Abstract
A deterministic model of the growth of greenhouse tomatoes (Lycopersicon esculentum Mill), written in Pascal computer language, was developed based on a leaf assimilation model, a respiration theory, and a theory that the photosynthesis rate is controlled by both environmental conditions and leaf carbohydrate level. The model was applied to estimate the effect of carbon dioxide enrichment on tomato fruit yield, and tested with data obtained from two experiments conducted in College Station, Texas, U.S.A. in 1983 through 1984. Tomatoes were grown at 340, 700, and 1000ppm (on a volume basis) of carbon dioxide (CO2) in three 2×2×10m translucent chambers inside a double-layered, polyethylene greenhouse.
The measured values of the CO2 assimilation rate and the dry mass accumulation rate of tomatoes were consistently higher than the calculated ones, but the prediction of the fruit growth and yield were rather accurate. The potential use of the model is in predicting the effects of environmental factors, or in estimating the effect of a new climate control method under a variety of environmental conditions. It could possibly also be a subroutine in an integrated greenhouse model, which predicts growth and yield of the crop in the greenhouse as well as the energy, water, and CO2 requirements, all from the environmental conditions outside.
