EN
The effects of the exogenous growth regulators abscisic and gibberellic acids (ABA and GA3) on the activity of arginine (ADC) and ornithine decarboxylases (ODC) during dormancy breaking were studied in beech seed. During cold-stratification at 3°C, ADC and ODC activity increased rapidly starting from week 7 in embryo axes and week 8 in cotyledons. At 15°C, ADC activity was higher than ODC activity in embryo axes until week 7 and in cotyledons until week 8. Exogenous growth regulators clearly affected ADC and ODC activity. In embryo axes, ADC activity reached its maximum under the influence of GA3 between weeks 4 and 8. In the control variant (water temp. 3°C), enzymatic activity was moderately high, peaking in week 9 when a high proportion of seeds already showed germinability. In cotyledons the influence of GA3 on ADC activity was noticeable particularly during the first and last weeks. In the control variant the pattern of changes in the activity of this enzyme was similar but at a much lower level. ABA in both organs clearly inhibited ADC activity, but particularly at the end of the experiment. ODC activity in all variants of the experiment was higher in embryo axes than in cotyledons. The dynamics of change in ODC activity were similar to the changes in ADC activity in embryo axes and in cotyledons.