With the end of the civil war in Lebanon in 1990, the demand for low-maintenance landscape plants has been increasing as a result of extensive reconstruction projects. The Lebanese flora was last described by Mouterde (1966, 1970). Since then, the natural vegetation has experienced habitat fragmentation and destruction as a result of tourism and urban expansion, overgrazing, overexploitation of natural resources, and the impact of successive wars. The Lebanese government has been taking in situ conservation measures turning selected threatened habitats into ”protected areas” or ”nature reserves” (UNEP, 1996), but there are no ex situ biodiversity conservation programs such as growing native plants for landscape use. Currently in Lebanon, landscape woody plants are being imported from many countries (Italy, Spain, Syria, Egypt, United States), although a large number of Lebanese taxa have potential economic value for ornamental or medicinal use (UNEP, 1996). There is a great potential for developing a native plant production industry because of the country's floristic richness estimated at 3761 vascular plant species (UNEP, 1996).
Research in the field of nursery production is very limited in Lebanon. In contrast, a considerable number of research papers discuss recommended nitrogen (N) fertilizer rates for woody ornamentals grown in container production systems in the United States (Gilliam et al., 1980, 1984; Ingestad, 1979; Jull et al., 1994; Larimer and Struve, 2002; Lumis et al., 2000; Musselwhite et al., 2004; Stubbs et al., 1997; Wright and Niemiera, 1987). The recommended N fertilizer rates ranged from 20 to 400 mg N per liter depending on the species used and the frequency of fertilizer applications.
In a previous study, we demonstrated that another native Lebanese species, Cercis siliquastrum, Judas tree, was amenable to container production (Zahreddine et al., 2007a). This article describes a similar experiment with two additional native Lebanese species with ornamental traits, Malus trilobata (Schneid.) and Acer syriacum (Boiss. and Gaill.). The two species are not commonly grown in Lebanese nurseries and there are no reports on container production or nutrient partitioning of the species elsewhere.
Malus trilobata, “erect crab” or “three-lobed apple tree”, belongs to the Rosaceae family. It has an upright habit with horizontal branching and a mature height of 13 m (Anonymous, 1999). The leaves are maple-like and deeply three-lobed. They turn from orange to red to deep purple in the fall. The tree blooms during April and May producing white flowers and yellow fruits. Hillier and Sons (1973) reports that the species is distributed in the eastern Mediterranean region and northeast Greece adding that the species is comparatively rare and distinct; Mouterde (1966) also reported that it is rare but endemic only to Lebanon. In Lebanon, it is found in the supra-Mediterranean zone at an altitude of 1,000 to 1,500 m in association with Ostrya, Sorbus, Fraxinus, and Abies species in sandy loam, high pH soils (Zahreddine et al., 2007b).
Acer syriacum (Boiss. and Gaill.), Syrian maple, is in the Aceraceae family. It reaches 8 m tall. The leaves are semievergreen to evergreen, glabrous, with three short, acute, or broad lobes. If fall color develops, it ranges from yellow to pink. White to yellow flowers are produced from February to March and the tree develops divergent samaras. It is also native to Syria, Cyprus, and Palestine (Mouterde, 1966). The species grows in the thermo-Mediterranean zone in Lebanon (0 to 500 m altitude). It is reported to be indifferent to soil type but is mainly found in calcareous soils (Anonymous, 1999). Its wood is commonly used for firewood and cabinet making. There is some confusion regarding its taxonomy.
The purpose of this study was to determine the effects of two fertilizer rates on growth, dry weight distribution, mineral nutrient content and distribution, and mineral nutrient uptake efficiency of Malus trilobata and Acer syriacum container-grown seedlings.
Anonymous 1999 Les Principaux Arbres du Liban: La Fascicule des Essences Forestieres du Liban. Projet d'assistance a la protection de la couverture vegetale au Liban Ministry of Agriculture and European Union
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Gilliam, C.H., Still, S.M., Moor, S. & Watson, M.E. 1980 Effects of three nitrogen levels on container-grown Acer rubrum HortScience 15 641 642
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Lumis, G., Purvis, P. & Taurins, L. 2000 Flood irrigation of container-grown Euonymus and Thuja as affected by fertilizer rate and substrate J. Environ. Hort. 18 13 17
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Stoven, A. 2004 Development of an Ohio tree liner production system using retractable-roof greenhouses Graduate School of The Ohio State University MSc Thesis.
Struve, D.K. 1995 Nitrogen, phosphorus and potassium recovery of container-grown red oak and blackgum seedlings under different fertilizer application methods J. Environ. Hort. 13 169 175
Stubbs, H.L., Warren, S.L., Blazich, F.A. & Ranney, T.G. 1997 Nitrogen nutrition of containerized Cupressus arizonica var. glabra ‘Carolina Sapphire’ J. Environ. Hort. 15 80 83
Xu, X. & Timmer, V.R. 1999 Growth and nitrogen nutrition of Chinese fir seedlings exposed to nutrient loading and fertilization Plant and Soil 216 83 91
Zahreddine, H.G., Struve, D.K. & Talhouk, S. 2007a Growth and nutrient partitioning of containerized Cercis siliquastrum L. under two fertilizer regimes Scientia Hort 112 1 80 88
Zahreddine, H.G., Barker, D.J., Quigley, M.F., Sleem, K. & Struve, D.K. 2007b Patterns of woody plant species diversity in Lebanon as affected by climatic and soil properties Lebanese Science Journal 8 21 44