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Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms. Allelochemicals are a subset of secondary metabolites, which are not required for metabolism (i.e. growth, development and reproduction) of the allelopathic organism. Allelochemicals with negative allelopathic effects are an important part of plant defense against herbivory.〔 Allelopathy is characteristic of certain plants, algae, bacteria, coral, and fungi. Allelopathic interactions are an important factor in determining species distribution and abundance within plant communities, and are also thought to be important in the success of many invasive plants. For specific examples, see spotted knapweed (''Centaurea maculosa''), garlic mustard (''Alliaria petiolata''), ''Casuarina/Allocasuarina'' spp., and nutsedge. The process by which a plant acquires more of the available resources (such as nutrients, water or light) from the environment without any chemical action on the surrounding plants is called resource competition. This process is not negative allelopathy, although both processes can act together to enhance the survival rate of the plant species. ==History== The term allelopathy from the Greek-derived compounds ''allelo-'' and ''-pathy'' (meaning "mutual harm" or "suffering"), was first used in 1937 by the Austrian professor Hans Molisch in the book ''Der Einfluss einer Pflanze auf die andere - Allelopathie'' (The Effect of Plants on Each Other) published in German.〔 He used the term to describe biochemical interactions that inhibit the growth of neighbouring plants, by another plant. In 1971, Whittaker and Feeny published a study in the journal ''Science'', which defined allelochemicals as all chemical interactions among organisms. In 1984, Elroy Leon Rice in his monograph on allelopathy enlarged the definition to include all direct positive or negative effects of a plant on another plant or on micro-organisms by the liberation of biochemicals into the natural environment. Over the next ten years, the term was used by other researchers to describe broader chemical interactions between organisms, and by 1996 the International Allelopathy Society (IAS) defined allelopathy as "Any process involving secondary metabolites produced by plants, algae, bacteria and fungi that influences the growth and development of agriculture and biological systems." In more recent times, plant researchers have begun to switch back to the original definition of substances that are produced by one plant that inhibit another plant.〔 Confusing the issue more, zoologists have borrowed the term to describe chemical interactions between invertebrates like corals and sponges.〔 Long before the term allelopathy was used, people observed the negative effects that one plant could have on another. Theophrastus, who lived around 300 BC noticed the inhibitory effects of pigweed on alfalfa. In China around the first century AD, the author of ''Shennong Ben Cao Jing'' described 267 plants that had pesticidal abilities, including those with allelopathic effects.〔Chang-Hung Chou, ("Introduction to allelopathy" ), 2006, Part 1, 1-9, 〕 In 1832, the Swiss botanist De Candolle suggested that crop plant exudates were responsible for an agriculture problem called soil sickness. Allelopathy is not universally accepted among ecologists and many have argued that its effects cannot be distinguished from the competition which results when two (or more) organisms attempt to use the same limited resource, to the detriment of one or both. Allelopathy is a direct negative effect on one organism resulting from the input of substances into the environment by another. In the 1970s, great effort went into distinguishing competitive and allelopathic effects by some researchers, while in the 1990s others argued that the effects were often interdependent and could not readily be distinguished.〔 However, by 1994 Dr. D. L. Liu and Dr. J. V. Lowett at the Department of Agromony and Soil Science, University of New England in Armidale, NSW, Australia wrote two papers 〔 Liu D and Lovett J (1994) Biologically active secondary metabolites of barley I Developing techniques and assessing allelopathy in barley Journal of Chemical Ecology 19:2217-2230. 〕 〔Liu D and Lovett J (1994) Biologically active secondary metabolites of barley. II. Phytotoxicity of barley allelochemicals Journal of Chemical Ecology 19:2231-2244.〕 in the Journal of Chemical Ecology that developed methods to separate the allelochemical effects from other competitive effects, using barley plants and inventing a process to examine the allelochemicals directly. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Allelopathy」の詳細全文を読む スポンサード リンク
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