Exogenous melatonin enhances flooding tolerance in maize and is associated with coordinated redox, metabolic, and chloroplast responses.

Exogenous melatonin improves maize flooding tolerance by 18.24% grain yield and enhances photosynthesis, water content, and antioxidant activity under flooding stress.

• Why it matters: Flooding stress damages maize energy metabolism, redox balance, and photosynthesis, limiting crop productivity; understanding mitigation strategies is vital for crop resilience.
• What they did: The study applied a 2×2 experimental design with maize seedlings exposed to flooding with or without melatonin, analyzing transcriptomic, metabolomic, and hormone profiles to identify physiological and molecular responses.
• The result: Melatonin treatment increased leaf area, photosynthetic rate, stomatal conductance, and water content while decreasing H2O2, NO, and ethanol levels, with associated improvements in chloroplast structure and antioxidant enzyme activities, supporting an integrated stress response.