The range of hormesis doses of gamma-irradiation by the dose dependence of the growth parameters of the main roots of pea seedlings is established. The mitotic index (MI) of cells of the apical meristem of a root, the levels of cytokinins, and the $\alpha$-amylase activity in cotyledons of seedlings are assessed in control and experience. In the exposed roots, the stimulation of MI and the increased level of synthesis of cytokinins that precedes the stimulation of MI are observed. This confirms the hypothesis about the possible role of post-radiation degradation products of DNA in the synthesis of cytokinins. The results of studies of the dynamics of the $\alpha$-amylase activity in cotyledons of pea seedlings lead to the conclusion about the relative independence of the growth activity of roots on the trophic factor on the early stages of development of seedlings.