Abstract:
Rhizobacteria were isolated from the rhizosphere of rice and weeds in rice field in Nakhon Ratchasima using TSB medium. In this study, we obtained 52 and 37 rhizobacterial isolates from rhizosphere of rices and weeds, respectively. Bacterial cells were Gram-positive and Gram-negative, Bacilli, rod and cocci. All obtained isolates were members of the phylum Proteobacteria, Actinobacteriota , and Firmicutes. The obtained were identified as various genera Bacillus , Paenibacillus , Priestia , Fictibacillus , Microbacterium , Micrococcus, Pseudomonas, Enterobacter, Kosakonia , Dickeya , and Aeromonas. These rhizobacteria demonstrated the ability to produce indole-3-acetic acid, hydrogen cyanide, and ammonia, all of which are plant-growth-promoting attributes, with some also contributing to weed growth suppression. Moreover, these isolates exhibited their antagonists against Curvularia sp. , Alternaria alternata , and Fusarium moniliforme. Four rhizobacterial isolates, W1-5, W2-5, and W3-5, including the isolate R7-9 were selected for the experiment of weed growth inhibition.Surface-sterilized Bermuda seeds were dropped with bacterial culture supernatant containing IAA compared to the control (sterilized water and TSB medium). The results showed that all four IAA-producing rhizobacteria could reduce the growth of Bermuda grass. Seeds that were exposed to a high concentration of IAA resulted in inhibition of root development and inhibition of plant growth. These rhizobacteria have efficacy that should be further tested for use in inhibiting weed growth and developing them as herbicides.