Allelopathic effects of root exudates of some weeds on germinability and growth of radish (Raphanus sativus L.) and cucumber (Cucumis sativus L.)

The Allelopathy phenomenon is an important component in a natural and an agro-ecosystems causing a stimulatory or inhibitory effect in crop production through the release of allelochemicals to the environment. In this study, the allelopathic effect on seed seed germination, seedling growth, fresh weight, dry weight, vigor index, total chlorophyll and carotenoid contents of radish (Raphanus sativus L.) and cucumber (Cucumis sativus L.) to the root exudates of Ageratum conyzoides L. (T1), Leucas aspera (Willd.) Link. (T2), Scoparia dulcis L. (T3), Spilanthes acmella L. (T4) and Vernonia patula (Dryand.) Merr. (T5) were studied in the laboratory. Results showed that the concentrated aqueous root exudates of T5 exerted highly reduced the effect of all the parameters as compared to control (distilled water) followed by T4. However, T2, T3, and T1 showed the least inhibitory effect on both the test crops. In comparison to cucumber, radish was more sensitive to inhibitory effects of aqueous root exudates of these five weeds. The result suggested that the root exudates may affect radish and cucumber seeds due to the inhibitory effect of allelochemicals which were present in the tested weeds.