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Mason T. MacDonald, Rajasekaran R. Lada, Martine Dorais, and Steeve Pepin

, increases cellulase activity in needles, and triggers needle abscission ( MacDonald et al., 2011a ). Several studies have linked declining XPP to needle abscission in conifers ( Chastagner and Riley, 2003 ; Hinesley and Snelling, 1991 ; Montano, 1985

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Jeong-Ho Lee

available for wholesale, by mail order, and from a few retail nurseries. The Ansu Pine Plantation has stocks of these cultivars available for general distribution. Literature Cited Bitner, R.L. 2007 Conifers for gardens: An illustrated encyclopedia Timber

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F.J. Bigras and A.L. D'Aoust

Seventeen weeks old white spruce seedlings were hardened under 8 h or 16 h photoperiod for 28 d at 15°C (12 h) followed by 21 d at 3°C (8 h photoperiod) and 28 d at 0°C without light. Dehardening conditions were a 14 h photoperiod at 10°C for 21 d followed by 18 d at 20°C. Frost tolerance of whole plants and exised organs were measured at regular intervals. An earlier rehardening was observed for plants hardened under short day treatments. Similar results have been reported for black spruce in independant studies. Hypotheses to explain this phenomenon will be presented based on bud phenology, mineral content, sugar analyses and morphological data.

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Grant Jones*, Bert Cregg, and Katrina Schneller

The genus Abies is a member of the family Pinaceae and consists of approximately 55 species found mainly in upper latitudes or higher elevations in the northern hemisphere. Firs generally prefer cool, well-drained sites with acidic soil. Fir trees are occasionally used as landscape trees but are more commonly grown as Christmas trees. Recently, the Michigan State Univ. Forestry Dept. and the Michigan Christmas tree industry initiated a field test of exotic firs (Abies sp.) for potential use as Christmas trees. In the present study we expanded the evaluation of these exotic fir species to include their suitability as landscape trees and to characterize their tolerance to various environmental stresses. We compared foliar nutrition, gas exchange, chlorophyll fluorescence, and shoot morphology of 23 Abies species and hybrids planted at three horticultural research stations in Michigan. Foliar nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), boron (B), zinc (Zn), and copper (Cu) were correlated (P < 0.05) with soil pH. Species and hybrids varied (P <0.05) in maximum photosynthetic rate, water use efficiency, chlorophyll fluorescence, and the ratio of total needle area to projected needle area. We will discuss the significance of these traits in relation to selecting trees adapted for use in the Midwestern landscape.

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Gerald A. Tuskan, Emile J. Poisson, and Wayne A. Sargent

Benzylaminopurine and chlorflurenol were applied to 2-1 nursery stock of Scots pine and ponderosa pine and 2-0 nursery stock Colorado blue spruce and Black Hills spruce to determine if crown morphology was influenced by varying combinations of the two plant growth regulators. Four levels of benzylaminopurine, 0, 250, 750 and 1250 ppm, and two chlorflurenol levels, 0 and 1% (v/v) were tested. Morphological response to treatments was significantly enhanced when treatments were applied to open, elongating buds. Benzylaminopurine significantly increased bud and shoot formation, while chlorflurenol significantly reduced height and increased branch length at species dependent concentrations. The two plant growth regulators lacked positive synergistic effects.

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Gerald A. Tuskan, Emile J. Poisson, and Wayne A. Sargent

Benzylaminopurine and chlorflurenol were applied to 2-1 nursery stock of Scots pine and ponderosa pine and 2-0 nursery stock Colorado blue spruce and Black Hills spruce to determine if crown morphology was influenced by varying combinations of the two plant growth regulators. Four levels of benzylaminopurine, 0, 250, 750 and 1250 ppm, and two chlorflurenol levels, 0 and 1% (v/v) were tested. Morphological response to treatments was significantly enhanced when treatments were applied to open, elongating buds. Benzylaminopurine significantly increased bud and shoot formation, while chlorflurenol significantly reduced height and increased branch length at species dependent concentrations. The two plant growth regulators lacked positive synergistic effects.

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L.E. Hinesley, D.M. Pharr, L.K. Snelling, and S.R. Funderburk

Foliar raffinose and sucrose concentrations in eastern white pine (Pinus strobus L.), eastern redcedar (Juniperus virginiana L.), Leyland cypress (×Cupressocyparis leylandii Dallim.), and Virginia pine (Pinus virginiana L.) were measured monthly over 2 years. During cold weather, foliage of white pine and redcedar contained higher concentrations of raffinose and sucrose than did Leyland cypress and Virginia pine. Rafflnose concentrations were highest during winter and were best correlated with the frequency of occurrence of daily minima ≤ 1.7C during the 30 days before sampling. Sucrose concentrations, which also reached maximum levels during the winter, were best correlated with the frequency of occurrence of daily minima ≤ 7.2C in the prior 30 days. Sucrose concentrations were relatively high during fall and spring. Raffinose and sucrose concentrations increased in response to recurring low temperature, with correlations highest for raffinose.

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John T. Harrington and James T. Fisher

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Robert J. Rouse, Paul R. Fantz, and Ted E. Bilderback

Japanese cedar [Cryptomeria japonica (Thun. ex L.f.) D. Don. (Taxodiaceae)] cultivars have become quite popular in the U.S. landscape and nursery industries. Their popularity is expected to increase as more attractive and adaptable horticultural selections gain recognition. Taxonomic problems include an inadequate inventory of selected variants cultivated in the United States, instability of names at the infraspecific taxonomic level, poor descriptions of the cultivars, and a lack of representative specimens and identification aids to help horticulturists identify unknown specimens. A study of Cryptomeria japonica cultivated in the United States is needed to address these problems.

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Bridget K. Behe, Rachel M. Walden, Marcus W. Duck, Bert M. Cregg, Kathleen M. Kelley, and R.D. Lineberger

An aging American population may be less willing than a younger population to install and remove a live, fresh-cut evergreen tree in their home for Christmas celebrations. An alternative to using traditional, large, fresh-cut or potted Christmas trees could be forcing these evergreen species in a small (≈1-L) container that could be displayed on a tabletop. We initiated this study to determine consumer preferences and marketability for six evergreen tree species produced for tabletop display and used three decoration themes and three price points. We constructed a web-based survey in which 331 participants were compensated with a $5 e-coupon for viewing 27 photographs of tabletop trees and providing preference and use information. The conjoint model accounted for 91.2% of the variance and showed that consumers valued tree species as the most important attribute (61% of the tree value), with decoration color/theme the second most important feature (27%) and, last, price (12%). Black Hills spruce (Picea glauca var. densata (Moench) Voss) was the most preferred species overall, and red was the most preferred decoration theme. Logically, the lowest price point was the most preferred. However, price was the most important attribute for participants younger than 25 years. The importance of price decreased as participant age increased until age 60, when price became a more important component. With a cost of production of $5.45 and decoration and shipping estimated at an additional $4.00, the product could be a profit generator priced at any of the tested price points ($14.95 and above).