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ALLELOPATHY
ALLELOPATHY |
Allelopathy is the detrimental effects of chemicals or exudates produced by one (living) plant species on the germination, growth or development of another plant species (or even microorganisms) sharing the same habitat.
Allelopathy does not form any aspect of crop-weed competition, rather, it causes crop-weed interference, it includes competition as well as possible allelopathy. Allelo chemicals are produced by plants as end products, by-products and metabolites liberalised from the plants; they belong to phenolic acids, flavanoides, and other aromatic compounds viz., terpenoids, steroids, alkaloids and organic cyanides. Allelopathic Effects of Weeds on Crops (1) Maize:
(2) Sorghum:
(3) Wheat:
(4) Sunflower:
(i) Root exudation of maize inhibits the growth of Chenopodium album (ii) The cold water extracts of wheat straw when applied to weeds reduce germination and growth of Abutilon sp. Allelopathic effects of weeds on weeds
Factors influencing allelopathy a. Plant factors i. Plant density: Higher the crop density the lesser will be the allelo chemicals it encounters b. Climatic factors: The soil & air temperature as well as soil moisture influence the allelo chemicals potential ii. Life cycle: If weed emerges later there will be less problem of allelochemicals iii. Plant age: The release of allelochemicals occurs only at critical stage e.g. in case of Parthenium, allelopathy occurs during its rosette & flowering stage. iv. Plant habit: The allelopathic interference is higher in perennial weeds. v. Plant habitat: Cultivated soil has higher values of allelopathy than uncultivated soil. c. Soil factors: Physico-chemical and biological properties influence the presence of allelochemicals. d. Stress factors: Abiotic and Biotic stresses may also influence the activity of allelochemcals Mechanism of action of allelochemicals
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Last modified: Monday, 18 June 2012, 9:38 AM