Mitigating chromium toxicity and enhancing rice productivity in chromium-affected regions of Odisha, India
摘要
Heavy metals, particularly chromium (Cr), poses serious concern regarding contamination and its accumulation in soil impacting crop growth, yield, food safety besides environmental safety and human health in Cr-contaminated areas. An experiment was conducted to evaluate application of various amendments (viz. biochar and vermicompost) besides irrigation practices for alleviating Cr toxicity in rice. The experiment was laid out in a factorial complete randomized design with three factors i.e. Cr stress, amendment application and irrigation practice. The elevated Cr levels significantly inhibited plant growth parameters, yield attributes, and ultimately grain (12%) and straw (10%) yield of paddy. Higher Cr levels in the soil significantly (p ≤ 0.001) increased Cr uptake by rice plants, with the highest accumulation observed in roots (637 mg kg−1), followed by straw (37 mg kg−1) and grain (19.8 mg kg−1). Application of vermicompost resulted in increased root length (8.6%) and volume (52%), reduced Cr uptake, improved plant height, number of tillers per hill, and overall yield attributes leading to increased yield (27%) of paddy. Furthermore, maintaining continuous flooding up to flowering stage of rice as an irrigation practice significantly reduced the Cr uptake by rice plant (11%) and Cr content in rice grain (18%). The functional groups of organic amendments serve as ligands, binding heavy metals to form stable organic-metal complexes, while flooding creates anaerobic conditions that reduce the availability of hexavalent Cr. Therefore, the management practice includes application of vermicompost at 10 t ha−1 with continuous flooding up to flowering stage can be recommended for paddy cultivation to mitigate Cr toxicity, reducing Cr accumulation in grains and enhancing rice productivity in Cr-contaminated regions.