The performance of Bacillus pumilus in boosting edamame yield is triggered by highly water-soluble phosphate fertiliser

The utilisation of biofertilisers in food crops has gained significant attention, as cultivation practices now focus not only on increasing productivity but also on promoting environmental sustainability. In this study, we evaluated the effectiveness of the phosphate-solubilising bacterium Bacillus pumilus (BP) in edamame cultivation using different types of phosphate (P) fertiliser: rock phosphate (RP) and superphosphate (SP-36). The bacterial strain isolated from the ebb-tide peatlands of South Kalimantan, Indonesia, was tested in a pot experiment conducted under 65.75 % shading, with both SP-36 and RP applied at 100 kg ha-1. Our bacterial strain exhibited moderate phosphate solubilisation ability. The strain exhibited greater effectiveness when combined with SP-36, a highly water-soluble P fertiliser, rather than RP, both in enhancing edamame yield to a potential yield of 13.08 t ha-1 and in increasing available P in the growing media by 63.10 %. The primary yield contributing components were the number of pods (122.67) and seeds (275.67) per plant. A synergistic relationship between the number of nodules and yield improvement was observed in this treatment. Our strain enhanced nodule formation even in the absence of P fertiliser. Limited light intensity delayed flowering, which normally occurs 30 days after planting (DAP). However, the earliest flowering period was obtained when the bacterial strain was incorporated with SP-36 (39.67 days). The increase in yield associated with bacterial inoculation was accompanied by a slight increase in total chlorophyll content. In conclusion, BP has strong potential as an inoculant to optimise edamame yield, particularly when used in conjunction with a highly water-soluble P fertiliser. However, because this study was conducted under controlled pot and shaded conditions, further field-scale evaluation under different environmental conditions is required before these findings can be broadly applied.