Gas exchange and growth of bell pepper grown in different substrates under salinity stress

Abstract

Physicochemical qualities of the substrate, such as moisture retention capacity and retention of exchangeable bases, enable better photosynthetic activity and plant growth gains in semi-hydroponic cultivation. The aim of this study was to evaluate the effect of different substrates on physiology and growth of bell peppers cultivated under salinity stress. The research was conducted in a greenhouse, in randomized block design, 3 x 4 factorial scheme, using three substrates [coconut fiber, sand, mixture (coconut fiber + sand (1:1)] and four electrical conductivity levels of the nutrient solution (2.2; 3.5; 4.5 and 5.5 dS/m), with three replications. At 72 days after transplanting, we evaluated gas exchanges in plants through stomatal conductance, transpiration rate, photosynthesis, water use efficiency and intrinsic water use efficiency. At 120 days after transplanting, the plants were collected and evaluated in relation to leaf dry mass, stem dry mass, fruit dry mass and total dry mass. Salinity stress affected gas exchange in bell pepper plants in all substrates, especially at higher salt levels. Coconut fiber provided better physiological and growth conditions for bell pepper grown under salinity stress. Bell pepper can be grown under salinity levels up to 3.5 dS/m using coconut fiber or the mixture of coconut fiber and sand (1:1) as substrates.