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E Jay Holcomb

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E. Jay Holcomb and Robert Berghage

Easter lily plants (Lilium longiflorum Thunb.), derived from tissue culture and grown continuously, were subjected to various photoperiod and chilling treatments. Lilies grown with daylength extended either with high-intensity discharge (HID) or incandescent lights flowered in the same number of days, but had more flower buds with HID lamps. Flowering was delayed and plants produced more leaves as photoperiod was reduced from 16 to 12 hours. The numbers of leaves, primary, secondary, and tertiary flowers, and the time to flower were all significantly reduced as the duration of extended lighting was increased from 0 to 6 weeks. As the number of weeks of cooling at 5°C increased from 0 to 5, time to flower was significantly reduced.

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Noreen S. Khoury and E. Jay Holcomb

Greenhouse substrates are designed to allow maximum aeration. Substrate water holding capacity can be increased by media compaction.

Six inch standard pots, fitted with gas tight openings for removing gas samples, were filled with Metromix 350 and Peatwool at 2 different compaction rates. Half the pots were planted with rooted cuttings of Poinsettia pulcherrima `Glory' and half were left fallow. Air samples were taken at both wet and dry soil moisture conditions at early, mid point and at the end of the cropping cycle. In general, wet substrates had higher CO2 than drier substrates and more compacted substrates had higher CO2 than less compacted.

CO2 decreased with time in all treatments. The highest CO2 levels occurred in wet heavily compacted Peatwool with a plant and the lowest occurred in dry Metromix with no plant.

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E. Jay Holcomb and Paul N. Walker

Coal gasification slag is an ash byproduct remaining after the volatization process. This material is currently under utilized. A series of experiments were conducted to determine the suitability of coal gasification slag as a growing medium or growing medium amendment. Chrysanthemums, lettuce, poinsettias and some bedding plants were grown in slag or slag amended media in an ebb and flow fertigation system. Slag alone has a high pH and initial slag samples had some very small particle sizes. Plant growth in slag alone was poor because of high pH and low aeration. When slag was amended with moss peat, the pH was lowered to an acceptable range and the aeration was better. Plant growth in peat-slag media was equal to plant growth in a peat-perlite mix. Media composed of peat-slag and bark were also successful in producing crop growth equal to peat-perlite. There were no nutritional problems growing in slag amended media except that boron uptake by chrysanthemum was greater than in other media. Eliminating the small particle sizes by washing the slag makes the slag easier to handle, but does not produce crop growth equal to slag amended media.

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Thomas M. Contrisciano and E. Jay Holcomb

The objective of this research was to develop a mineral wool based growing medium for the horticultural industry. Two types of hydrophilic mineral wool, clean wool (CW) and unclean wool (UC) were used unamended, as well as both types in combinations with 25, 50, and 75 percent peat moss (PM). A control of 100 percent (PM) was also used. Unamended CW had a low bulk density, excellent water holding capacity, good aeration, but high pH. Once PM was added to CW, bulk density still remained low, water holding capacity and aeration remained good, and the pH dropped to a more suitable level. Unamended UW had a high bulk density, good water holding capacity, poor aeration, and high pH. Once PM was added to UW, bulk density decreased, water holding capacity remained good, aeration increased, and pH decreased to a more optimal level. Impatiens `Violet' and Begonia `Whiskey' were grown in the nine treatments for six and nine weeks respectively. At harvest, plant growth was evaluated by height, diameter, fresh weight, dry weight, and tissue analysis. Plant growth response showed plants grown in unamended CW, UW, and PM were smaller in size and lighter in fresh and dry weights than those in 50 percent wool/50 percent PM. The plants grown in 25 and 75 percent PM were similar to the 50 percent wool/50 percent PM in size and weight.

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Jay Young, Charles Heuser, and E.J. Holcomb

The use of spent mushroom compost (SMC) as a media amendment for containerized greenhouse and nursery crop production is a promising alternative to disposal of this by-product of mushroom production. Fresh SMC is the compost that is removed from the mushroom house and used without further weathering. The objectives of this study include first, identification of key factors involved its successful use and second demonstration of the effective use of SMC by nurserymen. The plant material used includes both bedding plants and woody perennial species. Results demonstrate that the key factor in the use of SMC for plant production is high soluble salts. Leaching can reduce the high soluble salts. In addition, special consideration should be given to the reduction in potted media volume over time due to composting that continues after the material is removed from mushroom production. SMC as the sole growing media was not as effective as when SMC was amended with a commercial nursery growing mix. Several species were grown in 0%, 25%, 50%, 75%, and 100% mixtures of SMC and a commercial nursery mix. All species grew well in 50% SMC/50% nursery mix.

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E. Jay Holcomb, Robert Berghage, and William Fonteno

The concepts of container water-holding capacity and air-filled porosity are important yet complicated for students interested in containerized crop production; however, both of these concepts can be observed and understood more completely if students develop a moisture retention curve. Our objectives were to describe an easy-to-construct and economical apparatus for creating a moisture retention curve and then to compare this curve with one generated by standard methods. The student method (column method) is constructed from plastic pipe cut into 5-cm sections. The sections of pipe are individually packed with a substrate then stacked and taped together, resulting in a 60-cm column of the substrate. The column is saturated and allowed to drain for 24 h. Then, the column is taken apart and the water content of each section determined gravimetrically. The water content of each section is graphed against height so that the result is a moisture retention curve. Data are presented to show the curve developed from the column method is similar to the curve developed by standard soil moisture tension method. The moisture retention curve can provide a better understanding of water and air holding capacities of substrates.

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Jonathan Phillips, E. Jay Holcomb, and Kathleen Kelley

Three intercept surveys were conducted at the Southeast Research and Extension Center in Landisville, Pa., at three separate field days during the period of 28 July to 4 Aug. 2004 to determine grower (n = 78), retailer/landscaper (n = 52), and consumer (n = 55) interest in annual planters. Survey participants were self-selected and asked to answer questions evaluating their preferences and past experience with annual planters. Consumer participants also evaluated planters based on flower-color harmony, container style, and price on a scale of 1 to 7 (1 = very unlikely to purchase, 7 = very likely to purchase) and answered sociographic and demographic questions. Container evaluations were analyzed using conjoint analysis to determine consumer preferences. Price was found to be the most important factor, accounting for 43.1% of the decision to purchase an annual planter. No significance was found comparing the lowest ($19.98) and middle ($29.98) prices; however, both were significantly more preferred than the highest price point ($39.98). Color harmony was the next most important factor, accounting for 34.9% of the decision to purchase followed by container style (22.0%). When asked what they would pay, on average, for the containers on display, consumer participants responded with a price of $25.68. A majority of retail/landscape participants in this study had never sold annual planters within their company (75.0%), whereas a majority of grower participants had produced annual planters in the past (75.0%). Retailer/landscape participants also indicated that they would charge their customers an average retail price of $31.67, which was 14% less than the growers’ suggested average retail price of $36.83 based on the $21.68 wholesale price they assigned.

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E. Jay Holcomb, Silvia Gamez, David Beattie, and George C. Elliott

Ebb-and-flow irrigation reduced water and fertilizer use by ≈ 40% when compared to overhead hand-watering by hose in the production of Hedera helix. In contrast, water and fertilizer use were not significantly different between ebb-and-flow and drip irrigation systems in the production of Asiatic hybrid lilies. Adequate growth of Hedera helix `Baltica' was obtained with 50 mg N/liter of 20-10-20 (20N-4.4-16.6K) or 20-19-18 (20N-8.4P-14.9K). Also, good market-quality hybrid lilies were produced with 75 mg N/liter of 20-19-18 (20N-8.4P-14.9K), 16-4-12 (16N-1.8P-10K), 20-0-20 (20N-0P-16.6K), and 20-10-20 (20N-4.4P-16.6K).

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Yuan-ling P. Lin, E. Jay Holcomb, and Jonathan P. Lynch

Alumina granules charged with P were used as an amendment to improve the ability of a soilless medium to retain P and provide it to plants. Commercially available alumina was acidified, saturated with P, and evenly distributed in a medium of peat, vermiculite, and sand to grow potted marigolds (Tagetes spp.) to a commercially salable stage. Marigolds grown in medium amended with P-charged alumina had adequate nutrition and similar or superior shoot growth (as measured by height, number of branches, and flower production) and fresh and dry weights compared to marigolds grown using commercial fertilizer. Phosphorus-charged alumina at 1% or 2% of total medium volume was sufficient to grow marigolds for at least 8 weeks and substantially reduced P leaching compared to conventionally fertilized controls. Alumina amendments in this range did not cause Al toxicity, as evidenced in root growth and leaf Al content.