Interactive Effects of Water Salinity and Water-Deficit on Biochemical Content and Photosynthetic Activity of Melon (Cucumis melo L.) Seedlings

The deleterious effects of abiotic stress factors, which have emerged in the context of global climate change, have a detrimental impact on agricultural production. Irregularity in seasonal rainfall and high temperatures make it difficult to meet the water needs of the plant. In addition, intensive fertilization, monoculture and use of poor-quality water in irrigation in vegetable fields cause salinity problems. It has been observed that both stress factors cause yield and quality losses in vegetable farming. For this purpose, in the present study, five different salt (NaCl-S) levels {control S1 (mains water=500 µmhos), S2 (2000 µmhos), S3 (4000 µmhos), S4 (6000 µmhos) and S5 (8000 µmhos)} and three different irrigation water levels (full irrigation-I100, 75% irrigation-I75 and 50% irrigation-I50) were applied to melon seedlings in the study and their effects on photosynthetic activity and biochemical changes were tried to be determined. The study revealed that elevated levels of both stress factors resulted in a reduction in the growth of melon seedlings. Conversely, the findings indicated that superoxide dismutase (SOD) enzyme activity served as a significant indicator under both stress factor conditions. Furthermore, an increase in SOD activity was observed as stress levels escalated. In addition, it was seen that saline waters higher than 4000 µmhos would have a toxic effect on melon seedlings. It is important for the sustainability of melon farming that 25% water restriction can be applied in regions where irrigation water is limited.