AMELIORATIVE EFFECTS OF SALICYLIC ACID AND PLANT GROWTH-PROMOTING BACTERIA ON IONIC AND BIOCHEMICAL RESPONSES OF WHEAT UNDER SALINITY STRESS

Abstract

Salinity stress is a major constraint, severely affecting ionic homeostasis, photosynthetic pigments, primary and secondary metabolism in wheat plants. The present study investigated the ameliorative effects of salicylic acid (SA) and salt-tolerant plant growth-promoting bacteria (PGPB) on wheat (Triticum aestivum L.) under NaCl induced salinity stress. In this study, wheat seedlings were exposed to 50 and 100 mM NaCl and then treated with SA, individual PGPB isolates (B1 and B2), or their combinations. Salinity stress markedly enhanced the Na⁺/K⁺ ratio and reduced the total chlorophyll, total protein, total sugar, reducing sugar, and total phenolic content in wheat seedlings compared with the control. However, the application of SA and PGPB, either individually or in combination, mitigated the adverse effects of salinity and improved the measured physiological and biochemical attributes. Among all the treatments, the most pronounced improvement under both salinity levels was shown by the treatments having the combined application of SA with both PGPB isolates (SA + B1 + B2).  It has been shown that application of SA and PGPB, either individually or in combination, lowers the Na⁺/K⁺ ratio and results in greater accumulation of chlorophyll, protein, total sugars, reducing sugars, and phenolic compounds compared with the respective salt-stressed controls. Overall, the findings suggest that the combined application of SA and salt-tolerant PGPB is a promising strategy for improving and maintaining physiological and biochemical performance in wheat under saline conditions.