Biochemical responses of melon salinity under saline stress

Abstract

Abstract Salinity limits melon production and can affect plant growth, metabolism, and physiological performance. Thus, this study aimed to evaluate the physiological and biochemical responses of Cucumis melo L. genotypes subjected to different salinity levels. The experiment was conducted in a greenhouse using a randomized block design with a factorial arrangement (5 × 3), five replications, and 75 experimental units. Treatments consisted of five salinity levels (ECw = 0.5, 1.5, 3.0, 4.5, and 6.0 dS m−1) and three melon genotypes (A35, A24, and the Sancho hybrid). The genotypes showed distinct responses to salinity. A35 exhibited greater salinity tolerance, maintaining relative water content and increasing carbohydrate accumulation (119%), while reducing H2O2 (17.9%), MDA (34.9%), and electrolyte leakage (37.2%). Sancho showed increases in APX (191.3%) and SOD (283.3%) activities, accompanied by reductions in H2O2 (63.8%) and MDA (54.3%). In contrast, A24, despite high carbohydrate accumulation (473%) and SOD activity (248%), did not reduce oxidative damage due to the reduction in APX activity under high salinity. These results indicate that the melon response to salinity involves the coordination of osmotic adjustment, antioxidant defense, and maintenance of cellular integrity.