Rice biochar improves wheat performance under salinity stress: evidence from growth, ionic balance, oxidative stress mitigation, and soil chemical improvement

Salinity severely limits wheat productivity by affecting plant growth, disrupting water relations, ionic homeostasis, photosynthetic efficiency, and oxidative metabolism. This study evaluated the effects of rice biochar on wheat (Triticum aestivum L.) under salinity levels of 0, 4, 8, and 12 dS m−1, with and without 3% rice biochar. Salinity reduced growth, yield, chlorophyll content, relative water content, and K⁺/Na⁺ ratio, while elevating Na⁺ accumulation, electrolyte leakage, MDA, proline, and antioxidant enzyme activities (SOD and CAT), along with soil EC. Rice biochar partially alleviated these effects by improving growth and yield, enhancing K⁺/Na⁺ ratio, improving soil chemical properties, and reducing membrane damage. Changes in proline and antioxidant enzymes reflected physiological responses to salinity and biochar. qRT-PCR revealed altered expression of stress-responsive genes following biochar application, indicating molecular modulation. Correlation and PCA revealed associations between productivity and chlorophyll, water status, and K⁺/Na⁺ ratio, confirming biochar's role in enhancing wheat salt tolerance.