@incollection{fdi:010024694,
  title = {{R}ice field cyanobacteria : ecology, contribution to soil fertility and practical utilisation},
  author = {{R}oger, {P}ierre-{A}rmand},
  editor = {},
  language = {{ENG}},
  abstract = {{N}itrogen is usually the limiting factor to high yields in rice fields. {T}herefore, use of {BNF} as an alternative or supplementary source of {N} for rice has been the major approach in microbiological management of wetland rice. {A}mong {N}2-fixing micro-organisms present or introduced in rice fields, cyanobacteria play a major role. {F}ree 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. {S}ymbiotic forms were also used for centuries in rice fields in {C}hina and {V}ietnam, allowing significant yields (2-5 t ha-1) to be obtained through labor-intensive and quite sophisticated green manuring technology. {R}esearch on free-living and symbiotic cyanobacteria as biofertilisers for rice reached intensive development in the 70's and the 80's. {S}ince then, the number of research papers dealing with these topics has markedly declined. {R}esearch 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. {I}noculation of rice fields with selected or transformed strains is not a proven technology. {O}n 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. {O}ver the long term, biological engineering of cyanobacteria may design "super {N}2- fixing cyanobacteria" but the characteristics that will enable them to survive, develop, and fix {N}2 in rice fields are still not known. #{A}zolla$ has proved useful as a nitrogen biofertiliser in {C}hina and {V}iet-{N}am. {C}urrently it's use has drastically diminished in these countries and #{A}zolla$ has not been adopted in most of the countries where it was tested for adoption as green manure for rice. {P}rogress in strain collection, selection, hybridization, and recombination has opened ways to alleviate many environmental and nutritional limitations of #{A}zolla$. {H}owever, the socio-economic limitations are the most important and are probably increasing in relation to changes in agricultural policies and practices. {B}ut recent studies have shown that #{A}zolla$ has a potential not only as a green manure, but as a multipurpose biofertiliser that can also decrease {N} losses by ammonia volatilisation. {I}t 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-#{A}zolla$ cultivation. {T}he potential of #{A}zolla$ as a multipurpose crop, which may revive interest in its use, will decide the extent of its future utilization. ({R}{\'e}sum{\'e} d'auteur)},
  keywords = {{ECOLOGIE} ; {BACTERIE} ; {RIZIERE} ; {FIXATION} {BIOLOGIQUE} {DE} {L}'{AZOTE} ; {RIZ} {FLOTTANT} ; {SYMBIOSE} ; {BIOMASSE} ; {RENDEMENT} ; {APPLICATION} {AGRONOMIQUE} ; {PRATIQUE} {CULTURALE} ; {INOCULATION} ; {FERTILISATION} {DU} {SOL} ; {MICROBIOLOGIE} {DU} {SOL} ; {ASIE}},
  booktitle = {{N}itrogen assimilation by plants : physiological, biochemical and molecular aspects},
  numero = {},
  pages = {199--226},
  address = {{E}nfield, {N}ew {H}amshire},
  publisher = {{S}cience {P}ubl.},
  series = {},
  year = {2001},
  ISBN = {2-7380-0716-3},
  ISSN = {1144-7605},
  URL = {https://www.documentation.ird.fr/hor/fdi:010024694},
}