Ameliorative effect of calcium nitrate on cucumber and melon plants drip irrigated with saline water

Cucumber (Cucumis sativus cv. Orlando) and melon (Cucumis melo cv. Ananas) were field grown to investigate the effects of supplementary calcium nitrate applied to irrigation water on plant growth and fruit yield of salt stressed and unstressed cucumber and melon plants. Treatments were (1) control: normal irrigation water (C); (2) normal irrigation water plus supplementary 5 mM Ca(NO) added to the irrigation water (C + CaN); (3) salt treatment: C plus 60 mM NaCl added irrigation water (C + S); and (4) supplementary Ca(NO): C + S plus supplementary 5 mM Ca(NO) added to the irrigation water (C + S + CaN). Plants irrigated with water containing high NaCl produced less dry matter, fruit yield, and chlorophyll than the control treatments of both species. Supplementing irrigation water with Ca(NO) resulted in increases in dry matter, fruit yield, and chlorophyll concentrations over plants irrigated with saline water. Membrane permeability increased with C + S treatment for both species. Supplementary Ca(NO) restored membrane permeability. Sodium (Na) concentration in plant tissues increased in leaves and roots in the elevated NaCl treatment. Concentrations of Ca and N in leaves were decreased in the high salt treatment and fully restored by supplementary Ca(NO). These results clearly show that supplementary Ca(NO) can partly mitigate the adverse effects of saline water on both fruit yield and whole plant biomass in melon and cucumber plants.