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  • Author or Editor: Jeff L. Sibley x
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Stem cuttings of Hydrangea paniculata Sieb., Rosa L. `Red Cascade', Salvia leucantha Cav., and Solenostemon scutellarioides (L.) Codd `Roseo' were inserted into six rooting substrates: monolithic slag [(MgFe)2Al4Si5O18], sand, perlite, vermiculite, Fafard 3B, or fine pine bark. Rooting, initial shoot growth, and ease of dislodging substrate particles from root systems upon bare-rooting by shaking and washing cuttings rooted in monolithic slag were compared to cuttings rooted in the five other substrates. Rooting percentage, number of primary roots per rooted cutting, and total root length per rooted cutting for cuttings rooted in monolithic slag were generally similar to the five other substrates. Particles of monolithic slag were dislodged more readily from root systems by shaking than were the other substrates. Gentle washing removed almost all particles of monolithic slag and sand from the root systems of all taxa and removed almost all particles of pine bark from all taxa except S. scutellarioides `Roseo'. Monolithic slag had a bulk density similar to sand, retained less water than the other substrates, and was similar to perlite, vermiculite, and pine bark in particle size distribution. Our studies indicate that monolithic slag, where regionally available, could provide a viable material for producing bare-root cuttings.

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A substrate component (WholeTree) made from loblolly pine (Pinus taeda L.) was evaluated along with starter fertilizer rate in the production of greenhouse-grown petunia (Petunia ×hybrida Vilm. ‘Dreams Purple’) and marigold (Tagetes patula L. ‘Hero Spry’). Loblolly pine from a 12-year-old plantation were harvested at ground level, chipped, and further processed through a hammer mill to pass a 0.64-cm screen. The resulting WholeTree (WT) substrate was used alone or combined with 20% (WTP2) or 50% (WTP5) (by volume) Canadian sphagnum peatmoss and compared with an industry standard peat-lite (PL) mix of 8 peatmoss : 1 vermiculite : 1 perlite (by volume). Substrates were amended with 1.78 kg·m−3 dolomitic lime, 0.59 kg·m−3 gypsum [CaSO4-2(H2O)], 0.44 kg·m−3 Micromax, 1.78 kg·m−3 16N–2.6P–9.9K (3- to 4-month release), and 1.78 kg·m−3 16N–2.6P–10.8K (5- to 6-month release). A 7N–1.3P–8.3K starter fertilizer (SF) was added to each substrate at 0.0, 1.19, 2.37, or 3.56 kg·m−3. Container capacity (CC) was greatest for PL and decreased as the percentage of peatmoss in the substrate decreased with WT having 35% less CC than PL. Conversely, air space (AS) was greatest for the WT and decreased as percentage of peatmoss increased with PL containing 33% less AS than WT. In general, petunia dry weight was greatest for any substrate containing peatmoss with a SF rate of 2.37 kg·m−3 or greater. The exception was that petunia grown in WT at 3.56 kg·m−3 SF had similar dry weight as all other treatments. Marigold dry weight was similar for all substrates where at least 2.37 kg·m−3 SF was used.

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International undergraduate study programs give students an advantage in the job market, broaden their understanding of and experience with other cultures, and allow them to develop professional international contacts. Since 2003, faculty and administrators in the Department of Horticulture at Auburn University have been providing horticultural study tours for faculty and undergraduate and graduate students in horticulture. In 2003 and 2004, undergraduate students and faculty participated in an about 10-day non-credit study tour of gardens in London and southeastern England. In 2005, undergraduate students, a graduate student, and faculty participated in an 8-day non-credit study tour of gardens, horticultural production facilities, and natural ecosystems in Costa Rica. All of these tours in 2003 to 2005 occurred during the break between spring and summer semesters. In 2005, a 6-week study abroad program (1 June to 15 July) was offered at a college in northwestern England. Students received 13 hours of credit for four classes: Landscape Gardening, History of Garden Design, International Agriculture Seminar, and Herbaceous Plant Materials. In addition to class time, trips were arranged each week to regional gardens and retail and production facilities. Plans for 2006 include a week-long non-credit study tour of gardens and production areas in The Netherlands during the break between spring and summer semesters, a 2-week study tour of government, university, and agricultural production areas in Hungary in July (offered in conjunction with the College of Agriculture), and a repeat offering of the study abroad program in England.

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Performance evaluation of red maple (Acer rubrum L.) selections in the southeastern U.S. was initiated in November 1988. Seven cultivars, `Autumn Blaze', `Autumn Flame', `Morgan', `Northwood', `October Glory', `Franksred' (Red Sunset TM) and `Schlesingeri', from tissue culture and a group of seedlings obtained from a single source were container grown for 18 months prior to field planting in March 1990. All plants have received drip irrigation in the field. Since field planting, 'Autumn Flame', and 'Autumn Blaze' exhibit the greatest growth rate based on annual height and caliper data. 'Schlesingeri' and 'Northwood' had the least growth. Gas-exchange measurements taken in June 1992, showed 'Schlesingeri' and 'Northwood' to have the greatest photosynthetic activity and transpirational water loss while 'October Glory' and 'Frankred' had the least.

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The unprecedented, yet sustained, growth of undergraduate enrollment in the Department of Horticulture at Auburn University can be attributed to many factors, including an increased industry demand for horticulture graduates nationwide. Perhaps the basis of some of Auburn's growth, while appearing to be unique, may be of value in other programs. This paper chronicles the growth of the Auburn Department of Horticulture undergraduate program and highlights some of the traditional teaching methods employed within the department as well as some unique methods that contribute to the program. The paper offers ideas and practices that may be beneficial to other horticulture programs and may encourage teaching faculty at other institutions to publish similar departmental profiles that may prove beneficial to colleagues.

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The influence of three shade levels on propagation of golden barberry (Berberis koreana Palib. × B. thunbergii DC.) selection `Bailsel' was evaluated in studies initiated 29 Apr. and 18 Sept. 1998. After 57 days, root ratings were higher in plants under 70% and 80% shade treatments than 60% shade for both studies. In study one, viability was lower among plants under the 60% shade level than those under 70% or 80% shade levels. Viability among treatments was similar in study two. Based on visual observations, leaf retention appeared greater under the 70% and 80% shade treatments than the 60% shade treatment for both studies. Cuttings rooted under 70% and 80% shade levels generally had a uniform golden hue, whereas the foliage of those rooted under 60% shade often had a red hue and showed signs of desiccation for both studies. Root dry weights were greater for cuttings under the 60% shade levels than 70% or 80% shade.

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Net photosynthesis (Pn), stomatal conductance (Cs), transpiration (Ts), and water use efficiency (WUE) were determined with a LICOR 6250 Portable Photosynthesis System for four cultivars of Acer rubrum L. under light intensities ranging from 300 to 1950 μmol·m-2·sec-1 photosynthetically active radiation (PAR). As PAR increased, there was a linear relationship for Pn, Cs, and Ts for the cultivars `Franksred' (Red Sunset TM) and `October Glory'. In contrast, the cultivars `Schlesingeri' and `Northwood' had quadratic relationships for Pn and Cs as PAR increased. Ts was quadratic for `Schlesingeri' and had a linear relationship for `Northwood.' WUE was quadratic for each of the four cultivars.

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Lotus (Nelumbo) is a highly valued plant with a long history for vegetable, ornamental, and medicinal use. Little information is available on the effects of planting time on performance of lotus, especially when grown in containers. The objectives of this study were to find a suitable planting time and to determine best management practices that are of importance for container lotus production. Effects of planting time and disbudding on plant growth indices in southeast Alabama were evaluated in a container production system for the ornamental lotus, N. nucifera ‘Embolene’. Results indicated that plant growth indices were little influenced by different planting dates in March, but were much influenced by planting dates with a difference over a month between February and May. Plants potted and placed outdoors in March and April performed best, and lotus planted in the greenhouse in February and planted outdoors in February and May performed worst. Flower number was not largely influenced by the planting time, but flowering characteristics, especially the flowering peaks, were different among treatments. Planting lotus outdoors between March and May produced the largest return. Influence of planting time on plant growth indices of lotus appeared to be explained by effects of growth-season climate conditions after planting. Disbudding had no impact on plant height but significantly increased underground fresh weight and the number of propagules. Therefore, disbudding should be considered a best management practice to maximize the yield of rhizomes or propagules. Positive linear, quadratic, or cubic relationships were detected among emerging leaf number, underground fresh biomass, and propagule number. Based on the regression models, the yield of lotus rhizomes or propagules can be predicted by the number of emerging leaves. This research provided a guide for nurseries, researchers, and collectors to select the best time to plant lotus outdoors.

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This study reports on the performance of 34 clones of crapemyrtle (Lagerstroemia indica L., L. fauriei Koehne, and L. indica × L. fauriei hybrids) grown in field plots at four locations representative of different environments in the southeastern United States. Traits evaluated were spring leaf-out and initiation of flowering in the second season after field planting and plant height after 3 years of growth. Cluster analysis (Ward's method) was used for grouping and comparison of means across locations for each trait. Best linear unbiased prediction was used for estimating random effects in linear and generalized linear mixed models to better determine the general performance of the clones under a variety of environmental conditions. Each clone's trait stability was quantified using the regression of an individual genotype's performance for each of the three studied traits on an environmental index based on the trait mean for all genotypes grown in an environment. Sequence of clone leaf-out and size rankings were more stable across the environments than the sequence in which the various clones initiated flowering. L. fauriei clones and clones originating from the initial cross between L. indica and L. fauriei were generally later to leaf out, earlier to flower, and more vigorous growers than L. indica or the complex L. indica × L. fauriei clones that were evaluated. First flowering was affected by environmental variation more with interspecific hybrids than with L. fauriei and L. indica clones. Performance, particularly with respect to plant height, of several clones did not agree with previously published classifications. Information generated by this study will allow crapemyrtle breeders, landscape professionals, and consumers to better select the most appropriate crapemyrtle clone for a particular application.

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Each year, over 16 million tons of poultry litter is produced in the United States. Federal and state regulations now limit the amount of poultry litter that can be land-applied, making it difficult to store and dispose of poultry litter. The objective of this study was to evaluate composted poultry litter (CPL) as a fertilizer source for bedding plants at various rates in comparison with commercially available inorganic fertilizers in regard to plant growth and nutrient leaching. Two experiments were conducted to evaluate use of CPL as fertilizer for landscape annual bedding plants. Petunia spp. ‘Celebrity Red’ and Verbena hybrida ‘Quartz Scarlet’ were planted in raised beds simulating an urban landscape. Before planting, 10 inorganic fertilizer or CPL treatments were incorporated into the raised beds, including Peafowl® brand garden-grade fertilizer 13N–5.6P–10.9K (13-13-13) at rates of 4.9 g N/m2 and 9.8 g N/m2, Polyon® 13N–5.6P–10.9K (13-13-13) at rates of 4.9 g N/m2 and 9.8 g N/m2, and CPL at rates of 4.9 g N/m2, 9.8 g N/m2, 19.6 g N/m2, 29.4 g N/m2, 39.2 g N/m2, and 49 g N/m2. Use of CPL incorporated into landscape planting beds as a fertilizer source resulted in plants equal to or larger than plants grown with conventional inorganic fertilizers. Nitrate (NO3) and ammonia (NH4) levels in leachates from plots amended with CPL were comparable with plots amended with commercial inorganic fertilizers and nitrogen (N) levels were in most cases less in plots fertilized with CPL when compared with inorganic fertilizers when the same N rate was applied. Composted poultry litter may not be able to fully replace inorganic fertilizers, but it can reduce inorganic fertilizer requirements and provide an environmentally sound alternative to poultry waste disposal as well as provide beneficial aspects for plant growth in annual bedding plants.

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