2018 年 62 巻 3 号 p. 109-114
In water yam (Dioscorea alata L.), bulbils are formed on the axil of their stems and have the potential as seeds for propagation. However, little is known about their growth and development or their dormancy. This research is aimed at obtaining the basic information concerning bulbil dormancy and the formation process in the water yam.
The effects of temperature on bulbil sprouting was examined and anatomical observations were carried out. Bulbil sprouting was promoted under high-temperature storage while inhibited under low-temperature storage, suggesting that the characteristic of bulbil sprouting is similar to that of the tubers in water yam, and the dormancy period is controlled by temperature. Anatomical observations of sprouting bulbils revealed apical buds with bud primordia in all of them at harvest, while observations during plant growth shown the formation of bulbils on the axil, with obvious bulbils developing 165 days after planting. In anatomical observation, no bulbils were observed at 135 DAP, and organs observed at this stage were thought to be axillary buds. Small globular tissues were then observed on the axil at 150 DAP, followed by obvious bulbils at 165 DAP, along with axillary buds. That is, the bulbils appeared in the endo-/eco-dormant phase, along with the development of axillary buds, suggesting a short period of endo-dormancy. The use of water yam bulbils as seeds for propagation, therefore, requires careful control of storage temperature and dormancy conditions.