Relationship between water use and urea application in salt-stressed pepper plants
Pepper (Capsicum annum cv. 11B14) was grown in pots containing soil. The relationships between urea application and water use by salt-stressed pepper plants were 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 urea: C + S plus supplementary 0.2 or 0.4 g urea kg soil (C + S + U). Plants grown in high salt had less dry matter, water use, fruit yield, and chlorophyll than those in the control treatment. Supplementing the soil with 0.2 and 0.4 g urea kg increased dry matter, water use, fruit yield and chlorophyll concentrations compared to the high salt treatment. Membrane permeability increased with high NaCl application. Supplementary urea maintained membrane permeability. Sodium (Na) concentration in plant tissues increased in leaves and roots in the elevated NaCl treatment. Concentrations of nitrogen (N) in leaves were lower in the high salt treatment than in the controls. For the high salt treatment, supplementing the soil with urea at 0.4 g kg resulted in N levels similar to those of the controls. These data clearly indicate that supplementary urea can overcome the effects of high salinity on fruit yield and whole plant biomass in pepper plants.