2007 Fiscal Year Final Research Report Summary
Mechanism of thermo-responses of a rice plant for panicle initiation and temperature sensing locations
| Project/Area Number |
17380153
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Agricultural environmental engineering
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| Research Institution | National Agricultural Research Organization |
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Principal Investigator |
OKADA Masumi National Agricultural Research Organization, National Agricultural Research Center for Tohoku Region, Climate Change Research Team, Team leader (10355274)
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| Co-Investigator(Kenkyū-buntansha) |
ITO Kikukatsu Iwate University, Faculty of Agriculture, Professor (50232434)
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| Project Period (FY) |
2005 – 2007
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| Keywords | rice / development / panicle initiatio / photo-periodic response / thermo-response / basal vegetative growth |
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| Research Abstract |
The objectives of the present study are to understand the mechanism of thermo-responses of a rice plant for panicle initiation and finally to contribute toward evaluating developmental responses under global changes and fluctuating climate conditions. We observed changes of panicle initiation stage under controlled day length, air temperature and flood water temperature and found the way how temperatures affected rice panicle initiation.
1. Leaf development was determined by water temperature alone up to the 10th leaf stage and was affected neither by day length nor by air temperature.
2. Neither day length nor air temperature affected panicle initiation before the 7th leaf age stage. This suggested that a flowering signal receptor appeared at a growing apex around the 7th leaf age stage. A basal vegetative growth phase before the expression the signal receptor was, thus, determined by water temperature ; namely growing point temperature.
3. Short day conditions below a critical day length initiated a panicle immediately as soon as the receptor was activated. Air temperature did not affect this process.
4. Under long day conditions a panicle was not initiated soon after the 7th leaf age stage, but higher air temperature tended to promote panicle initiation. Air temperature induced panicle initiation in many of cultivars even under 24h day length after a sufficiently long time of a period.
5. Air temperature, therefore, did not affect panicle initiation under short day length, but did under long day length.
6. Leaf blade was suggested to be a temperature sensing position, while influence of leaf sheath temperature was negligible.
7. In case of a usual cropping time for cv. Akitakomachi in northern Tohoku region, the effect of water temperature on days from emergence to panicle initiation was evaluated as 4.3 day/℃ and the effect of air temperature as 1.5 day/℃. The former effect was thus three times as large as the latter one.
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