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Rebecca E. Scoville and Todd P. West

The objective of this study was to investigate the effects of multiple nutrient salt formulations and different plant growth regulator concentrations on initiation and proliferation of axillary shoot culture of tropical hibiscus (Hibiscus rosa-sinensis L.). Combinations of five thidiazuron (TDZ) concentrations (0, 10-6, 10-7, 10-8, or 10-9 M) in conjunction with two 6-benzylaminopurine (BA) concentrations (0, 10-5 M) and two indole-3-butryic acid (IBA) concentrations (0, 10-5 M) were compared to determine which plant growth regulator combination(s) would stimulate the proliferation of the most viable axillary shoots. Also, five nutrient salt formulations (MS, 1/2 MS; Macro MS, WPM, LP, or DKW) ranging from high to low salt formulations were studied to determine a suitable nutrient medium formulation for axillary shoot proliferation. Nodal explants that were 2 cm in length were used to initiate cultures and were maintained on the various medium treatments plus 30 g·L-1 sucrose and 7 g·L-1 agar at a pH of 5.8. Explants were incubated about 30 cm beneath cool-white fluorescent lamps that provide a photon flux of about 40 μM·m-2·s-1 for a 16-hour photoperiod at 25 ± 3 °C. Nodal explants were transferred every 3 weeks for a total culture period of 12 weeks. At each transfer date data were collected on node number, axillary shoot number and length. Initial results indicate that high nutrient salt formulations coupled with low TDZ concentrations performed better at axillary shoot initiation. Poor shoot elongation was observed and further research needs to be performed to address this issue.

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Todd P. West and Thomas W. McCutcheon

The objective of this study was to investigate the use of hornfaced bees (Osmia cornifrons Radoszkowski) as a successful sustainable alternative for pollination of commercial highbush blueberry (Vaccinium corymbosum L.). The hornfaced bee is native to Japan and introduced to the United States in 1977 by the USDA. Hornfaced bees have been shown to be 300× more efficient in pollinating apples than honey bees. Hornfaced bees are active for 4–6 weeks (April to June), and then the adults die. The rest of the year (10 months), dormant hornfaced bees exist inside nest cells located in cardboard straws stored away from berry production areas. Currently, there are no reports on hornfaced bee use available for blueberry farmers. Five pollinator treatments were compared in 2005 including: hornedfaced bees; honey bees; bumble bees; natural pollinators; and no pollinators. Enclosed pollination cages were constructed around mature field-grown highbush blueberry plants to prevent mixing of pollinator treatments. Each cage contained a single pollinator treatment except for the natural pollinator treatment. The five pollinator treatments were replicated three times inside separate netted cages on the farm. Three branches per plant were randomly selected that had a minimum of five fruiting buds and blossom number recorded. After pollination occurred the cages were removed to allow the berries to ripen. Ripe fruit were picked weekly over the season (July to August), with the fruit from each sample being counted and weighed. Blossom number was compared to fruit number and weight to determine efficiency of pollination as a result of the pollinator treatments. The results showed that hornfaced bees pollinated blueberries as well as or better than the other pollinators.

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S. Christopher Marble and Todd P. West

Multistate collaborations enable extension professionals to reach their audience across a region with similar production challenges. The objective of this article is to introduce the three proceeding manuscripts delivered at the American Society of Horticultural Sciences annual conference in Atlanta, GA, as part of a workshop entitled “Advancing Technology Adoption and Achieving Extension Impact: A Working Group Success Story.” Topics discussed in the following manuscripts include the development of a multistate working group and the advantages associated with participation, development and impact of book or electronic book publications, and survey results from more traditional hands-on workshops. The goal of this workshop was to provide guidance to others who wish to establish multistate, multidisciplinary collaborative teams as well as use new education formats.

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Todd P. West, Gregory Morgenson, Larry Chaput, and Dale E. Herman

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Todd P. West, Gregory Morgenson, Larry Chaput, and Dale E. Herman

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Samuel G. Obae, Hillar Klandorf, and Todd P. West

American ginseng (Panax quinquefolius L.) is an economically important perennial herb whose root is highly valued in the Orient for its medicinal properties. The root grows into different morphotypes, notably “bulb or round” (BLB), “man-like” (ML), and “straight or stick” (STK), and these roots are valued differently by consumers because they are assumed to have different medicinal qualities. Currently, wild-growing and field-cultivated plants are the major source of ginseng roots available on the market; however, because of declining wild populations and the lengthy time required in field cultivation to produce marketable root size, in vitro propagation has been sought as a potential alternative to supply ginseng's bioactive components (ginsenosides). The objectives of this study were: 1) to evaluate how explants derived from the three root morphotypes (lines), BLB, ML, and STK, responded to in vitro callus induction and growth; 2) to compare ginsenosides profiles and content among stock roots and their callus tissues; and 3) to assess genetic diversity among stock roots. Root explants were cultured on solid Murashige and Skoog medium supplemented with 1.0 mg·L1 2,4-D and 0.1 mg·L1 kinetin for 12 weeks. Explants from the three lines exhibited varied callus induction response, growth, and ginsenosides production. Explants from the ML line induced callus faster, were prolific in growth, and accumulated more biomass compared with explants from BLB and STK lines. ML lines (both stock roots and calluses) had significantly higher total ginsenosides content than either BLB or STK lines. There were positive and highly significant correlations between total ginsenosides content of stock roots and callus tissues and callus dry weights. Ginsenosides profiles varied among lines. ML lines exclusively exhibited low Rg1/high Re ginsenosides profiles, whereas BLB and STK lines exhibited mixed Rg1/Re profiles. Random amplified polymorphic DNA (RAPD) analysis of stock roots showed genetic variations within and among lines; however, there was no clear link between DNA bands or band patterns and ginsenoside profiles or content. Overall, these results showed that ginsenoside content of stock roots directly influenced callus induction response and subsequent callus biomass and ginsenoside content. These results provide information that could be useful in selecting suitable stock plants for in vitro production of ginsenosides. Also, because there are no ginseng cultivars, this information would be useful in advancing breeding efforts toward selecting superior cultivars for this species. Chemical names used: 2,4-dichlorophenoxyacetic acid (2,4-D)

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Todd P. West, Gregory Morgenson, Larry Chaput, and Dale E. Herman

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Todd P. West, Samuel L. DeMarais, and Chiwon W. Lee

Temperate-zone woody plant species generally require seed stratification to overcome embryo dormancy. Embryo dormancy is variable in japanese tree lilac (Syringa reticulata) with a recommendation of 30- to 90-days stratification at 1–5 °C. Cultivar propagation generally is done by grafting onto seedling rootstocks. It would be advantageous to rootstock seedling production to be able to reduce or eliminate the need for seed stratification to increase germination numbers as well as having production moved from field beds to greenhouses for quicker production of high-quality rootstock plants suitable for grafting. Research objective of this study was to determine if “green” seed could be used without the need of stratification for japanese tree lilac seedling production. Seed capsule fresh weight and seed moisture content were evaluated to determine if these factors could be used as predictors of germination percentages. Seed was randomly collected at the North Dakota State University campus in Fargo, ND, for seven consecutive weeks starting in Sept. 2011 and 2012. Germination and seed moisture tests were performed weekly. Germination percentage was highest (89.5%) at week 2 and steadily decreased to 0% at week 7. Germination percentages were 77.5%, 89.5%, 78.5%, 67%, 24.5%, 1.5%, and 0% for consecutive collection weeks 1–7, respectively. Seed moisture content was 59.0%, 52.6%, 49.8%, 51.8%, 44.5%, 27.4%, and 8.6% for collection weeks 1–7, respectively. Germination percentage was directly correlated with seed moisture content and decreased as seed capsules matured (natural drying and splitting of capsule seem to disperse seed) during the fall season. Data suggest that timing of fall seed collection from japanese tree lilac is critical and must be done before maturation of the seed capsule to avoid the stratification requirement. Seed capsules with an average fresh weight higher than 0.2 g and seed moisture content greater than 50% produced the highest germination rates without requiring stratification.