| Project/Area Number |
11660269
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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 |
Zootechnical science/Grassland science
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| Research Institution | Shizuoka University |
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Principal Investigator |
SAWADA Hitoshi Shizuoka University, Faculty of Agriculture, Professor, 農学部, 教授 (10183831)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2001: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | White clover / Seed reproduction / Seed set / Reproductive ecology / Population dynamics / Flower-head / Grazed sward / Clonal plant / クローン成長 / 開花習性 |
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| Research Abstract |
The aims of this research are to deepen our understanding of the seed reproductive ecology of white clover. A series of experiments were conducted using two cultivars, Kopu (large-leaved) and Tahora (small-leaved). Major results are described below. A common environment experiment showed that Kopu exhibited larger flower-heads and wider arrangement of flower-heads per genet than Tahora. A factorial experiment, in which both of defoliation stress and resource level were manipulated, was conducted to examine the plastic responses of the cultivars. The experiment showed that the seed reproductive characters differed in the extent of the responses, and even seed number per pod (which determine seed set rate) and individual seed size decreased due to strong defolation stress. It also showed that the cultivars had complex patterns of the plastic responses to moderate defoliation stress. Resource level affected the plastic responses to defoliation stresses subtly. The results obtained in this research and the previous studies suggest that the genotypes which have many flower-heads and long periods of flowering at individual level and asynchronous seed germination would be advantageous in persisting. I also conducted the observation on reproductive ecology in fields. It clearly showed positive relationships among population size, seed set rate and visitation frequency of pollinators. The populations with extremely small size had low visitation frequency of pollinators, resulting in reduction in seed set rate. Marked reduction in seed set rate can impose serious limitation to successful restoration. It is highly possible in the grazed swards with small isolated patches of white clover. It would be essential to self-restoration of clover content that the abundance and distributional pattern of adults are proper for the seed set.
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