The Role of Exogenous Methyl Jasmonate in the Morphophysiology and Postharvest Attributes of Drought-Stressed Radish

Radish is a nutrient- and antioxidant-rich root vegetable whose growth is strongly affected by water availability, highlighting the need for strategies to enhance drought tolerance. Methyl jasmonate (MeJa) is a bioregulator involved in plant stress responses. This study evaluated the role of MeJa in alleviating water deficit effects in radish. Plants were maintained under well-watered conditions (80% water retention capacity) or subjected to total irrigation restriction from 15 to 30 days after sowing (DAS). Foliar applications of 100 µM MeJa or water were performed at 7, 14, and 21 DAS. Growth, gas exchange, chlorophyll fluorescence, photosynthetic pigments, relative water content, electrolyte leakage, and storage root quality were assessed. Water deficit reduced relative water content and increased electrolyte leakage, indicating oxidative damage, which impaired growth and gas exchange. MeJa application reduced electrolyte leakage but did not mitigate drought-induced reductions in growth or gas exchange. Notably, water deficit increased sugar, mineral, and antioxidant contents in roots, regardless of MeJa treatment. Overall, although MeJa modulated some stress-related physiological responses, enhancing antioxidant defenses, it was insufficient alone to improve drought tolerance in radish.