EFFECT OF IONIZING IRRADIATION OR HEAVY-M ETALS ON THE FREQUENCY OF CHROMOSOME-ABERRATIONS IN SPRING BARLEY LEAF MERISTEM

The results of a vegetative experiment on the induction of genetic eff ects in barley leaf meristem exposed to ionizing irradiation and heavy metals are presented. It is shown that a cytogenetic test for the fre quency of aberrant cells in the intercalary meristem fully provides th e sensitivity and informativity required by biological test systems us ed to indicate weak exposure to different technogenic factors. In part icular, it was demonstrated that sensitivity of the test to ionizing i rradiation is comparable with the sensitivity of a classic test on the frequency of chromosome aberrations in peripheral blood lymphocytes ( and allows one to register structural mutations induced with doses of the order of several cGy). It was shown that the dose-effect relations hips for all the factors assayed is clearly nonlinear. At low doses an d concentrations, the frequency of cytogenetic aberrations increases m ore rapidly than at high doses. The different character of relationshi ps is caused by diverse mechanisms induced by the factors analyzed.