Enhancing maize yield and antioxidant capacity with glyphosate-resilient rhizobacteria in glyphosate contaminated...

Glyphosate, a commonly utilized herbicide in agriculture, poses significant threats to microbial diversity, soil fertility, human health, and agricultural productivity due to its frequent and intensive application. To mitigate these challenges, we investigated the potential of plant growth-promoting rhizobacterial strains tolerant to glyphosate (GLY) to alleviate its toxicity and enhance maize growth.

Eleven pre-isolated bacterial strains were assessed for their ability to promote maize growth and reduce phytotoxicity at 100 and 200 mg kg^- 1 GLY in soil. Among them, five GLY-tolerant bacterial strains (E. cloacae, E. ludwigii, K. variicola, P. aeruginosa and S. liquefaciens) exhibited notable resistance. These strains exhibited positive qualitative characteristics, including 1-aminocyclopropane 1-carboxylate (ACC) deaminase activity, oxidase and catalase production, indole-3-acetic acid synthesis, and siderophore production. Moreover, these five GLY-tolerant strains reduced the toxicity and improved the biological traits of the maize plants. Inoculated plants average improved chlorophyll SPAD value by 43%, shoot and root dry biomass by 59 and 1.02-fold, respectively, and 100-grains weight by 23% compared to control at 100 mg kg^- 1 of GLY. Also, there was an average reduction of catalase by 32% and electrolyte leakage by 68% in inoculated treatments compared to uninoculated control at 100 mg kg^- 1 of GLY. Additionally, average improvement in peroxidase by 1.09-fold, polyphenol oxidase by 1.6-fold, and superoxide dismutase by 1.2-fold was recorded in inoculated plants than control at 100 mg kg^- 1 concentration of GLY.

Current findings highlight the remarkable ability of the isolated strains to withstand high GLY concentrations, produce plant growth-promoting compounds, and enhance maize growth through GLY detoxification. These findings offer promising strategies for improving maize productivity in GLY-contaminated soils, thus contributing to sustainable agriculture and environmental health.