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Allelopathic effects of Japanese knotweed and its
success as an invasive speciesTy Oliver
Edgewood CollegeMay 2010
Can survive in areas beyond native range Adaptable Often aggressive Exotic or native species Reproduction
What defines a species as “invasive”?
Large populations Compete for
resources Replace or damage
native species Resistance to pests
and diseases
Problems
http://www.aldertreegarden.com/images/DSCN0508.jpg
Fallopia japonica Polygonaceae family Perennial Herbaceous Native to Asia,
specifically Japan, Taiwan, and northern China
Commonly invades riparian areas and areas with recent disturbances
Japanese knotweed
http://shizuokagourmet.files.wordpress.com/2009/04/itadori-japanese-knotweed.jpg
Competition among plants via biochemicals
Anthraquinones found in rhizomes
Suspected to contribute to Japanese knotweed’s success as invasive
Allelopathy
http://www.languard.co.uk/invasive-weed-management/images/japanese-knotweed-rhizome.jpg
What effect would the compounds found in the rhizomes of Japanese knotweed on an organism like fast plants (Brassica rapa)?
Question
The compounds found in the rhizomes of Japanese knotweed would have an allelopathic effect on fast plants.
Inhibit germination and if germination were successful, stunt growth of fast plants in terms of height and biomass
Hypothesis
Collected rhizomes Made extract from collected rhizomes Extract was made in varying concentrations
◦ ½ extract: 50mL extract + 50mL DI◦ ¼ extract: 25mL extract + 75mL DI◦ 1/8 extract: 12.5mL extract + 87.5mL DI
Methods
8 fast plants per group Control group: 5mL of DI added Experimental groups:
◦ 5mL ½ extract added◦ 5mL ¼ extract added◦ 5mL 1/8 extract added
Control and Experimental Groups
24-hour fluorescent lighting Grown in film canisters with potting soil and
one pellet of fertilizer Final height was taken after flowering Number of seeds germinated Total biomass
Constants and Data Collection
The allelopathic compounds in Japanese knotweed rhizomes have an effect on the growth of fast plants in terms of plant height and biomass, but no significant effect was seen on germination.
Results
Germination
Control 1/2 Extract 1/4 Extract 1/8 Extract0
1
2
3
4
5
6
7
8
9
Number of Germinated Seeds
Seed
s
Plant Height
Control 1/2 Extract 1/4 Extract 1/8 Extract0
5
10
15
20
25
30
35
Average Plant Height
Hei
ght
(cm
)
Biomass
Control 1/2 Extract 1/4 Extract 1/8 Extract0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Biomass
Wei
ght
(g)
Negative effect on plant height and biomass No significant effect on germination Concentration of extract doesn’t seem to
matter
Conclusions
