Propagation studies of sugar maple (Acer saccharum Marsh.)

Abstract

Sugar Maple (Acer saccharum Marsh.) is a very important tree species and is known not only for its sap in the production of maple syrup, but also for its superior hardwood quality and popular ornamental properties. In the effort to improve the diversity of the hardwood tree species in Manitoba, an effective propagation method for sugar maple is needed. The study tested several propagation techniques namely in vitro shoot organogenesis, induced embryo conversion and rooting of greenwood cuttings. Shoot multiplication was achieved using bud and embryo explants, however the rate of shoot production was very low implying that the culture conditions required some optimizations. Dormant isolated embryos were induced to germinate and convert into whole plants in vitro, eliminating the need for long stratification period. The study found the highest embryo conversion frequencies by the addition of cytokinin 6-benzylaminopurine (BAP) at 0.5-1.5 mg/L or thidiazuron (TDZ) at 0.01 mg/L into the culture medium. Greenwood cuttings of several hardy cultivars, including ‘Jefcan’, ‘Bailsta’ and ‘Green Mountain’ were compared for rooting capacity. In 2008, cutting type, rooting hormone and collection time were found to significantly influence rooting. In the following year, the study was expanded to compare different rooting conditions, using peat-perlite mix in fog system, sand beds under intermittent misting, and commercial peat plugs under automated misting system. Rooting was improved by selecting for medial-type cuttings and by promoting cutting survival through the the use of peat-based rooting medium and the maintenance of cool temperatures during the rooting period. The application of auxin did not increase rooting frequency of ‘Jefcan’ cuttings, but considerably improved the quality of roots produced, which may affect cutting survival upon transplantation.