Responses of Growth, Physiological and Anatomical Characteristics of Resistant and Sensitive Cultivars of Cucumis inodorous L. to Salt Stress

In order to study the effect of irrigation with saline water on physiology, biochemical, and anatomy characteristics, growth, and yield of different melon cultivars, an experiment was performed in split-plot with randomized complete block design with three replications. Treatments were two melon cultivars resistant to salinity (Sooski and Diamond) and two sensitive cultivars (Daregzi and Zard Ivanaki) with two salinity levels [0 (control) and 8 dS m-1 of NaCl] of irrigation water. The results showed that fresh and dry weight of shoot, fruit and seed weight, fruit acidity, fruit firmness, fruit length/diameter, fruit number and yield, photosynthesis rate, transpiration, and stomatal conductance decreased by irrigation with saline water. Under salinity condition, resistant cultivars showed the highest amount of the abovementioned parameters and had higher proline, phenol, and antioxidant activity. Generally, the results showed that by applying salt stress, growth parameters, photosynthetic parameters, and quantitative characteristics of the fruit decreased. This decrease was lower in Sooski resistant cultivar. It seems that melon cultivars achieved their resistant; firstly, improving yield instead of vegetative growth; secondly, increasing antioxidant and phenol content to reduce deleterious salinity effect, and finally, increasing TSS to have more osmotic adjustment for promoting photosynthesis at the acceptable level for producing enough assimilate for commercial yield under salinity conditions.