Review Of Japanese Barberry And Allelopathy Screening Methods

There are four criteria common to identified invasive plants. The first one is that the species is not indigenous to the biogeographical region in question. The second criteria is that the species has become naturalized and is becoming more abundant and/or more widely distributed. The third criteria is that there is a nuisance or pest value attached to the species in question and the last characteristic of an invasi

Field screening is when the donor plant is grown outside with one or more species of receiver plants planted grown around the donor plant. This type of test is considered to be more ecological valuable, because the environment is more natural and unable to be totally controlled. Chemical screening bioassay is done when the suspected phytotoxin can be isolated and identified. It is the process of growing plants in different concentration of the phytotoxin to see which concentration is most affective (Wu H, Pratley J, et al 2001). Chemical screening can also be combined with field screening. An example of this technique is an experiment that tested the reaction of corn and soybeans atrazine when grown at varied densities in the phytotoxins presence. The experiment showed that the allelopathic effect of phytotoxins could be density-dependent. The more plants present, the less effective the phytotoxin because smaller than lethal amounts are being absorbed by each individual plant (Thijs, Shann, et al 1994).

Do to the expense of chemical isolation and identification a multi-step process is generally recommended for allelopathy evaluation. Instead of going straight to the quantification of allelochemicals, preliminary screenings are performed to qualitatively determine that a plant does produce allelochemicals. Bioassay screenings are recommended for a plant suspected of allelopathic tendencies. A target or receiver species is the species of plant negatively affected by the donor species. A donor species is the plant effectively inhibiting growth in another species whether it is by allelopathy or successful resource competition. If a plant passes the initial testing for allelopathy in a laboratory then it is recommended to test the plant in a more realistic outside environment. After the initial screenings are completed then an attempt to isolate the compound responsible for the allelopathic response, called an allelochemical or phytotoxin, could be made.

Japanese barberry (Berberis thunbergii) is an invasive species in the United States. It belongs to the family Berberidaceae and is native to Japan. The Japanese barberry is a deciduous shrub three to six feet tall with alternating deciduous leaves that are ovate and have a smooth edge. The leaves are wider at the base then they are at the tip. At each node there is a single spine. The leaves are green in the summer and can be orange to purplish color in the fall. The Japanese barberry has small yellow flowers in April and red berries around October. Many cultivars of the Japanese barberry have been bred for use in landscaping. They are easily propagated by seed and by cuttings (Silander and Klepeis 1999). Japanese barberries are distributed from Maine as far s

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