Efficacy of Characterized Prosopis Wood Biochar Amendments in Improving Growth, Nitrogen Use Efficiency, Nitrate Accumulation, and Mineral Content in Cabbage Genotypes

This study was carried out to elucidate the impact of Prosopis wood biochar on growth, nitrogen use efficiency, and mineral profile of two genotypes of cabbage ( Brassica oleracea L. capitata ). The genotypes were grown under four different treatments of biochar: BT 0 (control), BT 1 (2.5% biochar), BT 2 (5% biochar), and BT 3 (7.5% biochar). Prior to its application, biochar was characterized to know about its morphological and physicochemical properties by performing scanning electron microscopy–energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD) analysis. Pre-treated Prosopis -derived wood biochar was found to contain mesoporous structures and diverse functional groups. It was also found to contain considerable amounts of nutrients like carbon, nitrogen, sulfur, and calcium. The results revealed that growth, chlorophyll content, soluble sugar content, soluble protein levels, and nitrogen use efficiency increased following the biochar amendment compared to control. In the leaves of tested cabbage genotypes, the activity of nitrogen-metabolizing enzymes like nitrate reductase, nitrite reductase, and glutamine synthetase was significantly increased by biochar amendment; however, glutamate synthase activity was not significantly increased. Moreover, application of biochar significantly decreased the amount of nitrate in the tissue. Furthermore, biochar significantly increased concentrations of minerals like phosphorus, potassium, calcium, magnesium, iron, and zinc in the leaves of tested genotypes. Together, our study proposes that biochar amendments (2.5–7.5%) can be employed as an effective strategy to improve growth and nitrogen use efficiency by regulating nitrogen-metabolizing enzymes, lowering tissue nitrate levels, and maintaining or improving nutritional quality of cabbage.