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Julia Charlotte Robinson, Guochen Yang, Sanjun Gu, and Zhongge (Cindy) Lu

Black cohosh (Actaea racemosa L.), a medicinal herb commonly used in herbal supplements for the treatment of various ailments, is a perennial herb that grows naturally under shade conditions in temperate forest regions. This project studied the growth and rhizome yield of Black cohosh under shade conditions of 0%, 40%, 60%, and 80% in a high tunnel (9.1 m wide × 29.3 m long) on the North Carolina Agricultural and Technical University Farm. Seed rhizomes were planted in raised beds incorporated with 9070 kg/acre compost and preplant fertilizer on 29 May 2016. There was one row per bed, with in-row spacing at 45.7 cm, and one drip line per bed for irrigation. Fertigation was done weekly through the drip tapes with Multi-K 13–0–46 (27.2 kg N/acre) during the growing season. Beds were mulched after sprouting. Growth data of fully mature plants were collected on canopy width and length, total number of stems per plant, stem diameter, and length/height; and rhizome fresh and dry weight. Data were analyzed at the 0.05 level of significance. Plant canopy, stem diameter, and length/height were significantly greater in 40% shade (average, 504.7 × 472.6 mm, 3.7 mm, and 135.9 mm, respectively) than in other shade conditions, with the smallest sizes in 0% shade (average, 255.8 × 255.7 mm, 2.1 mm, and 95.4 mm, respectively). There were no significant differences between the 60% and 80% shade conditions in plant canopy, stem diameter, and length/height. However, the total number of stems per plant (4.9) in 0% shade was significantly more than those in other shade conditions, with the least of stems per plant (2.9) in 80% shade. Rhizome fresh and dry weight per plant were the greatest (164.6 and 48.1 g, respectively) in 40% shade, and the least (77.8 and 22.5 g, respectively) in 0% shade. The results indicate that optimum growing conditions for Black cohosh was in 40% shade with a Daily light integral (DLI) between 15 and 0 mol/m2/day, and a day- and nighttime temperature difference between 8.3 and 2.7 °C.

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Harbans L. Bhardwaj

Winter legume cover crops have been successfully used to meet N needs of many summer crops, but they are not being used extensively in Virginia and the mid-Atlantic region, especially for specialty crops such as muskmelon and sweet corn. The objective of these studies was to determine the potential of winter legume cover crops in meeting N needs of muskmelon (Cucumis melo L.) and sweet corn (Zea mays L.). Comparisons of performances of muskmelon and sweet corn, grown after lupin (Lupinus albus L.), hairy vetch (Vicia villosa Roth.), Austrian winter pea ([AWP] Pisum arvense L.), and control fertilized with 112 kg N ha–1, and unfertilized control were made during 1999, 2000, and 2001. The interactions between cover crop treatments and years were, generally, significant. The muskmelon fruit yields were 53.6, 45.0, 23.1, 13.0, and 5.6 Mg·ha–1 during 1999; 27.8, 26.3, 8.6, 5.8, and 2.2 Mg·ha–1 during 2000; and 41.1, 39.9, 25.5, 21.4, and 2.1 Mg·ha–1 during 2001 respectively for lupin, hairy vetch, AWP, 112 kg N ha–1, and control. Similar results were obtained for number and size of muskmelon fruits. The sweet corn ear yields (Mg·ha–1) were 8.5, 5.6, 3.1, 1.5, and 0.7 during 1999; 5.2, 3.9, 4.0, 4.8, and 1.2 during 2000; and 2.6, 2.4, 1.9, 2.0, and 0.9 during 2001, respectively for lupin, hairy vetch, AWP, 112 kg N ha–1, and control. White lupin and hairy vetch, as winter cover crops, were superior than AWP and 112 kg N ha–1 for sweet corn ear number and size, and plant height. These results demonstrated that winter legume crops, especially lupin and hairy vetch, can be excellent winter cover crops for meeting N needs of muskmelon and sweet corn.

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Ved Parkash, Sukhbir Singh, Manpreet Singh, Sanjit K. Deb, Glen L. Ritchie, and Russell W. Wallace

improved irrigation management practices, which can help conserve water and sustain crop production in water-limited areas ( El-Mageed and Semida, 2015 ; Howell, 2001 ). Deficit irrigation (DI) is one of those potential water conserving irrigation

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M. Rangappa and H.L. Bhardwaj

Cover crops offer an excellent source of nutritional requirements for production of vegetables in sustainable agricultural system. By using this concept, field experiments were conducted in l998 at three locations in Virginia; Petersburg, James City, and King and William County, and five cover crop treatments; Hairy Vetch (HV), Crimson Clover (CC), HV+Rye, CC+Rye, and a conventional bare-ground control were used for their potential support of nutritional requirements for production of a seedless watermelon crop. The results indicated that the yield levels of seedless watermelon following cover crop treatments had significantly higher number of fruits per acre and the crimson clover treatment had higher fruit size in one of the sites (King William County) as compared to the other four treatments and two sites suggesting that cover crop/crops alone have the potential to support nutritional requirements for seedless watermelon to sustain production, thus becoming a viable and profitable alternative to using inorganic nitrogen source. The effects of cover crops on chemical composition of seedless watermelon were generally not significant. The results also indicated that watermelons produced using sustainable crop production methods are comparable to those produced using conventional methods. Our studies support using seedless watermelon as a viable alternative and high-value cash crop for Virginia farmers' especially tobacco growers, other small-scale producers, and limited resource farmers.

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Jonathan M. Frantz

Greenhouses that are well sealed can result in carbon dioxide (CO2) drawdown and suppressed plant growth. While growers can add supplemental CO2, it is unknown how supplemental CO2 fits within the framework of sustainable crop production in greenhouses. In this study, supplemental CO2 was used in combination with reduced temperatures to evaluate the productivity of ‘Grand Rapids’ lettuce (Latuca sativa) compared with a traditionally maintained, warmer, and well-insulated greenhouse without supplemental CO2 at a commercial facility. Simulations using Virtual Grower software based on identical greenhouses compared fuel use and carbon (C) consumed because of heating and CO2 supplementation. Models were verified with measurements in a well-sealed commercial greenhouse; CO2 quickly decreased to below 300 ppm in a nonsupplemented greenhouse containing plants. Supplemental CO2 boosted total leaf number and mass of lettuce even though temperatures were maintained 3 °F lower in elevated CO2 than in the traditional management scenario. Maintaining a cooler greenhouse but adding CO2 decreased total carbon (C) consumed (by combined fuel use and CO2 supplementation) by 7% during the 3-month season that required a well-sealed greenhouse. Additionally, fuel savings because of lower temperature set points paid for the cost of adding CO2. The use of CO2 enrichment should be considered as a tool in sustainable systems when its use can counteract the plant growth and development reductions brought on by lowered temperatures.

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Mohan Selvaraj* and Mathieu Ngouajio

The inclusion of cover crops into cropping systems may influence soil microbial activity which is crucial to sustained crop production. A study was conducted to measure short term effects of summer and winter cover crops on soil microbial biomass carbon (MBC) in a cucumber-tomato rotation system. The experiment was established in Summer 2002 as a factorial of summer cover crops (planted either as fallow or after harvest of cucumbers) and winter cover crops (planted in September). The design was a split-block with four replications. The main plot factor was summer cover crop and consisted of five treatments; sorghum sudangrass fallow (SGF), cowpea fallow (CPF), sorghum sudangrass after cucumber (SGC), cowpea after cucumber (CPC) and bareground fallow (BGF). The sub-plot factor was winter cover crop and consisted of three treatments including cereal rye (CR), hairy vetch (HV) and bareground (BG). In spring of 2003, soil samples were collected in each treatment at 30 days before (30 DBI), 2 days after (2 DAI) and 30 days after (30 DAI) cover crop incorporation. MBC was measured using the chloroform fumigation-incubation method. Both summer and winter cover crops affected soil microbial activity. MBC in the summer cover crop treatments at 30 DBI was 47.7, 51.4, 49.2, 43.7 and 42.5 μg·g-1 soil for SGF, CPF, SGC, CPC and BGF, respectively. At 30 DAI, 113.1, 88.9, 138.5, 105.6, and 109.3 μg·g-1 soil was obtained in SGF, CPF, SGC, CPC, and BGF plots, respectively. Soil MBC was similar at 2 DAI in the summer cover crop treatments. Among winter treatments MBC was similar at 30 DBI and 30 DAI, but significant at 2 DAI with values of 62.8, 53.3, 59.3 μg·g-1 soil for CR, BG, and HV, respectively.

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Chieri Kubota, Michael A. McClure, Nancy Kokalis-Burelle, Michael G. Bausher, and Erin N. Rosskopf

Grafting of vegetable seedlings is a unique horticultural technology practiced for many years in East Asia to overcome issues associated with intensive cultivation using limited arable land. This technology was introduced to Europe and other countries in the late 20th century along with improved grafting methods suitable for commercial production of grafted vegetable seedlings. Later, grafting was introduced to North America from Europe and it is now attracting growing interest, both from greenhouse growers and organic producers. Grafting onto specific rootstocks generally provides resistance to soilborne diseases and nematodes and increases yield. Grafting is an effective technology for use in combination with more sustainable crop production practices, including reduced rates and overall use of soil fumigants in many other countries. Currently, over 40 million grafted tomato seedlings are estimated to be used annually in North American greenhouses, and several commercial trials have been conducted for promoting use of grafted melon seedlings in open fields. Nevertheless, there are issues identified that currently limit adoption of grafted seedlings in North America. One issue unique to North America is the large number of seedlings needed in a single shipment for large-scale, open-field production systems. Semi- or fully-automated grafting robots were invented by several agricultural machine industries in the 1990s, yet the available models are limited. The lack of flexibility of the existing robots also limits their wider use. Strategies to resolve these issues are discussed, including the use of a highly controlled environment to promote the standardized seedlings suitable for automation and better storage techniques. To use this technology widely in North American fresh vegetable production, more information and locally collected scientific and technical data are needed.

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Tanner Donahoo, Lisha Zhang, Matthew Cutulle, and Abolfazl Hajihassani

Increasing regulations and restrictions regarding on-farm chemical use and growing consumer demands for organic food products warrant the development of efficient biological methods for plant disease control and pest management. Grafting and anaerobic soil disinfestation are two sustainable crop production techniques developed to control and regulate weeds, root-knot nematodes (Meloidogyne incognita), and soilborne pathogens. Therefore, the present study explores the economic impact of using grafting and anaerobic soil disinfestation, independently and in conjunction, to determine the best combination in terms of yield and net returns for producers. This study drew from tomato (Solanum lycopersicum) field trials conducted in 2020 on a 0.5-acre plot at the Clemson Coastal Research and Education Center in Charleston, SC, where five grafting and three anaerobic soil disinfestation treatments were used in combinations for comparisons. Each treatment combination was subjected to sealed (plastic mulch covering a plot punctured 5 weeks after applying anaerobic soil disinfestation treatment) and unsealed (plastic mulch covering a plot punctured immediately after the application of anaerobic soil disinfestation treatment) plot conditions during the anaerobic soil disinfestation phase of plant bed preparation. Treatment combinations with cottonseed meal carbon-sourced anaerobic soil disinfestation were unviable because of lower net returns compared with treatment combinations without anaerobic soil disinfestation in nearly every case. Grafting (‘Roadster’ self-grafted) combined with molasses and chicken manure carbon-sourced anaerobic soil disinfestation under unsealed plot conditions was the most optimal treatment combination in the field trials with the greatest gains (net return per acre) to producers. The positive synergistic effects of combining these methods suggest that grafting and anaerobic soil disinfestation yield better results in conjunction than separately.

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Allen V. Barker

preserves the topics of analysis of yield in the first book and updates the first publication with information of phenology, crop modeling, and sustainable crop production. The new book has 10 chapters of text with numerous line drawings and tables and over

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Jongtae Lee

). Characteristically, such a root system leads to the low density of roots in onion. This shallow root system means onion requires more fertilizer to produce the crop ( Brewster, 2008 ; Greenwood et al., 1982 ). For sustainable crop production, pesticides and