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ŠUMARSKI LIST 1-2/2019 str. 55     <-- 55 -->        PDF

Provenance variation in germination and seedling growth of Rhododendron ponticum L.
Varijabilnost provenijencija u klijavosti sjemena i rastu sadnica vrste Rhododendron ponticum L.
Muberra Pulatkan, Asena Sule Kamber
Rhododendron ponticum is a popular shrubby plant in landscape architecture planting designs. It is especially effective when used in large groups, due to its form, foliage and flower aesthetics, as well as its functional properties. The plant is indigenous tomany mountainous and forested areas of different elevations. In the present study, the germination success of Rhododendron ponticum seeds obtained from three different provenances in NE Turkey: Zafanos (39º46’N, 40º56’E, 592m), Maçka (39º39’N, 40º41’E, 1234m) and Zigana (39º24’N, 40º39’E, 1744m) was investigated under greenhouse conditions (25 ± 2ºC, 70 ± 2% Humidity). After germination, seedling sizes and root length were determined. The highest germination rate (78.91%) was obtained with the seeds collected from Maçka (1234m). The development of the seedlings demonstrated that the greatest height and root length values were obtained with the seedlings collected at the Zafonos site (592m).It was found that germination success was not effectively correlated with the rate of seedling development.
Key words: Rhododendron ponticum; germination; seedling growth; provenance variation
The genus Rhododendron of the Ericaceae family contains over 600 species (Cross, 1975). It is a shrubby plant with many aesthetic qualities, such as having fragrant, brightly-colored flowers in many different colorsblossoming at different periods, beautiful autumn colors and attractive foliage.
The natural habitat of Rhododendron is generally the mountains, wherethe climate and soil conditions are most suitable for the growth of Rhododendron and result in its prevalence around the world. This terrain can be characterized by abundant rain and cool-temperate to cold temperatures (Reiley 1995). The most common Rhododendron habitats include the southernmost upland parts of Asia (Coombes 1998), much of Northern Europe and North America, and they occur extensivelyin China and the Himalayas. They are also found in the southern Black Sea area, the south-eastern corner of the Caucasus, northeastern Turkey and southeastern Bulgaria, as well as in Lebanon, Southwest Spain and Central Portugal (Jessen at al. 1959; Cross 1975; Davis 1978).
The Rhododendrons often have shallow roots. The roots beneath the organic foliage layer also developwith the materials in the soil layer outside the soil and demonstrate a rapid and broad growth on the surface (Clarke 1982).