| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1991: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1990: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
This investigation was carried out to analyze the effect of changes in the photoperiod and temperature conditions on the initiation of the growth and enlargement of the tubers in yams, Dioscorea spp. .
At the early stage of development of the yam plants, the growth and enlargement of the tubers began when the plants were exposed to a 9 hour day length thirty times.
At middle stage of development, the growth and enlargement of the tubers started when the plants were exposed to a day length of 11 hours ten times. The weight of tubers increased proportionally to the increase of the number of exposures.
Although yam tubers did not require a low temperature for the initiation of growth and enlargement, the development of the tubers in which growth had already been initiated was promoted by the exposure to low temperatures at night.
Based on the results obtained, it appeared that the shortening of the day length was the main factor causing the growth and enlargement of tubers in yams.
The reaction response of yam to short day treatment varies to some extent among varieties, and the effect of the treatment is in the final size of the tuber at riaturity. Depending upon the treatment, it was observed that while the moisture content of the tuber at maturity decreased, the viscoty of its juice increased.
From the above result, it was proved that short day not only controls the commencement of enlargement of the tuber, but also promotes its maturing growth.
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