Biochar Enhances Nutrient Uptake, Yield, and NHX Gene Expression in Chinese Cabbage Under Salinity Stress

Salinity is a major limiting factor for all food crops, mainly Chinese cabbage. This study aimed to investigate the effects of biochar (BC) on physiological, biochemical, and molecular responses of Chinese cabbage grown under salinity stress in an open field. We supplied three concentrations of BC (5, 10, and 15 t/ha) to the 200 mM NaCl salinity-stress-induced field, which enhanced physical and chemical properties of the soil. Under salinity stress, BC increased photosynthetic pigments and reduced proline and H₂O₂ contents. Notably, 5 t/ha BC boosted plant growth, biomass, and yield by >40% and inhibited ROS accumulation under salinity stress. BC also promoted the concentrations of various key micronutrients, particularly Fe and Zn, in Chinese cabbage under salinity stress, which may contribute to improving the nutrient content. BC under salinity stress significantly induced the expression of <i>NHX</i> family genes (<i>BoNHX1</i> and <i>BoNHX2</i>). Among these, the <i>BoNHX1</i> gene was found to be highly expressed in shoot and root tissues of Chinese cabbage grown under salinity stress with BC. Identification of this key candidate gene will lay the groundwork for further functional characterization studies to elucidate its role under salinity stress with BC. This study comprehensively analyzes the physiological, biochemical, and molecular impacts of BC application in Chinese cabbage under salinity stress. This study found that the application of 5 t/ha significantly improved various physiological and biochemical traits of Chinese cabbage under salinity stress compared to the other treatments. The outcome of this study provides novel insights into the bioprotective role of BC, offering a valuable foundation of organic supplements for farmers while also highlighting potential research directions for enhancing crop resilience and productivity in economically important crops.