Fresh seeds of Lonicera fragrantissima incubated at 15/6, 20/10, 25/15, 30/15, and 35/200C did not germinate after 2 wk incubation in light. Following a 12-wk stratification period at 25/150C in light, seeds germinated to 0-48% at 15/6-35/200C after 2 wk incubation in light. However, stratification in light at 50C for 12 wk did not break dormancy, i.e. 0% germination. Embryo length in fresh seeds incubated in light at 25/150C increased 103% (0.7-1.5 mm), while those incubated at 50C increased only 15% (0.7-0.9 mm). Peak germination of seeds sown in a nonheated greenhouse on 23 June 1997 occurred between 18 and 25 November 1997, when mean weekly maximum and minimum temperatures were 13.3 and 90C, respectively. In L. japonica 0-9%, 31-44%, and 69-99% of fresh, warm-stratified, and cold-stratified seeds, respectively, germinated at 15/6-35/200C. Embryo length in fresh seeds incubated for 12 wk at 25/150C in light increased 67% (1.2-2.1 mm), while those incubated at 50C increased only 15% (1.2-1.4 mm). Fresh seeds of L. maackii germinated to 0-32% at 15/6-35/200C after 2 wk incubation in light. Both a 12-wk cold stratification period and a 12-wk warm stratification period broke dormancy in seeds of this species. Seeds cold-stratified for 12 wk germinated to 76-99% at 15/6-35/200C, and those warm stratified for 12 wk germinated to 96-100%. Embryo length in fresh seeds incubated for 8 wk at 25/150C in light increased 208% (1.2-3.7 mm), while those incubated at 50C increased 108% (1.2-2.5 mm). Peak germination of L. maackii seeds sown on 24 October 1996 occurred between 11 and 18 March 1997, when mean weekly maximum and minimum temperatures were 17.7 and 80C, respectively. Thus, although these three Lonicera species have morphophysiological dormancy, its depth differs among them, in the following order: L. fragrantissima > L. japonica > L maackii.

Key words: dormancy, germination, Lonicera fragrantissima, Lonicera japonica, Lonicera maackii , seed