Pear twig biochar combined with nitrogen fertilizer regulates morpho-physiological growth, copper uptake and tuber quality of potato (Solanum tuberosum L.) grown in polluted soil

Application of pear twig derived biochar and nitrogen fertilizer is strategic for addressing the challenges posed by copper pollution in soils. Their combined use aims to improve plant health and promote sustainable agricultural practices, which leads to better potato growth and quality. Therefore, this study was carried out to investigate the effects of different levels of pear twig biochar (B0:0, B1:3, B2:5, B3:7% w/w) combined with nitrogen fertilizer (N0:0, N1:150, N2:200, N3:250, N4:300 mg kg- 1) on morpho-physiological growth and copper uptake of potato cultivated in Cu polluted soil. Results showed that combined approach of pear twig biochar and nitrogen significantly influenced morpho-physiology, antioxidant enzyme activity, mineral content and tuber quality of potato. B2N3 significantly increased the plant height and chlorophyll in plants as compared to B0N0 (control). Malondialdehyde and proline contents were highest in control; however, maximum reductions in MDA and proline contents were recorded at B2N4 (70.32% and 92.12% at budding stage, respectively) and at B2N3 (82.44% and 91.93% at flowering stage, respectively). Likewise, B2N3 showed maximum reduction in activities of peroxidase (7343.47 and 11077.27 U g-1), catalase (1184.98 and 165.64 U g-1) and superoxide dismutase (14.84 and 19.94 U g-1) at budding and flowering stages, respectively. However, lowest contents of soil available Cu (2.03 +/- 0.5 mu g g-1) and tuber flesh Cu (4.44 +/- 0.3 mu g g-1) were recorded at B2N3 as compared to control. Interestingly, 7% biochar at all levels of nitrogen exhibited a significant decrease in soil available Cu and tuber flesh Cu. Tuber quality traits were also significantly improved at B2N3 as compared to control. However, future research and field trials can help refine the best practices for integrating these elements in different agricultural systems.