Enhancement of growth and normal growth parameters by foliar application of potassium and phosphorus in tomato cultivars grown at high (NaCl) salinity
Three tomato (Lycopersicon esculentum) cvs., Rio Grande, Monika Fl, and Marylin Fl, were grown hydroponically in a controlled temperature (CT) room for 6 weeks to investigate the effectiveness of foliar application of supplementary potassium (K) and phosphorus (P) to the leaves of plants grown at high NaCl concentration (60 mM). Supplementary 5 mM K and P as KHPO was supplied via leaves to the plants grown at high NaCl (60 mM) twice a week for 4 weeks. The plants grown at high NaCl produced less dry matter and chlorophyll than those at normal nutrient solution for all three cultivars. Membrane permeability increased with high NaCl application and these increases in membrane permeability were decreased by supplementary K and P. Daily water use by plant was decreased with high NaCl application and increased with supplementary P and K. Foliar application of supplementary K and P resulted in increases in dry matter and chlorophyll concentrations for all three cultivars. These increases were greater in Monika Fl and Marylin Fl than Rio Grande. Sodium (Na) concentration in plant tissues increased for all three cultivars in the elevated NaCl level. Concentrations of P and K were at deficient ranges in the plants grown at high NaCl levels and these deficiencies were corrected by supplementary K and P application via leaves.