Study of Allelopathic Activity of Common Sowthistle Weed (Sonchus oleraceus L.)

Abstract

The present work was conducted to study the allelopathic activity of Common Sowthistle weed (Sonchus
oleraceus L.) belongs to family Asteraceae growing in agricultural fields in Benghazi using Radish
(Raphanus sativus L.) as test plant. Flowers, leaves, stems and roots aqueous extracts of Sonchus
oleraceus L. at 1%,5% and 10% concentrations were applied to determine their effect on seed
germination, germination index (GI), speed/rate of germination (SG/RG), seedling vigor index (SVI), root
length (RL), hypocotyle length (HL), seedlings fresh weight (FW) and seedlings dry weight (DW) of Radish
under laboratory conditions. The aqueous extracts of all plant parts caused inhibitory effects on all
measurement, which increased progressively on increasing the concentration of extracts. On the other
hand, at low concentration (1%) stimulation of some traits of different plant parts was recorded. These
results could be explained in the light of the facts that a higher plants release a diversity of
allelochemicals into the environment, which include phenolics, alkaloids, long-chain fatty acids,
terpenoids, and flavanoids. The compounds exhibit a wide range of mechanisms of action effect on DNA
(alkaloids), photosynthic and mitochondrial function (quinines), phytohorme activity, ion uptake and
water balance (phenolics).