Selection, Characterization and Application of Rhizobacteria and its Effect on Chili ( Capsicum annuum L.) Plant Growth

摘要

Background and Objective: Phosphate solubilizing bacteria and nitrogen fixation bacteria as inoculant will increase the availability of phosphate and nitrogen for plants. The aim of this study was to isolate phosphate solubilizing rhizobacteria that could fix atmospheric nitrogen and to measure its effect on chili plant growth in a greenhouse experiment. Materials and Methods: Soil samples for bacterial isolation were collected from cultivation area of chili plants. All samples were selected and characterized each ability in solubilizing phosphate and fixing nitrogen. Selected isolates were identified by using gene 16S rRNA and potential isolate was used as inoculant on chili plants. Results: Three selected isolates of KD2.10, KD2.13 and KE2.15 showed the higher value of phosphate solubilizing index and produced soluble phosphate as much as 102.83, 102.5 and 101.5 mg L–1, respectively. The nitrogenase activity was measured by acetylene reduction assay methods. Isolates KD2.10 and KE2.15 produced ethylene with the amount of 0.0614 and 0.0728 ppm h–1, respectively, whereas isolate KD2.13 could not be measured. The three isolates were categorized as Gram-negative bacteria and isolate KD2.10, KD2.13 and KE2.15 closely related to Burkholderia cepacia , Burkholderia diffusa and Enterobacter cloacae , respectively. The use of Burkholderia cepacia KD2.10 on chili plant growth could increase the plant height, number of leaves, wet and dry weight and plant root length. Conclusion: Isolate Burkholderia cepacia KD2.10 as phosphate solubilizing and nitrogen fixing bacteria was suggested as an effective inoculant in improving the growth of chili plants in a greenhouse experiment.