Melatonin-Induced Mitigation of Salinity Stress and Enhancement of Barley Productivity

Abstract

Melatonin (N-acetyl 5-methoxy tryptophan) is an important hormone and plant growth regulator that promotes the stress tolerance and development of plants, regulates sleep, and acts as an antioxidant in humans. In Pakistan, people consume excessive amounts of salt, which is associated with various health issues, including hypertension and kidney disease. Agricultural production in plant species that have a high tolerance to salinity stress, particularly in barley (Hordeum vulgare L.), which ranks fourth in world production, is highly sensitive to salinity stress. Salinity resulted in negative effects on germination percentage, yield, and tolerance to biotic and abiotic stresses, thus posing a serious threat to global food security, particularly in countries like Pakistan. This research evaluates the ameliorative effects of melatonin against salinity stress in barley, focusing on parameters such as plant height, chlorophyll contents, relative water content, water potential, and yield. The objective of this study was to evaluate the potential of the action of melatonin on barley plants under salt stress. The study utilized a fully randomized design featuring a factorial arrangement. Six treatments were conducted involving salinity and Melatonin application, revealing a significant positive correlation between chitosan foliar application and enhanced performance of Barley plants under salt stress conditions. Analysis of findings showed that melatonin significantly improves barley performance in growths under salt stress with the following increases as compared to untreated plants: plant height (20.43%), grain weight (28 %), grain yield (38.82 %), biological yield (16.85 %), harvest index (19.15 %), relative water content (12.74 %), water productivity (14.16 %), and chlorophyll content (86.72 %). The results disclose that melatonin can improve barley growth and productivity through the amending of photosynthesis; avoiding oxidative stress; and facilitating nutrient assimilation, all of which could afford melatonin to remediate for sustainable agriculture and food security in saline soils.