Top-Level Crop Models for Advanced Life Support Analysis 2000-01-2261

We have developed top-level crop models for analysis of Advanced Life Support (ALS) systems that use plants to grow food. The crops modeled are candidates for ALS use: bean (dry), lettuce, peanut, potato (white), rice, soybean, sweet potato, tomato, and wheat. The crop models are modified versions of the energy cascade crop growth model originally developed for wheat by Volk, Bugbee, and Wheeler. The models now simulate the effects of temperature, carbon dioxide level, planting density, and relative humidity on canopy gas exchange, in addition to the effects of light level and photoperiod included in the original model. The energy cascade model has also been extended to predict the times of canopy closure, grain setting (senescence), and maturity (harvest) as functions of the environmental conditions. The definition of one model parameter, the carbon use efficiency (net photosynthesis/gross photosynthesis), was revised on a twenty-four hour basis, which gives a more intuitively correct model behavior. In addition, the dependence of canopy quantum yield (moles of carbon/moles of photosynthetic photon flux) on temperature, carbon dioxide, and light level is incorporated into the modified models. The model parameters were calibrated using canopy gas exchange data for wheat, soybean, white potato, and lettuce.