Cytogenetical and biochemical investigations of common oak (Quercus robur L.) were applied in order to find suitable markers in bioindication of oak populations. In cytogenetical analyses the chromosome aberration and mitotic index were recorded. Chromosome banding, B-chromosomes, location and number of nuclear organizer regions were indicated using Giemsa C-banding method, fluorescence staining and silver impregnation. In biochemical analyses SDS-electrophoresis of soluble proteins and isoelectric focusing of isoperoxidases were used.

A plant test system by the classification of chromosome aberration in the root tip meristems of young spruce plants (Picea abies (L.) Karst.) has been used to study the environmental influence on the genetic material of trees at natural sites and under defined conditions of greenhouses and open-top chambers. All our results suggest that this plant test system is a valuable tool in environmental monitoring.

Annual research has proven that the level of the so called natural cytogenetic damage to Norway spruce in Slovenia has been correctly estimated at 8. The results of cytogenetic bioindication calculated in accordance with this level show that average cytogenetic damage in the period from 1985 to 1992 enable us to determine environmental influences on the expression of cytogenetic damage.