Exogenous Ethanol Application Enhances Drought Tolerance and Fruit Quality in Melon (Cucumis melo L.) Across Seasons

The exogenous application of ethanol has been reported to enhanced plant tolerance to various abiotic stresses.Most of these findings have been derived from studies on leafy vegetables and model species, whereas fruit-bearing horticultural crops have received comparatively little attention.In particular, the effect of ethanol on melon (Cucumis melo L.), a major fruit vegetable, remain largely unexplored.In this study, melon plant was irrigated with nutrient solutions supplemented with ethanol at varying concentration (0, 25, 50, and 100mM) prior to imposition of drought stress.Morphological traits, leaf physiological responses and fruit characteristics were subsequently assessed during both spring and summer growing season.Gas-exchange parameter (photosynthetic rate, stomatal conductance, and transpiration rate) initially decreased with increasing ethanol concentration within 6 hours after drought stress, but gradually recovered within 24h, exhibiting consistent patterns across both seasons.Notable seasonal variation was observed in fruit attributes: in spring, soluble solids content (Brix) and antioxidant compounds increased progressively with ethanol concentration, whereas in summer the highest Brix was recorded at 50mM, and neither total phenolic content nor DPPH radical-scavenging activity differed significantly among treatments, except for the lowest value in the control.These findings suggest that ethanol application enhances stress perception and promotes sugar accumulation as well as antioxidant capacity in melon fruit, thereby providing a potential strategy to improve fruit quality under drought conditions.