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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.

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


(plasma physics)
The harmful effect of one plant or microorganism on another owing to the release of secondary metabolic products into the environment.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The phenomenon of allelopathy may be employed to tackle these problems (Cheema et al., 2012).
Allelopathy has been proposed as a mechanism of defense used by invasive plants toward native species through the production of chemical substances (Callay et al., 2000; Qin et al., 2006).
1995) have adequately investigated the role of chemical allelopathy. There are three requirements (Hay 1996) that must be fulfilled to demonstrate that potential hosts are chemically resistant to epiphytic organisms: (1) unusual host resistance to fouling, (2) a secondary compound with an effect on colonizers, and (3) the presence of the secondary compound on host surfaces.
Rice, Allelopathy, Academic Press, Orlando, Fla, USA, 2nd edition, 1984.
We addressed the primary question, the importance of allelopathy in determining the success of and impact of goldenrods in old field succession, in two ways.
Thus, Key biological attributes of Lantana that make this species among the world's 100 worst invasive weeds include fitness homeostasis, phenotypic plasticity, widespread dispersal by birds that feed on its fruit, a broad geographic range, vegetative reproduction, fire tolerance, ability to compete effectively with the native flora, and allelopathy (Munir, 1996).
It turns out that there is an element of allelopathy about the caffeine in coffee grounds too.
Parthenium manipulates the ecology of fields, affects yield of crops, and invades forests through its aggressive nature and allelopathy (hindering development of different plants).
It was explained that parthenium manipulates the ecology of fields, affects crop yields, and invades forests through its aggressive nature and allelopathy (hindering the development of different plants).
In Southeast Asia, he said every year, invasive species cost at least US$ 33 billion, reducing the total GDP by 5 percent, adding that Parthenium manipulates the ecology of fields, affects yield of crops and invades forests through its aggressive nature and allelopathy (hindering development of different plants).
2011), tolerates a broad range of moisture and salinity conditions (Ewe and Sternberg 2002, 2003; Mytinger & Williamson 1987), exhibits allelopathy (Morgan & Overholt 2005; Donnelly et al.