Salt Stress Affects the Growth and Yield of Wheat (Triticum aestivum L.) by Altering the Antioxidant Machinery and Expression of Hormones and Stress-Specific Genes

Understanding physiological responses in saline agriculture may facilitate wheat breeding programs. Based on a screening test, the Ningmai-14 (NM-14) and Yangmai-23 (YM-23) wheat cultivars were selected for further experiments to understand the underlying salinity tolerance mechanism. This study investigated the effects of five salinity levels such as Control (CK) = 0 (without NaCl stress), S1 = 0.20%, S2 = 0.25%, S3 = 0.30% and S4 = 0.35% of NaCl concentrations of soil on wheat plants. The results showed that increased salinity concentration reduced the growth and yield of wheat cultivars (NM-14 and YM-23). However, YM-23 (12.7%) yielded more than NM-14 at maximum salinity stress. The higher salinity (S4) increased the concentration of Na+ (4.3 to 5.8-fold) and P contents (2.5 to 2.2-fold), while reducing the average concentrations of K+, Cu, and K+/Na+ ratio. The higher salinity (S4) reduced the spikelet length by 21.35% (followed by grain spike(-1)), and the starch content by 18.81%. In the YM-23 cultivar, higher salinity increased superoxide dismutase (SOD), total antioxidant capacity (TAC), and amylase. Compared to NM-14, induced expression of TaYUC2, 6, and TaGA13ox, 20ox genes were recorded in YM-23. Similarly, in YM-23 the stress-specific genes such as TaHSP70, 90 were enhanced whereas, TaSOS1, 2 were suppressed. Overall, our study revealed that salt tolerant cultivars modulate hormonal and antioxidant activities, thus maintaining high growth.