Studies of high desert hoop house agriculture: Exploring new techniques for produce production and the potential benefits and drawbacks of hoop house use.
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Authors
Horton, Eric
Issue Date
2018
Type
Thesis
Language
Keywords
Hoop house , Ultraviolet radiation
Alternative Title
Abstract
Produce in northern Nevada is successfully grown within hoop houses. Unfortunately, few studies have tested the benefits or drawbacks of hoop house use. Ultraviolet (UV) radiation is known to be reduced in hoop house environments, potentially limiting production of secondary compounds that benefit human nutrition. In hoop houses, supplemental UV radiation could be a useful and cost effective way to improve product quality and end-consumer health. In one study, supplemental UV treatment was applied to Lactuca sativa (lettuce) in greenhouses and hoop houses at 64.4±0.9 J m-2 min -1 for varying durations. Leaf samples from plants grown with supplemental UV treatment were then compared to samples from plants grown without supplementation. In the greenhouse, no significant difference in antioxidant content or specific leaf area (SLA) was found. In hoop houses, a roughly three-fold increase in tocopherol content was found with 120 minutes of supplemental UV treatment twice a day, but no other plant response variables that were measured were significant. These conflicting results between greenhouse and hoop house experiments suggest that further study is needed in the hoop house environment to determine if other factors interact with supplemental UV treatment to affect tocopherol production. Nonetheless, we concluded that, at this time, no recommendations can be made to local farmers to use supplemental UV radiation to increase L. sativa quality. In addition to the supplemental UV experiments, four studies were completed in hoop houses and nearby uncovered plots to investigate certain aspects of hoop house agriculture. The first study documented environmental data from both hoop houses and uncovered plots, and we concluded hoop houses created a microclimate with greater air temperature and soil water content. The second study tested the effect of planting date on the antioxidant content of winter greens, Eruca sativa (arugula) and Spinacia oleracea (spinach), and we concluded that planting date does not have a significant effect on antioxidant content. However, tocopherol content in spinach and ascorbic acid content in both arugula and spinach increased over winter from December to March regardless of when the greens were planted in the fall. The third and fourth studies tested consumer preference for three varieties of heirloom Lycopersicon lycopersicum (tomato) called Black Cherry, New Yorker, and Pink Berkeley Tie Dye (PBTD). The third study tested consumer preference among these three varieties, and we concluded that Black Cherry and New Yorker tomatoes were preferred equally over PBTD. The fourth study tested consumer preference between samples harvested from an early planting date versus samples harvested from a later planting date of the same variety. We concluded that early planting of New Yorker and PBTD tomatoes produce more preferred fruit and that Black Cherry tomatoes have no major preference based on planting date.