Shelf Life and Quality of High Tunnel and Open-field Tomatoes

The utilization of high tunnels for tomato production has rapidly expanded in the United States due various reasons including the expansion of organic and local markets. However, little is known about the effect of the high tunnel production system on tomato (Solanum lycopersicum) nutritional and physical quality at harvest and during storage. In particular, the effect of high tunnel production on tomato shelf life has not been reported. The aim of this work was to determine how high tunnel production affects postharvest losses, quality and shelf life of organically-grown tomatoes compared to the open-field. Tomatoes (cv. BHN 589) were grown at the Kansas State University Olathe Horticulture Research and Extension Center during summer 2013. In the high tunnel system, fabric mulch was used for weed control and drip irrigation was utilized. An equivalent open-field plot was planted at the same time using typical commercial open-field production practices including plasticulture with raised beds and drip irrigation. Tomatoes were harvested at breaker and pink maturity stages and stored at 12.5^οC for 21 days. Fruit respiration was measured every 12 hours during storage. Additionally, color (CIE L*a*b* scale) as well as incidence and severity of decay were evaluated daily. Fruit samples were evaluated at days 0, 5 and 10 for physical and nutritional quality analysis. Tomatoes grown in the high tunnel had significantly lower respiration rates compared to open field (6.75 and 7.93 mg CO₂ per kg-h, respectively). Furthermore, high tunnel tomatoes showed reduced incidence and severity of postharvest disease, and the mean values of the area under the disease progress curve (AUDPC) were significantly lower (P<0.05) for the fruit grown in the high tunnel. Fruit grown in the high tunnel fruit remained marketable (severity rating <3) for the entire 14-day time period while fruit grown in the open-field were not marketable after 10 days in storage. The tomatoes grown in the open-field had significantly higher total antioxidant activity than tomatoes grown under high tunnel conditions throughout storage. The utilization of high tunnels for organic tomato production by local growers could lead to the reduction of food losses by extension of postharvest shelf life. However, tomatoes grown in the high tunnel had lower nutritional quality than the ones grown in the open-field. Further experiments are needed to determine if this trend is consistent across growing seasons and geographic regions.