Melatonin-mediated cross-stress protection in tomato under individual and combined salinity and drought stress.

Melatonin enhances tomato tolerance to combined salinity and drought stress, increasing dry weight by approximately 37% and reducing MDA by nearly 40% under stress conditions.

• Why it matters: Salinity and drought frequently co-occur, threatening tomato production, and the protective mechanisms of melatonin in this context are not fully understood, limiting its application.
• What they did: The study applied 100 μM foliar melatonin to tomato plants exposed to salinity (0 or 100 mM NaCl) and drought (90 or 60% field capacity), measuring growth, water status, photosynthesis, and biochemical responses after three weeks.
• The result: Melatonin improved growth, water content, ion balance, and antioxidant activities under all stress conditions, especially combined stress, suggesting it promotes ion homeostasis, ROS detoxification, and osmotic regulation to confer stress protection.