Simulation of growth and development processes of spring wheat in responseto CO2 and ozone for different sites and years in Europe using mechanisticcrop simulation models
F. Ewert et al., Simulation of growth and development processes of spring wheat in responseto CO2 and ozone for different sites and years in Europe using mechanisticcrop simulation models, EUR J AGRON, 10(3-4), 1999, pp. 231-247
The response of crop growth and yield to CO2 and ozone is known to depend o
n climatic conditions and is difficult to quantify due to the complexity of
the processes involved. Two modified mechanistic crop simulation models (A
FRCWHEAT2-O3 and LINTULCC), which differ in the levels of mechanistic detai
l, were used to simulate the effects of CO2 (ambient, ambient x2) and ozone
(ambient, ambient x1.5) on growth and developmental processes of spring wh
eat in response to climatic conditions. Simulations were analysed using dat
a from the ESPACE-wheat project in which spring wheat cv. Minaret was grown
in open-top chambers at nine sites throughout Europe and for up to 3 years
at each site.
Both models closely predicted phenological development and the average meas
ured biomass at maturity. However, intermediate growth variables such as bi
omass and leaf area index (LAI) at anthesis, seasonal accumulated photosynt
hetically active radiation intercepted by the crop (Sigma IPAR), the averag
e seasonal light use efficiency (LUE) and the light saturated rate of flag
leaf photosynthesis (A(sat)) were predicted differently and less accurately
by the two models. The effect of CO2 on the final biomass was underestimat
ed by AFRCWHEAT2-O3 due to its poor simulation of the effect of CO2 on till
ering, and LAI.LINTULCC overestimated the response of biomass production to
changes in CO2 level due to an overprediction of the effect of CO2 on LUE.
The measured effect of ozone exposure on final biomass was predicted close
ly by the two models. The models also simulated the observed interactive ef
fect of CO2 and ozone on biomass production. However, the effects of ozone
on LAI, Sigma IPAR and A(sat) were simulated differently by the models and
less accurately with LINTULCC for the ozone effects on LAI and Sigma IPAR.
Predictions of the variation between sites and years of growth and developm
ent parameters and of their responses to CO2 and ozone were poor for both A
FRCWHEAT2-O3 and LINTULCC. It was concluded that other factors than those c
onsidered in the models such as chamber design and soil properties may have
affected the growth and development of cv. Minaret. An analysis of the rel
ationships between growth parameters calculated from the simulations suppor
ted this conclusion. In order to apply models for global change impact asse
ssment studies, the difficulties in simulating biomass production in respon
se to CO2 need to be considered. We suggest that the simulation of leaf are
a dynamics deserves particular attention in this regard. (C) 1999 Elsevier
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