Rhizosphere Engineering of Rice with Plant Growth Promoting Rhizobacteria (PGPR) Elicits Crop Growth and Soil Microcosm in Blue-R Dye Contaminated Soil

This investigation was conducted to determine the ability of plant growth-promoting rhizobacteria (PGPR) to elicit growth of rice plants (var. CO51) in soil incubated with Blue-R textile dye. Two commercial strains of PGPR, nitrogen-fixing Azospirillum lipoferum Az204 and phosphorus-solubilizing Bacillus megaterium var phosphaticum PSB1, were used to prepare a carrier and liquid-based formulations. Seed biotization of carrier-based PGPR consortium followed by a foliar spray substantially resulted in a higher plant biomass, germination percent, and vigor index as compared to non-inoculated plants in Blue-R-amended soil. The photosynthetic efficiency is also higher, which is evident by the total chlorophyll content in PGPR-treated seedlings. Similarly, the carrier-based PGPR inoculated plants revealed higher nutrient uptake as well as N, P, and K content in shoots as compared to the non-inoculated plants. PGPR inoculation through seeds showed better survival and colonization of A. lipoferum Az204 and B. megaterium PSB1 in the rhizosphere. A. liopferum Az204 remarked good colonization in inner tissues of roots, stems, and leaves. It was concluded that PGPR application through seeds enhances crop fitness, modulates rhizosphere services, and alleviates oxidative stress caused by Blue-R in rice plants. Therefore, rhizosphere engineering by PGPR through seeds followed by subsequent foliar sprays can be used as a sustainable strategy for textile wastewater-irrigated soils.