What is allelopathy


The term ALLELOPATHY denotes that body of scientific knowledge which concerns the production of specific biomolecules by one plant, mostly secondary metabolites, that can induce suffering in, or give benefit to, another plant. This concept suggests that biomolecules (specifically termed allelochemicals ) produced by a plant escape into the environment and subsequently influence the growth and development of other neighbouring plants.

There is convincing evidence that allelopathic interactions between plants play a crucial role in natural as well as in manipulated ecosystems :
  1. The credit for a specific vegetational pattern has mostly been given to the competition. However, in recent times evidence is accumulating that all types of plants, viz. herbs, shrubs and trees, allelopathically affect the patterning of vegetation, largely in their immediate vicinity.
  2. One of the most worked out aspects of allelopathy in manipulated ecosystems is the role of allelopathy in agriculture. In this, the effects of weeds on crops, crops on weeds and crops on crops have been invariably emphasised. In addition, the possibility of using allelochemicals as growth regulators and natural pesticides (number of them are either commercially available or in the process of large-scale manufacture) promotes sustainable agriculture.
  3. Allelopathic interactions have been demonstrated to play a crucial role in natural as well as man-made forests. Such interactions are pivotal in determining the composition of the vegetation growing as understorey and in understanding the forest regeneration problems. Results obtained so far have shown that almost all types of plants (viz. angiosperms, gymnosperms, lower plants like ferns and micro-organisms, including mycorrhizae) present in forests indulge in allelopathic interactions.
  4. Some of the recent fundings have demonstrated that tree-crop interactions may have significant bearings on the total productivity of an agroforestry system (simultaneously or sequentially combined production of crops and forest plants). Therefore, it seems essential that the allelopathic compatibility of crops with trees should be checked before being introduced to an agroforestry system.

The above-quoted examples are some of the major aspects of allelopathic interactions in natural and manipulated ecosystems. Research is continuing in all these areas and many few ideas have been floated in an attempt to understand the phenomenon of allelopathy more deeply and to exploit it more fully to boost the production of manipulated ecosystems.

You can see below two examples of allelopathy :

  1. Allelopathic effects of fern frond aqueous extracts on spruce seeds germination.

    Athyrium filix-femina produces phenolic compounds (mainly catechol, p-hydroxybenzoic and protocatechuic acids) which induce necrosis of radicule during germination of Picea abies seeds.

  2. Allelopathic effects of protocatechuic acid on a spruce mycorrhizal fungus growth.

    This phenol is one of the components of the spruce forests humus. Its natural concentration ranges around 10 E-5 M and growth tests of Cenococcum geophilum shown that even naturally occurring concentration inhibit growth of this fungus.

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