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Analysis and modeling of the use of nitrate in connection with its availability and growth. Case of study in tomato (Solanum lycopersicium)

Abstract : This work has two objectives: (1) the experimental study of plant nitrate assimilation and growth in the diel cycle under contrasted conditions of nitrate nutrition ranging from deficiency to plethora; (2) the development of a model capable to simulate these functions. The study focused on young tomato plants grown hydroponically in a growth chamber using a recirculating nutrient system capable to control precisely the nitrate concentration in solution and to measure continuously plant nitrate uptake rates. The rate of plant nitrate assimilation was calculated from the time based differences between the amounts of nitrate taken-up and stored as free ions in the tissues of plants harvested periodically over the day and night cycle. The most significant results are: a marked diel periodicity of nitrate assimilation independent of the nutritional diet; a uniform rate of nitrate uptake under conditions of low N-nutrition contrasting with a marked oscillatory pattern under a plethora of NO3- ; a nearly threefold decrease in NO3- assimilation rate for NO3- sufficient plants suddenly deprived of nitrogen; a slighter effect of the changes of nutritional regimes on root compared to shoot growth. The results have been interpreted considering various stores (1) of nitrate, which uncouples assimilation from uptake, (2) of free amino acids, which detaches growth from NO3- assimilation. It is proposed a model in which growth is fuelled by the flux of free amino acids produced by the assimilation of endogenous NO3- . Among the workable plant representations, considering three organs, namely the leaf blades, the stems and the roots, produced the best simulations both for growth and NO3- assimilation patterns. In this model, the stems are the central store of nitrate. The simulations reproduce several plant characteristics: diel periodicity in the rate of NO3- assimilation; major role of leaves under ample nutrition; magnified role of roots under low N nutrition; uniform growth rate under all circumstances. This modelling stage has highlighted a lack of knowledge in two important domains: the formalism of NO3- transport between organs and the C x N interaction in particular during the phase of resource utilization for growth rather than during their acquisition process.
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Submitted on : Friday, March 27, 2009 - 8:00:00 AM
Last modification on : Friday, March 27, 2009 - 8:00:00 AM
Long-term archiving on: : Thursday, September 30, 2010 - 8:33:01 PM


  • HAL Id : pastel-00004242, version 1



Ruth Huanosto-Magaña. Analysis and modeling of the use of nitrate in connection with its availability and growth. Case of study in tomato (Solanum lycopersicium). Sciences of the Universe [physics]. AgroParisTech, 2008. English. ⟨NNT : 2008AGPT0055⟩. ⟨pastel-00004242⟩



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