N 2 Fixation by Azospirillum brasilense and Its Incorporation into Host Setaria italica
| Autor: | P. G. Heytler, Ralph W. F. Hardy, Yaacov Okon |
|---|---|
| Rok vydání: | 1983 |
| Předmět: |
Rhizosphere
Setaria Ecology biology food and beverages chemistry.chemical_element Nitrogenase General Microbial Ecology Azospirillum brasilense biology.organism_classification Nitrate reductase Applied Microbiology and Biotechnology Nitrogen Horticulture Agronomy chemistry Shoot Nitrogen fixation Food Science Biotechnology |
| Zdroj: | Applied and Environmental Microbiology. 46:694-697 |
| ISSN: | 1098-5336 0099-2240 |
| DOI: | 10.1128/aem.46.3.694-697.1983 |
| Popis: | Growth and nitrogen fixation were followed during the life cycle of Setaria italica (foxtail millet) inoculated with Azospirillum brasilense in controlled-environment growth chambers. The plants were fertilized at seeding with a limiting amount of combined nitrogen and maintained with an N-free mineral solution. During maturation of the plants, substantial nitrogenase activity, measured by acetylene reduction, developed in the rhizosphere, with total fixation estimated to be equivalent to 20% of the N in the inoculated plants. The peak of this activity coincided with depletion of soluble nitrogen from the system, which in turn was reflected by a sharp decrease in the nitrate reductase activity of the leaves. A. brasilense was found in association with the root populations at 8 × 10 7 cells per gram of dry weight. An increase in shoot growth occurred at this time, but no significant increase in total plant nitrogen could be demonstrated. 15 N 2 enrichment experiments confirmed that fixation was occurring, but only about 5% of the nitrogen fixed by A. brasilense was incorporated into the plants within 3 weeks. There was thus no evidence of direct bacterium-to-plant transport of fixed nitrogen, but rather a slow transfer suggesting the gradual death of bacteria and subsequent mineralization of their nitrogen, at least under growth-room conditions. |
| Databáze: | OpenAIRE |
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