| Project/Area Number |
08044197
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
作物学
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| Research Institution | Tokyo University of Agriculture and Technology |
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Principal Investigator |
HIRASAWA Tadashi Tokyo University of Agriculture and Technology, Faculty of Agriculture, Professor, 農学部, 教授 (30015119)
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| Co-Investigator(Kenkyū-buntansha) |
KOBATA Tohru Shimane University, Faculty of Life and Environmental Science, Professor, 生物資源科学部, 教授 (60186723)
OOKAWA Taiichiro Tokyo University of Agriculture and Technology, Faculty of Agriculture, Assistan, 農学部, 助手 (80213643)
ISHIHARA Kuni Utsunomiya University, Faculty of Agriculture, Professor, 農学部, 教授 (70014925)
IWAMA Kazuto Hokkaido University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (70144219)
HSIAO Theodore C. University of California, Davis, Department of Land, Air and Water Resouces, Pro, 土地・空気・水資源学科, 教授
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| Project Period (FY) |
1996 – 1998
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| Keywords | cytokinin / exudation / nitrogen / leaf senescence / photosynthesis / root / soil moisture / water use efficiency |
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| Research Abstract |
The effects of atmospheric and soil moisture conditions on root system development and root functions and the effects of root functions on growth and dry matter production of crop plants were investigated for increasing water and fertilizer use efficiencies. The following results were obtained.
(1) Potato plants were grown in Sapporo, Hokkaido and in Davis, California under irrigated and unirrigated conditions and root system development was compared. The plants grown under unirrigated conditions developed root system well compared with the plants grown under irrigated conditions. However, the plants grown in Davis had a larger and dense root system even under the same irrigation treatment.
(2) Simple equations for estimating water use efficiency were derived. These might be applicable to maize and cotton canopies without explicit upscaling for most part of the day.
(3) When maize plants were irrigated after grown under deficient soil moisture conditions, leaf senescence delayed and leaf photosynthetic rate was kept high significantly compared with the continuously irrigated plants and the unirrigated plants. Drastic increase of root exudation after the irrigation was observed and the exudation sap contained higher concentration of N, K and other nutrients.
(4) The reduction in chlorophyll content and photosynthetic rate of a leaf due to senescence was promoted in maize plants growing under deficient soil moisture conditions. Total amount of cytokinin and nitrogen, transported to shoots from roots decreased in the plants. The infusion of cytokinin into a stem suppressed the reduction in leaf chlorophyll content and photosynthetic rate in the plants under deficient soil moisture conditions. This result indicate that cytokinin transported from roots would be important in keeping leaf chlorophyll content and photosynthetic rate high under deficient soil moisture conditions.
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