Mitigation Effects of Foliar-Applied Hydrogen Peroxide on Drought Stress in Sorghum bicolor

Global climatic change and increasing climatic instability threaten crop productivity. Due to climatic change, drought stress is occurring more frequently in crop fields. In this study, we investigated the effect of treatment with hydrogen peroxide (H2O2) before leaf development on the growth and yield of sorghum for minimizing the damage of crops to drought. To assess the effect of H2O2 on the growth of sorghum plant, 10 mM H2O2 was used to treat sorghum leaves at the 3-leaf stage during growth in field conditions. Plant height, stem diameter, leaf length, and leaf width were increased by 7.6%, 9.6%, 8.3% and 11.5%, respectively. SPAD value, chlorophyll fluorescence (Fv/Fm), photosynthetic rate, stomatal conductance, and transpiration rate were increased by 3.0%, 4.9%, 26.0%, 23.4% and 12.7%, respectively. The amount of H2O2 in the leaf tissue of sorghum plant treated with 10 mM H2O2 was 0.7% of the applied amount after 1 hour. The level increased to approximately 1.0% after 6 hours. The highest antioxidant activity measured by the Oxygen Radical Absorbance Capacity assay was 847.3 μmol·g-1 at 6 hour after treatment. However, in the well-watered condition, the concentration of H2O2 in the plant treated by the foliar application of H2O2 was 227.8 μmol·g-1 higher than that of the untreated control. H2O2 treatment improved all the yield components and yield-related factors. Panicle length, plant dry weight, panicle weight, seed weight per plant, seed weight per unit area, and thousand seed weight were increased by 8.8%, 18.0%, 24.4%, 24.7%, 29.9% and 7.1%, respectively. Proteomic analysis showed that H2O2 treatment in sorghum increased the tolerance to drought stress and maintained growth and yield by ameliorating oxidative stress.