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The biochemical interactions among all types of plants, including microorganisms. The term is usually interpreted as the detrimental influence of one plant upon another but is used more and more, as intended originally, to encompass both detrimental and beneficial interactions. At least two forms of allelopathy are distinguished: (1) the production and release of an allelochemical by one species inhibiting the growth of only other adjacent species, which may confer competitive advantage for the allelopathic species; and (2) autoallelopathy, in which both the species producing the allelochemical and unrelated species are indiscriminately affected. The term allelopathy, frequently restricted to interactions among higher plants, is now applied to interactions among plants from all divisions, including algae. Even interactions between plants and herbivorous insects or nematodes in which plant substances attract, repel, deter, or retard the growth of attacking insects or nematodes are considered to be allelopathic. Interactions between soil microorganisms and plants are important in allelopathy. Fungi and bacteria may produce and release inhibitors or promoters. Some bacteria enhance plant growth through fixing nitrogen, others through providing phosphorus. The activity of nitrogen-fixing bacteria may be affected by allelochemicals, and this effect in turn may influence ecological patterns. The rhizosphere must be considered the main site for allelopathic interactions.

Allelopathy is clearly distinguished from competition: In allelopathy a chemical is introduced by the plant into the environment, whereas in competition the plant removes or reduces such environmental components as minerals, water, space, gas exchange, and light. In the field, both allelopathy and competition usually act simultaneously.



the effect of plants on one another as a result of their secretion of various substances. Four groups of such substances are known. Substances of two of the groups are formed by microorganisms: antibiotics, which suppress the vital activity of other organisms, and “maras-mines” (wilting substances), which act on higher plants. Substances of the two other groups are secreted by higher plants: phytoncides, which suppress the vital activity of microorganisms, and cholines, which retard the growth of higher plants. Sometimes a positive influence is observed by one plant upon another, which is particularly important in agrophytocenoses. The phenomenon of allelopathy must be taken into consideration in growing agricultural plants (including crop rotation and mixed sowings).


Grodzinskii, A. M. Allelopatiia v zhizni rastenii i ikh soobshchestv. Kiev, 1965.
Fiziologo-biokhimicheskie osnovy vzaimnogo vliianiia rastenii v fitotsenoze. Moscow, 1966.


(plasma physics)
The harmful effect of one plant or microorganism on another owing to the release of secondary metabolic products into the environment.
References in periodicals archive ?
Perspectives on allelopathy in mexican traditional agroecosystems: A case study in Taxcala.
Now-a-days throughout the world allelopathy is being focused by the researchers and agriculture scientists as alternative of herbicides, cheap and environment friendly approach for effective and sustainable management of weeds in field crops.
A similar hypothesis was proposed by Lange and Reynolds (1981), who indicated that allelopathy may be exacerbated in areas with low rainfall because allelopathic chemicals would concentrate in the upper soil surface rather than leach through the soil profile with heavy rainfall.
When she had a project that required the work of a biochemist that subsequently led to important findings about allelopathy, she said she never had trouble finding summer money for research once the chemistry department got involved.
3] studied the marigold and pigweed allelopathy by intercropping for the management of tomato early blight disease.
Cover crops suppress weeds, out-competing them for water and nutrients and shading them under a canopy, sometimes releasing chemical compounds that inhibit germination of weed seeds--a phenomenon called allelopathy.
Allelopathy provides a relatively cheaper and environmental friendly weed control alternative [1, 2], It is becoming increasingly difficult to ignore the role of allelopathy in plants.
According to David Gealy, a plant physiologist at ARS's Dale Bumpers National Rice Research Center in Stuttgart, the new line is the top pick of some 50 total rice lines that were selectively developed for such traits as high grain yield and quality, early maturity, stem strength, pest and disease resistance, and allelopathy to barnyardgrass and other weeds.
Allelopathy is the negative effect of chemicals released by one plant species on the growth and reproduction of another [1].