Background. Various plant hormones are used (cytokinins, auxins) to increase the regeneration efficiency and the net reproduction rate of buckwheat in vitro. However, the growth and development rates of plantlets have been noted to be low under these conditions. For this reason, search for the plant extracts that are able to stimulate the regenerative ability of plants is a promising direction of biotechnological research.Materials and methods. Aseptic single-node cuttings of common buckwheat plantlets (varieties Dikul and Izumrud) were grown on MS nutrient media with plant extracts from Fagopyrum esculentum and Reynoutria japonica (0.1, 0.5, and 1%) for 21 days. The following morphobiological paramaters of the plantlets were evaluated: plant height, the number of internodes, the number of leaves, leaf length, and the number and length of roots.Results. Dealcoholized aqueous solutions of the extracts from F. esculentum and R. japonica in the studied concentrations (0.1-1%) significantly stimulated the growth and development of the buckwheat plantlets increasing their net reproduction rate (4.00-6.00) and rhizogenesis. The media with the plant extracts in concentrations of 0.1-0.5% were observed to produce the strongest positive effect. As the result, the morphobiological characteristics of the plantlets and the success rate of the micropropagation were the highest.

The role of plant extracts in the process of induction of embryogenic structures and its following development in plants is revealed. Thus, the addition in the culture medium of the extracts diluted in DMSO increases the rate of gynoand androgenesis on 2.4% as compared with control. Experimentally proved that the plant extract derived from the reproductive organs of certain genotype increases the morphogenetic potential of isolated organs only of the same genotype.