The estimation of the influence of external conditions on marker enzymes phenotypic classes ratios in agamospermous sugar beet progenies has been carried out. It has been shown that different ways of flowering sugar beet plant branches isolation lead to different ratios of marker enzyme phenotypes in a developing agamospermous seed progeny. The obtained data are an additional confirmation of the hypothesis about the presence of differential chromosomes polyteny and its dependence on external conditions.