that phenolic allelochemicals released from root and residues are responsible for
growth inhibition of Oryza sativa [27]. Four biological active compounds, namely,
4-hydroxy-3,5-dimethoxybenzaldehyde, (À) loliolide, 3-ß-hydroxy-5a,6a-epoxy-7megastigmen-9-one, and 3-hydroxy-ß-ionone, have been isolated from Bangladesh
indigenous rice (Oryza sativa L. variety, Boterswar) [4], and these four compounds
synergistically suppressed the growth of Echinochloa crus-galli more strongly than
the individual compounds.
Allelopathic activity and total phenolic content of water extract of shoot and root
of foremost plant species which grow in 1-year-old and 2-year-old clear-cuts of scot
Pinus sylvestris were studied [28]. Extracts of Rumex acetosella and Calluna
vulgaris show the strongest allelopathic activity which inhibits seed germination
benzoic acid
Chlorogenic acid
Vanillic acid
p-coumaric acid
trans-cinnamic acid
Ferulic acid
p-hydroxybenzoic acid
salicylic acid
syringic acid
cis-cinnamic acid, 1-O-cis-cinnamoyl-β-Dglucopyranose
6-O-(49-hydroxy-29-methylenebutyroyl)-1-Ocis-cinnamoyl-β-D-glucopyranose
Fig. 2 Structure of allelochemical isolated from Spiraea thunbergii and Eucalyptus species
19 Plant Allelochemicals and Their Various Applications
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