Tomatoes require relatively high light and high temperatures for rapid growth and good production. In cropping environments, however, productivity in terms of yield is most likely to be limited by the fruitfulness of the plant and the ability of the grower to protect the fruit from damage. As Jones (1980) comments: "The key to yield success is to obtain a good fruit set on each cluster and to ripen the fruit as quickly as possible ... The loss of one or two fruit per cluster or a missing cluster will significantly reduce yield. 'Thus, genetic traits, environmental conditions and cultural practices predisposing plants to unfruitfulness, physiological disorders and fruit defects are also significant limitations to productivity. Comparing production of tomatoes from varying environments is highly subjective. Many people who have worked with tomatoes in many environments feel that given reasonable cultural conditions, tomatoes will produce at about the same rate. For example' ... per plant fruit yields do not vary much for best fruit yields obtained under these wide ranges growing conditions. Per plant yields will be from 8-12 pounds of fruit during the normal growing season ... These yields can be increased only by keeping the plant alive and productive during a longer period of time. One