Semiarid regions are frequently affected by low water availability, which hinders the development of horticultural species such as melon (Cucumis melo L.). In this context, techniques that enhance drought tolerance are essential for more effective crop management. This study aimed to evaluate the tolerance and antioxidant activity of different melon cultivars using seed pre-treatment with stress-attenuating agents. The experiment was conducted in two stages, both arranged in a completely randomized design with four replicates of 50 seeds. In the first stage, a 3 × 5 factorial scheme was used, combining three levels of water deficit (0.0, −0.15, and −0.3 MPa) and five melon cultivars (“Dali”, “Premier”, “Supreme”, “Imperial 45”, and “Asturia”). The second stage consisted of the two previously selected cultivars (one sensitive and one tolerant), subjected to combinations of water deficit and attenuating agents: T1 = 0.0 MPa (control), T2 = −0.15 MPa (water deficit), T3 = −0.15 MPa + hydropriming (12 h), T4 = −0.15 MPa + gibberellic acid, T5 = −0.15 MPa + ascorbic acid, T6 = −0.15 MPa + salicylic acid, and T7 = −0.15 MPa + hydrogen peroxide. In the first stage, morphological and biochemical variables were evaluated. In the second stage, the same variables were analyzed, along with citrulline content, hydrogen peroxide and malondialdehyde levels, and the activity of superoxide dismutase, catalase, and ascorbate peroxidase. Overall, salicylic acid mitigated the effects of water stress on germination, seedling length, and dry mass in the cultivar Dali. For the sensitive cultivar (Imperial 45), hydrogen peroxide reduced the production and accumulation of H2O2, mainly through the action of the enzymatic antioxidant system, resulting in improved germination performance under water deficit.
Sousa et al. (Thu,) studied this question.