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Inoculations with the two fungi and were made in two series of progeny tests each containing full-sib families planted at two sites and on grafts of the parents in two seed orchards. Significant variation among families in lesion lengths after inoculation was found for both fungi and a predominantly additive inheritance was indicated. The estimates of narrow sense heritability were 0.13 and 0.22 for and , respectively. The estimate of the genetic correlation between the lesion lengths of the two fungi was as low as 0.12. Significant variation in lesion lengths was also found among parental clones, and within ramets of the same clone, in the seed orchards. In one of the series a high positive correlation (râ=â0.88) was found between the lesion lengths of the male parents and offspring, but not for the female parents and off-spring. The results confirm earlier conclusions that the genetic variation and heritabilities are large enough for practical breeding for resistance.Heterobasidion parviporumCeratocystis polonicaH. parviporumC. polonicaH. parviporum

After a presentation of basic biodiversity concepts, reviews are made of studies reporting genetic implications of tree improvement activities: seed treatments, seedling production, provenance transfers, plus tree selection, seed production in seed orchards and progeny testing. Several of the activities may influence the genetic structure and diversity of the planted forests. The general conclusion is, however, that planted forests are at least as genetically diverse as the natural stands that they replace. The diversity in forest management and use is best assurance for the future adaptability of the forests.

This paper summarises the main topics and conclusions from the joint meeting of two IUFRO working parties, S2.04-02, Breeding theory and progeny testing, and S2.02-16, Seed orchards, held in Tuusula, Finland on September 10â15, 1991. It concludes the main topics that need more research in these disciplines and future trends in the research.

Abstract: We present results from early tests and field trials of offspring from two Norway spruce (Picea abies (L.) Karst.) seed orchards containing clones that have been transferred from high [...]