ABSTRACT
This study investigates the presence and potential benefits of plant growth-promoting bacteria (PGPB) within the root nodules of groundnut (Arachis hypogaea) plants. Groundnut plant sample with a healthy nodulation was harvested and put a polyethylene bag and taken to the laboratory for analysis. In order to identify the bacterial present in the nodule sample, cultural and morphological analysis such as; shape, size, elevation, margin, colour, cell type, cell arrangement, motility, Gram stain, oxidase, catalase, citrate and indole were carried out. Bacterial counts revealed varying concentrations in different samples, with sample B displaying the highest count of 3.51x104 cfu/ml. The plant growth promoting traits (such as ammonium production, hydrogen cyanide and indole acetic acid) were also carried out. Through a combination of biochemical, morphological, and plant growth-promoting tests, four key bacterial strains, namely Azobacter, Pseudomonas putida, Enisifer melitoli and Bradyrhizobium japonicum, were identified within the root nodules. Azobacter and Pseudomonas putida were positive to ammonium production test and only Pseudomonas putida was positive to indole acetic test (IAA) for the plant growth promoting test. These bacteria exhibit distinct mechanisms for enhancing plant growth, including biocontrol potential and the promotion of nutrient uptake. The presence of these beneficial bacteria in the root nodules of groundnut plants holds promising implications for sustainable agriculture. The biocontrol potential and growth-promotion properties may reduce the reliance on synthetic fertilizers and enhance crop yields. Further research into the environmental conditions favoring these bacteria proliferation and practical applications for farmers to harness their potential could pave the way for more eco-friendly and productive agricultural practices. Findings shed light on the intricate interactions between groundnut plants and PGPB, providing valuable insights into harnessing the potential of these beneficial microorganisms for enhancing crop productivity. This research contributes to our understanding of plant-microbe interactions and offers practical implications for optimizing groundnut cultivation practices in an environmentally friendly and economically viable manner.
