Biochar-Improved Growth and Physiology of Ehretia asperula under Water-Deficit Condition

Ehretia asperula’s physiological responses to growth performance following oak-wood biochar application under water stress conditions (WSC) and no water stress conditions (non-WSC) were investigated in a pot experiment. Biochar (WB) was incorporated into the soil at concentrations of 0, 5, 10, 15, and 20 tons ha−1 before transplanting Ehretia asperula in the pots. One month after transplanting, Ehretia asperula plants were put under water stress by withholding water for ten days. Water stress significantly decreased the growth and physiology of Ehretia asperula. Under WSC, the application of WB at the concentrations of 15 and 20 tons ha−1 to the soil increased the plant height; number of leaves; fresh and dry weight of the roots, shoots, and leaves; Fv/Fm; chlorophyll content; leaf relative water content; and soil moisture as well as decreased the relative ion leakage. The application of WB enhanced drought tolerance in Ehretia asperula plants by lowering the wilting point. The findings suggest that WB application at the concentration of 15 tons ha−1 could be recommended for ensuring the best physiological responses and highest growth of Ehretia asperula plants.