Progrès dans la science et la technologie des cultures

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Screening and Evaluation of Plant Growth Promoting Rhizobacteria from Potential Bread Wheat (Triticum aestivum L.) Rhizospheric Soil at Lemo Woreda, Southern Ethiopia

Yehuala Alemneh, Meseret Chimdessa

Plant growth-promoting rhizobacteria are a group of bacteria that survive inside and outside of the plant tissue and promote plant growth through direct or indirect mechanisms. Different microbial based approaches, in the form of bio fertilizers, bio-stimulants, and/or bio pesticides are currently proposed as alternatives for improving crop yield. A particular group of microorganisms, termed plant growth-promoting rhizobacteria (PGPR), positively influence plant growth, and represent promising sustainable solutions to increase plant biomass production. Therefore, the current study was conducted with the objective of isolation of plant growth promoting rhizobacteria (PGPRB) from wheat rhizospheric soil and screening for the primary growth-related trait, evaluation of potential PGPRB at the greenhouse for wheat growth performance, and identification through biochemical characterization. Accordingly, in this study, a total of 8 plant growth-promoting rhizobacteria were isolated from the rhizospheric soil by serial dilution. The bacterial isolates were screened for primary growth-promoting traits such as phosphate solubilization, IAA production test at different concentrations of L-tryptophan, and ammonia production test. From the isolated bacteria three isolates such as HUPGPRBW-1, HUPGPRBW-2, and HUPGPRBW-3 were solubilized phosphorous, produced IAA and produced ammonia. The highest IAA production (32.7 μg/ml) was observed in HUPGPRBW-1 isolates and the lowest production (7.5 μg/ml) of IAA was recorded in HUPGPRB W-7 isolates. In this study, 37.5% of isolates fulfilled the primary screening test and were used for further greenhouse evaluation. Accordingly, three isolates were tested for greenhouse experiment using a completely randomized design and all 3 isolates significantly increased all the selected plant growth parameters such as shoot length, root length, shoot, and root fresh and dry weight as compared to the control. Among the 3 isolates, two isolates (HUPGPRBW-1 and 2) showed the highest stimulator effect on the shoot and root growth as compared with the control group. Thus, the use of plant growth-promoting rhizosphere bacteria could be useful to improve wheat production and productivity