2017 ASHS Annual Conference

Florida’s subtropical climate of mild winters, with high temperature and humidity in other seasons varies greatly from other states. This may lead to a different focus in high tunnel application. An organic tomato trial was conducted in Citra, FL during spring 2016 to determine the impacts of open field and high tunnel production systems and grafting on fruit quality. Non-grafted ‘Garden Gem’ and ‘Tribute’ tomatoes as well as plants grafted onto ‘Multifort’ were grown. The experiment was arranged in a split-split plot design with three replications, with production system as the whole plot factor, cultivar as the subplot factor, and grafting as the sub-subplot factor. There were four harvests of fruit at the pink and red stages. Red fruit were processed immediately for fruit quality analyses while pink fruit were held at 12.5°C or 25°C until full ripe before analyses. Additional pink and red fruit were used for shelf life testing. In 2016, tomato shelf life was significantly impacted by the high tunnel production system, though results varied by cultivar (due to tomato type) and harvest stage. Fruit from high tunnels harvested pink had significantly longer shelf life than open field fruit for both ‘Tribute’ (128%) and ‘Garden Gem’ (15%) due to reduced decay. Shelf life for fruit harvested red was only significantly different for ‘Tribute’, with high tunnel fruit lasting 78% longer. Fruit quality analyses showed that vitamin C, total antioxidant capacity, carotenoids, beta-carotene, total soluble solids (TSS), titratable acidity (TA), and pH varied greatly between cultivars, production systems, and harvest maturity stages. Total phenolics was the only characteristic that was affected uniformly across all treatments, being significantly lower in fruit from high tunnels compared with open field, while grafting had no effect. Lycopene was not significantly affected by the production system in either cultivar for fruit harvested pink and ripened postharvest, but significantly increased in high tunnel fruit harvested at the red stage. Grafting effects were more uniform across cultivars, with no significant effect on total antioxidant capacity, lycopene, beta-carotene or total phenolics. Storage temperature had a significant effect on fruit composition for ‘Garden Gem’, as demonstrated by an increase in carotenoids, lycopene, beta-carotene, and pH when stored at the higher temperature, while TA was significantly decreased. Overall, the results demonstrated that the potential benefits of high tunnel production and grafting on tomato fruit quality depend on the cultivar and harvest maturity selected.