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In recent decades, the application of biochar to improve soil fertility and soil physical property and also enhance crop tolerance to abiotic stress has been proposed by researchers. Therefore, the effect of three levels of biochar (zero, 40, and 80 Mg ha-1) produced from wheat straw, irrigation water salinity (0.6, 6, and 12 dS m-1), and three irrigation regimes (50, 75, and 100% of crop water requirement) on wheat grain ions and soil ions concentration as well as some soil physical properties after wheat harvest were investigated under greenhouse conditions. The results showed that the Na+ and K+ concentration in soil significantly increased by application of biochar and also salinity, while application of 50% deficit irrigation significantly declined the Na+ and K+ concentration in soil. Also, the soil ECe of the highest level of biochar and salinity increased 2.1 and 1.59 times that of without biochar and salinity, respectively, while application of deficit irrigation significantly declined the soil ECe due to lower application of saline water and lower accumulation of salt. Considering the main effects of treatments, application of the highest level of biochar (80 Mg ha-1) increased the K+ concentration in grain, while application of saline water (6 and 12 dS m-1) and deficit irrigation (75% and 50 %) both declined the K+ concentration in grain. The application of biochar enhanced the soil water holding capacity. In conclusion, it is recommended to apply wheat straw biochar to increase soil fertility and increased water storage capacity in the soil. Finally, the application of non-saline biochar is suggested to prevent salinization and the destruction of agricultural soil. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]