CONSERVATION, PROPAGATION, DEVELOPMENT AND UTILIZATION OF XEROPHYTIC SPECIES OF THE NATIVE GREEK FLORA TOWARDS COMMERCIAL FLORICULTURE

Abstract

Plant material originating in wild populations, collected from various areas of Greece, has been maintained at the Laboratory of Conservation and Evaluation of Native and Floricultural Species. In the frame of the conservation program of the Balkan Botanic Garden of Kroussia (BBGK) the original collections count more than 1700 accession numbers of taxa, 17% from Labiatae family. Six aromatic species (Thymus plasonii, Th. longicaulis subsp. chaubardii, Th. degenii, Teucrium divaricatum, T. polium, T. chamaedrys) were studied. Rooting of softwood cuttings was tested for all plants using various concentrations of auxins. Young individuals produced were transplanted in trays and later in bigger pots until their final transplanting at sea level as well as at 600 meters altitude in ex situ conservation area at BBGK, northern Greece. Growth and development of the plants were monitored in every stage. The rooting percentage, the number of roots and the root length were analyzed. Data were used to provide a propagation protocol for each species. Growth and development occurred rapidly and plants showed adaptability in dry climatic conditions. The six species studied, most of them Greek and/or Balkan endemics, not cultivated in other Botanic Gardens (according to Botanic Garden Conservation International database): (a) showed excellent results when propagated by softwood cuttings, (b) present an impressive effect in landscaping due to their inflorescence and/or foliage and (c) show tolerance in low-water regimes; therefore are suggested as suitable for xeriscaping (environmental friendly landscaping rock gardens). INTRODUCTION It is estimated that up to 100,000 plants, representing more than one third of the entire world's plant species, are currently threatened or face extinction in the wild. Botanic Gardens are playing a key role in the conservation and maintenance of plants for the future. An important outcome of the 2nd World Botanic Gardens Congress in Barcelona, Spain in April 2004 was the development of a series of 20 targets for botanic gardens to be achieved by 2010, and as a contribution towards the Global Strategy for Plant Conservation (CBD, 2002). These targets briefly relate in: a) Understanding and documenting plant diversity b) Conserving plant diversity c) Using plant diversity sustainably d) Promoting education and awareness about plant diversity e) Building capacity for the conservation of plant diversity Even though Balkan Botanic Garden of Kroussia (BBGK) is a newly established garden, its objectives completely agree with the 20 targets for botanic gardens by the year 2010. The Laboratory of Conservation and Evaluation of Native and Floricultural Species and BBGK greatly contribute to the development of models with protocols for plant conservation and sustainable use, based on research and practical experience, for the rare and threatened species of Greece. Priority is given to support, promote and contribute to the integrated conservation and management of the medicinal-aromatic plants and other Proc. XXVII IHC-S5 Ornamentals, Now! Ed.-in-Chief: R.A. Criley Acta Hort. 766, ISHS 2008 206 major socio-economically valuable plants (e.g., Maloupa et al., 2000, 2003, 2005) and the maintenance of associated indigenous and local knowledge around them. Greek flora is one of the richest in the world concerning aromatic and pharmaceutical plants (Polunin, 1997; Kokkini, 1994; Kokkini et al., 1989a). Unique species and special climatic conditions make the Greek and Balkan area ideal for the selection of such kind of plants. The use of these species is in high demand, as they are related to among others, ornamental, pharmaceutical and aromatic industry. The Labiatae family includes a wide variety of species valued for their uses as culinary, medicinal, aromatic, and ornamental plants. Thymus spp. are hardy creeping perennials grown as ground covers for small spaces or in containers. They are widely used in food, pharmaceutical and cosmetics industry due to their essential oils which also have antioxidant, antispasmodic and antiseptic properties (Economou et al., 1991). The concentration of the essential oils varies greatly among the species of the genus and it is found increased at the Mediterranean endemic species (Rey, 1992; Kokkini et al., 1989). The genus Teucrium comprises more than 300 species, 49 of which grow in Europe, mostly in the Mediterranean basin. Teucrium spp. have been used as medicinal herbs for over 2000 years, as diuretic, tonic, antipyretic, antispasmodic, cholagogic and many of them are used in folk medicine (Galati et al., 2000). Furthermore, they are often pruned for their green or silver foliage into garden borders or in knot gardens. Three species of the genus Thymus (Th. plasonii, Th. longicaulis subsp. chaubardii and Th. degenii) and three species of the genus Teucrium (T. divaricatum, T. polium and T. chamaedrys) were studied. Plant material was collected form its natural habitats, maintained in mother plantation, asexually propagated, cultivated at pots, evaluated in dry conditions and applied in environmentally friendly landscaping (xeriscaping). MATERIALS AND METHODS Plant Material All native plants maintained at the nursery of the Laboratory derive from natural populations as a result of botanic expeditions conducted at floristically important areas (e.g., National Parks, NATURA 2000 sites and other protected areas). For each plant, sitespecific information was kept (location, region, altitude, longitude and latitude) as well as a detailed habitat description. All plants collected, received immediate care in the nursery. They are designated as stock plants, planted at big containers or special places according to their needs, taken special treatments since they recover from transplantation shock. Thymus and Teucrium species were collected from different areas of Greece between 1997-1999 (Table 2). Asexual Propagation Research on the asexual propagation of the six species was conducted. Softwood tip cuttings of 5-7 cm were taken during winter from mother plants developed inside the greenhouse. The effect of the auxin indole-3-butyric acid (IBA) at four different concentrations (0, 2000, 4000 ppm and powder 0.066% v/v) on root formation was tested. Cuttings were placed in propagation trays in a substrate of peat (Klasmann, KTS 1) and perlite (1:3 v/v) and maintained at bottom heat benches in a plastic greenhouse. Soil temperature was kept at 18-21°C, while air temperature was 15-25°C depending on weather conditions. Relative humidity was approximately 70-85% (mist). Experiments lasted for 15 days, followed a randomized design with 50 replications per treatment, and repeated twice. At the end of that period the number of rooted cuttings, number of roots and root length was measured. Rooted was expressed as %. Analysis of variance was performed with the General Linear Model procedure (SPSS 11.0 statistical package) and mean separation with Duncan's Multiple Range Test. Significance was recorded at P≤0.05.