Abstract
By using two varieties, Norin No. 1 (many panicle type) and Zosan No. 1 (heavy panicle type) an experiment was made in the growth cabinet to examine the influence of light and dark temperature range on the emergence and growth of tillers. Light temperatures adopted were 15°, 20°, 25°, 30°, 35°, and 40°C, and dark temperatures 15°, 20°, 25°, and 30°C ; 23 combinations were made of these temperatures excepting the combination of 40°C in the light period with 30°C in the dark. Light and dark temperature ranges plotted were 0°, 5°, 15°, 20° and 25°C. The daylength was controlled so that the light period could be 16 hours and the dark 8 hours. Observations of the emergence of tillers were carried out in response to the leaf age of the main stems. The results were : 1) In the case of Norin No. 1,tillers emerged and elongated on Katayama's theory of tillering in the temperature range from 20°C to 40°C under conditions of the above-mentioned respective temperature ranges. 2) The temperature range suitable for tiller emergence and elongation was narrower in Zosan No. 1 than in Norin No. 1 and the number of tiller decreased especially in the high temperature range. High temperature was the controlling factor in tiller emergence.
