2005 Fiscal Year Final Research Report Summary
Iodine uptake and "Akagare" disease of rice plants
| Project/Area Number |
15580051
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plant nutrition/Soil science
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| Research Institution | Kyoto Prefectural University |
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Principal Investigator |
YAMADA Hidekazu Kyoto Prefectural University, Graduate school of agriculture, Professor, 農学研究科, 教授 (60094405)
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| Project Period (FY) |
2003 – 2005
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| Keywords | iodine / "Akagare" disease / molecular iodine / soil soluble iodine / soil |
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| Research Abstract |
Rice plants, cultivated in a soil with an abundance of iodine accumulate iodine in large quantities and take a physiological disorder ("Akagare" disease) due to the toxicity of iodine.
1.The absorption mechanism of iodine by rice plants was studied. Although iodine is harmful to plants, rice plants absorbed iodine more selectively than bromine. To explain this selective absorption, the following hypothesis was proposed : rice plants oxidize iodide ion to form molecular iodine via the oxidizing power of their roots, and absorb the molecular iodine formed more selectively than iodide ion. Bromine, by contrast, is absorbed by rice plants only in the form of ion. According to this hypothesis, there should be a significant correlation between the oxidizing power of the rice roots and the amount of iodine absorbed. Then, the relationship between the oxidizing power of the roots and the concentration of iodine absorbed was studied in a water culture using 8 varieties of rice plants. A significant correlation was found between the oxidizing power and the concentration of iodine absorbed by the roots. However, no relationship was found between the oxidizing power of the roots and the amount of bromine absorbed.
2.The relationship between soil soluble iodine and "Akagare" disease of rice plants was examined. Seedlings of rice plant 20 days after germination were cultivated in soils rich in iodine for 29 days. 1)The concentration of iodine absorbed by rice plants correlated positively with the concentration of soil soluble iodine. 2)Height and dry weight of shoot of rice plant decreased with the increase in the concentration of iodine absorbed by the rice plant. 3)The symptom of "Akagare" disease became remarkable, when the concentration of iodine in rice plant(shoot) was over 200 mg/kg(dry weight). 4)A remarkable difference in resistance to "Akagare" disease among varieties of rice plants was recognized.
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Research Products
(2 results)
