Carbon and nitrogen nutrition of nodulated roots of grain legumes

Abstract

The spatial and temporal relationships between carbon (C) metabolism and nitrogen (N) nutrition in grain legumes are of great academic interest with the added bonus that any data for economically important species may ultimately prove useful to breeders and growers. So far there are no data which can be used to relate differences in carbon usage by any symbiotic association with differences in economic yield. Much research has focussed on the dependence of dinitrogen fixation on photosynthate supply, on the C–N relationships of nodulated roots and nodules and on diurnal and seasonal profiles of dinitrogen fixation. In all these aspects a plethora of responses have been described, often based on insufficiently proven measurement techniques; consequently unequivocal conclusions cannot be drawn. We know little about within‐species differences due to cultivar, strain of Rhi‐zobium or environment, or about the proportions of any heritable variations which might be sufficiently large to merit inclusion among the selection criteria of grain legume breeders.

Carbon Dioxide Fixation in Roots and Nodules of Alnus glutinosa

“…Although lesser activities of other carboxylating activities have been reported (8,15), PEP' carboxylase appears to be the primary enzyme responsible for CO2 fixation in these tissues (22). The specific roles of this enzyme in the metabolism of these tissues are not fully understood.…”

Phenotypic plasticity of Neonotonia wightii and Pueraria phaseoloidesgrown under different light intensities

“…Symbiotic atmospheric N fixation may use up to 33% of the C photoassimilated by the host (Michin et al 1981). Conversely, N 2 fixation in the Leguminosae may promote higher growth and photosynthetic rates (Lüscher et al 1998).…”

Analysis of factors controlling dinitrogen fixation and nitrogen release in soybean using pod removal, stem girdling, and defoliation

“…The reduction in the content of atmospheric nitrogen by root nodules depends on the supply of photosynthates by the legume to provide substrates for the generation of energy and reductants (Phillips 1980;Minchin et al 1981;Ohyama and Harper 1991). Several experiments have confirmed the importance of the photosynthate supply to the nodules in the reduction process (Lawn and Brun 1974;Walsh et al 1987;Fujita et al 1988).…”