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  • Author or Editor: B. Jordan x
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The U.S. Environmental Protection Agency limits the amount of nitrate and phosphate, yet these nutrients are applied in relatively large amounts during crop production. The objective of greenhouse studies conducted in 2002–05 was to determine the effects of calcined, attapulgite-type clays used as substrate amendments during production of containerized poinsettias, chrysanthemums, and ornamental grasses. Crops were grown with recommended rates of controlled-release fertilizers and irrigation volumes set to achieve a leaching fraction around 0.2. Results with poinsettias grown in substrates amended with clays were as follows: EC of leachate from poinsettia was reduced by up to 39% in the first few weeks after potting; orthophosphate concentration in leachate was reduced by up to 74% in peat-based substrate; cumulative irrigation volume required to produce plants in 16.5-cm containers was reduced by 11%. With two chrysanthemum cultivars, clays reduced EC of leachate and increased plant growth. A non-calcined clay reduced growth of poinsettia and `Oborozuki' Japanese sweetflag grass, but not `Karl Foerster' feather reed grass. Results from these studies suggest that, with controlled irrigation volumes, calcined clays added to a peat-based substrate can reduce leachate nutrient concentrations and reduce crop water requirements without negatively affecting crop growth or quality.

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Although the size of pot mums can be controlled with retardants, the use of such chemicals may become limited. Genetically dwarfing current cultivars may be an alternative. Using a construct including a chimeric oat phytochrome structural gene, tobacco phenotypes have been produced that strongly resemble retardant-treated plants. We wished to insert this construct in mum by using particle bombardment and determine the effects on plant size and flowering dynamics. A target system was developed using `Iridon' mum leaf sections regenerated on an IAA/BA medium. Shoots developed from surface cells principally at the cut edges. Regenerates were grown-on through flowering and no visual aberrations were apparent. Levels of 50 to 100 mg/l kanamycin were inhibitory to bud development. Sections were exposed to gene transfer and shoots recovered that appear resistant to kanamycin. Some appear chimeric while others appear to be escapes stimulated by a `feeder' effect from nearby transformed cells. Further analyses will determine whether some plants are stably transformed. (Supported by a Duffett Research Grant from Yoder Brothers, Inc.)

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The term Ethnobotany describes the study of people's relationships to plants as foods, fibers, medicines, dyes, and tools throughout the ages. Using the student active technique of experiential learning, undergraduate students enrolled in landscape design and implementation classes at Clemson University planned and installed an Ethnobotany garden in partnership with the South Carolina Botanical Garden (SCBG) staff, volunteers, and Sprouting Wings children. Sprouting Wings is an after-school gardening and nature exploration program for under-served elementary school students. College students and faculty working on this service-learning project contributed over 1,000 hours to their community while learning more about both the art and the science of landscape design and implementation. Students enrolled in the landscape Implementation class were surveyed to evaluate their perceptions on a variety of possible learning outcomes for this class. Students indicated that their service learning experience with the Ethnobotany project allowed them to acquire and practice new skills, broadened their understanding of the surrounding community, increased their ability to work in real world situations, introduced new career possibilities, gave students a better understanding of their course work, increased their ability to work on a team, increased their knowledge of environmental sustainability, and allowed them to discover or develop leadership capabilities. In a survey question regarding preference for service learning rather than traditional classes, the majority of students prefer the service learning pedagogy. In addition, most students reported a high degree of initiative for this project in their reflections.

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Grafting watermelon (Citrullus lanatus) is a common practice in many parts of the world and has recently received increased interest in the United States. The present study was designed to evaluate early season growth, yield, and fruit quality of watermelon in response to grafting and in the absence of known disease pressure in a fumigated system. Field experiments were conducted using standard and mini watermelons (cv. Exclamation and Extazy, respectively) grafted onto 20 commercially available cucurbit rootstocks representing four species: giant pumpkin (Cucurbita maxima), summer squash (Cucurbita pepo), bottle gourd (Lagenaria siceraria), and interspecific hybrid squash [ISH (C. maxima × Cucurbita moschata)]. Nongrafted ‘Exclamation’ and ‘Extazy’ were included as controls. To determine early season growth, leaf area was measured at 1, 2, and 3 weeks after transplant (WAT). At 1 WAT, nongrafted ‘Exclamation’ produced the smallest leaf area; however, at 3 WAT, nongrafted ‘Exclamation’ produced the largest leaf area in 2015, and no differences were observed in 2016. Leaf area was very similar among rootstocks in the ‘Extazy’ study, with minimal differences observed. Marketable yield included fruit weighing ≥9 and ≥3 lb for ‘Exclamation’ and ‘Extazy’, respectively. In the ‘Exclamation’ study, highest marketable yields were observed in nongrafted ‘Exclamation’, and ‘Exclamation’ grafted to ‘Pelops’, ‘TZ148’, and ‘Coloso’, and lowest marketable yields were observed when using ‘Marvel’ and ‘Kazako’ rootstocks, which produced 47% and 32% of nongrafted ‘Exclamation’ yield, respectively. In the ‘Extazy’ study, the highest marketable yield was observed in nongrafted ‘Extazy’, and ‘Kazako’ produced the lowest yields (48% of nongrafted ‘Extazy’). Fruit quality was determined by measuring fruit acidity (pH), soluble solids concentration (SSC), lycopene content, and flesh firmness from a sample of two fruit from each plot from the initial two harvests of each year. Across both studies, rootstock had no effect on SSC or lycopene content. As reported in previous studies, flesh firmness was increased as a result of grafting, and nongrafted ‘Exclamation’ and ‘Extazy’ had the lowest flesh firmness among standard and mini watermelons, respectively. The present study evaluated two scions with a selection of 20 cucurbit rootstocks and observed no benefits in early season growth, yield, or phytonutrient content. Only three of 20 rootstocks in each study produced marketable yields similar to the nongrafted treatments, and no grafted treatment produced higher yields than nongrafted ‘Exclamation’ or ‘Extazy’. Because grafted seedlings have an associated increase in cost and do not produce increased yields, grafting in these optimized farming systems and using fumigated soils does not offer an advantage in the absence of soilborne pathogens or other stressors that interfere with watermelon production.

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