The Screening of Plant Growth-promoting Rhizobacteria based on the Ability to Promote the Growth and Nodulation of Soybean (Glycine max L.) Seedlings

Plant growth-promoting rhizobacteria (PGPR), which were isolated from the plant rhizosphere, decrease the addition of chemical fertilizer (N) and promote plant growth. Some PGPR isolates can fixate nitrogen, solubilize phosphate, produce phytohormones, and control soil pathogens. This study has focused on isolating rhizobacteria from root nodules of Edamame, Glycine max L, Dieng Peanut, Solanum sp. and Peanut root. Eleven isolates were assayed to examine their activities, including the ability of nitrogen fixation, produce Indol Acetic Acid hormone, siderophore, ammonia, and catalase activity. Furthermore, 11 isolates were tested to promote soybean growth in pot experiments using sterile sand media and the test of symbiotic capacity. The results showed that six isolates (RhizE2, RhizE3, RhizE4, RhizKdKbm1, Bio2DW, and Bio3DW) could form root nodules, and four isolates (RhizE2, RhizE3, RhizKdKbm1, and Bio2DW) showed a symbiotic capacity of more than 90%. RhizE2 significantly increased the number of nodules and dry weight of the entire plant (24.08 g) in comparison with plants without inoculation and added N fertilizer (11.59 g) and added N fertilizer (19.60 g). RhizE2 can be further developed as a biological fertilizer agent, especially for soybean plants. From all parameters observed, the plants inoculated with RhizE2 showed the best growth result.