The allelopathic effects of plants

THE ALLELOPHATIC EFFECT
OF PLANTS
Raluca Elena Hedes

STRUCTURE:
PART 1: Clarifying THEORETICAL CONCEPTS and TERMINOLOGY
¨ PART 2: Aspects of PRACTICAL APLICABILITY
¨ PART 3: SOURCES
¨ PART 4: Q&A
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The term allelopathy…
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1937 – introduced by Prof. Hans Molisch

Derived from the Greek words:
Allelon = of each other
Pathos = to suffer

Definition
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1996 - The International Allelopathy Society:

“Any process involving secondary metabolites produced by plants, micro-organisms, viruses, and fungi that influence the growth and development of agricultural and biological systems (excluding animals), including positive and negative effects” (Torres et al. 1996 in Kruse et al. 2000)

Definition (simplified J )

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Biochemical inhibition of one plant by another through the release of allelochemicals Source: Muller, 1969

Allelochemicals
Chemicals released from plants and imposing allelopathic influences
¨ Allelochemicals can be found in several parts of the plant: • roots
• rhizomes
• leaves
• stems
• pollen
• seeds
• flowers
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Source: Kruse, M., et al., (2000). Ecological Effects of Allelopathic Plants – a Review

Allelopathy and Competition
Competition – the process in which the reaction of a plant reduces the level of some necessary factor to the detriment of another plant sharing the same habitat ¨ E.g. radiant energy, oxygen, CO2, mineral nutrients, water ¨ Allelopathy does NOT involve the depletion of a necessary factor and depends upon the addition of a deleterious factor (a chemical compound)
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Source: Muller, 1969

Dependence
The phenomenon of favorable response to any reaction upon the habitat by another organism
¨ When allelopathy favors the existence of some species – dependence based upon chemical reactions ¨ When competition favors the existence of some species – dependence based upon physical reactions ¨