Dry matter distribution in tomato and cucumber.

A model to simulate dynamically the distribution of dry matter between leaves, stem, roots and individual cucumber fruits or tomato clusters of fruits is described. The simulated dry matter distribution is regulated by the sink strengths of the plant organs. These sink strengths can be quantified by their potential growth rates, i.e. the growth rates under conditions of non-limiting assimilate supply. Potential dry weight and time from flowering until harvest of tomato clusters of fruits decreased with increasing temperature (17, 21 or 25 °C). However, the relation between sink strength (potential growth rate) and developmental stage of a cluster (time after flowering / time from flowering until harvest) appeared to be almost independent on temperature. In the model the sink strengths of leaves, stem and roots were assumed to be constant. For cucumber the dry matter distribution between leaves, stem and roots indeed was found to be independent on fruit load. The simulated dry matter distribution between tomato leaves, stem and individual clusters of fruits corresponded reasonably well to measured data from a glasshouse experiment.