Abstract
Seeds of Michelia compressa and Pachylarnax sinica of the Magnoliaceae exhibit dormancy.
Poor germination and non-uniform emergence of seeds in the nursery were found after sowing.
Thus, the aim of this study was to determine the germination requirements of seeds of the 2 species
in order to provide an effective protocol to produce plants. Up to 80~90% of fresh seeds of
M. compressa harvested from Chuyunshan and Wushikeng germinated at alternating temperatures
of 25/15, 20/10, and 15/5℃ in light, and other high temperatures such as 30/20, 30/15℃ and constant
temperature at 25℃ had low germination percentages. However, up to 30~40% of seeds of
P. sinica germinated at the above 5 temperatures in light except for 15/5℃, and germination percentages
among the incubation temperatures did not significantly differ. Embryos of the 2 studied
species were small, and they had to grow 2.5~2.6-fold before radical emergence. The speed of
embryo growth responded to the germination speed. Seeds of M. compressa began to germinate
in 3~4 wk, and temperature affected seed germination; thus, they exhibited morphophysiological
dormancy. Further, cold stratification at 5℃ for 8~12 wk and gibberellic acid treatment enhanced
Michelia seed germination. Thus, the seed population exhibited non-deep simple morphophysiological
dormancy. Seeds of P. sinica germinated completely within 4 wk, thus, they exhibited
only morphological dormancy. Seeds of M. compressa with a moisture content of ≤ 9.0% stored at
5 or -20℃ and in liquid nitrogen retained their germinability for at least 3 yr, indicating that they
had orthodox storage behavior. Cold stratification of seeds of M. compressa at 5℃ for 8~12 wk is
recommended to increase the germination speed and produce uniform seedlings.