Interaction effects of biochar levels, irrigation regimes, and irrigation water salinity levels on wheat: I: Physiological parameters, evapotranspiration, and yield

Biochar, as a soil amendment, improves soil fertility and enhances crops productivity under water or salinity stresses. This study aimed to investigate the effects of biochar application rates (zero, 40, and 80 Mg ha-1) under three irrigation regimes (50, 75, and 100% of plant water requirement) and salinity levels (0.6, 6, and 12 dS m-1) on physiological parameters, evapotranspiration, and growth of wheat grown under greenhouse condition. The experiment was performed in a complete randomized design with a factorial arrangement in four replications. Application of a high level of salinity (12 dS m-1) declined wheat grain yield by 28%, 57%, and 75% in comparison with that at 0.6 dS m-1 under zero, 40, and 80 Mg ha-1 biochar application, respectively. The results showed that application of 80 Mg ha-1 biochar decreased wheat evapotranspiration by 24.4% in comparison with that at no biochar application. In addition, the application of biochar improved wheat stomatal conductance and canopy temperature under both abiotic stress conditions. Salinity (12 dS m-1) and deficit irrigation (50 %), respectively declined wheat evapotranspiration by 19% and 15% in comparison with that at 0.6 dS m-1 and full irrigation. Also, the application of biochar and salinity both declined the root length density due to the accumulation of salt around the root. It is concluded that 40 Mg ha-1 of biochar can be applied as a soil amendment to improve wheat yield and reduce evapotranspiration under applied deficit irrigation and salinity stress.