Simulating switchgrass growth and development under potential and water-limiting conditions

Anticipating a demand for switchgrass (Panicum virgatum L.) as a source for biofuel production, a crop simulation model of this crop can be a component of a biofuel decision support system. The objective of this eff ort was to develop and test a model for switchgrass, based on robust empirical relationships between plant behavior and the environment. The model simulates date of annual growth initiation (AGI), anthesis, aboveground biomass, leaf area index (LAI), and water balance components with a daily time step for crops grown under potential and water- limiting conditions. Daily weather data (solar radiation, maximum and minimum temperature, and rainfall), soil available water-holding capacity (AWHC), and the fraction of AWHC at the date of AGI (FAWHC-AGI) are required inputs. Two cultivar-specifi c parameters, the maximum rate of development at the optimum temperature (R _max) and maximum LAI (MAXLAI), synthesize diff erences in development and growth between cultivars. Tested against 10 independent data sets, the model generated good predictions of date of anthesis (root mean square error [RMSE] = 3 d) and aboveground biomass (RMSE = 1.5 Mg ha ^-1).