Salicylic acid ameliorates salinity tolerance in maize by regulation of phytohormones and osmolytes

Salinity is one of the most widespread stresses responsible for water and soil pollution across the globe. Salicylic acid (SA) has a major role in defence responses against various abiotic stresses. In the current study, SA (0.05 mmol) influences were evaluated in mitigation of the negative impact of salinity (40 and 80 mmol NaCl) in the maize plant. NaCl stress-induced significant accumulation of organic osmolytes (total soluble sugars (TSS), total soluble protein (TSP), and proline) by 35.6, 66.2, and 89.2%, respectively, with 80 mmol NaCl. In addition, salinity is also responsible for the elevated accumulation of inorganic osmolytes (Na⁺ and Na⁺ /K⁺ ratio) by 202.4% and 398.8%, respectively, and for the reduction in the K⁺ and Ca²⁺ levels by 48.6% and 58.9%, respectively, with 80 mmol NaCl. Moreover, salinity stress reduced phytohormones (indoleacetic acid (IAA) and gibberellic acid (GA3)) by 48.8% and 59.8%, respectively, with 80 mmol NaCl; however, abscisic acid (ABA) was increased by 340.5% with 80 mmol NaCl. Otherwise, SA application caused an additional enhancement in TSS, TSP, proline, K⁺, Ca²⁺, IAA, and GA3 contents but decreased the Na⁺, Na⁺ /K⁺ ratio, and ABA to an appreciable level. In conclusion, SA pre-soaking mitigates the negative impact of NaCl toxicity in maize through the regulation of phytochromes and various organic and inorganic osmolytes, which may ameliorate salinity tolerance in maize.