In winter crops, leaf area is a major determinant of the final yield,
and is substantially affected by losses occurring during vegetative gr
owth. Here, we propose and test a submodel simulating the development
of leaf area and pod area, along with leaf senescence, for winter oils
eed rape (Brassica napus L.), which was included in a CERES-type model
for rape adapted from CERES-N Maize. This crop model, called CERES-Ra
pe, has components for crop phenology, net photosynthesis, N uptake, a
nd assimilate partitioning. As a new feature compared to previously pu
blished work, che leaf area submodel includes senescence from shading
due to competition for light in the canopy, and from leaf N deficienci
es. The model has been developed and parameterised on a 1-yr-long expe
riment with three fertilizer N treatments in northeastern France, duri
ng which measurements of senescing parts allowed calibration of the eq
uations for leaf area index (LAI) senescence and total generated LAI.
The leaf area submodel, once coupled to the CERES-Rape model, was test
ed against two additional experiments from Denmark and northern France
. This process-oriented submodel proved accurate for the simulation of
actual LAI whether in the calibration or in the validation phase, wit
h an overall Root Mean Square Error (RMSE) of 0.496 m(2) m(-2), fallin
g close to the mean experimental standard deviation. Extrapolation did
not require any further adjustment, although a different cultivar was
involved. (C) 1998 Elsevier Science B.V. All rights reserved.