Selection of mixed inoculants exhibiting growth-promoting activity in rice plants from undefined consortia obtained by continuous enrichment

• Published in: Plant and soil 2014-02, Vol.375 (1-2), p.215-227
• Main Authors: Vanegas, Javier, Uribe-Vélez, Daniel
• Format: Article
• Language: English
• Subjects: Acid production; Acid soils; Agricultural research; Agricultural soils; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Bacteria; Biochemistry and biology; Biological and medical sciences; Biomedical and Life Sciences; Chemical, physicochemical, biochemical and biological properties; Culture media; Ecology; Flowers & plants; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; greenhouses; Growth; Growth (Plants); growth promotion; Health aspects; indole acetic acid; Irrigation systems; Life Sciences; Microbiology; Nitrogen fixation; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant growth; Plant growth promoters; Plant growth promoting rhizobacteria; Plant Physiology; Plant roots; Plant Sciences; Plants; production technology; Regular Article; Rhizobium; Rhizosphere; Rice; roots; Roots (Botany); soil; Soil inoculation; soil sampling; Soil science; Soil Science & Conservation; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-013-1960-1

AIMS: The main objective of this study was to test the hypothesis that isolating and characterizing bacterial suspensions (undefined consortia) from the root/rhizosphere of rice will contribute to the selection of mixtures of rhizobacteria with better growth-promoting activity of rice plants. METHODS: Bacterial consortia were obtained from roots/rhizosphere soil samples of rice plants grown under upland and irrigated production systems. Those undefined consortia were subjected to five consecutive passes every 7 days in NFb (N-free broth) semisolid medium. Thereafter, strains of each growth-promoting consortia were isolated by plating on three different culture media. Then, undefined consortia, as well as mix and single bacterial strains, were characterized in terms of indoleacetic acid production, nitrogen fixation capacity, and growth promotion of rice plants. RESULTS: Of the 72 consortia analyzed, 41.7 % and 50.0 % increased nitrogenase activity and the production of indolic compounds, respectively, after 5 continuous passes in NFB medium. Three undefined consortia, 11 single strains and 5 strain mixtures, exhibited plant growth promotion in rice plants under greenhouse conditions. CONCLUSIONS: Continuous enrichment in Nfb medium of undefined consortia from root/rhizosphere soil is a good strategy for the selection of plant growth-promoting bacteria for rice plants.