Plant-mediated processess to acquire nutrients: nitrogen uptake by rice plants |
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Authors: | Kirk G.J.D. |
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Affiliation: | (1) International Rice Research Institute, MCPO Box 3127, 1271 Makati City, Philippines |
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Abstract: | The ways in which root–soil interactions can control nutrient acquisition by plants is illustrated by reference to the N nutrition of rice. Model calculations and experiments are used to assess how uptake is affected by root properties and N transport through the soil. Measurements of the kinetics of N absorption and assimilation and their regulation, and of interactions between NH4+ and NO3– nutrition, are described. It is shown that uptake of N from the soil–-as opposed to N in ricefield floodwater which can be absorbed very rapidly but is otherwise lost by gaseous emission–-will often be limited by root uptake properties. Rice roots are particularly efficient in absorbing and assimilating NO3–, and NH4+ absorption and assimilation are stimulated by NO3–. The uptake of NO3– formed in the rice rhizosphere by root-released O2 may be more important than previously thought, with beneficial consequences for rice growth. Other root-induced changes in the rice rhizosphere and their consequences are discussed. |
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Keywords: | ion uptake kinetics modelling rhizosphere roots |
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