Arboriculture & Urban Forestry 33(4): July 2007 281 locations. One possible explanation is the provenance sources for the seed-grown B. nigra seedlings. Experiments under controlled conditions indicated that wa- ter-deficit stress reduced tree height of birch genotypes (Fort et al. 1998; Pääkkönen et al. 1998; Wang et al. 1998). Similar reductions were observed for most birch trees investigated under the field conditions at Fayetteville (data not shown). Betula populifolia ‘Whitespire’ was reported to be better adapted to dry sites than B. nigra, B. maximowicziana, B. papyrifera, B. pendula, and B. populifolia in a study under controlled conditions (Ranney et al. 1991). However, its growth was among the lowest at Fayetteville (Figures 1 and 2), and the difference between the growth of WW plants and WS plants was not significant (data not shown). Dirr’s (1998) observation at a nursery indicated that ‘Cully’ was superior in every aspect when compared with ‘Whitespire’. CONCLUSION Based on the tree survival, growth, and annual change of the 20 birch genotypes, B. nigra ‘Cully’, B. בRoyal Frost’, B. pendula, B. nigra ‘BNMTF’, B. davurica, and B. papyrifera could survive and be used for landscape use in the southern United States. Betula pendula ‘Trost’s Dwarf’, B. ermanii, B. albosinensis, B. populifolia ‘Whitespire’, B. papyrifera ‘Uenci’, B. lenta, B. maximowicziana, B. utilis var. jacque- montii, and B. alleghaniensis would not perform well in land- scapes in the southern United States. Of the six birch genotypes recommended for the southern United States, Betula nigra ‘Cully’, B. nigra ‘BNMTF’, and B. davurica have creamy white to reddish brown peeling bark. Betula בRoyal Frost’, B. pendula, and B. papyrifera have distinguished white bark. Leaves on B. בRoyal Frost’ are burgundy red in spring and the color fades off slightly during summer, and turned to red or orange–red in the fall. The other five genotypes have yellow fall foliage. All six genotypes have pyramidal habit and could be used as speci- men or shade tree in the landscape. Acknowledgments. We thank Manjula Carter for technical assis- tance at the Southwest Research and Extension Center, Hope, AR, and for financial assistance from the Research Incentive Grant Pro- gram at the University of Arkansas. LITERATURE CITED Atkinson, M.D. 1992. Betula pendula Roth (B. verrucosa Ehrh.) and B. pubescens Ehrh. Journal of Ecology 80: 837–870. Dirr, M.A. 1998. Manual of woody landscape plants: Their identification, ornamental characteristics, culture, propa- gation and uses. 5th ed. Stipes Publishing L.L.C., Cham- paign, IL. Farrar, J.L. 1995. Trees of the northern United States and Canada. 1st ed. Iowa State University Press, Ames, IA. Fort, C., F. Muller, P. Label, A. Granier, and E. Dreyer. 1998. Stomatal conductance, growth and root signaling in Betula pendula seedlings subjected to partial soil drying. Tree Physiology 18:769–776. Furlow, J.J. 1990. The genera of Betulaceae in the southeast- ern United States. Journal of the Arnold Arboretum 71: 1–67. Krussmann, G. 1984. Manual of cultivated broad-leaved trees and shrubs. 1st ed. Timber Press, Beaverton, OR. Ladjal, M., D. Epron, and M. Ducrey. 2000. Effect of water deficit preconditioning on thermotolerance of photosys- tem II and susceptibility of photosynthesis to heat stress- ing cedar seedlings. Tree Physiology 20:1235–1241. Pääkkönen, E., J. Vahala, M. Pohjolai, T. Holopainen, and L. Kärenlampi. 1998. Physiological, stomatal and ultrastruc- tural ozone responses in birch (Betula pendula Roth.) are modified by water stress. Plant, Cell & Environment 21: 671–684. Ranney, T.G., R.E. Bir, and W.A. Skroch. 1991. Comparative water deficit resistance among six species of birch (Betula): Influence of mild water stress on water relations and leaf gas exchange. Tree Physiology 8:351–360. Ranney, T.G., and M.M. Peet. 1994. Heat tolerance of five taxa of birch (Betula): Physiological responses to supra- optimal leaf temperatures. Journal of the American Soci- ety for Horticultural Science 119:243–248. Santamour, F.S. Jr. 1999. Progress in the development of borer-resistant white-barked birches. Journal of Arbori- culture 25:151–162. Santamour, F.S. Jr., and L.N. Lundgren. 1997. Rhododendrin in Betula: A reappraisal. Biochem. Systemat. Ecol. 25: 335–341. Wang, J.R., C.D.B. Hawkins, and T. Letchford. 1998. Rela- tive growth rate and biomass allocation of paper birch (Betula papyrifera) populations under different soil mois- ture and nutrient regimes. Canadian Journal of Forest Re- search 28:44–55. Zwack, J.A., and W.R. Graves. 1998. Leaf water relations and plant development of three freeman maple cultivars subjected to water deficit. Journal of the American Soci- ety for Horticultural Science 123:371–375. Mengmeng Gu (corresponding author) (formerly) Department of Horticulture University of Arkansas Fayetteville, AR 72701, U.S. (currently) Department of Plant and Soil Sciences Mississippi State University PO Box 9555 Mississippi State, MS 39762, U.S.
[email protected] ©2007 International Society of Arboriculture
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