Hello Wei,
The CSM model used in DSSAT4 varies in how it deals with CO2 effects.
Grain legumes, tomato, cotton, etc. are based on the CROPGRO model. The
default mode involves a hedge-row photosythesis sub-model that scales up
leaf-level photosynthesis to the canopy level. The leaf level model is
based on the Farquhar approach. Cereals (rice, wheat, corn, sorghum etc.)
are based on the CERES model which uses a factor (given in the SPE file)
to increase RUE. These are the main effects in the CSM model, but CO2
also affects canopy conductances, which can affect the crop water balance.
A major concern is whether there are interactions of canopy temperature
and CO2 that also should be considered. If elevated CO2 reduces stomatal
conductance, canopy temperature will increase. An increase in canopy
temperature might accelerate development, shortening the growth cycle and
reducing productivity and yield. To model this one needs to run a canopy
energy balance. Furthermore, elevated CO2 makes photosynthesis per se more
heat tolerant.
A lesser concern is that CO2 may act like a growth regulator. A few
reports exist where elevated CO2 was associated with changes in
respiration rates or in leaf anatomy that are difficult to attribute to
indirect effects of greater assimialte supply.
While we often have to use the best available models in order to meet
immediate research or decision support needs, there is still ample scope
for further research on crop response to CO2.
Best regards,
Jeff
Jeffrey W. White
USWCL, USDA-ARS
4331 E Broadway Rd
Phoenix, AZ 85040
Tel. 1-602-437-1702 x 268
Fax 1-602-437-5291
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Subject
CO2 fertilization effect on crop
Dear Colleagues
I am now simulating the rice and maize production under climate change
scenarios, I know that DSSAT4 consider the fertilization effect of CO2 on
crop photosynthetic ratio and WUE, but it is very difficult to know the
detail relationship of Photosynthetic ratio and Concentration of CO2, is
there any literatures which talk about this problem, or anyone know it?
Thank you very much
Merry Chrismas.,
Wei Xiong
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