Variability of morphometric parameters in naturalized and cultivated Hydrangea macrophylla Ser. plants under different environmental conditions

Plants cultivated in humid subtropics of Russia are mostly exotic species. One of them, Hydrangea macrophylla Ser., can grow in city parks and gardens, as well as in the forest of Sochi suburb as a component of adventive flora, thus, the H. macrophylla habitat conditions differ significantly. To estimate the genetic resources, implement breeding programs and optimize plant cultivation, an adaptability and intraspecial variability of plants must be evaluated. In our observation in Sochi region during 2006-2008 carried out on the Black Sea coast (in the garden-museum «Tree of Friendship» and in Kuban Subtropical Botanic Garden) and in the mountain area (Krasnaya Polyana and Solokh-Aul settlements), a phenotypic variability of morphological traits was analyzed in naturalized and cultivated H. macrophylla plants (Madame Faustin Travouillon and Madame Faustin Travouillon cultivars), and an influence of the external conditions to the range of variations was investigated. It was shown that genotype considerably influenced the plant height (63.5 %), leaf length (82.0 %), inflorescence diameter (19.3 %) and bract length (84.1 %). Climatic factors of the year also affected leaf width in both cultivars (22.5 %). With increase in height above sea level (400-600 m in settlements Krasnaya Polyana and Solokh-Aul) most of the morphometric parameters increased. Maximum changes were observed in inflorescence diameter and bract length (30.1-55.4 % in Madame Faustin Travouillon and 26.5-71.5 % in Madame Maurice Hamard), indicating optimization of a complex of abiotic and edaphic factors at this high-rise level. The lowest variability (5.5-12.3 %) was indicated in shoot length both in cultivated and naturalized plants. In general, naturalized and cultivated plants differed considerably. The bract length and inflorescence diameter were the most variable, at 37.5-80.1 % and 17.9-31.2 %, respectively, when compared in H. macrophylla from city biocoenoses and settlements of Krasnaya Polyana and Solokh-Aul being higher in naturalized plants. Leaf length variation in cultivated plants ranged from 15.8 to 20.7 % being at 34.9 % in plants grown in Solokh-Aul. Thus, the range of variability on most of the tested morphological traits was wider in the naturalized plants if compared to the cultivated plants with slightly changed parameters. Therefore, the plants growing in city biocoenosis are more leveled on an individual development.