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J.W. Buxton and T. Phillips

In class demonstrations, it is almost impossible to maintain the same water: air ratio in growing media. If some treatments result in greater plant growth than others, treatment effects on plant growth are often confounded with the effect of water: air ratio in the growing media. In a laboratory demonstration of nutrient deficiencies symptoms in plants, a controlled water table irrigation system maintained a constant water: air ratio in the growing media regardless of the nutrient deficiency affect on plant growth. The modified capillary mat irrigation system consists of one mat edge extending over the edge of the bench into a narrow trough on the side of the bench. The nutrient solution level in the trough is controlled by a liquid level controller, so it is at a fixed distance below the bench surface. The nutrient solution is drawn upward by capillarity to the bench surface and then moves by capillarity over the bench. The system automatically maintains a constant air: water ratio in the growing media. A standard Hogland solution was modified to demonstrate deficiencies in N, P, K, Mg, Ca, Cu, Fe, and Zn on corn, squash, radish, soybeans, and marigold. Seeds were germinated and grown to maturity in either a 10- or 15-cm pot. Students set up the demonstration, were provided instruction in preparing solutions, regularly observed plant growth, and answered questions at the end of the study about differences in plant growth observed. However, possibly because low concentrations of some minor elements in the capillary mat, Zn deficiency was not observed and other elements, although resulting in poor growth compared to the control, did not show severe deficiency symptoms.

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Robert T. Eddy and Phillip J. Belfiore

Many studies have described the ability of individuals with mental disabilities to learn vocational tasks commonly performed in greenhouses, and a survey of horticulture employers reports a favorable perception toward the work habits of these individuals. Productivity data are not available from these studies, however. We sought to quantify productivity of individuals with and without mental disabilities performing entry-level greenhouse tasks. Information on ten tasks was compiled from surveys of four vocational centers with greenhouse production and six commercial greenhouses. Individuals with mental disabilities produced at rates of 46% to 192% of corresponding commercial rates, with seven often skills performed. above 75% of the commercial rate. The results from this pilot study suggest that individuals with mental disabilities can achieve satisfactory productivity in real work settings. While significance was not achieved due to limitations of the study, the results provide a baseline for further study by other researchers. The practical significance of these findings can be judged by trainers and employers.

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Phillip C. Flanagan and W.T. Witte

Previous research at this facility has shown that copper sulfate, when incorporated with latex paint and applied to the interior surfaces of tube trays, was effective in chemically root pruning Quercus acutissima seedlings. Only 20% of deflected roots continued to grow after contacting Cu treated tube walls compared to controls. Treated plants showed a reduction of fibrous roots on the plug surface. Height and caliper were not affected by Cu treatments during chemical root pruning in the tube tray. Time required for regeneration of new roots was not affected by Cu treatments. Seedlings from each treatment were planted and grown two seasons under field conditions to observe effects on growth and root regeneration. No treatment effects occurred for height or caliper. Oak seedlings chemically root pruned with Cu exhibited more lateral growth and branching than control plants.

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J.W. Buxton and T.D. Phillips

Students in plant science courses have difficulty thoroughly understanding the effect of water stress on net photosynthesis and its consequences—reduced plant growth, productivity, quality, and profit. A laboratory demonstration utilizing a controlled water table irrigation system (CWT) provides a nearly constant plant water potential. Pots are placed on a capillary mat with one end suspended in a trough with nutrient solution. The vertical distance from the solution surface to the pot bottom determines the water potential; the water potential is 0 when the pot bottom is at the same level as the nutrient solution. The greater the vertical distance from solution to the pot bottom, the lower the water potential. For this demonstration, the bench was sloped from 0 to 10 cm above the solution over a distance of 90 cm. Corn, squash, soybean, fescue, and marigold seed were directly sown to either 9- or 15-cm pots and then placed on the CWT sloped bench at five vertical distances above the solution. Weekly, students observed plant growth and at the end of 8 weeks evaluated root and shoot growth. For all species, plant growth was indirectly related to the distance above the nutrient solution. Plants at near 0 water potential were much larger than those grown 8 to 10 cm above the solution.

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Phillip C. Flanagan and W.T. Witte

Interior surfaces of tube trays were painted with white exterior acrylic latex paint and white interior latex paint containing 0, 50, or 300 gm/1 copper sulfate. Germinated Quercus acutissima seedlings were used to study chemical root pruning effects and subsequent root regeneration. After 16 weeks, only 0.73 roots per seedling continued growth after being deflected by the tubewall painted with 100gm/1 compared with 3.67 for the control. Fibrous roots were reduced when in contact with cu treated surfaces. Height and caliper were not affected at any treatment level. Three weeks after transplanting to larger untreated containers, height and caliper were still unaffected by any cu treatment. Time required for regeneration of new roots was not affected by cu treatments.

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Willard T. Witte, Scott Schlarbaum, Roger Sauve and Phillip C. Flanagan

Since 1988, efforts have been underway to establish a nursery research station in McMinnville, Warren County, Tennessee. Approximately 80 acres of farm property adjacent to the Collins scenic river has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining grant funds via the Capacity Building Grants Program to initiate a plant evaluation and introduction program. Replicated trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, Ulmus. Herbaceous genera are Echinacea, Hemerocallis, Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Additional grant proposals have been recently submitted.

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Phillip C. Flanagan, Roger Sauve and Willard T. Witte

The Tennessee State University Nursery Crops Research Station is located at McMinnville in Middle Tennessee. This is a major nursery production area with a USDA Zone 6b climate and 134 cm mean annual rainfall.

Approximately 4 ha has been established, with drip irrigation, for comparative evaluation trials of Acer, Cornus, Lagerstroemia, Quercus, Syringa and Ulmus. Plants are being evaluated for: 1) landscape performance - growth, drought tolerance, heat/cold tolerance, 2)ornamental characteristics - bloom. leafcolor, fall color, shape, 3) resistance to disease and pests, and 4) adaptability for production under commercial conditions. Acquisition of plant materials began in 1992 with the collection and planting of more than 120 spp/cv of Acer. Plantings in 1994 consisted of Cornus = 100 spp/cv; Lagerstroemia = 70 spp/cv; Quercus ≈ 90 spp/cv; Syringa ≈ 50 spp/cv and Ulmus ≈ 30 spp/cv.

The long term objective is the establishment of a comprehensive evaluation program for the nursery industry of Tennessee.

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Nathan C. Phillips, Steven R. Larson and Daniel T. Drost

Three wild onion species native to the intermountain west in the United States—Allium acuminatum, A. brandegei, and A. passeyi—show horticultural potential, but little is known about patterns of genetic diversity among localized populations and geographical regions. We examined amplified fragment length polymorphisms (AFLP) within and among five Allium acuminatum, four A. brandegei, and three A. passeyi collection sites in Utah. These three congeners with contrasting abundance and distribution patterns provide an opportunity to investigate the role of geographic distance, altitude, and rarity in patterns of genetic divergence. The collection sites were selected along an altitudinal gradient to reflect ecogeographic variation. Individual plants from each of the 12 sites were genotyped using six AFLP primer combinations detecting DNA variation within and among all three species. Genetic differences between species were high enough to render comparisons among species impractical, so each species was analyzed separately for differences between populations and variability within populations. Similarity coefficients were significantly greater within collection sites versus among collection sites indicating divergence between populations. Within-population genetic diversity was not correlated with elevation for any of the three species. Analysis of molecular variance revealed that 66% (A. acuminatum), 83% (A. passeyi), and 64% (A. brandegei) of observed variation is found within populations. Genetic divergence among populations (ФST) was higher in the widely distributed species, suggesting that interpopulation gene flow may be negatively correlated with range size. Allium acuminatum and A. brandegei individuals cluster into groups corresponding strictly to collection sites based on neighbor-joining analysis of the total number of DNA polymorphisms between individual plants. Allium passeyi populations, however, had less overall genetic variation between populations. Genetic isolation by distance appeared responsible for much of the variability among populations, although there was one notable exception showing significant differences between two geographically close populations in A. acuminatum.

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Nathan C. Phillips, Steve R. Larson and Daniel T. Drost

The genus Allium is distributed worldwide and includes about 80 North American species, with at least 13 occurring in Utah. Our study focuses on the population dynamics of three Allium species native to Utah; Allium acuminatum, A. brandegei, and A. passeyi. In conjunction with our studies of life history, growth characteristics, demographics, and habitat, we are interested in determining the levels of genetic variation in these species. This study examines amplified fragment length polymorphism (AFLP) within and among five Allium acuminatum, four A. brandegei, and three A. passeyi populations native to Utah. These species have contrasting abundance and distribution. The study populations were selected along an elevation gradient to represent within-species habitat differences. About 10–20 plants from each of the 12 populations were genotyped using six AFLP primer combinations, which detect DNA variation within and among all three species. These data will be used to compare levels of genetic variation and isolation among populations and species.

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Willard T. Witte, Scott Schlarbaum, Roger Sauve and Phillip C. Flanagan

Efforts have been underway since 1988 to establish a nursery research station in McMinnville, TN. Approximately 80 acres of farm property has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining funding via the Capacity Building Grants Program to initiate a plant evaluation and introduction program at the new station. Initial trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, and Ulmus. Herbaceous genera are Echinacea, Hemerocallis, and Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Complementary grant proposals have been recently submitted. Design, funding and support of all Tennessee introduction and evaluation programs will be discussed.