Particularities of micropropagation of valuable genotypes of the genus Populus L. in vitro

The peculiarities of morphogenesis, the process of shoot proliferation multipli-cation of different genotypes of poplar in culture in vitro, which were distinguished by high economic value in experimental plots, forest plantation and variety test plots, were studied. The optimal composition of the culture medium and the concentration of hormones for the initiation of the in vitro culture, shoot proliferation and multipli-cation was determined. An accurate protocols for the in vitro propagation of the 7 clones Ukrainian breeding of poplars: «Zahidna», «Perspectivna», «Lubens`ka», «L`vivs`ka», «Gul-liver», «Druzhba», «Novoberlins`ka» have been developed. The cuttings from the plants were harvested before the beginning of the growing season. Annual shoots were germinated under laboratory conditions to produce green non-lignified shoots with active growth points, which were used for in vitro culture. Origin of plant material was sterilized with used the method developed by the URIFFM. Surface sterilization: plant material was immersed in household detergent «Domestos» (a concentrated solution of sodium hypochlorite and synthetic deter-gents) diluted with distilled water on a 3 : 1 ratio for 5 minutes. Plant material was washed three times with sterile distilled water to remove re-sidual corrosive substances. After this, the explants were immersed in ethanol (70%) for 5 minutes. At the end of sterilization, the material was washed three times with sterile distilled water. Explants were planted on a culture medium under conditions of the laminar box. In our experiments MS (Murashige and Skoog medium), WPM (Woody Plant Medium) and GD (Gresshoff & Doy) medium supplemented with 0.1-0.3 mg/l 6-benzyladenine (BAP) were used. Morphogenetic activity of all studied poplars clones after several passages was high in all selected cultural medium and all concentration of 6-benzyladenine. At the same time, the influence of the cultural medium on the success of shoot proliferation was significant. The possibility of shoot proliferation was due to the salt composition of the culture medium (83.8%), by the concentration of hormones (0.3%), and 15,9% was due to the action of factors that were not counted, including the influence of the geno-type. Shoot proliferation was slightly better on the MS medium (61.7% and 72.3% with the addition of 6-benzyladenine at a concentration of 0.1 mg/l and 0.3 mg/l, re-spectively). It was established that the formation of adventitious buds by explants was due to the concentration of hormones (69%), by the salt composition of the medium (22%), and by the action of other factors (9%). It was also observed that the genotype has been significant effect on all the characteristics that were studied. The most promising morphogenetic activities were clones of poplars «Perspectivna», «Lubenska», «Druzhba», and «Novoberlins`ka». The proliferation of shoots occurred intensively in the clones of «Druzhba» and « Za-hidna «. Clones of «Zahidna», «Gulliver», «Druzhba» and «Novoberlins`ka» showed the best ability to form adventitious buds. Bud initiation and shoot proliferation were found to be best on Murashige and Skoog»s (MS) medium supplemented with 6- benzyladenine at a concentration of 0,3 mg/l (BAP).