Mesorhizobium improves chickpea growth under chromium stress and alleviates chromium contamination of soil

Abstract

Environmental pollution has become a transnational issue that impacts ecosystems, soil, water, and air and is directly related to human health and well-being. Chromium pollution decreases the development of plant and microbial populations. It warrants the need to remediate chromium-contaminated soil. Decontaminating chromium-stressed soils via phytoremediation is a cost-effective and environmentally benign method. Using multifunctional plant growth-promoting rhizobacteria (PGPR) lower chromium levels and facilitates chromium removal. PGPR work by altering root architecture, secreting chemicals that bind metals in the rhizosphere, and reducing phytotoxicity brought on by chromium. The present study aimed to investigate the chromium bioremediation capacity of metal-tolerant PGPR isolate while promoting the growth of chickpeas in the presence of varying levels of chromium (15.13, 30.26, and 60.52 mg/kg of chromium). The isolate, Mesorhizobium strain RC3, substantially reduced chromium content (60.52 mg/kg) in the soil. It enhanced the root length by 10.87%, the shoot length by 12.38%, the number of nodules by 6.64%, and nodule dry weight by 13.77% at 90 days. After 135 days of sowing, more improvement in the root length (18.05), shoot length (21.60%)the chlorophyll content (6.83%), leghaemoglobin content (9.47%), and the highest growth in the crop seed yield (27.45%) and crop protein content (16.83%)The isolate reduced chromium accumulation in roots, shoots, and grains chickpea. Due to chromium bioremediation and its plant growth-promoting and chromium-attenuating qualities, Mesorhizobium strain RC3 could be used as a green bioinoculant for plant growth promotion under chromium stress.