Ameliorative effects of potassium phosphate on salt-stressed pepper and cucumber

Bell pepper (Capsicum annuum cv. Urfa Isoto) and cucumber (Cucumis sativus cv. Beith Alpha F1) were grown in pots containing field soil to investigate the effects of supplementary potassium phosphate applied to the root zone of salt-stressed plants. Treatments were (1) control: soil alone (C); (2) salt treatment: C plus 3.5 g NaCl kg soil (C + S); and (3) supplementary potassium phosphate: C + S plus supplementary 136 or 272 mg KH PO kg soil (C + S + KP). Plants grown in saline treatment produced less dry matter, fruit yield, and chlorophyll than those in the control. Supplementary 136 or 272mg KH PO kg soil resulted in increases in dry matter, fruit yield, and chlorophyll concentrations compared to salt-stressed (C + S) treatment. Membrane permeability in leaf cells (as assessed by electrolyte leakage from leaves) was impaired by NaCl application. Supplementary KH PO reduced electrolyte leakage especially at the higher rate. Sodium (Na) concentration in plant tissues increased in leaves and roots in the NaCl treatment. Concentrations of potassium (K) and Phosphorus (P) in leaves were lowered in salt treatment and almost fully restored by supplementary KH PO at 272 mg kg soil. These results clearly show that supplementary KH PO can partly mitigate the adverse effects of high salinity on both fruit yield and whole plant biomass in pepper and cucumber plants.