Melatonin as a protective signal in oats: enhancing salinity tolerance for sustainable agriculture on marginal lands

Abstract

Soil salinity poses a major constraint and a primary threat to global food security, demanding sustainable strategies to maintain crop productivity on marginal lands. This study evaluated the role of exogenous melatonin (50 and 100 & micro;M) in enhancing salt stress resilience in two oats (Avena sativa L.) varieties exposed to 120 mM NaCl in a completely randomized design. Salinity stress markedly reduced plant biomass, chlorophyll stability, and relative water content while promoting excessive accumulation of toxic ions and reactive oxygen species. Melatonin pretreatment-particularly at the 50 & micro;M, effectively mitigated these adverse effects by acting as a physiological priming agent. Melatonin induced a coordinated plant's stress response reprogramming, evidenced by elevated activities of antioxidant defense system (CAT, POD, and APX) and a significant reduction in oxidative damage indicators such as H2O2 and malondialdehyde (MDA). Additionally, melatonin improved ionic homeostasis, resulting in significant recovery of vegetative growth and approximately a 50% increase in grain yield under saline conditions. These findings highlight melatonin as a promising eco-friendly approach for improving oat performance in salinity stressed environment.