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.
Background and Aims An 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. Methods The 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 Results Simulations 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. Conclusions This conceptual framework provides a model of nitrate uptake that is able to respond to external nitrate fluctuations at both functional and structural levels.
Clermont Universités, Université Blaise Pascal, UMR 547 PIAF, BP 10448, F-63000 Clermont Ferrand, France.
Philippe
P
Malagoli
Erwan
E
Le Deunff
D008954:Models, Biological; D009566:Nitrates / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D013816:Thermodynamics
D009566:Nitrates
Brassica napus; Flow–Force interpretation; N uptake modelling; N uptake regulation; Nitrate; functional–structural plant model; nitrogen uptake efficiency; root development; root longevity