UC Berkeley

There are various mechanisms through which plant’s growth and yield can be promoted by plant growth promoting rhizobacteria (PGPR) that reside inside the soil. The use of pesticides, chemical fertilizers and other supplements could be replaced by PGPR. There are various substances produced by the rhizosphere microorganisms that are important for growth promotion as they affect morphology of plants indirectly. Their nodulation activity, biofilm formation, root colonization were observed and characterized for solubilization of phosphate, production of indole acetic acid and fixation of nitrogen. It was found that ten out of seventeen isolates from chickpea had positive nitrogen fixing activity but at varying levels and the range of fixed nitrogen was 136.666 to 303.666 nmoles C2H2 reduced/h/mg protein. Bacterial isolate CM1 showed maximum nitrogen fixation ability. Thirteen isolates produced IAA in the range of 3.833-18.100 µg/mL. Bacterial isolate, CM1 produced maximum indole acetic acid. Among chickpea bacterial isolates, sixteen were positive in phosphate solubilizing ability while only one was negative. Range of phosphate solubilization among chickpea isolates was 4.533-12.333µg/mL. Maximum value for phosphate solubilization was observed in CM4. Potential root nodulating bacteria were identified using 16S rRNA sequence analysis. CM1, CM2, CM3, CM5, CM6, CM11, CM15, CM24 and CM25 were identified as Mesorhizobium ciceri while CM4 as Mesorhizobium mediterraneum.