Humic Acid and Jasmonic Acid Improves the Growth and Antioxidant Defense System in Salt Stressed - Forage Sorghum Plants

Abstract Salinity is one of the primary abiotic stresses that cause several negative physiological and biochemical changes due to the oxidative stress caused by the generation of ROS. The effect of foliar application of jasmonic acid (JA) and humic acid (HA) as a fertilizer on growth and biochemical attributes exposed to salinity stress was investigated. Soil treated with NaCl at levels of 0 (S0), 2 (S1), and 4 g NaCl kg-1 dry soil (S2) and fertilized with 0 (HA0), 3 (HA1), and 6 g HA kg-1 dry soil (HA2). The plant spray with three JA levels (0, 5, and 10mM JA). Under salinity, JA and HA significantly improved all parameters tested. Salinity stress increased carotenoid, soluble protein content, SOD and MDA. In contrast, salinity stress reduced plant height, leaf area index, relative growth rate, proline content, POD, CAT, and APX. Under S2, HA2 rate increased plant high (9.69%), relative growth rate (70.79%) and CAT (45.47). While, HA1 increased leaf area index (12.45%), chlorophyll content (22.32%), carotenoid contents (38.05%), SOD (20.93), MDA (17.95%), POD (24.64%) and APX (21.67%). At S2, the highest plant height, chlorophyll content, soluble protein content and APX value recorded at 5mMJA, while, the highest value of leaf are index, carotenoid contents, proline, MDA, POD and CAT was achieved at 10mMJA. This study revealed that the level of 10 mM JA and HA1 had a positive effect on forage sorghum plants physiological responses. Furthermore, the results showed that jasmonic acid and humic acid successfully mitigated salinity stress's adverse effects.