The Efficiency of Humic Acid for Improving Salinity Tolerance in Salt Sensitive Rice (Oryza sativa): Growth Responses and Physiological Mechanisms

Abstract High-yielding rice cultivars exhibit a great performance in non-saline fields; however, their growth and productivity are greatly reduced salt-affected lands. Humic acid has promising stress-mitigating potential can be effective improving salt tolerance salinity sensitive cultivars. Herein, seeds of Giza 177 (high-yielding but salt-sensitive cultivar) were primed 40 mg/l humic acid, sown, maintained. Then physiological responses the acid-primed plants to increased levels (EC: 0.55, 3.40, 6.77, 8.00 mS/cm) evaluated at reproductive stage. Increasing induced progressive retardation plant height, leaf area, fresh dry weights. Such was associated with Na + buildup shoot root, high electrolyte leakage accumulation malondialdehyde, total soluble sugars, sucrose, glucose, proline, proteins, flavonoids, phenolics. In contrast, K , /Na ratio, carbohydrates, activity catalase, peroxidase, polyphenol oxidase. enhanced under saline conditions. The acid-induced improvement reduction toxicity, increasing regulating osmolytes concentration, enhancing activities antioxidant enzymes thus reduce oxidative stress. These results indicate that successfully salinity-induced damage, improved metabolism, maintained active irrigation.