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Jonathan M. Frantz

floricultural crops, P supply can influence flowering and plant height. Whitcher et al. (2005) observed increases in plant height and flower number with both new guinea impatiens ( Impatiens hawkeri ) and vinca as P supply and foliar concentrations increased

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Glenn B. Fain, Charles H. Gilliam, Jeff L. Sibley, and Cheryl R. Boyer

form three species of processed whole pine trees as alternative growth substrates for container-grown annual vinca. Materials and methods Eight- to 10-year-old loblolly pine, longleaf pine, and slash pine were harvested at ground level and the entire

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Michael R. Evans, Andrew K. Koeser, Guihong Bi, Susmitha Nambuthiri, Robert Geneve, Sarah Taylor Lovell, and J. Ryan Stewart

to container capacity and filled to 1 cm from the container rim. Six-leaf plugs (#177 square with plug volume of 5 mL) of ‘Cooler Grape’ vinca were transplanted into the containers. Containers were placed in a greenhouse either individually directly

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Marc van Iersel

Auxins are commonly used to induce root formation during in-vitro culture of higher plants. Because transplanting is often accompanied by root damage and loss of small roots, auxins also could be beneficial in minimizing transplant shock. Vinca (Cataranthus rosea) seeds were germinated in a peat-lite growing mix and transplanted into pots (55 mL) filled with a diatomaceous earth (Isolite) 10 days after planting. Pots were then placed in a tray containing 62.5 mL of auxin solution per pot. Two different auxins [indole-acetic acid (IAA) and naphtylacetic acid (NAA)] were applied at rates ranging from 0.01 to 100 mg/L. Post-transplant growth was slow, possibly because of Fe+2-deficiencies. Both IAA (1–10 mg/L) and NAA (0.01–10 mg/L) significantly increased post-transplant root and shoot growth. As expected, NAA was effective at much lower concentrations than IAA. At 63 days after transplant, shoot dry mass of plants treated with 0.1 mg NAA/L was four times that of control plants, while 10 mg IAA/L increased shoot dry mass three-fold. High rates of both IAA (100 mg/L) and NAA (10–100 mg/L) were less effective. The highest NAA rate (100 mg/L) was phytotoxic, resulting in very poor growth and death of many plants. These results suggest that auxins may be a valuable tool in reducing transplant shock and improving plant establishment.

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Adam F. Newby, James E. Altland, Daniel K. Struve, Claudio C. Pasian, Peter P. Ling, Pablo S. Jourdan, J. Raymond Kessler, and Mark Carpenter

AS at a given VWC or GWC ( Raviv and Lieth, 2008 ). The objective of this experiment was to determine the effects of two substrates and two substrate matric potential ranges on annual vinca growth, applied irrigation, leachate volume, and plant water

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Yan Chen, Regina Bracy, and Allen Owings

Annual vinca, Catharanthus roseus, is exceptionally adaptive to the summer heat and the sandy loam or clay soil in the southeastern region and provides season-long blooms once established in landscape plantings. A wide variety of colors, sizes, and applications are available for landscape use. However, diseases such as alternaria leaf spot and phytophthora leaf blight are prevalent in this region in vinca plantings. Effective disease control requires frequent fungicide application that is expensive and may pose negative effects on the environment. Proper planting techniques including date of planting, fertilization rate at planting, and variety selection may improve plant growth, reduce disease severity, and save landscape service business labor in disease management. Plants of three varieties: open-pollinated `Cooler Hot Rose', F1 hybrid `Titan Rose', and trailing variety `Mediterranean Lilac' were planted on 1 Apr. or 1 May in landscape plots. Plants were at the same growth stage at the time of planting and were fertilized with Osmocote 14–14–14 (3 months) at 0, 35, 70, or 140 g·m2. Plant growth index indicates that plant growth increased significantly at increasing fertilization rates; however, plant overall quality ratings were not significantly different among fertilized plants. Disease incidence in July suggests that late planting may reduce alternaria leaf spot in open-pollinated and hybrid upright type vinca. Disease severity in August was more pronounced on trailing vinca and more severe when plants were not fertilized or fertilized with the highest fertilization rate. Tissue analysis indicates that trailing vinca `Mediterranean Lilac' may require less fertilization than upright type.

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Arianna Bozzolo and Michael R. Evans

, ‘Orbital Cardinal Red’ geranium, ‘Better Belle’ pepper, and ‘Cooler Grape’ vinca were sown onto the surface of the peat, and the seeds were covered with a 4-mm top coating of either vermiculite or cork granulates. The mini-plug trays were placed on expanded

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Marc van Iersel

Transplanting often causes root damage, and rapid root growth following transplanting may help to minimize the effects of transplant shock. The objective of this study was to determine the effects of NAA and IAA on posttransplant growth of vinca (Catharanthus roseus L.). Bare-root seedlings were germinated in a peat-based growing mix and transplanted into diatomaceous earth 10 days after seeding. Immediately after transplanting, seedlings were drenched with several concentrations of IAA or NAA (62.5 mL/plant). Both auxins increased posttransplant root and shoot growth, but the response was dose-dependent. The maximum growth occurred at concentrations of 10 mg·L-1 (IAA) or 0.1 mg·L-1 (NAA). The growth-stimulating effect of these auxins decreased at higher rates and NAA was highly toxic at 100 mg·L-1, killing most of the plants. Unlike the growth of bare-root seedlings, plug seedling growth was not stimulated by drenching with NAA solutions. These results show that auxins have the ability to stimulate posttransplant growth of vinca, but their effects may depend on the application method, rate, and timing, and transplanting method. Chemical names used: 1-naphthaleneacetic acid (NAA); 1-indole-3-acetic acid (IAA).

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Kimberly A. Poff and Jayne M. Zajicek

Uniconizole has great potential for use in both the landscape and nursery industry for improved plant quality, more efficient maintenance techniques, and increased water conservation. A study was conducted to evaluate the effects of uniconizole and methods of application on growth, development, and water use of asiatic jasmine and vinca. Treatments consisted of 1.25 mg A.I., 2.5 mg A.I., or 5 mg A.I. applied in a 25 ml spray or 25 ml soil drench. Another study was conducted to determine if the growth regulation effects could be overcome by direct application of GA. GA3 and GA4+7 were applied at rates of 2.5 mg A.I., 12.5 mg A.I., or 25 mg A.I. in a 25 ml solution after growth reduction had occurred. The 5 mg A.I. uniconizole spray and drench treatments were most effective in reducing growth and whole plant transpiration for asiatic jasmine and vinca respectively. Transpiration per unit leaf area was not reduced for any treatment except for asiatic jasmine at the highest drench rate.

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Karen L. Panter, Amy M. Briggs, Michael J. Roll, and Steven E. Newman

The objective of this study was to determine which combination of three types of irrigation systems, three fertilization method, and four growing media produced optimum growth of flowering vinca, Catharanthus roseus. Irrigation systems used included ebb-and-fl ood, drip, and pulse; fertilization methods included slow release, prepackaged, and custom mixed; and the four growing media were peatmoss:perlite:vermiculite (1:1:1, by volume), peatmoss:rockwool (1:1, by volume), and 0.6-cm diameter shredded rubber or fabric from waste tires: vermiculite:peatmoss (1:1:2, by volume). Four replications of five plants each were used in each of the 36 treatment combinations. Plants were potted 29 and 30 May 1996 in 10-cm containers, grown for 10 weeks, and harvested 6 Aug. 1996. The drip-irrigated benches were irrigated once per day for 15 s. Pulse-irrigated benches were watered twice per day for 6 s. This resulted in the drip- and pulse-irrigated plants receiving a similar volume of water daily. Ebb-and-fl ood benches were filled once per day with drainage occurring 15 min after filling. Ending plant heights and dry weights indicated that those plants in the prepackaged fertilizer/drip or ebb-and-fl ood irrigation/shredded tire fiber growing medium were comparable to plants grown in the peatmoss:rockwool medium with the same fertilizer and irrigation methods.