Evaluation of Previously Isolated and Characterized Phosphate Solubilizing Bacteria with Plant Growth-Promoting Potentials for Rice Grown Ferruginous Ultisol Soil in Benin City, Edo State, Nigeria

Abstract

The objective of this paper is to evaluate the potentials of previously isolated and characterized phosphate solubilizing bacteria (PSB) [Bacillus cereus strain GGBSU-1, Proteus mirabilis strain TL14-1, and Klebsiella variicola strain AUH-KAM-9] with plant growth-promoting (PGP) capabilities on growth properties of rice plants under ferruginous ultisol (FU) conditions through a rhizo-inoculation strategy. The rice seeds were sown in a composite FU soil sample and a humus soil (control) and then rhizo-inoculated along the root region of the growing rice seedling at 16 days after sowing. The rice plant was studied for differences in morphological, physiological, and biomass parameters for 16 weeks after rhizo-inoculation. Results showed that the FU soil used in the study had high pH, low bioavailable phosphorus and high iron levels which has led to low growth properties of rice seeds sown in FU soil without rhizo-inoculation. After rhizo-inoculation, a significant improvement was observed in the rice plant grown in the FU soil, as against the control and the rice plant in FU soil without inoculation except for terpenoid, which is usually known to signify biotic stress and as part of plant defense mechanism. This research suggests that PSB rhizoinoculation technique can be used in improving growth properties of rice plants even under FU conditions.