Salicylic Acid and Hydrogen Peroxide Improve Antioxidant Response and Compatible Osmolytes in Wheat (Triticum aestivum L.) Under Water Deficit

A pot experiment was undertaken to evaluate the effect of priming with salicylic acid (SA) and hydrogen peroxide (H2O2) on induction of drought tolerance in two contrasting wheat genotypes C-306 (relatively drought resistant) and HD-2329 (relatively drought susceptible). The seeds were pretreated with SA (0.5 mM) and H2O2 (10 mM) separately as well as in combination and were subjected to water deficit condition at early seedling stage (23 days after sowing) by withholding irrigation. The decrease in moisture content (dry weight basis) as compared to control was 13.48% (0–15 cm), 11.05% (15–30 cm) and 10.19% (30–45 cm). Proline content was found to elevate along with increase in total soluble sugars and K content in leaves of treated plants during water deficit. Combined application of SA and H2O2 also increased total chlorophyll and carotenoid content with reduced TBARS reflecting enhanced membrane stability during water deficit. SOD and APX activities were considerably increased along with rise in the levels of GR and CAT indicating elevated ROS scavenging mechanism. Thus, pretreatments of seeds with a combination of SA (0.5 mM) and H2O2 (10 mM) increased accumulation of compatible osmolytes, elevated antioxidant response and improved photosynthetic pigments during water deficit stress.