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Evaluating the CROPGRO–Soybean Model Ability to Simulate Photosynthesis Response to Carbon Dioxide Levels
Author(s) -
Alagarswamy G.,
Boote K. J.,
Allen L. H.,
Jones J. W.
Publication year - 2006
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2004-0298
Subject(s) - photosynthesis , carbon dioxide , atmospheric sciences , productivity , ecosystem , flux (metallurgy) , leaf area index , canopy , environmental science , agronomy , mathematics , chemistry , biology , botany , ecology , physics , organic chemistry , economics , macroeconomics
Atmospheric carbon dioxide concentration [CO 2 ] will increase in the future and will affect global climate and ecosystem productivity. Crop models used in past assessments of climate change effect on ecosystem productivity have not been adequately tested for the ability to simulate ecosystem responses to [CO 2 ]. Our objective was to evaluate the ability of the default CROPGRO–Soybean model to predict the responses of net leaf photosynthesis ( A ) and canopy photosynthesis ( A can ) to photosynthetic photon flux (PPF) at different [CO 2 ]. We also compared the default leaf photosynthesis equations in CROPGRO with the full Farquhar equations for ability to predict the response of A to [CO 2 ]. Simulated and observed A and A can were light saturated at 800 μmol m −2 s −1 . PPF at ambient [CO 2 ] but did not light saturate at PPF >1100 μmol m −2 s −1 at elevated [CO 2 ]. Observed and simulated A responded asymptotically to increasing intercellular [CO 2 ]. The CROPGRO default photosynthesis equations and the Farquhar equations simulated A equally well at all [CO 2 ]. Doubled [CO 2 ] increased simulated A by 52% and A can by 42%; these values are close to the increases of 39 to 48% for A and 59% for A can reported in the literature. Root mean square errors for simulated A and A can were low, and Willmott's index of agreement ranged from 0.86 to 0.99, confirming that the CROPGRO model with default photosynthesis equations can be used to evaluate potential effects of [CO 2 ] on soybean photosynthesis and productivity.