Growth of Tomato Plants and Fruit Production in High Humidity and at High Temperature1

Abstract Tomatoes grown in Tucson, Ariz., in a closed, humid greenhouse, compared with those grown in a normal, vented one, lacked vigor in spring, were prone to high-temperature injury in summer, and had poor fruit-set in both seasons. Elongation of plants in the humid house during early growth exceeded that in the normal house only when RH was near 100%. Occurrence of microbial diseases of leaves or fruits was insignificant. High humidity reduced fruit quality in summer but not in spring. High humidity induced uneven coloration, cracking, and surface dullness. These defects reduced yields of marketable fruit an estimated 56%. ‘Large Red Cherry’ and ‘Floradel’ grew reasonably well in a high-humidity, high-temperature environment but 9 other cultivars did not. The results of these experiments are relevant to crop production in environments found in closed greenhouses designed for coastal desert areas and in open fields in the tropics.