Peculiarities of determining the morphogenesis of plants Corylus avellana L. and Prunus dulcis (Mill.) D.A.Webb in vitro culture

ABSTRACT The purpose of the research was to identify the physiological–biochemical and anatomical–morphological peculiarities found during in vitro cultivation of Corylus avellana L. and Prunus dulcis (Mill.) D.A.Webb, which occur as a result of the action of trophic and phytohormonal determinants. The research was conducted on three hazelnut varieties (Trapezund, Jefferson, Tonda Gentile Romana) and four almond varieties (E5 Borozan, M41 Alex, Georgia, Louise). A theoretical and experimental rationale for their use in the microclonal propagation of these cultures has been developed. The effectiveness of the preparatory stage before introduction into aseptic conditions for growing mother plants in closed soil conditions with scattered artificial lighting and microbiological protection has been proven. This reduced self-intoxication by oxidation products with phenol-like substances and microflora contamination of primary explants. Among the nutrient media compared, the best was Nas and Read (NRM) for hazelnuts and Nas Almond Medium (NAM) for almonds. Passaging on the same media leads to a decrease in regeneration indicators. In regenerants of almonds, the rosette of the shoots was noted, and in hazelnuts, the death of apical buds was also found. To prevent this, alternating NRM and driver and kuniyuki walnut (DKW) media for hazelnuts and NAM and Quirin and Lepoivre (QL) for almonds was effective. Long-term cultivation on media with a high content of synthetic analogues of phytohormones leads to the accumulation of phytotoxic effects with each subsequent passage. The phytotoxic effect of cytokinins was manifested in hyperhydration of shoots and of auxins in callus fertilisation. On comparing the ontogenesis of regenerants from explants isolated from mother plants aged 30–180 days, it was found that the optimal age for hazelnut and almond was 90 days. To reset the trophic and hormonal determinants, the introduction of explant donors into a state of dormancy has been successfully used. At the final fourth stage of microclonal propagation, in order to adapt plants simultaneously with an increase in the number of regenerants, it is effective to use the photoautotrophic method of microclonal propagation with intensive lighting and air enriched with carbon dioxide. For the transition of plants from conventional heterotrophic propagation to autotrophic cultivation, an intermediate stage of pre-adaptation of regenerants in wet chamber conditions is effective.