An updated model for nitrate uptake modelling in plants. II. Assessment of active root involvement in nitrate uptake based on integrated root system age: measured versus modelled outputs |
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Authors: | Philippe Malagoli Erwan Le Deunff |
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Affiliation: | 1.Clermont Universités, Université Blaise Pascal, UMR 547 PIAF, BP 10448, F-63000 Clermont Ferrand, France;2.INRA, UMR 547 PIAF, F-63100 Clermont Ferrand, France;3.Université de Caen Basse-Normandie, UMR EVA, F-14032 Caen cedex, France;4.INRA, UMR 950, Écophysiologie Végétale & Agronomie Nutritions NCS, F-14032 Caen cedex, France |
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Abstract: | Background and AimsAn updated version of a mechanistic structural–functional model was developed to predict nitrogen (N) uptake throughout the growth cycle by a crop of winter oilseed rape, Brassica napus, grown under field conditions.MethodsThe functional component of the model derives from a revisited conceptual framework that combines the thermodynamic Flow–Force interpretation of nitrate uptake isotherms and environmental and in planta effects on nitrate influx. Estimation of the root biomass (structural component) is based upon a combination of root mapping along the soil depth profile in the field and a relationship between the specific root length and external nitrate concentration. The root biomass contributing actively to N uptake was determined by introduction of an integrated root system age that allows assignment of a root absorption capacity at a specific age of the root.Key ResultsSimulations were well matched to measured data of N taken up under field conditions for three levels of N fertilization. The model outputs indicated that the two topsoil layers (0–30 and 30–60 cm) contained 75–88 % of the total root length and biomass, and accounted for 90–95 % of N taken up at harvest.ConclusionsThis conceptual framework provides a model of nitrate uptake that is able to respond to external nitrate fluctuations at both functional and structural levels. |
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Keywords: | Nitrate, N uptake regulation, Flow– Force interpretation, nitrogen uptake efficiency, root development, root longevity, functional– structural plant model, N uptake modelling, Brassica napus |
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