2010 年 54 巻 3 号 p. 67-70
Earlier flowering and harvesting are important to increase the price of Japanese pepper (Zanthoxylum piperitum (L.) DC. f. inerme Makino). The present study was conducted to evaluate the effects of the temperature on the flowering time of Japanese pepper for earlier flowering and fruit harvesting. Potted seedlings were transferred to greenhouses with minimum temperatures of 5, 10 and 15°C after breaking of dormancy. The plants grown in the 15°C treatment reached the full bloom stage three weeks earlier than the plants grown in the 5°C treatment. The number of flowers per inflorescence did not differ between the treatments. Lock of sprouting was observed in the 15°C treatment, suggesting that the sprouting rate tended to be lower than that in the 10 and 5°C treatments. The cluster-bearing shoot rate (rate of shoots that sprouted and bore flowers in all the sprouts of fruiting mother shoots) for fruiting mother shoots with a length ranging from 10 to 30 cm in the 15°C treatment was significantly lower than that in the 5°C and 10°C treatments. Rapid increase of temperature to 15°C after breaking of dormancy led to earlier flowering, but reduced the number of flowers in Japanese pepper trees. Maintenance of a minimum temperature of 15°C after breaking of dormancy could promote early flowering and fruiting. However, the rate of cluster-bearing shoots was higher by the transfer to 10°C than to 15°C. These results suggested that the transfer of Japanese pepper trees to the greenhouse at 10°C may promote earlier flowering and increase the cluster-bearing shoot rate a long with reducing the cost of fuel.
