Reducing Preharvest and Postharvest Losses in Organic Spinach and Tomato through the Implementation of High Tunnels

The increased market demand for organic and/or local fresh produce is changing the way food is being grown. For many growers, the implementation of high tunnel production systems has been effective at increasing yield of numerous crops. However, little is known about the effect of this production system on the quality and shelf-life of the produce. Our objective was to determine how high tunnel production affects the pre-harvest and postharvest losses, of organic tomato and spinach compared to the open-field. Two tomato cultivars, ‘BHN 589’ and ‘Cherokee purple’, in addition to ‘Corvair’ spinach were grown at the Kansas State University Olathe Horticulture Research and Extension Center from 2013 to 2015. We utilized a split-plot randomized complete block design with six replications and typical production practices for the area. Tomatoes were harvested at pink maturity stage and stored at 12.5^οC and 25^oC for 21 days. For spinach, fully mature leaves were harvested and stored at 3^oC and 13^oC for 18 days. Respiration rate, overall quality, texture, color, as well as nutritional quality were evaluated for both crops during storage. Organoleptic quality was evaluated for tomatoes, and water loss and leaf area was measured for spinach. Pre-harvest losses can include overall crop productivity as well as the proportion of marketable crops grown and both parameters were improved by the implementation of high tunnels. Main effects showed that high tunnel production had 116% higher yield compared to the open-field in 2015 (P<0.01). Spinach marketability was 82.2% in the high tunnel whereas in the open-field it was 55.9% (P<0.05), and similar results were seen in tomato in 2014. For both crops, the ones grown in the open-field had higher respiration rates. Spinach grown in the high tunnel had slightly higher overall quality compared to the open-field, and quantitative texture analysis indicated the leaves were more tender. ‘BHN 589’ tomato grown in the high tunnel were sweeter compared to the tomatoes grown in the open-field based on lower acidity measurements. The same trend was observed for ‘Cherokee purple’, but only for fruit stored at 12.5^oC. There were no differences for antioxidant capacities in ‘BHN 589’, but were observed for ‘Cherokee Purple’ after 10 and 15 days in storage at 12.5 ^oC (P<0.01). Our results indicate that the utilization of high tunnels for organic and/or local production of fresh produce could reduce pre-harvest losses and help growers obtain high quality crops with longer shelf-life.