Nitrogen fixation (C2H2 reduction) in soil samples from rhizosphere of rice grown under alternate flooded and nonflooded conditions |
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Authors: | V Rao Rajaramamohan J L N Rao |
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Institution: | (1) Division of Soil Science and Microbiology, Central Rice Research Institute, 753006 Cuttack, India |
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Abstract: | Summary In a greenhouse study the influence of alternate flooded and nonflooded conditions on the N2-ase activity of rice rhizosphere soil was investigated by C2H2 reduction assay. The soil fraction attached to roots represent the rhizosphere soil. Soil submergence always accelerated N2-ase and this effect was more pronounced in planted system. Moreover, rice plant exhibited phase-dependent N2-ase with a maximum activity at 60 days after transplanting. The alternate flooded and nonflooded regimes resulted in alterations of the N2-ase activity. Thus, the N2-ase activity increased following a shift from nonflooded to flooded conditions, but the activity decreased when the flooded soil was returned to nonflooded condition by draining. However, the differential influence of the water regime on N2-ase was not marked in prolonged flooded-nonflooded cycles. Microbial analysis indicated the stimulation of different groups of free-living and associative N2-fixing microorganisms depending on the water regime. |
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Keywords: | Flooded Nitrogenase activity Nonflooded Rhizosphere soil Rice |
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