Differences of Seed Germination Characters between Two Types of Imperata cylindrica (L.) BEAUV. Characterized by Flowering Phenology

Abstract

Two types of Imperata cylindrica had reported from the Nohbi Plain in Japan. The early flowering type had named E-type and the late flowering type had named C-type. Recently, we found both E-type and C-type populations in the Miyazaki Plain. This is the first case for finding two types of Imperata cylindrica except the Nohbi Plain. We tried to compare the biological characters between E-type and C-type. This paper deals with differences of seed germination characters between two types of Imperata cylindrica considering sib effect. The germination percentages of sibs in E-type were higher than C-type under constant temperature and dark condition. There was remarkable effect on dormancy breaking by light and/or temperature fluctuation in seed of C-type. Result of Nested MANOVA considering sib effect shows the significant effect on interaction between type and temperature fluctuation. It can be says that seeds of C-type were dormancy but seeds of E-type were almost non-dormancy. There were linear relationships between incubation temperature and germination speed in both types. But, there are clear differences in line segment and line slope between two types. Line slopes of sibs in E-type were steeper than C-type. Threshold temperature in germination of sibs varied from 12.9℃ to 13.7℃ in C-type and from 14.4℃ to 15.9℃ in E-type. From these results, it is clear that there are clear differences in seed germination characters between E-type and C-type in Imperata cylindrica. These differences would be strong correlated to reproductive habit in the field.