Evaluating the Impact of Plant Growth-Promoting Rhizobacteria Inoculums and Metabolites on Germination and Vigor Index of Sesame Seedlings

Abstract

Plant growth promoting rhizobacteria (PGPR) offer an eco-friendly alternative and are capable of promoting plant growth and improving soil health. The present study investigates the potential of PGPR on germination and vigor enhancement of sesame (Sesamum indicum) under greenhouse conditions. This research evaluates the effects of two microbial inoculation methods (seed treatment and soil drenching) on sesame growth parameters. The inoculums and metabolites of 15 respective rhizobacterial isolates, which were previously identified as growth promoters were used for the study. The inoculums and metabolites were applied to sesame seeds and soil in various treatment groups. The treatment groups used for the study were inoculum + seed treatments, inoculum + soil treatments, metabolite + seed treatments, metabolite + soil treatments, water + seed treatments (control A) and soil treatments (control B). Over a 20-day period, plant height, percent germination and vigor index were measured. The results revealed that seed treatments with inoculums of Bacillus cereus (OP830502), Bacillus thuringiensis (OP830494), and Providencia vermicola (OP830490) significantly increased vigor index and germination rates, when compared to the controls. Soil treatments with certain inoculums also showed enhanced germination and vigor index. In addition, seeds planted in soils treated with the respective metabolite before planting gave varying results, with some metabolites significantly improving vigor index and germination rates while no significance improvement was observed in others. The findings suggest that specific PGPR strains and application methods can effectively promote sesame growth, which could serve as sustainable alternative to chemical fertilizers.