Publications des scientifiques de l'IRD

Roger Pierre-Armand. (2001). Rice field cyanobacteria : ecology, contribution to soil fertility and practical utilisation. In : Morot-Gaudry J.F. (ed.). Nitrogen assimilation by plants : physiological, biochemical and molecular aspects. Enfield, New Hamshire : Science Publ., p. 199-226. ISBN 2-7380-0716-3. ISSN 1144-7605.

Titre du document
Rice field cyanobacteria : ecology, contribution to soil fertility and practical utilisation
Année de publication
2001
Type de document
Partie d'ouvrage
Auteurs
Roger Pierre-Armand
In
Morot-Gaudry J.F. (ed.), Nitrogen assimilation by plants : physiological, biochemical and molecular aspects
Source
Enfield, New Hamshire : Science Publ., 2001, p. 199-226 ISBN 2-7380-0716-3 ISSN 1144-7605
Nitrogen is usually the limiting factor to high yields in rice fields. Therefore, use of BNF as an alternative or supplementary source of N for rice has been the major approach in microbiological management of wetland rice. Among N2-fixing micro-organisms present or introduced in rice fields, cyanobacteria play a major role. Free living indigenous forms have spontaneously unabled modest but constant yields (1-2 t ha-1) to be obtained for centuries after continuous cropping without N fertiliser addition. Symbiotic forms were also used for centuries in rice fields in China and Vietnam, allowing significant yields (2-5 t ha-1) to be obtained through labor-intensive and quite sophisticated green manuring technology. Research on free-living and symbiotic cyanobacteria as biofertilisers for rice reached intensive development in the 70's and the 80's. Since then, the number of research papers dealing with these topics has markedly declined. Research on free-living cyanobacteria has shown that, as an additional source of N for rice, they have a moderate potential of about 30 kg N ha-1 crop cycle-1 which may translate to a yield increase of 300-450 kg ha-1. Inoculation of rice fields with selected or transformed strains is not a proven technology. On the other hand, the knowledge acquired on the general ecology of the rice field floodwater during these studies has unabled practical recommandations to optimise its management in a way that favors BNF by cyanobacteria, improves chemical N fertiliser utilisation, and helps controlling populations of detrimental invertebrates. Over the long term, biological engineering of cyanobacteria may design "super N2- fixing cyanobacteria" but the characteristics that will enable them to survive, develop, and fix N2 in rice fields are still not known. Azolla has proved useful as a nitrogen biofertiliser in China and Viet-Nam. Currently it's use has drastically diminished in these countries and Azolla has not been adopted in most of the countries where it was tested for adoption as green manure for rice. Progress in strain collection, selection, hybridization, and recombination has opened ways to alleviate many environmental and nutritional limitations of Azolla. However, the socio-economic limitations are the most important and are probably increasing in relation to changes in agricultural policies and practices. But recent studies have shown that Azolla has a potential not only as a green manure, but as a multipurpose biofertiliser that can also decrease N losses by ammonia volatilisation. It can also be a weed suppressor, a potassium source through its ability to concentrate this element, an animal feed, and a primary producer in rice- fish-Azolla cultivation. The potential of Azolla as a multipurpose crop, which may revive interest in its use, will decide the extent of its future utilization. (Résumé d'auteur)
Plan de classement
Bactéries [074MICFLO01] ; Fixation biologique de l'azote [084SYMBIO02]
Descripteurs
ECOLOGIE ; BACTERIE ; RIZIERE ; FIXATION BIOLOGIQUE DE L'AZOTE ; RIZ FLOTTANT ; SYMBIOSE ; BIOMASSE ; RENDEMENT ; APPLICATION AGRONOMIQUE ; PRATIQUE CULTURALE ; INOCULATION ; FERTILISATION DU SOL ; MICROBIOLOGIE DU SOL
Description Géographique
ASIE
Localisation
Fonds IRD [F B010024694] ; Montpellier (Centre IRD)
Identifiant IRD
fdi:010024694
Contact