The level of free (PAs) and conjugated (CPAs) soluble polyamines in leaves ofChenopodium album was determined using the fluorometric method for dansy lated derivatives. The tests made at the 4-6 leaf growth stage showed that the concentration of PAs in susceptible (S) and resistant (R) biotypes ranged between 32-43 μg and 45-56 μg per 100 μl of cell sap, respectively. The analyses performed later, namely at the beginning of flowering showed that the difference in the level of polyamines between Sand R biotypes was greater. In this case the amount of PAs in biotype S ranged between 15-34 μg and in biotype R between 51-73 μg per 100 μl of cell sap. Therefore, the level of PAs cans act as an indicator for susceptibility or resistance of C. album biotypes to atrazine.

The study examined changes in lysine decarboxylase (LDC), ornithine decarboxylase (ODC) and tyrosine decarboxylase (TyDC) activity in tissues of pea (Pisum sativum L.) infested by the pea aphid (Acyrthosiphon pisum Harris). The aphid induced increased ODC activity after one day and at two weeks. The effect was clearly systemic. TyDC activity increased after one day and at one week at feeding sites (aerial parts), while LDC activity increased only after one day of infestation and then decreased. Attack by aphids also affected enzyme activity in root tissues not directly damaged by the herbivores. The mechanisms of the response induced by pea aphid infestation in pea are discussed.