GENETIC-VARIATION AMONG CLONES OF PICEA-ABIES IN RESISTANCE TO GROWTHOF HETEROBASIDION-ANNOSUM

An inoculation experiment with Heterobasidion annosum on 98 four-year- old Picea abies clones was conducted on rooted-cuttings under greenhou se conditions. One isolate of H. annosum and 10 ramets of each clone w ere used. After 34 days of incubation, fungal growth in sapwood and le sion length in the inner bark were measured. There were significant di fferences among clones in lesion length in the inner bark and in funga l growth in sapwood. Broad sense heritability was 0.35 for fungal grow th and 0.27 for lesion length in the inner bark. Fungal growth and les ion length showed strong genotypic correlation. Bud-flushing index of the clones was correlated with mean fungal growth, whereas the growth termination index was not. Fungal growth in sapwood and lesion length in the inner bark of cuttings were not correlated with the mean height and provenance of 15-year-old ramets of the same clones in previously conducted field tests.