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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 ?
seed extracts decreased the percentage of germination of lettuce seeds, indicating allelopathic interference of chemical compounds (Delgado & Barbedo, 2011).
The waxy cuticle of each gland encapsulates the sticky resin until it is needed for protection from herbivory (or to attract humans who disseminate it) and abscise readily as a convenient way of delivering its evolutionarily common allelopathic aromatic constituents, in addition to its evolutionarily unique cannabinoids.
For both organs, the fractions obtained with the solvent n-hexane had higher levels of inhibitory activity, which suggests that substances with allelopathic potential present in D.
2013c,d) benefits of managing cover crops with herbicide or mowing before main crop sowing are: reducing competition for water in the early crop development, promotes decomposition of cover crop residues or weeds, which can provide nutrients to the crops, improves uniformity of sowing; reduce possible allelopathic effects of cover crops or weeds, and provides increased in crops yield.
This could indicate that the action of microcystins as allelopathic compounds on photoautotrophic competitor organisms has a low probability.
Allelopathic effects of extracts from wheat and its secondary metabolite 2, 4-dihydroxy-7methoxy-1, 4- benzoxazin-one on weeds.
Root exudate is allelopathic in invaded community but not in native community: field evidence for the novel weapons hypothesis.
Knox, An investigation on suppressing capabilities of some allelopathic plants against Parthenium hysterophorus L.
Macharia and Peffiey (1995) reported the allelopathic effect of Allium fistidosum and A.
According to Ceruks, Romoff, Favero, and Lago (2007), this group has different species with high allelopathic activity, the action of which is mainly due to phenolic constituents with toxic actions.