The von Bertalanffy growth model for horticulture: Predicting tomato size at harvest

Traditionally, crop load and fruit yield from previous seasons are used as indicators for prediction of fruit size. Disregarding the inevitable biological variation between fruit, von Bertalanffy (1938) described the growth, expressed as length, of virtually any living organism. The model is here extended to include the variation between individuals in a batch. Using this extended model, fruit size and its variation can be predicted, using measurements of a large number of fruit at a single point during early development. The diameter of 200 tomatoes was measured 15 days after full bloom (DAFB). Using the density function derived from the extended von Bertalanffy model, and applying prior knowledge of some of the model parameters, the variation in size at harvest could be predicted. Validation of the results was obtained by comparing the predicted sizes with the diameters of the same tomatoes at harvest.