The strawberry tree (Arbutus unedo L.) selection in Turkey
Introduction
The strawberry tree (Arbutus unedo L.) which belongs to the genus Arbutus of Ericaceae family within Ericales is a typical evergreen plant of Mediterranean-climate. It is native to Greece, Lebanon, Ireland, Southern Europe and Anatolia (Karadeniz and Şişman, 2003). It is a bushy shrub of 1.5–3 m tall, but occasionally can reach up to 9–12 m in height (Tutin et al., 1981, Seidemann, 1995, Anonymous, 2004a). A. unedo L. distribution ranges from an altitude of 700 to 1000 m. The tree can grow on alkaline and relatively acidic soils (pH 5–7.2) (Anonymous, 2004b, Krussmann, 1982). Propagation of the strawberry tree is difficult by seed because of genetic variations and specific requirements of seed germination (Mereti et al., 2003, Tilki, 2004). Rooting percentage of cuttings is relatively low, which was determined to always be less than 65% in ex vitro (Mereti et al., 2003). In in vitro, successful results in terms of rooting and survival rate were obtained in woody plant medium (WPM) containing auxins and peat-perlite (1:4) mixture (Mereti et al., 2002, Mereti et al., 2003).
The strawberry tree is a valuable ornamental plant due to its attractive red fruits in the fall and winter, and pinkish-white flowers in the fall. Its fruits are processed into traditional products such as jam, marmalade, wine, alcohol and liqueur (Seidemann, 1995, Mulas and Deidda, 1998, Alarco-E-Silva et al., 2001, Soufleros et al., 2005), and consumed as fresh fruit. Mature A. unedo fruits are characterized by the excessive value of sugars/acids ratio and high content of non-volatile and phenolic acids, and terpenoid compounds (Ayaz et al., 2000, Alarco-E-Silva et al., 2001). Its flowers are a significant source of nectar for bees (Floris et al., 1992, Soro and Paxton, 1999). The fruits are also rich in mineral elements and vitamin C (Baytop, 1984, Alarco-E-Silva et al., 2001). The leaves of A. unedo are used in herbal medicine because of their antiseptic, diuretic and astringent properties (Karıkas et al., 1986, Sakar et al., 1991), and in the chemical industry because of its high tannin content (Vidrich et al., 1980). The leaves also have strong antioxidant activity (Pabuçcuoğlu et al., 2003).
Today uses of the strawberry tree are a result of traditional habits rather than of economics because of heterogeneity of its plants, the lack of selection, varietal identification and missing of genotypes (Jaradat, 1995). Although there are a number of studies on the chemical constituents of fruits and leaves (Ayaz et al., 2000, Alarco-E-Silva et al., 2001, Kıvçak et al., 2001a, Kıvçak et al., 2001b, Kıvçak and Mert, 2001, Pabuçcuoğlu et al., 2003), the breeding programs to obtain A. unedo cultivars with high fruit quality have rarely been attempted. Selection of A. unedo were mainly made in China and it was mentioned regarding cultivars named ‘Zaose’ (Songlin et al., 1995), ‘Dongkui’ (Jihua et al., 1997), ‘Daliziyangme’, ‘Baiyangmei’, ‘Zaohongmei’ and ‘Dahuamei’ (Cai-Huang, 1997). In Italy, the fruit characteristics of 20 different A. unedo genotypes were determined in Sardinia (Mulas et al., 1998). And also in Turkey, the phenological and pomological characteristics of A. unedo genotypes and A. andrachne L. species were determined (Karadeniz et al., 1996, Karadeniz et al., 2003, Gözlekçi et al., 2003, Şeker et al., 2004).
Two significant species of Arbutus genus, Arbutus unedo L. and Arbutus andrachne L. are commonly found in the flora of Turkey (Anşin and Özkan, 1993). Kocayemiş is a common Turkish name for strawberry tree fruit (Arbutus unedo L.). In Turkey, strawberry trees grow in maquis areas of the Mediterranean, Aegean, Marmara and Black Sea coasts (Yaltırık and Erdinç, 2002). A. unedo has been extensively found in the central North and North-west of Turkey (Davis, 1972). The strawberry tree population is generally located along the coasts in these two areas. They are rapidly disappearing because of new constructions on the shorelines. Recently, the number of facilities for tourism has dramatically increased in these areas at the expense of the strawberry tree population. Further disturbance of the habitat can bring the strawberry tree population to the brink of extinction. The purpose of this study was to select the A. unedo genotypes of superior fruit quality from the Northwestern part of Turkey, to thus help prevent extinction and to allow extensive cultivation of the strawberry trees.
Section snippets
Material and methods
This study was conducted the regions of Sinop and Samsun in 2003 and 2004. In Sinop, the study took place in the areas of Ayancık, Gerze, Erfelek and in central county. In Samsun, the study was conducted in Yakakent county. Elevation of Sinop and Yakakent are 3-1605 and 3-690 m, respectively. In these areas, the natural habitat of the A. unedo was located in between 3-83 m above sea level extensively and between 41°46′ to 41°56′N lat. and 34°41′ to 35°12′E long. Average annual rainfall is 679–1077
Results and discussion
Forty-nine strawberry tree genotypes from Ayancık, Gerze and Erfelek counties in Sinop and Yakakent County in Samsun province were examined in the year 2003. Thirteen genotypes including 57MK01, 57A10, 57GÇ01, 57GÇ08, 57A19, 57A04, 57A15, 57A01, 57A07, 57EŞ01, 57A14, 57A13, 55YÇ03 yielded the highest scores (Table 2). The genotypes 57A22, 57AK01 were added into the list in 2004. However, 4 genotypes (57A19, 57MK01, 57EŞ01, 55YÇ03) were eliminated since they did not fruit bear. Thus, 11
Conclusion
Here, we determined some characteristics of the strawberry tree grown in the Northwestern part of Turkey and selected its genotypes that had the best qualities for the characteristics tested. We will try to propagate these selected genotypes in our future studies. Thus, the strawberry tree will continue to survive and produce better quality fruits in new environments.
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