Problems in Building Computer Models for Photosynthesis and Respiration

We present a set of differential equations that tie together changes in dry weight, photosynthesis, and respiration in the plant, and which follow the status of the carbohydrate reserve. We discuss some of our efforts to measure components of these equations, emphasizing difficulties in estimating gross photosynthesis. We need quantitative estimates of respiration in the light caused by the accumulation of photosynthate, to add to measurements of net CO2 exchange. Also needed are quantitative estimates of reductant produced and used in metabolism not associated with respiration or the carbon balance. The role of photorespiration is still confusing.