diversity, activity, and effectiveness of rhizobium bacteria as plant growth promoting rhizobacteria (pgpr) isolated from dieng, central java

Background and objectives: this study was aimed to isolate rhizobium spp., from the plant rhizosphere and to investigate their effects on the growth of peanut (arachis hypogaea l.) as plant growth-promoting rhizobacteria (pgpr). materials and methods: the isolates were characterized using yema, yema + congo red, and yema + bromothymol blue (btb) media. the rhizobium was tested qualitatively for their ability to produce indole acetic acid (iaa), siderophores, proteases, nitrogenases as well as phosphate solubilizing activity. a greenhouse experiment was carried out to elucidate the effect of rhizobium inoculation on arachis hypogaea l. growth. results: eleven isolates were obtained in yema media and they were red-pink in the yema + congo red media. the yema + btb test showed that 2 isolates were slow-growing and the rest were fast-growing isolates. seven isolates produced siderophores, 5 were capable of phosphate solubilizing, 9 isolates produced protease enzyme, 4 isolates could produce iaa, and 7 isolates could fix nitrogen. the b1 and the combination of some high trait-isolate treatments in y gave the best results on arachis hypogaea l. growth. conclusion: these isolates can be developed as biological fertilizer agents for the peanut plant