Dynamics of nitrogen uptake and mobilization in field-grown winter oilseed rape (Brassica napus) from stem extension to harvest. II. An 15N-labelling-based simulation model of N partitioning between vegetative and reproductive tissues.
OBJECTIVE
Oilseed rape (Brassica napus) has often been used as a catch crop to deal with the issue of N leaching, but for this to be effective, prediction of the crop's N uptake capability and N partitioning is required. The aim of this work was to build a compartmental model of N dynamics in oilseed rape, based on the kinetic description of N uptake, partitioning and mobilization in each organ.


METHODS
In this study, logistic and exponential equations were fitted to the N relations of each compartment, especially the leaf at each node. Data previously obtained from an 15N-labelling field experiment was used to quantify the partitioning of total N content, the allocation of N taken up and subsequent changes in the sink/source status for endogenous N in each tissue throughout the growth cycle.


CONCLUSIONS
This modelling approach provides a unique tool for the quantitative estimation of cycling of endogenous N in relation to changes in N uptake at the whole-plant level. Furthermore, as oilseed rape is known to release large amounts of N to the soil during spring through leaf loss, this model was used to identify potential methods for improving the N harvest index of the crop. Simulations showed that N content or yield could be improved by 15% by optimizing N transfer from vegetative to reproductive tissues and by reducing the residual %N (DW) in abscised leaves.
Malagoli
P
P
UMR INRA-UCBN 950 EVA, Ecophysiologie Végétale, Agronomie et Nutritions N, C, S. Institut de Biologie Fondamentale et Appliquée, Université de Caen Basse Normandie, 14032 Caen Cedex, France.
Laine
P
P
Rossato
L
L
Ourry
A
A
D001693:Biological Transport, Active; D029688:Brassica napus / Q000378:metabolism*; D003198:Computer Simulation; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D018547:Plant Stems; D013997:Time Factors
D009587:Nitrogen Isotopes; D009584:Nitrogen