Characterization of PGPR isolated from rhizospheric soils of various plant and its effect on growth of radish (Raphanus sativus L.)

Abstract

Plant growth promoting rhizobacteria (PGPR) are commonly used as biofertilizers for agricultural crops. In addition, screening and selection of effective PGPR for a particular plant is necessary to meet plants specific need and condition. Present study was aimed to obtain PGPR isolates which are effective and compatible for Radish. A total of 15 PGPR isolates had been isolated from various plant roots and in vitro screening was done for different plant growth promotion activities. The result showed that 7 isolates were able to produce IAA at the range of 10.2-125.3 μg ml−1, 10 isolates were positive for phosphate solubilizing, 10 isolates had nitrogen fixing activities, 11 isolates were protease positive, 12 isolates were capable to produce ACC-deaminase enzyme, 7 isolates produced siderophore, 8 isolates produced HCN, and 9 isolates produced ammonia. The effect of 15 PGPR on Radish growth in the green house showed that all isolates had effects on increasing growth and tuber formation compared to control. Nine isolates significantly increased the wet weight shoot plants, the highest effect was reached by Kbm 10.3 isolate (168.5 g), while control only reached 81.5 g. Eight isolates had a significant effect on increasing tuber formation, the highest was Kbm 2.10 isolate (176 g), while control only reached 54.7 g. Kbm 10.3 and Kbm 2.10 isolates seemed to have the highest impact in promoting growth and tuber formation. Those two isolates were analyzed using 16s rDNA sequences, they have close evolutionary relationship with Bacillus megaterium (Kbm 2.10) and Paraburkholderia tropica (Kbm 10.3).