Integrating rice straw biochar with malic acid and exopolysaccharides-producing Bacillus cereus NM28 enhances chromium stress tolerance in tomato.

Chromium (Cr) is a highly toxic heavy metal being enters the soil ecosystem by anthropogenic activities, including irrigating wastewater coming from leather industries. Cr adversely affects plant growth and physiology (reduced photosynthesis, oxidative damage, nutritional imbalance). Various methods are being used for its alleviation, but use of organic amendments is gaining importance. That's why current study reports the potential of integrating biochar with Bacillus cereus NM28 to enhance Cr stress tolerance in tomato plants. The results showed that Cr stress significantly decreased tomato growth, but the integrated application of biochar with malic acid and exopolysaccharides producing Bacillus cereus NM28 improved the parameters under study by reducing the adverse effects of Cr stress improving the root dry weight, shoot dry weight, SPAD value, and total chlorophyll contents by 28, 27, 23, 22, and 54%, respectively, at 150 µg mL^-1 of Cr stress. For instance, integrated application has been found to decrease the stress indicators viz. proline and antioxidant status, except ascorbate peroxidase (APX) to alleviate Cr stress. In conclusion, combined use of biochar and Bacillus cereus NM28 offers a promising, eco-friendly strategy to alleviate Cr toxicity in tomato plants, enhancing growth and physiological health while contributing to improved soil quality.