Differential Plant Growth Promotion Under Reduced Phosphate Rates in Two Genotypes of Maize by a Rhizobial Phosphate-Solubilizing Strain

Abstract

The biotechnological manipulation of phosphate-solubilizing bacteria (PSB) is gaining prominence to improve the poor phosphorus (P) availability in the soil and maintain crop yields. In this study, we investigated how Rhizobium sp. B02 inoculation influences maize crop development and whether its use reduces phosphate fertilizer rates. We conducted growth promotion assays using P fertilizer doses in two maize genotypes under greenhouse conditions. Morphometric, physiological, and productivity parameters were assessed in three phenological stages: tillering (V5), tassel (VT), and maturity (R6). Maize response was significantly influenced by both inoculation and plant genotype, showing that the plant-promoting effect of inoculation is substantially more prominent in the white endosperm than in the yellow endosperm maize genotype. The development of maize in all phenological stages was promoted by inoculation with Rhizobium sp. B02. The most significant influence of inoculation was observed on shoot dry weight, relative chlorophyll content, shoot P concentration, leaf area, photosynthetic rate, 1,000-grain weight, and grain yield. A 17% gain in grain yield, representing 20 g plant−1, was obtained by inoculation with 50% diammonium phosphate (DAP) compared with the control treatment at the same dose. The complete fertilization control was phenocopied by the white endosperm inoculated at 50% DAP in all productivity parameters. Therefore, half of the P fertilization in white endosperm was replaced by inoculation with Rhizobium sp. B02. Herein, we report the potential of a Rhizobium strain in a non-legume crop to improve P management.

Efficacy of DAP coated with bacterial strains and their metabolites for soil phosphorus availability and maize growth

“…Findings of this study showed that application of coated DAP enhanced plant biomass and physiological characters. Our results were confirmed by findings of Beltran-Medina et al 51 , that physiological attributes of plants were improved due to the application of PSB. The application of PSB reduces the pH by releasing organic acids in the rhizosphere, which increases the availability of inorganic P for plants.…”