Abstract
We investigated the germination traits of Fraxnus lanuginosa fruits which were collected in Yamagata Prefecture, in the northern part of Honshu, Japan. While fruits set at 5°C were in quiescence showing negligible germination, more than 90% of germinations were obtained from fruits set at temperatures above 10°C. These results indicate that fruits of F. lanuginousa do not acquire dormancy. Since removal of the pericarp from the seed significantly enhanced the germination rate, intact fruit shows delayed germination due to pericarp. Further experiments on pericarp revealed that germination delay was caused by the hardness of the pericarp which mechanically inhibits the inner embryo from growing. Moist chilling treatment for three months improved germination rate which suggests that cold moist conditions under snow cover during the winter season remove the mechanical inhibition and fruits will germinate simultaneously at the beginning of the following spring. The above result was opposite that in a previous paper using the fruits from Hokkaido showing dormancy; thus geographical variation in germination/dormancy traits might exist in F. lanuginousa fruits.
