Modelling of water potential and water uptake rate of tomato plants in the greenhouse: preliminary results.

A dynamic model is presented which predicts water potential and water uptake rate of greenhouse tomato plants using transpiration rate as input. The model assumes that water uptake is the resultant of water potential and hydraulic resistance, and that water potential is linearly related to water content of the plant. A comparison of measured and predicted values shows a reasonable correspondence. Values used for the coefficients of the model are 0.9 bar g min-1 for root resistance, 3 bar g min-1 for whole plant resistance and 4x10-3g g-1 bar-1 for capacitance. A sensivity analysis shows that for tomato an accurate determination of resistances is more important than an accurate determination of capacitance. Models like this can be incorporated in crop growth models. They may contribute to the optimization of plant growth through control of transpiration rate and control of the root zone climate in soilless culture.