Indigenous plant growth-promoting rhizobacteria as biofertilizer candidates for hybrid maize in acidic soils

Abstract

Maize (Zea mays L.) is a major staple crop, but its cultivation on acidic soils is constrained by low pH, nutrient deficiencies, and aluminum toxicity, which together limit soil fertility and plant growth.Exploiting indigenous plant growth-promoting rhizobacteria (PGPR) offers a sustainable approach to improving nutrient availability and reducing reliance on synthetic fertilizers.This study aimed to isolate and characterize rhizosphere bacteria associated with hybrid maize grown on acidic ultisol in the Moncongloe District (South Sulawesi, Indonesia) and to evaluate their biofertilizer potential.Soil samples from five locations yielded ten representative bacterial isolates that were screened in vitro for indole-3-acetic acid (IAA) production, biological nitrogen fixation, and phosphate solubilization.Two superior isolates, TJMS19 and TJMTE54, exhibited high nitrogen-fixation capacity (up to 49.07 mg L) and strong phosphate-solubilizing ability (up to 14.54 mg L), while TJMTE54 also produced the highest IAA level (6.55 mg L).Inoculation of hybrid maize seedlings with these isolates significantly increased plant height, root length, and fresh biomass compared with the uninoculated control.Molecular identification based on 16S rRNA gene sequences showed that TJMS19 is closely related to Bacillus paramycoides, whereas TJMTE54 clusters within the genus Pseudomonas.The combined physiological traits and growth-promotion effects indicate that these indigenous PGPR strains are promising candidates for development as eco-friendly biofertilizers to enhance hybrid maize productivity on acidic, marginal soils.

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