Variations in the response of different lines and hybrids of melon (Cucumis melo var. cantaloupensis) under salt stress.

This study was carried out in order to determine the variability of melon response to salinity. This was done by evaluating the responses of 7 elite lines, 8 double haploid lines and 14 F1 hybrids of melon (Cucumis melo var. cantaloupensis) grown in nutrient solution with 200 mM NaCl at early developmental stage. The severity of leaf symptoms caused by 200 mM NaCl using a 1-5 symptom scale. The most susceptible genotypes were line 3 and line 5 with 4.50 and 4.16 scales values, respectively, while the tolerant genotypes were F1-4 and line 11 with 1.15 and 1.22 scale values, respectively. Under saline conditions, the genotypes showed average 62% reduction in plant height, 54% reduction in shoot dry weight and 30% reduction in root dry weight and 21% reduction in root length compared with the control group. Leaf chlorophyll of salt susceptible genotypes (line 3 and line 5) was decreased, while chlorophyll of salt tolerant genotypes (line 11 and F1-4) increased. A positive correlation was found between Na concentration of plant and severity of leaf symptoms in genotypes grown under 200 mM NaCl salt stress. Generally, with genotypes low scale values were affected by salt stress and genotypes salt uptake were more affected by salt stress. These result indicated that both shoot Na concentration and the severity of leaf symptoms could be used together as screening parameters for salinity stress in early growth stages of melon