1985 Volume 54 Issue 3 Pages 344-350
Morphological feature of the shoot tip of the Japanese radish during transition into flowering was investigated by using the scanning electron microscope (SEM). The radish was vernalized by a low temperature (5°C) for 30 days in order to induce flowering. The radish was then transplanted into a water culture during the month of September. The induced plants bolted and flowered with an average of 12 and 29 days after transplanting, respectively, while the non-induced plants failed to bolt within the designated period (72 days after transplanting). At the anthesis stage, the number of leaves on main flower stalk was 12.4 per plant. This included 3.2 deformed leaves (small size, no or less than two lobes and pointed leaf apex) which developed near the top of the plant. The characteristics of these deformed leaves are discussed.
The periodical sampling of shoot tips observed by SEM showed that the development of meristem from the vegetative stage to the flower bud initiation stage should consist of four stages. They are: (a) vegetative stage (flattened, <250μm in diameter), (b) dome shaped stage (>300μm in diameter), (c) initiation of lateral meristem at the young leaf axils, and, (d) individual flower bud initiation of apical meristem. Flower initiation should be indicated at lateral meristem initiation stage, especially flowering occurring under unfavorable conditions. The growth and development of lateral meristem were of the same pattern as those found in apical meristem.