Advances in hydrogen-rich water for plant abiotic stress management: antioxidant regulation, hormonal crosstalk, and signal integration.

Abiotic stresses such as salinity, heavy metal toxicity, drought, and extreme temperatures severely limit plant growth and agricultural productivity by disrupting cellular homeostasis and inducing excessive reactive oxygen species (ROS) accumulation. Hydrogen-rich water (HRW), has emerged as a promising eco-friendly strategy for enhancing plant stress tolerance. This review synthesizes current knowledge on HRW-mediated stress alleviation, offering an integrated framework of antioxidant regulation, hormonal crosstalk, and signal transduction. HRW confers protection through selective scavenging of cytotoxic radicals while preserving signaling ROS, upregulates enzymatic and non-enzymatic antioxidants to maintain redox balance, regulates ion homeostasis and osmolyte accumulation, and protects chloroplast and mitochondrial integrity. Furthermore, HRW modulates gene expression and stress-responsive pathways via interactions with phytohormones and gaseous signaling networks. This integrated approach distinguishes the present work by bridging previously dispersed mechanistic insights across multiple stress types. Despite promising findings, challenges remain regarding hydrogen perception mechanisms, application standardization, and field-level validation. Advancing these areas will support the integration of HRW into sustainable agricultural practices for improved crop resilience.