Characterization of Plant-Growth Promoting Diazotrophic Bacteria Isolated from Field Grown Chinese Cabbage under Different Fertilization Conditions

摘要

Diazotrophic bacteria isolated from the rhizosphere of Chinese cabbage were assessed for other plantgrowth promoting characteristics viz., production of IAA, ethylene, ACC deaminase, phosphate solubilization,and gnotobiotic root elongation. Their effect on inoculation to Chinese cabbage was also observed undergrowth chamber conditions. A total of 19 strains that showed higher nitrogenase activity identified by 16SrRNA gene sequence analysis were found to be the members of the genera Pseudomonas and Agrobacteriumbelonging to α- and γ-Proteobacteria groups. These strains were also efficient in producing IAA and ACCdeaminase though they produced low levels of ethylene and no phosphate solubilization. In addition, in-oculation of selected diazotrophic bacterial strains significantly increased seedling length, dry weight, andtotal nitrogen when compared to uninoculated control. The colonization of crop plants by diazotrophicbacteria can be affected by many biotic and abiotic factors, and further studies are oriented towards inves-tigating the factors that could influence the establishment of a selected bacterial community.