Synergistic effect of Leclercia adecarboxylata CIP 82.92 and rice husk biochar on yield enhancement and cadmium reduction in mung bean

Mung bean ( Vigna radiata L.) is a vital legume crop widely grown in Asia, valued for its nutritional qualities and nitrogen-fixing ability. However, its productivity is challenged by cadmium (Cd) contamination in soils, which poses risks to crop yield and food safety. This study aimed to isolate indigenous endophytic bacteria capable of promoting mung bean growth while reducing Cd uptake, and to evaluate the combined effect of bacterial inoculation with rice husk biochar (RHB) in field trials conducted over two consecutive seasons (2023–2024 and 2024–2025) in Cd-contaminated soils of An Giang province, Vietnam. Leclercia adecarboxylata CIP 82.92 (strain CIP) was isolated from mung bean (MB) roots and characterized for morphological, biochemical, and molecular features, confirming its identity and nitrogen-fixing potential. Field experiments used a randomized complete block design with two factors: inoculation with CIP 82.92 and three RHB application rates (0, 5, and 10 t ha⁻¹), with chemical fertilizers uniformly applied. Results demonstrated that inoculation with CIP 82.92 significantly enhanced plant growth parameters, biomass, and yield components, while RHB application further improved these effects, showing a synergistic interaction. Importantly, Cd accumulation in seeds and aerial parts was markedly reduced by combined treatment, alongside improvements in seed protein and lipid content. The beneficial outcomes were more pronounced in the second year, indicating cumulative soil health benefits. This study highlights the integrated use of strain CIP 82.92 and RHB as an effective, eco-friendly approach to increase mung bean productivity and food safety in Cd-contaminated agricultural systems.