Effect of nutrient density on the growth processes of micro plants of native Don varieties in in vitro culture

During microclonal propagation, agar is widely used as a thickener for solid or semi-solid nutrient media used as substrates for the regeneration and cultivation of micro plants. This component is strictly controlled and is suitable for microclonal reproduction tasks. The low turbidity of the forming gel when using agar allows to observe the development of roots, and the high strength of the gel (about 1000 g/cm2 ) allows you to use low concentrations (0.4-0.6 %). The most commonly used concentration of agar in most formulations is 0.75 %. At the same time, higher concentrations of agar are rare in studies, and are usually used to slow down growth processes and prolong the continuous cultivation period. In our study, the expediency of using high concentrations of agar to create and maintain a test tube collection of native Don varieties was studied. The studies were carried out on the following varieties: Sibirkovyi, Pukhlyakovskiy belyi, Krasnostop zolotovskiy, Sypun chernyi, Plechistik oboepolyi, Bessergenevskiy No. 10, against the background of two variants of concentration of 0.6 % agar in the control and 0.15 % in the experimental version. During the experiment, we found that the reaction of test tube plants to increased and decreased concentrations of agar in the nutrient medium is variety-specific. Thus, we found a slowdown in growth processes with an increase in agar concentration in the Sibirkovyi, Pukhlyakovskiy belyi and Krasnostop zolotovskiy varieties. Trends in the better development of micro-shoots on a nutrient medium with increased nutrient density in the varieties Sypun chernyi, Plechistik oboepolyi and Bessergenevskiy No. 10 were showed. At the same time, a pattern was found in all varieties with an increased concentration of agar, a smaller number of roots are formed, but their length increases.