Dormancy-breaking and germination requirements for seeds of Diervilla lonicera (Caprifoliaceae), a species with underdeveloped linear embryos

Dormancy-breaking requirements and type of dormancy were determined for see ds of Diervilla lonicera Mill. Seeds have an underdeveloped linear embryo t hat is about 35% of the length of the seed at maturity. Embryos (in intact seeds) grew at 25:15%C but not at 5%C. Up to 85% of the freshly matured see ds had morphological dormancy (MD), and thus, they germinated within about 30 days on a moist substrate in light at 30:15%C; a maximum of 3% of the se eds germinated in constant darkness. The other portion of fresh seeds had n ondeep simple morphophysiological dormancy (MPD) and required a period of w arm stratification or treatment with GA(3) to break dormancy. These seeds a lso required light to germinate. In contrast, cold stratification induced d ormancy, and dry storage for up to 1 year did not effectively break dormanc y. Seeds with MD germinated to significantly higher percentages on soil tha n on filter paper or on sand. Seeds sown on soil in a non-temperature-contr olled greenhouse in mid-November germinated mostly in late May, whereas tho se sown in mid-April germinated in early May. Apparently, embryos of Novemb er-sown seeds were induced into physiological dormancy during winter. Thus, seeds had MPD in spring and needed several weeks of warm temperatures for dormancy break, embryo growth, and germination. This is the first report on seed dormancy in the genus Diervilla.