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The effects of water regime on phosphorus responses of rainfed lowland rice cultivars

Huguenin-Elie, O. ; Kirk, G. J. D. ; Frossard, E.

In: Annals of Botany, 2009, vol. 103, no. 2, p. 211-220

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    Titre
    • The effects of water regime on phosphorus responses of rainfed lowland rice cultivars
    Auteur
    • Huguenin-Elie, O.. International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines
    • Kirk, G. J. D.. International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines
    • Frossard, E.. Swiss Federal Institute of Technology (ETH Zürich), Institute of Plant Sciences, Eschikon 33, CH-8315 Lindau, Switzerland
    Type de document
    • Postprint
    Langue
    • Inglese
    Publié dans
    • Annals of Botany, 2009, vol. 103, no. 2, p. 211-220. Oxford University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:291810
    Summary
    Background and Aims Soil phosphorus (P) solubility declines sharply when a flooded soil drains, and an important component of rice (Oryza sativa) adaptation to rainfed lowland environments is the ability to absorb and utilize P under such conditions. The aim of this study was to test the hypothesis that rice cultivars differ in their P responses between water regimes because P uptake mechanisms differ. Methods Six lowland rice cultivars (three considered tolerant of low P soils, three sensitive) were grown in a factorial experiment with three water regimes (flooded, moist and flooded-then-moist) and four soil P levels, and growth and P uptake were measured. Small volumes of soil were used to maximize inter-root competition and uptake per unit root surface. The results were compared with the predictions of a model allowing for the effects of water regime on P solubility and diffusion. Key Results The plants were P stressed but not water stressed in all the water regimes at all P levels except the higher P additions in the flooded soil. The cultivar rankings scarcely differed between the water regimes and P additions. In all the treatments, the soil P concentrations required to explain the measured uptake were several times the concentration of freely available P in the soil. Conclusions The cultivar rankings were driven more by differences in growth habit than specific P uptake mechanisms, so the hypothesis cannot be corroborated with these data. Evidently all the plants could tap sparingly soluble forms of P by releasing a solubilizing agent or producing a greater root length than measured, or both. However, any cultivar differences in this were not apparent in greater net P uptake, possibly because the restricted rooting volume meant that additional P uptake could not be converted into new root growth to explore new soil volumes