Qualitative In Vitro Evaluation of Plant Growth Promoting Activity of Selected Microbial Isolates Used for Biofertilizer Application

Abstract

The use of microbial strains with plant growth promoting (PGP) properties is advisable as a sustainable alternative to chemical fertilizers to improve soil fertility and crop yields. The present study identify 12 specific microbial isolates (7 bacterial and 5 fungal isolates) to have PGP activity viz. atmospheric N fixation, phosphate and potash solubilization, indole acetic acid (IAA) production, and cellulase production. This research work was conducted at the Laboratory of Plant Protection Faculty of Agriculture University of Bengkulu in 2020. The results showed that N fixation ability was observed in Bacillus megatrium, Bacillus sp., Azotobacter sp., and Pseudomomas fluorescent. The highest phosphate solubilization index for bacterial isolate (1.95) was observed in Bacillus sp. and for fungal isolate (1.38) was in Aspergillus niger. The highest potash solubilization index for bacterial isolate (1.86) was observed in P. fluorescent andfor fungal isolate (2.06) was in Paeceilomyces sp. IAA production activity was observed in all isolates tested (except for Paeceilomyces sp. and Trichoderma sp.). Cellulase production trait was observed in all isolates tested. The highest cellulase production index was observed in Azotobacter sp. (1.71) for bacteria and Saccharomyces sp. (1.31) for fungi. Thus, the 12 isolates hold promise to be used as a biofertilizer through their potential PGP traits.