Integrating morpho-physiological and biochemical traits to assess drought stress and recovery tolerance in eggplant

Drought stress poses a significant risk to crops in future climates and represents a major challenge for maintaining global food security. In this study, we examined the morpho-physiological and biochemical responses of eggplant plants (Solanum melongena L.) under severe drought stress and recovery conditions. Statistical analysis revealed significant differences between treatments. Drought stress resulted in a notable reduction in shoot dry biomass by approximately 60.9% compared to control plants, while structural traits such as leaf size, root length, and internode distance remained relatively statistically unchanged. Rehydration increased the number of leaves and both shoot and root dry biomass by 29.4%, 122.2%, and 57.1%, respectively, approaching the control value. Drought stress significantly increased photosynthetic pigments (chlorophyll a, b, and carotenoids) and water status traits, including leaf water potential, stomatal conductance, and relative water content, which improved after rehydration. In terms of osmoregulation and antioxidant capacity, proline levels surged over 13 times under drought stress but dropped by 85.3% after rehydration to control levels; additionally, drought stress increased L-phenylalanine ammonia-lyase activity and polyphenol content by 34.2% and 87.8%, respectively, both of which significantly declined after rehydration. Principal component analysis revealed that eggplant plants manage drought stress through increased proline accumulation, enhanced secondary metabolism, and physiological adjustments for water management. These findings underscore the importance of developing drought-resilient crops to sustain food security amid climate challenges.