ADAPTATION OF TRIPLOID ASPEN TO EX VITRO CONDITIONS USING A HYDROPONIC SYSTEM

The results of the studies of the features of adaptation of triploid aspen regenerants obtained in vitro using a hydroponic system are discussed in the article. Triploid clones of aspen ( Populus tremula L.) are characterized by rapid growth, high wood quality and increased resistance to diseases and pests compared to diploid clones and can be used to create forest plantations. Use of clonal micropropagation is advisable to preserve the valuable gene pool of triploid forms of aspen, while the adaptation of plants to ex vitro conditions is the most difficult process. Growing plants using the hydroponic method has several advantages. Triploid aspen regenerants, in which the length of the green mass prevails over the root mass, have a normal development without signs of infection and a good turgor of the green mass when they are removed from the test tube during the adaptation. Triploid aspen regenerants with decapitation of the apical shoot have the ratio of the lengths of the green mass to the root mass is close to 1:1, while the predominance of roots with values above the average is observed. Aspen plants with a predominance of root mass over green are formed from regenerants with leaving of 2 internodes and have an average of 2 roots of the first order. Triploid aspen plants-regenerants with biometric parameters of roots 5-7 cm and green mass up to 5 cm had the highest survival rates (94.7-100 %). A gradual decrease in the leaf surface area contributes to a better survival of regenerants, while it is necessary to reduce the humidity level from 100 % at the initial stage of adaptation to 60 % within 5 days, then - on 20 % with an interval of 3 days. The period of adaptation of triploid aspen plants in a hydroponic system is 16 days.