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Ex-situ conservation of wild pear, Pyrus L. (rosaceae) species at the Yerevan botanic garden, Armenia

Volume 7 Number 1 - January 2010
J. A. Akopian

Armenia is a centre of diversity for wild pear species and the collection at the Yerevan Botanic Garden provides a useful resource for researchers and educationalists.

Introduction

The ‘Flora and Vegetation of Armenia’ plot at the Yerevan Botanic Garden holds one of the oldest ex-situ collections in the Caucasus. The collection contains up to 1,000 species of Armenian flora. Plants of various types (herbs, semi-shrubs, shrubs, trees) and bio-ecological groups (geophytes, succulents, lianas, water-plants etc.) are included in the collection. This collection reflects the main elements of the plant kingdom in the Armenian Republic, with models of the main types of plant communities recreated, including those threatened in the wild. The most characteristic taxonomic composition of the flora is selected for each type of vegetation modelled at the plot. Priority is given to rare and threatened species, endemics, insufficiently studied species, and to the species of educational, ornamental or economic value.

“Crop wild relatives are an important focus of the collections at the Yerevan botanic garden”

The long history of introducing wild plants into cultivation at the plot has contributed to ex-situ conservation of the biodiversity of Armenia, including genetic resources of native crop wild relatives (CWR). Special attention has been given to the crop wild relatives since 2007, when the collection was enriched during field surveys conducted within the framework of the UNEP/GEF funded Crop Wild Relatives projects. Today the plot includes more then 200 CWR species (from 130 genera), relatives of food, fodder, ornamental, industrial and medicinal crops (Akopian, 2009). Also there are 38 wild relative species from 25 genera of pome, stone, small fruit, vine, nut and other fruit crops. Among them the collection boasts wild pear species native to the Armenian flora.

The territory of Armenia, especially the southern and south-eastern regions of the country is a center of high polymorphism and local narrow endemism in the genus Pyrus (Akopian, 2007). Intensive speciation in the genus has been promoted by several factors, including spatial isolation due to fragmentation of the land; drying of the climate, intensive hybridization, as well a long history in the area of breeding new pear varieties from ancestral species, which escape back to wild. Speciation processes in the pear forests of Armenia continue today (Mulkidzhanyan, 1973).

Creation of an indigenous wild pear collection at the ‘Flora and vegetation of Armenia’ Plot was initiated in the middle of the last century and continues to the present. Pear specimens were collected from their natural habitats from various districts of Armenia and replanted in the plot. The life cycle of wild pears is up to 50-80 years. Under ex-situ conditions, as in nature, wild pears propagate by seeds and by root suckers. The plants flower in April - May, before the leaves appear and they are cross-pollinated by insects. Fruits ripen from September to October. All ex-situ species observed are relatively drought-tolerant and frost-resistant, and do not demand highly fertile soils. Presently the following species of Pyrus are maintained at the plot (see Table 1):

Table 1. Wild pear collection at the ‘Flora and vegetation of Armenia’ plot.

Pyrus L. species Origin (districts of Armenia)Initial materialYear of first introduction
P. caucasica Fed.Gegharkunik, KotaykSeedlings1952,1969
P. georgica Kuth.MeghriSeeds1955
P. medvedewii RubtzovVayots DzorSeedlings1958
P. oxyprion WoronowMeghriSeedlings1955
P. salicifolia Pall.MeghriSeedlings, seeds1955
P. sosnovskyi Fed.KotaykSeedlings1974
P. takhtadzianii Fed.Vayots DzorSeedlings1958
P. tamamschjanae Fed.KotaykSeedlings1974
P. zangezura MaleevSjunikSeedlings1968, 1982

 

The characteristics of some of the species are provided below:

P. caucasica Fed. Tree 10 - 20 m high, thorny, Buds are from pale rose to white, flowers white, fruits round or slightly oblate. In the ex-situ collection, it is weakly shade tolerant and is resistant to diseases. It has a dense and beautiful wood. Fruits have a varied taste and are used fresh and dried, for production of vinegar and wine, and for cooking. In horticulture the seedlings of P. caucasica are used as a rootstock for cultivated pears. It is considered to be the ancestor of several native pear cultivars.

In Armenia it grows in broad-leaved forests, by river valleys, from 600 to 2,200 masl. The species was described from Armenia. General distribution: Caucasus, Northern and South-Western Anatolia. Highly polymorphic species, allied species is P. communis L.

P. georgica Kuth. Tree, seldom shrub, 3-9 m high, thorny. Flowers are plentiful, small. On the plot it blooms earlier than other pear species. Fruits are numerous, small, globular-pear shaped, green, very soft and sweet.

In Armenia it grows in broad-leaved forests, on arid slopes, from 1,200 up to 2,500 masl. The species was described from Georgia, it is endemic to Caucasus. The allied species are P. elaeagnifolia Pall, P. salicifolia Pall.

P. medvedevii Rubtzov. Tree 10-12 m high, usually thorny. Fruits are small, green-yellow, soft, sour-sweet.

In Armenia P. medvedevii grows in arid light forests, from 1,400 up to 2,200 masl. It was described from Nakhichevan. Endemic to and rare in Southern Transcaucasia. The allied species: P. еlaeagnifolia Pall., P. salicifolia Pall., P. syriаca Boiss.

P. oxyprion Woronow. Tree up to 5 m high, with dense canopy, thorny. Fruits pear-shaped, green, very hard, ripen late. It is very ornamental with glossy green leaves, and numerous rose-coloured flowers.

In Armenia it grows in arid light forests, from 1,400 up to 1,900 masl. The species was described from North-Eastern Anatolia. General distribution: Southern Transcaucasia, Northern Iran, North-Eastern Anatolia. The allied species are P. salicifolia Pall., P. syriaca Boiss., P. fedorovii Kuth.

P. salicifolia Pall. Tree 5 - 10 m high, very thorny. Flowers are from light rose to white. Fruits usually are single, round or pear-shaped, brown-golden. P. salicifolia is ornamental both in flowers and fruits. It is highly drought- and frost-resistant, can tolerate frosts down to -32оС. In horticulture its seedlings are widely used as rootstocks. P. salicifolia played an important role in the origin of cultivated pear varieties.

In Armenia it grows in mountain and arid light forests, on scree and rock slopes, in hill foots, from 600 up to 2,200 masl. The species was described from Ciscaucasia. General distribution: Caucasus, North-Western Iran, North-Eastern Anatolia. The allied species are P. elaeagnifolia Pall, P. georgica Kuth.

P. sosnovskyi Fed. Small tree or shrub with thick crown, Fruits are small, orbicular or shortly pear-shaped, yellow-green, soft, sour-sweet.

It grows in arid or broad-leaved and juniper forests, on the stony slopes, from 1,000 up to 2,000 masl. Endemic to and rare in Armenia. The allied species are P. communis L., P. caucasica Fed.

P. takhtadzhianii Fed. Thornless tree 5-7 m high, It has large, pear-shaped, brown, juicy fruits. According to some authors, it originated from ancient local pear cultivars, and is a secondary escape into the wild. P. takhtadzhianii is ornamental with a crown of grayish leaves of various shapes.

In Armenia it grows in broad-leaved and arid light forests, among mountainous xerophytic vegetation, from 800 up to 2,200 masl. The species was described from Armenia. Endemic to Transcaucasia. The allied species are P. communis L., P. elaeagnifolia Pall., P. salicifolia Pall.

P. tamamschjanae Fed. Tree 3-5 m high, usually thornless. Fruits are pear-shaped, sweet and soft, with the shape resembling that of cultivated pears. It is ornamental, especially in autumn with red colored leaves.

It grows in arid light and in broad-leaved forests, from 1,600 up to 2,200 m. Endemic to and rare in Armenia. The allied species are P. communis L., P. sosnovskyi Fed.

P. zangezura Maleev. Tree 10 m tall, usually thornless, Fruits pear-shaped-globular, after ripening soft, sour-sweet. P. zangezura is a highly frost - resistant species.

In Armenia it grows in broad-leaved mountainous forests, from 1,500 up to 2,300 m. The species was described from Armenia. Endemic to and rare in Southern Transcaucasia. The allied species is P. syriaca Boiss., which is one of main ancestors of cultivated pears.

Most of observed pear specimens have been growing in the plot collection for more than 30-50 years. The duration of plant specimens’ existence in the living collection is an important indicator of the capacity of wild plants to survive under ex-situ cultivation. So, all wild pear species introduced to the plot, can be classified as adaptable for ex-situ cultivation and conservation. Under ex-situ conditions they develop normally and multiply. At the plot they are also now represented by young specimens. Some wild pear species (P. caucasica, P. medvedevii, P. salicifolia, P. tamamschjanae) demonstrate potential for intensive vegetative reproduction under ex-situ conditions, thus providing living materials for rare species reintroduction to the natural habitats. Furthermore, most of the researched pear species are very ornamental and can be used in landscape gardening. They are valuable as food, medicinal and honey plants and for breeding drought-tolerant and frost - resistant pear cultivars.

The genus Pyrus poses difficulties for researchers, because of its remarkable species polymorphism and variability. The specimens in the collection are therefore interesting for scientific researches in the field of taxonomy, morphology and biology. Data obtained from the collection is used in the Institute of Botany’s Manual of Plants of Armenia. The collection also provides living ex-situ material for the forthcoming project ‘Fruits for a sustainable future - Assessing the patterns of diversity of the genus Pyrus in Transcaucasia’ within the context of the ‘Pan-Caucasian Plant Biodiversity Initiative - Developing tools for the Conservation of Plant Diversity in the Transcaucasus’.

The native wild pear collection also provides the basis for an exhibition that has educational significance and is of interest for visitors of the Yerevan Botanic Garden.

References

Akopian, J.A. 2009. Crop wild relative conservation on the plot ‘Flora and vegetation of Armenia’ of the Yerevan Botanical Garden. Electronic J. of Natural Sciences, 2(13): 3-7. website

http://www.epnet.com

http://www.ejns.sci.am

Akopian, J. A. 2007. On the Pyrus L. (Rosaceae) species in Armenia. Flora, vegetation and plant resources of Armenia, 16. Armenian Academy of Sciences, Yerevan. Pp. 15-26.

Mulkidzhanyan, Ya. I. 1973. New data on the pears of the Near East. Bulletin of Moscow Society of Naturalists, Biological Series, 78, 2. Moscow University Publishing, Moscow. Pp. 145 - 146.

J.A Akopian
Institute of Botany of the National Academy of Sciences,
Republic of Armenia.
E-mail: akopian_janna@inbox.ru