Genetic control of germination and the effects of accelerated aging in mountain hemlock seeds and its relevance to gene conservation

Genetic control of germination parameters and the effects of accelerated ag ing in mountain hemlock (Tsuga mertensiana [Bong.] Carr.) seeds were invest igated using standard germination tests and simulated aging, respectively. Germination parameters were studied on seeds collected from individual tree s from two natural populations (Sooke and San Juan) located on southern Van couver Island, BC. Strong genetic control was confirmed by the high heritab ility estimates that ranged from 0.35 to 0.82 (stratified) and from 0.58 to 0.73 (unstratified) for Sooke and from 0.30 to 0.85 (stratified) and from 0.45 to 0.84 (unstratified) for San Juan, Simulated aging was conducted on eight seedlots collected from natural stands representing the species distr ibution in British Columbia. Stratified and unstratified seeds were aged at 100% RH and 37.5 degrees C for 0 to 21 days at 3-day intervals. Seed aging accounted for the majority of variation which ranged from 97.61% to 99.86% of the total variation observed. Gradual loss of seed viability was observ ed over the aging treatments with a total loss of viability after aging for 12 days. Differential losses in viability among seedlots were maximum afte r aging for 6 days. Results are discussed in terms of the impact of long-te rm storage and the reliance on seed banks for ex-situ conservation of this species. (C) 1998 Elsevier Science B.V. All rights reserved.