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Hyung Jun Kim, Chris Harlow and Mary Peet

The objective of this study was to compare nutrient ion uptake and growth of Lycopersicum esculentum Mill. cvs. Trust, widely grown in North America, and Momotaro, widely grown in Korea and Japan. Tomatoes were planted July 2004, two per pot, in 36 perlite-filled pots fertigated with modified Steiner solution in a closed system. Inorganic ions (K, NO3-N, Mg, P, S) in the nutrient solution were measured weekly. Weekly solution uptake rate for both cultivars increased from 70 mg·MJ-1 irradiance at 36 days to 200 mg·MJ-1 at 133 days (end of experiment). The uptake rate of `Trust' was lower than `Momotaro' until 92 days after planting, then higher for the remainder of the experiment. This corresponded to lower leaf area in `Trust' prior to 92 days, then greater leaf area than `Momotaro'. Similarly, the nutrient uptake rate (ppm) of K, Ca, Mg, and S ions in `Trust' were lower than `Momotaro' until 92 days and higher after 92 days. The P uptake showed the opposite pattern with a higher uptake rate in `Trust' than `Momotaro' until 92 days and lower uptake thereafter. The N uptake rate did not differ between the cultivars. Thus, except for P and N, uptake of individual ions was proportional to total nutrient solution uptake. Plant height, number of clusters and total leaf area at 133 days was higher in `Momotaro' but fruit number and total aboveground dry weight (leaf, stem, and fruit) was higher in `Trust'. Percentage of total dry weight, represented by leaf and fruit in `Momotaro', were 40% and 41%, respectively, and 30% and 57%, respectively in `Trust'.

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Hyung Jun Kim, Chris Harlow and Mary Peet

Rhizomes of black cohosh (Actaea racemosa L.) grown in the deep woodland shade of eastern North America have been used historically as medicinals, but wild populations have declined because of collection pressure. The purpose of this study is to determine the potential for black cohosh production in perlite. Currently, cultivated plants represent just 3% of the total harvest. Perlite production should also result in clean, uniform plant material. Rhizomes were grown at 18 °C in controlled environment chambers in the North Carolina State University (NCSU) Phytotron in perlite for 42 days with fertigation 3, 6, or 12 times daily and 18.5, 21.5, or 24.5 °C root zone temperatures adjusted using heating cables. Leaf areas of the 21.5 and 24.5 °C root temperature treatments were greater than the 18.5 °C treatment. Stem number and new root number was highest in the 21.5 °C treatment. No effects of the fertigation treatments were significant. The second experiment was conducted 7 June–31 Oct. 2004 in a naturally lit temperature-controlled (22/18 °C) glass greenhouse in the NCSU Phytotron at nutrient solution EC levels of 0.7, 1.1, or 1.5 dS·m-1 and shading levels of 0%, 50%, and 75%. Highest leaf area and increase in fresh weight of the rhizomes over the experimental period was in the 50% shading treatment, but no significant effects of EC treatments were observed. Rhizome fresh weight increased 310% in the 50% shade, compared to 193% and 196% in the 0% and 75% shading treatments, respectively. In conclusion, black cohosh appears to prefer some shading during summer and 21.5 °C root temperatures. Low EC (0.7 dS·m-1) and infrequent watering (3 times daily) did not appear to limit growth in this system, but these results should be confirmed in larger studies in commercial greenhouses.

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Suzanne O’Connell, Cary Rivard, Mary M. Peet, Chris Harlow and Frank Louws

Organic and heirloom tomatoes are high-value products with growing demand but there are many challenges to successful cultivation. A systems comparison study was carried out to evaluate the production of the popular heirloom tomato ‘Cherokee Purple’ (Solanum lycopersicum L.) under high tunnel and open field systems in North Carolina from 2007 to 2008. Management of the high tunnel (i.e., temperature and irrigation), weather events as well as pest and disease pressure influenced crop quality and yield. The high tunnel and field systems achieved similar total yields (100 t·ha−1) the first season but yields were 33% greater in the high tunnel system than the field system in the second year (100 t·ha−1 and 67 t·ha−1, respectively). Both years, the tomatoes were planted in high tunnels 1 month earlier and harvested 3 weeks earlier than the field. The accumulation of ≈1100 growing degree-days (GDD) was required in both systems before 50% of the fruit was harvested. Fruit cracking, cat-facing, blossom-end rot, and insect damage were the major categories of defects in both systems. Incidence of both Tomato Spotted Wilt Virus (TSWV) and Gray Leaf Spot (GLS) were lower in the high tunnel compared with the field in 2007 and 2008, respectively. Results of this study suggest that with proper management techniques, high tunnels can optimize yields, increase fruit quality, and provide season extension opportunities for high-value horticultural crops.

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Olha Sydorovych, Cary L. Rivard, Suzanne O’Connell, Chris D. Harlow, Mary M. Peet and Frank J. Louws

In this study, we conducted an economic analysis of high tunnel and open-field production systems of heirloom tomato (Solanum lycopersicum) based on a two-year study at the Center for Environmental Farming Systems (CEFS) located in Goldsboro, eastern North Carolina. The research site was transitional organic using organically certified inputs and practices on land not yet certified. Production costs and returns were documented in each system and provide a useful decision tool for growers. Climatic conditions varied dramatically in 2007 compared with 2008 and differentially affected total and marketable yields in each system. Profits were higher in the open-field system and the high tunnels in 2007 and 2008, respectively. Sensitivity analysis was conducted using a range of market prices from $1.60/lb to $3.60/lb and a range of fruit marketability levels from 35% to 80%. Both systems were profitable except at the lowest price point and the lowest percent marketability level in high tunnel in 2007. At $2.60/lb, seasonal average sale price reported by growers for this region, and depending on percent marketability levels, the payback period for high tunnels ranged from two to five years. Presented sensitivity tables will enable decision makers to knowledgably estimate economic potential of open-field and high tunnel systems based on expected local prices and fruit quality parameters.