Effects of Day-length Treatment and Harvesting Time on the Flowering of Erianthus arundinaceus on Ishigaki Island, Japan

抄録

To improve the efficiency of intergeneric hybridization between sugarcane and Erianthus arundinaceus, we examined their responses to day-length and harvesting time on Ishigaki Island, Japan, in 2008 and 2009. To suppress floral initiation, the day-length was extended to 14 h by providing light to three E. arundinaceus clones, JW4, JW630, and IJ76-349 before sunrise. Then, to induce flowering, the day-length was reduced by 20 min/week until a day-length of 11.5 h was attained. The day-length treatment effectively delayed flowering in the JW4 and JW630 clones, whereas the light-treated IJ76-349 did not flower at all. Delays of 12 to 22 days and 14 to 25 days were confirmed in the JW4 and JW630 clones, respectively. Regarding the effects of harvesting time, April-harvested JW630 showed a 5-day delay compared to the February-harvested plants, while there was no significant difference in JW4. However, when we combined late harvesting and day-length treatment, significant delays of 15 days in JW4 and 33 days in JW630 were confirmed. Since the pollen of JW4 and JW630 successfully germinated after the day-length treatment, these treatments are considered to be useful for overlapping the flowering dates of sugarcane and Erianthus on Ishigaki Island.