РАННІ ЕТАПИ ОНТОМОРФОГЕНЕЗУ ДЕЯКИХ РІДКІСНИХ ВИСОКОГІРНИХ ВИДІВ РОДИНИ ASTERACEAE

Abstract

In the paper there are provided the results of examining the processes of latent and pregenerative period of four rare high-mountain Asteraceae plant species ( Aster alpinus , Saussurea alpina , Achillea schurii , A. lingulata ) sampled from the native populations in the Ukrainian Carpathians. The previously known from the literature data were confirmed: large seeds with higher content of reserved substances show lower values of seed germination ( Saussurea аlpina , Aster alpinus ). During the 5 month-period the highest level of seed germination was observed in Achillea schurii (84 %) and Achillea lingulata (75 %). Thus, the germination ability of seeds, stored 3-years, maintained high ( Achillea lingulata ), considerably decreased ( A. schurii , Saussurea аlpina ), or was completely lost ( Aster alpinus ). The seed germination intensity differed within studied species and was the highest during the first month in both Achillea species , and during the first and second two decades in Saussurea аlpina and Aster alpinus respectively. Germination started within first decade and appeared to be epigeal hypocotylar (but cotyledonal in Saussurea аlpina ). Lateral and additional roots appeared in one-month old seedlings of Achillea lingulata , in two-month old seedlings of Aster alpinus , and much la­ter in seedlings of Saussurea аlpina and Achillea schurii . Seedlings after forming the first leaf were transplanted into substrate from the Petri-dishes. Further morphogenesis processes were observed. The cotyledons died back in the 4–5-months old individuals ( Aster alpinus , Achillea lingulata ) and older ( Saussurea аlpina , Achillea schurii ). Juvenile individuals of four studied species formed the main shoots of rosette type. Yet, Aster alpinus and Achillea schurii individuals additionally formed elongated shoots. All immature individuals formed uniaxial main shoot. Though, it was also two-axial ( Aster alpinus , Achillea lingulata ) and three-axial ( A. schurii ) due to the development of aerial lateral shoots from the buds initiated in the axils of stem leaves. During the same ontogenetic state the formation of underground plagiotropic shoots was observed in Achillea schurii and Saussurea аlpina . The shoots origi­nated from the axillary buds within proximal three basal nodes buried in the substrate. Therefore, during pregenerative period there was observed the formation of rhizome, enab­ling the development of adaptations to the particular habitat.