High tunnels are used to modify the crop environment by trapping solar energy, providing protection from unfavorable weather events, and extending the growing season in temperate regions. This project assessed yield and quality in three independent cultivar trials of warm-season crops tomato (Solanum lycopersicum L.), bell pepper (Capsicum annuum L.) and cucumber (Cucumis sativus L.) grown under high tunnel production compared with an outdoor field in eastern and western North Dakota. Tomato yields in the high tunnel were increased by 1.4 times over the field trial yields. Yields from the pepper cultivar trials both inside the high tunnel and outside field were comparable to one another at 1.24 kg plant-1 and 1.06 kg plant-1, respectively. Cucumber yields in the high tunnel were increased by 1.7 times over the field trial yields. Results indicate that in North Dakota, high tunnels extended the growing season, and increased production relative to field conditions.

The growing season for vegetable crops is limited by freezing temperatures in arid high elevation climates such as northern Utah. Logan, Utah (41.73 N, 111.83 W, 1382 m elevation) has a short, variable growing season with an average frost-free period of 135 days. Extending the growing season provides growers with an opportunity to extend revenue into a normally unproductive period and benefit from out-of-season price premiums. High tunnels have been used to effectively extend the growing season for numerous crops by providing cold temperature protection. However, limited high tunnel research has been performed in arid high elevation regions that experience extreme temperature fluctuations. The use of high tunnels was investigated in North Logan, Utah to extend the growing season for tomatoes and lettuce. In 2009 and 2010, supplemental heating under low tunnels within high tunnels was investigated to provide early season cold temperature protection for tomatoes. Sunbrite tomatoes were transplanted into four high tunnels over three planting dates. Tomatoes were subjected to supplemental heating treatments including soil warming cables alone or in conjunction with 40-watt incandescent lights for air heating. The highest early season and overall yield was achieved with the 17 Mar. planting date. Early season yield was significantly less for the latest planting date (7 Apr.) compared to the 17 Mar. and 30 Mar. planting dates. Early season yield was significantly greater for treatment plots with soil plus air heating, and soil heating alone significantly improved total yield. The use of a vertical structure within a high tunnel was investigated to improve productivity for lettuce. Parris Island Cos lettuce was consecutively transplanted from spring 2008 to spring 2010 in a high tunnel at the same site. The vertical growing system allowed for 31 plants*m-2 in south oriented gutters, and 45 plants*m-2 in east/west oriented gutters compared to 25 plants*m-2 in the ground including space for maintenance. Root zone temperatures in the gutters fluctuated widely in response to air temperatures, and super-optimal soil temperatures impeded growth. Productivity (g*m-2) in the gutters was only significantly greater than productivity in the ground soil during the spring and fall months when soil and air temperatures were not frequently below 0 °C or above 24 °C. This thesis includes both research results and extension factsheets intended for growers interested in high tunnel production of tomato and lettuce.

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The project examines the possibilities to develop a local and sustainable model for food production in Uppsala with focus on diet, farming methods and different types of greenhouse installations. With the simulation software VIP energy 3.1.1 the energy balance and temperature development of greenhouses of different materials were calculated for different operating cases. The results were also compared when the greenhouse was installed stand-alone or integrated to the wall of a small standard or passive house. With a starch based diet and biological farming methods research suggests it is possible to produce food efficiently without compromising the environment or our health. The yearly food needs for a family of four that follows the suggested diet was estimated to 4362 kg and the outdoor land required to produce it was calculated to 4676 m2 through organic yield statistics. The area could however be reduced to 2813 m2 if the only starch staple in production was potatoes. The tender growing season in a greenhouse constructed with a covering of 5 mm glass or 5-16Ar-5 mm was calculated to 85 and 148 days respectively. The energy use required for year round production of mushrooms in the respective greenhouses was calculated to 53 or 16 kWh/m2,year. Half hardy plants required 399 or 173 kWh/m2,year and tender plants 953 or 358 kWh/m2,year. When the greenhouses were connected to the wall of a small house the heating demand could be reduced by up to 22 % depending on the operating case.