| Project/Area Number |
63540513
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
生態学
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| Research Institution | Faculty Science, Chiba University |
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Principal Investigator |
IKUSIMA Isao Chiba Univ. Prof., 理学部, 教授 (20009046)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Trapa natans var. japonica / Strategy / buried seed / rosette leaf / eutrophic water / Inba-numa / 印旙沼 / 埋土種子 / 群落維持機構 / 富栄養化水域 / 印旛沼 / ストラテジ-(戦略) / 葉の寿命 / 大形種子 / 群落維持 / 光合成速度 / 埋土種子個体群 / 発芽温度の閾値 / 種子生産 |
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| Research Abstract |
Trapa natans var. japonica had a high reproductivity and covered almost surface of an eutrophic lake, Inba-numa.
1 Strategy of the seed : The starch seed of the plant is regarded as one of the bigger seeds in aquatic macrophytes. The mean fresh weight was 7 g and the maximum weight reached 12 g. The mean economic rate of transformation from seeds to seedlings was 0.47. Large seedlings could produce floating-leaves to 2.2 m of depth in an eutrophyic water. The plant qiven priority to seed size rather than number as much as half of the normal value of the total insolation hours from August to October.
2 Strategy of the rosette leaf : LAI was less than 2 and a new leaf was constantly kept under good light condition. A new leaf came out every other day on main stem and about 30 leaves made up a rosette for seven months from May. The life span of leaves was as long as 25 days. The rosette produced 3to 5 well developed and large seeds.
3 Strategy at reproduction processes : Fruits had two types, the one was a floating type or a dispersal type and the other regard a conservative type, the fruit sunk near the mother plant. The buried seed germinated when the water temperature became higher than 10^ﾟC and the rate of germination reached 60 % and 92 % in the next year and the year after next year, respectively. The buried seed was prepared all year round.
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