Allelopathic responses of Conyza Canadensis (L.) cronquist: A cosmopolitan weed
2003
Shaukat, S.S. | Munir, N. | Siddiqui, I.A. (Karachi Univ. (Pakistan). Dept. of Botany)
The effects of Conyza canadensis (L.) Cronquist on seed germination and early seedling growth of six test plants namely tomato, radish, wheat, corn, millet and mungbean was investigated. Aqueous extract of C. canadensis at different concentrations (25, 50, 75 and 100 % stock solution) inhibited the germination, root and shoot growth of all the six test species. Germination was reduced by the shoot extract in the order: tomato greater than radish greater than millet = corn greater than mungbean greater than wheat. Both root and shoot growth of the test species were reduced to varying degree and shoot growth was usually affected to a greater degree than the root growth, particularly in tomato. Decaying shoot of C. canadensis in sandy-loam at 5, 10 and 20 g/400 g soil substantially inhibited germination and seedling growth of bulrush millet (Pennisetum americanum) at all the dosages and no germination occurred at the highest dosage (20 g/400 g soil). Bioassay of the ether extract of C. canadensis disclosed two significant zones of inhibition at Rf values of 0.2-0.3 3 and 0.7-0.8. Chromatography for the phenolics revealed the presence of four phenolic compounds: gallic acid, vanillic acid, catechol and syringic acid.
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