Testing Effects of Climate Change in Crop Models.

Simulation models can be used as strategic tools to evaluate the consequences of climate change on crop production, as well to evaluate shifts in management practices to mitigate the effects of climate change.  Prior to successful use of crop models as tools for such strategic purposes, it is important to test the crop models for their growth and yield responses to climate change factors.  Crop models include relationships that provide for sensitivities of photosynthesis, dry matter growth, reproductive processes and grain yield to CO₂, temperature, and water deficit.  It is important that model developers rigorously test their crop models for accuracy of response to these climate change factors.  Our goal in this paper is:  1) to evaluate crop models for response to climate change factors, 2) to discuss types of data needed to make such evaluations, and 3) to discuss parameterization of crop models for sensitivity to CO₂ and temperature, where new data has become available.  Data from experiments conducted under CO₂ and temperature treatments are available from controlled-environment chambers, open-top chambers, and free-air CO₂ enrichment studies.  Field studies conducted over elevations, latitudes, and sowing dates are useful for testing temperature sensitivity of crop models.  Responses of the DSSAT crop models to CO₂ and temperature were evaluated based on recent literature, and modifications of model parameters were considered.