APPLICATION OF A GREENHOUSE TOMATO-GROWTH MODEL (TOMGRO) TO FIELD-GROWN TOMATO

Development of a growth model for field-grown tomato (Lycopersicon esc ulentum Mill.) should assist growers and researchers/extension workers when interpreting results of field trials, with assessing the likelih ood of success for various management-practice changes, and with the s election of management strategies designed to shift production to more favorable marketing windows. Field growth data for tomato were collec ted during the spring of 1991 at Bradenton in west-central Florida, an d in 1992 at both Bradenton and Immokalee (in southwest Florida), Resu lts were subsequently fit to a previously-developed growth model for i ndeterminate, single-stemmed, greenhouse tomato (TOMGRO). Necessary ad aptations included allowance for the greater degree of branching in fi eld-grown settings, and for more-rapid leaf maturation and production of heavier (thicker) leaves in the field cultivar. With these modifica tions, vegetative growth of tomato (leaf numbers and weight, total bio mass production, leaf-area index, etc.) could be adequately described by the TOMGRO model. Fruit production was underpredicted by the model, in part because of differing harvest-stage between the greenhouse and field crops, Comparison of actual growth for a given site and season to TOMGRO predictions helps to quantify the effects of nutrient stress and pest damage on potential yields, Future efforts are being shifted to the crop-growth shell CROPGRO instead, because of its inclusion of hedge-row photosynthesis and water- and nutrient-uptake subroutines b etter adapted to field conditions.