Biological Weeds Control in Rice (Oryza sativa) using Beneficial Plant Growth Promoting Rhizobacteria

Weeds are termed as pests owing to their harmful impact on agroecosystems. Although the herbicidal weed control is the best strategy to control weeds but over and non-judicious use of herbicides resulted many negative impacts on human health and crop ecology. Weeds control through biological approach is considered less destructive. In this study, three efficient bacterial strains i.e., Pseudomonas putida, P. aeruginosa and P. alcaligenes, isolated during preliminary studies and their consortium were applied to Cyperus rotundus and Echinochloa colonum co-seeded with rice grown in pots. Effect of allelopathic bacteria on the infested rice and weeds were studied at tillering, booting and harvesting stage of rice. Results indicated that the applied strains significantly improved rice growth and yield and hindered the weeds germination to variable extent. The weeds infestation also decreased plant height, 1000-grain weight, spikelet length and nutrient concentration under control condition. However, the P. putida recovered the maximum losses in shoot dry weight and grain yield of rice infested with C. rotundus (42 and 78%, respectively) and E. colonum (78 and 69%, respectively). Nonetheless, allelopathic bacteria application also improved the gas exchange traits and nutrient contents of infested rice. In conclusion, inoculation with bacterial strains reduced the biomass of weeds and promoted the growth, yield and photosynthetic parameters of infested rice. Therefore, allelopathic bacteria application seemed a viable strategy to minimize the competition between rice crop and weeds; and these strains, P. putida in particular, can serve as biological control agents of rice weeds i.e., E. colonum, C. rotundus. (C) 2020 Friends Science Publishers