Characterization of phyllosphere methylotrophic bacteria isolated from the groundnut and their impact on growth, yield and quality of the kernel

Aim : The present study was undertaken to characterize and evaluate the habitat adopted methylotrophic bacteria on groundnut growth and yield at field level. Methodology : Nine elite methylotrophic bacterial isolates were selected based on early plant growth promotion and quantified for plant growth promoting (PGP) traits along with one standard strain, Methylobacterium thiocyanatum DSM 11490(T). Two field experiments were carried out with eleven different treatments arranged in a randomized block design with three replications. Bacterial inoculant was applied as seed treatment as well as foliar application at 35 and 70 days after sowing. Plant growth and yield parameters were estimated periodically and after harvest. Results : All the tested isolates exhibited multiple PGP traits. In Vriddhachalam, the yield of groundnut was significantly higher in Methylobacterium thiocyanatum VRI7-A4 (1688.9 kg ha(-1)) followed by Paenibacillus hunanensis COG-4 (1675.8 kg ha(-1)) compared to un inoculated control treatment. In Tindivanam, yield content of groundnut was found significantly higher in Methylobacterium thiocyanatum VRI7-A4 (1678.6 kg ha(-1)) followed by Pseudomonas psychrotolerans K-TMV7-6 ( 1667.5 kg ha(-1)). In addition, Methylobacterium inoculation increased the kernel protein content as compared to the control treatment in both the field experiments. Interpretation : The results showed that Methylobacterium populi TMV7-4, Methylobacterium thiocyanatum VRI7-A4, Pseudomonas psychrotolerans K-TMV7-6 may be used as bio-inoculant for groundnut crop.