ISHS Acta Horticulturae 630: XXVI International Horticultural Congress: Nursery Crops; Development, Evaluation, Production and Use
EFFECTS OF CUTTING TREATMENTS AND STRATIFICATION ON GERMINATION AND EMERGENCE OF FRAXINUS AMERICANA AND FRAXINUS PENNSYLVANICA |
| Authors: | J.A. Ashley, J.E. Preece |
| Keywords: | dormancy, green ash, seed, tree, white ash |
| Abstract:
Dormant, depericarped seeds of white ash (Fraxinus americana L.) and green ash (Fraxinus pennsylvanica Marsh.) were subjected to various treatments in a greenhouse environment. Most cut seeds had one third of the seed at the cotyledon end excised. When cut, dormant seeds were sown in a 2 sphagnum peat: 1 vermiculite: 1 perlite (by volume) medium in the greenhouse. Generally, green ash seeds had significantly greater emergence and survival than white ash seeds. Significantly more cut, dormant green ash seeds emerged and survived than intact seeds that had been stratified under moist, warm (25°C) conditions for 60 days followed by moist chilling (4°C) for 120 days. However, >55% of white ash seeds that were stratified for 30 days at 25°C followed by moist chilling for 60 days at 4°C emerged and survived. Cutting and other treatments to this species resulted in ≤15% emergence and survival. These results indicate that white ash has a deeper, more complicated dormancy than green ash, possibly involving lack of production of hydrolytic enzymes for sugar production. Green ash dormancy appears to involve growth inhibitors, but since cutting the seeds stimulates germination, this species seems to have sufficient sugars to provide the energy needs of the germinating embryo. Dormancy of neither species appears to involve immature embryos. | |
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