Efficacy of plant growth promoting (PGP) <i>Rhizobium</i> <i>sp.</i> adopted from <i>Arachis hypogaea </i>nodules and its impact on the host of <i>Sesbania</i> <i>sp.</i>

The intense competition for rhizobia in a variety of niches has resulted in their fitness. Screening of endophytic bacteria with plant growth-promoting traits has wider uses in crop yield.The present study aimed to evaluate the cross-inoculation of peanut root nodulating Bradyrhizobium sp. on the Sesbania host. The Arachis hypogea L. is the most popular legume collected from Madurai region, India, and was selected for Rhizobium isolation using yeast extract mannitol agar (YEMA) agar. The host specificity of isolated Rhizobium was tested on Sesbania sp. by seed priming, followed by qualitative plant growth promotion efficiency of isolates. Totally seven rhizobial strains were screened for plant growth-promoting traits (PGP), and two were found to be effective PGP and selected for the pot experiment. Isolates AH12 and AH15 were phylogenetically identified as Bradyyrhizobium arachidis PQ119952 and Bradyrhizobium japonicum PQ119954. Data compared the inoculation of seeds with AH12 and AH15 to those without inoculation in Sesbania. Test plants showed high efficiency for growth promotion on both Bradyrhizobial strains. Germination rate (76.6±0.57%), vigour index (547.6 and 552.2), vitality index (206.8 and 214.4), nodulation state, leghaemoglobin (LHB) and chlorophyll (1.48±0.13 and 1.58±0.12) content were increased significantly among the Bradyrhizobium-treated groups. The foliar application of both isolates was found to control the leaf spot Alternaria spp. infection. The cross-inoculation studies on Sesbania seeds showed that Bradyhizobium spp (multi-traits strains) improved all seed viability as well as the growth of plants and could form fully effective symbioses with strains in the genera.