LEAF ION CONTENT, YIELD AND FRUIT QUALITY OF FIELD-GROWN MELON UNDER SALINE CONDITIONS

Our knowledge of melon (Cucumis melo L.) response to salinity stress is limited under field conditions and then the genotype x environment interaction and heritability of agro-morphological traits are poor understood. A field trial (2014/2015) was carried out to evaluate the performance of 17 melon cultivars, including 16 native and one exotic (Galia), under salinity stress. Leaf ion concentrations, agronomic, morphological and fruit quality traits were evaluated and their heritabilities were estimated. The results showed significant effects of salinity stress and genotype on the studied traits except for days to anthesis and peel thickness. Salinity stress also caused significant reductions in fruit weight and leaf K+ concentration, while increasing leaf Na+ and Ca2+ concentrations and total soluble solids. The most salt-tolerant cultivars ('Sabouni' and 'Shahabadi-1') had higher fruit yield, low leaf Na+ and high leaf K+ concentrations and enhanced K+/Na+ ratio under stress conditions. In general, the heritability estimates were higher under control than under salinity conditions, and the highest heritability was observed for total soluble solids. In addition, fruit weight, number of fruit per plant and leaf Na+ concentration were the strongest predictors of fruit yield, explaining 92% of yield variation under salt stress. These observations suggest that indirect selection based on these traits would be effective in improving fruit production under saline conditions.