The effects of saline irrigation water on the growth and development of bell pepper (Capsicum annuum L.) grown using a plasticulture system

Salinity affects food production worldwide. Hence, appropriate management of saline water is important to reduce negative effects on plants, soils, and ultimately the groundwater. Peppers (Capsicum annuum L.) are moderately sensitive to salinity, and required a high water input to maximize yields. This project investigated the effects of varying levels of salinity (0.2 to 9.0 dS·m-1) and the use of drip irrigation and mulching as water management for peppers. During fruit development, stomata) conductance (gs), transpiration (E) and photosynthesis (A) decreased as salinity increased. Mulched plants had higher gs, E and A than the ones grown in bare soil. Growth was reduced by salinity but increased by mulching. Saline water levels above the control (0.2 or 0.5 dS·m -1) reduced marketable yield whereas mulched plants had higher marketable yields than plants grown in bare soil. Under limited salt leaching condition, mulched plants required less water at all levels of salinity than the ones grown in bare soil, resulting in less soil salinization. Effects of saline water on seedlings showed that final emergence was only reduced at salinities ≥3.5 dS·m-1. In general, growth (dry weight) and rates of gs, E and A were reduced at ≥2.5 dS·m-1. Applying saline water (2.5 dS·m-1) at different growth stages with limited salt leaching, showed that plants grown in bare soil were slower than mulched ones to recover normal physiology after periods of saline irrigation. Saline irrigation applied from fruit set onwards decreased marketable fruit production whereas mulched plants increased yields regardless of saline irrigation treatments. Under field conditions, saline water caused slight decreases in gs, E and A slightly when applied at flowering or fruit set rather than during vegetative growth. Mulched plants had higher rates of gs, E and A than plants grown in bare soil. Yield of fully ripened fruits was higher in mulched plants regardless of saline irrigation treatments. Under limited salt leaching condition, mulched plants were able to limit the negative effects of saline water compared with the ones grown in bare soil.