INDUCTION OF CHROMOSOMAL DAMAGE BY OZONE IN THE ROOT-MERISTEMS OF NORWAY SPRUCE

Spruce plants (one clone of Picea abies (L.) Karst.) were exposed in environmental chambers to different levels of ozone for 42 days to study the influences of enhanced ozone on root tip chromosomes directly after fumigation had ceased. No visible symptoms resulted from these treatments. The classification of chromosomal aberrations was used as a method to characterise the influences on the root tips caused by ozone. In comparison to the control the fumigated variant showed an increased number of chromosomal abnormalities. Another clone of Picea was used to investigate the 'post-fumigation long-term effect' in the genetic material caused by enhanced ozone. These clonal trees appeared to be relatively ozone-sensitive, as pigment reduction and chlorotic spots were observed directly after fumigation had ceased. The spruce trees were also exposed in environmental chambers to different levels of ozone for 24 weeks and then they were transferred to a field near the Institute. Some 21 months after the fumigation had ceased those trees that had been fumigated showed an increased number of chromosomal aberrations compared with the control. The observed chromosomal abnormalities in all the variants of the experiments consisted of chromosomal 'stickiness', chromosome breakage, and fragmentation.