Morphophysiological dormancy in seeds of Chamaelirium luteum, a long-liveddioecious lily

Freshly-matured seeds of Chamaelirium luteum have fully differentiated, but small, embryos; mean embryo length was about 1.0 mm. Since embryos in seed s of this species had to grow to 1.3-2.8 mm, depending on the individual se ed, before germination was possible, seeds have morphological dormancy. Emb ryos also are physiologically dormant; thus, the seeds have morphophysiolog ical dormancy (MPD). Cold stratification at 5 degreesC for 12 wk broke phys iological dormancy, but embryos in only about 20% of the seeds: grew to gre ater than or equal to1.3 mm during this treatment. After seeds that had bee n stratified in darkness at 5 degreesC for 12 wk were transferred to light at a simulated spring temperature (20/10 degreesC = April), embryos in all seeds grew to greater than or equal to1.3 mm within 12 days. Furthermore, s eeds receiving 12 wk of stratification in light at 5 degreesC had germinate d to 90-100% after 14 days in light at 15/6, 20/10, 25/15, and 30/15 degree sC. Seeds receiving light only during the stratification period at 5 degree sC or only during the 2-wk incubation period at the four temperature regime s germinated to 33-100%, whereas those in continuous darkness during both s tratification at 5 degreesC and incubation germinated to only 1-7%. Seeds o f C. luteum have nondeep simple MPD. In the field, mature seeds are dispers ed in mid- to late autumn, and cold stratification during winter breaks phy siological, but not morphological, dormancy of the embryo. However, embryo growth and germination occur rapidly as temperatures begin to increase in e arly spring.