GIBBERELLIN PRODUCING RHIZOBACTERIA Pseudomonas koreensis MU2 ENHANCE GROWTH OF LETTUCE (Lactuca sativa) AND CHINESE CABBAGE (Brassica rapa, chinensis)

摘要

Microbial biofertilizers are considered environmentally safe tool for the healthy production of a plant. Massive application of synthetic pesticides and fertilizers in agriculture has resulted detrimental effect on nature and human health. In the current study, we isolated several strains of rhizoshpheric bacteria through screening from the diversed agricultural soil of Daegu, South Korea. The growth promoting ability of the isolated strains was checked on gibberellin-deficient rice dwarf mutant Waito-C, lettuce var. cheongchima and chinese cabbage var. wangmat. The strain having the higher ability to promote the Waito-c growth was selected and further investigation was done. The selected isolate was identified as Pseudomonas koreensis MU2 through 16s rDNA gene sequence analysis. The cultural filtrate analysis revealed that the isolate could produce endogenous phytohormone gibberellic acid (GA1 and GA3) and organic acids, such as citric acid, malic acid, and tartaric acid. Pot experiment revealed that the inoculation of Pseudomonas koreensis MU2 significantly increased shoot length, root length, fresh biomass, and dry biomass of chinese cabbage and lettuce. These results suggest that the Pseudomonas koreensis MU2 might be the possible candidate for bio-fertilizer as a plant growth-promoting rhizobacteria in plant.