Contribution of mineral mobilizing fluorescent pseudomonads in growth promotion of rice (Oryza sativa L.) in nutrient deficient soil

In order to overcome the damages caused by conventional farming, excessive use of chemical and synthetic fertilizers and for stimulating plant growth, Rhizomicrobiome has been a strategic yet over exploited biological tool. Among rhizospheric microbial communities, use of fluorescent pseudomonads as biocontrol agents remains prominent due to their ability to produce a variety of antimicrobial secondary metabolites. However, Pseudomonas spp. also possess great abilities of nutrient mobilization and can effectively enhance the bioavailability of inorganic zinc and potassium salts to plants. In this study, ten Pseudomonas spp. strains including P. aurantiaca (GS1, GS3, GS4, GS6, GS7, FS2, ARS38, and PBSt2), P. chlororaphis (RP4), and P. fluorescens (RS1) were evaluated for promoting growth of rice under natural climate conditions. Pot-scale experiments with zinc solubilizing P. aurantiaca GS3 and GS7 showed significant increase in dry shoot and root weights of inoculated plants as compared to un-inoculated controls. Pot experiments with potassium-solubilizing pseudomonads including P. aurantiaca PBSt2, ARS38, GS3, GS4, GS7, P. chlororaphis RP4, and P. fluorescens RS1 showed increased biomass and weight of tillers, as compared to control plants. Maximum zinc concentration was recorded for the shoots and tillers of P. aurantiaca GS3-inoculated plants. However, maximum potassium concentration in shoots, roots, and tillers of rice plants was observed for P. aurantiaca ARS38-inoculated plants. A significant increase in plant biomass and weight of tillers was attributed to increased nutrient mobilization by biofertilizing Pseudomonas spp. Successful nutrient uptake and increased grain yield of rice suggest the use of biofertilizing pseudomonads to lessen the environmental burden of chemical pesticides and enhance plant productivity. (c) 2024 SAAB. Published by Elsevier B.V. All rights reserved.