La nécessité d'un programme d'amélioration de certaines essences forestières feuillues : Applications aux genres Juglans et Acer

Although most of our tree-breeding programs are concerned with coniferous forest species, we must not neglect the valuable hardwoods exploited in our region. The need of these programs for hardwoods is undeniable and they should be based, as much as possible, on genecological studies.One such study illustrates the wide variation in genetic adaptation of Juglans nigra and indicates its practical implications. Further, these results were obtained from a short-term study of 17 provenances for variations in frost-hardiness at a single location.Intra-specific variation is being investigated in Juglans cinerea, a more common species in our region than the one previously mentioned and one which is also in strong demand for furniture-making and wood sculpture. The resulting data will permit the selection of the best seed zones. Such a breeding program could eventually support far more than small, local industries.Another project involving Acer saccharum describes the variation in sugar-content of sap in three maple stands sampled each spring from 1965 to 1969. Two stands were very homogeneous compared to the third. The magnitude of the differences maintained throughout the study period led to the selection of nine genotypes whose sugar contents varied from 4.6% to 9.7%, indicating maximum genetic gains on the order of 150%.Continued research in vegetative propagation of Acer saccharum is needed for the production of clonal populations for breeding programs.