Effects of stratification and simulated aging on germination of Douglas-fir seed from a clonal seed orchard
Krakowski, J., El-Kassaby, Y. A.
2003.
Forest Genetics, Volume 10, Number 1: 65-70
Journal Article
Development
Western Canada
Seed from 15 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) clones were germinated in a factorial design with two pre-treatments (unstratified and stratified) and seven simulated aging periods (0,2,4,7, 10, 12 and 14 days). Simulated aging consisted of high temperature (40 C) and humidity (100 % RH) exposure, which simulates physiological stresses and consequent deterioration in long term storage. Seed deteriorated as aging treatments lengthened; no germination occurred after 12 days. Germination parameters (capacity, peak value, speed, completeness) were calculated, and pre-treatment and aging effects evaluated using a mixed model analysis of variance. Germination completeness and speed were higher after two days of aging for stratified seed, whereas only peak value increased for unstratified seed. After four days aging, all parameters decreased. Two days of aging enhanced germination capacity of unstratified seed by 15 %, but stratified seed was still 13 % higher. Douglas-fir seed should be stratified before germination, but unstratified seed can be exposed to 40 C and 100 % humidity for two days to augment seedling stock during the growing season. Ex situ Douglas-fir genetic resource conservation, as well as more adequate representation of planted genotypes across the landscape, can benefit from two days of aging, which would ensure slowly-germinating genotypes are represented in the population.
