Calcium nitrate as a remedy for salt-stressed cucumber plants
The effect of calcium nitrate [Ca(NO)] on growth and yield of cucumber (Cucumis sativus L. cv. Beit Alpha F1) plants grown in containers under high root-zone salinity was investigated. Treatments were: 1) control (C): soil only; 2) high salt treatment: C plus 3.5 g NaCl kg soil (C + S); and 3) Supplementary Ca and N: C + S plus supplementary 0.5 or 1 g Ca(NO) kg soil (C + S + CaN). Plants grown in high NaCl had less dry matter, fruit yield, and chlorophyll than those in the control treatment. Supplementing the soil with 0.5 and 1 g Ca(NO) kg increased dry matter, fruit yield, and chlorophyll concentrations compared to the high salt treatment. Membrane permeability increased with high NaCl application. Supplementary Ca(NO) maintained 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 lower in the high salt treatment than in the controls. For the high salt treatment, supplementing the soil with Ca(NO) at 1 gkg resulted in Ca and N levels similar to these of the controls. These results clearly show that supplementary Ca(NO) can overcome the effects of high salinity on fruit yield and whole plant biomass in cucumber plants.