Gopalakrishnan, S and Watanabe, T and Pearse, S J and Ito, O and Hossain, Z A K M and Subbarao, G V (2009) Biological nitrification inhibition by Brachiaria humidicola roots varies with soil type and inhibits nitrifying bacteria, but not other major soil microorganisms. Soil Science and Plant Nutrition, 55 (5). pp. 725-733.
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Abstract
The tropical pasture grass Brachiaria humidiola (Rendle) Schweick releases nitrification inhibitory compounds from its roots, a phenomenon termed 'biological nitrification inhibition' (BNI). We investigated the influence of root exudates of B. humidicola on nitrification, major soil microorganisms and plant growth promoting microorganisms using two contrasting soil types, Andosol and Cambisol. The addition of root exudates (containing BNI activity that is expressed in Allylthiourea unit (ATU)) was standardized in a bioassay against a synthetic inhibitor of nitrification, allylthiourea, and their function in soil was compared to inhibition caused by the synthetic nitrification inhibitor dicyandiamide. At 30 and 40 ATU g-1 soil, root exudates inhibited nitrification by 95% in fresh Cambisol after 60 days. Nitrification was also similarly inhibited in rhizosphere soils of Cambisol where B. humidicola was grown for 6 months. Root exudates did not inhibit other soil microorganisms, including gram-negative bacteria, total cultivable bacteria and fluorescent pseudomonads. Root exudates, when added to pure cultures of Nitrosomonas europaea, inhibited their growth, but did not inhibit the growth of several plant growth promoting microorganisms, Azospirillum lipoferum, Rhizobium leguminosarum and Azotobacter chroococcum. Our results indicate that the nitrification inhibitors released by B. humidicola roots inhibited nitrifying bacteria, but did not negatively affect other major soil microorganisms and the effectiveness of the inhibitory effect varied with soil type.
| Item Type: | Article |
|---|---|
| Divisions: | UNSPECIFIED |
| CRP: | UNSPECIFIED |
| Subjects: | Others > Soil Science |
| Depositing User: | Library ICRISAT |
| Date Deposited: | 27 Aug 2011 06:20 |
| Last Modified: | 27 Aug 2011 06:23 |
| URI: | http://oar.icrisat.org/id/eprint/598 |
| Official URL: | http://dx.doi.org/10.1111/j.1747-0765.2009.00398.x |
| Projects: | UNSPECIFIED |
| Funders: | Japan Society for the Promotion of Science |
| Acknowledgement: | The authors thank the Japan Society for the Promotion of Science for funding this work and would like to acknowledge the help of Dr Richard Strange (University College London, London, United Kingdom) who provided many suggestions to improve an earlier draft of this manuscript. |
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