to reduce crop productivity throughout the world. Wheat is sensitive cereal crop to drought stress after maize, especially during the critical growth periods (e.g., flowering stage). Drought led to the yield reduction among different species, in which maize had higher yield reduction (39.3%) compared to wheat (20.6%) by 40% water deficiency [5]. Drought is the most important one of abiotic stress factors that negatively influence the growth and production of various field crops [6,7,8,9,10]. Chen et al [18] remarked that the drought stress slowed down wheat growth and reduced grain yield by impacting the anthesis and grain-filling process, and decreased leaf water potential, stomatal conductance, and the photosynthesis
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