Impact of PGPR Consortium on Rice (Oryza sativa L.) Growth and Bioremediation in Contaminated Soils of Patna, India

Abstract

Rice (Oryza sativa L.) is a vital staple crop feeding over 50% of the global population, yet its production in Bihar, India, is hampered by low productivity and heavy metal contamination in soils, posing health risks. Excessive use of synthetic fertilizers exacerbates soil degradation and heavy metal accumulation, necessitating sustainable alternatives. This study evaluated the efficacy of a plant growth-promoting rhizobacteria (PGPR) consortium—Klebsiella pasteurii (PGPR1) and Enterobacter hormaechei (PGPR2) —on rice growth and bioremediation in contaminated soils of Patna. Soil samples from three rice fields (Khairatali, Maner, Patna City) were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cd) using atomic absorption spectroscopy (AAS) before and after PGPR treatment. A pot experiment assessed seed germination and growth parameters in sterilized soils inoculated with the consortium. Results showed a significant reduction in heavy metal concentrations post-treatment (e.g., Fe: 16.54 to 8.44 mg/L in Khairatali; Cd: 0.52 to 0.28 mg/L in Patna City). Seed germination increased from 55% (control) to 74% (treated), with Khairatali soil exhibiting the highest rate (90.68%). Growth parameters improved markedly, including seedling height (76%, 28.09 cm), root length (61%, 11.68 cm), and root dry weight (75%, 9.96 mg/plant) compared to controls. Statistical analysis (ANOVA, p < 0.001) confirmed these enhancements. The PGPR consortium offers a promising biofertilizer for improving rice productivity and soil health in contaminated regions of Patna, Bihar.