Different Levels of Irrigation Water Salinity and Biochar Influence on Faba Bean Yield, Water Productivity, and Ions Uptake

Abstract

ABSTRACT Greenhouse experiment was conducted to investigate the effect of different levels of irrigation water salinity (0.5, 2.5, 5 and 7.5 dS m−1) and wheat straw biochar (0%, 1.25%, 2.5%, and 3.75% w/w) on growth and yield of faba been using complete randomized design with three replications. Stomatal conductance (green canopy temperature) of faba bean increased (decreased) by application of biochar at each salinity level. The results showed increasing salinity to 2.5 dS m−1 at zero biochar application increased the seed yield through osmotic adjustment, while by declining the osmotic potential, the nutritional values of biochar caused the seed yield to increase by increasing salinity to 5 dS m−1. The root length density and root dry weight density in 0–8 cm soil layer declined under application of 3.75% w/w biochar in all salinity levels in comparison with that obtained in 2.5% w/w biochar, due to higher saline condition of the soil as result of higher biochar application. The results showed that addition of 2.5% w/w biochar can significantly mitigate salinity stress due to its high salt sorption capacity and by increasing potassium/sodium ratio in the soil. In general, since 2.5 % w/w biochar and salinity of 5 dS m−1 increased dry seed yield and irrigation water productivity compared with that obtained in control (B0S0.5), these levels are recommended to improve faba bean growth and yield; however, these levels have to be evaluated under field conditions.