Root Regeneration and Bud Dormancy of Sugar Maple, Silver Maple, and White Ash Seedlings: Effects of Chilling
The effects of chilling on root growth and bud dormancy of cold-stored (5°C) and nursery-lifted 2-0 silver maple, white ash, and the more difficult to establish sugar maple seedlings were examined. Bud dormancy of cold-stored sugar maple and white ash seedlings was broken after 2,500-3,000 hr of chilling at 5°C whereas silver maple required only 2,000-2,500 hr. No differences in time to first budbreak were observed between cold-stored and nursery-lifted stock. In all species, root regeneration, time to first budbreak (after transfer of seedlings to environmental conditions adequate for growth), and number of hours of chilling were strongly correlated. Increased periods of chilling enhanced the rate at which growth was resumed. Roots did not show a period of innate dormancy. New root development was observed at all sampling times from November to May regardless of the degree of chilling or state of bud dormancy. However, increased root regeneration coincided with loss of physiological bud dormancy in sugar maple and white ash seedlings. Maximum root regeneration was observed after 3,500 hr of chilling in all species. With further chilling, sugar maple, in contrast to silver maple and white ash, showed a rapid decline in root regeneration. In addition, sugar maple seedlings regenerated substantially fewer new roots than did silver maple or white ash. Observed differences between sugar maple, silver maple, and white ash seedlings in their ability to regenerate new roots at time of spring planting may account for the differences in ease of establishment on open-field sites in southern Ontario. FOREST SCI. 23:474-483.
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Document Type: Journal Article
Affiliations: Research Scientist at the Great Lakes Forest Research Centre, Canadian Forestry Service, Sault Ste. Marie, Ontario, Canada
Publication date: 01 December 1977