Plant Protection Department, Faculty of Agriculture, Fayoum, Cairo University Cairo, Egypt.
Annals of Agricultural Science, Cairo 50: 123–134, (2005).
C. rotundus leaves and tubers was tested for allelopathic potential against the weeds wild beet (Beta vulgaris), canary grass (Phalaris minor) and barnyard grass (Echinochloa crus-galli). In the laboratory, the crude extracts of leaves and tubers at 10, 20, 40 and 80% were applied on weed seeds and seed germination was observed. In the glasshouse (during 2003–04), ground tubers and leaves of C. rotundus were mixed with soil at 1.5, 3, 6 and 12 g per 500 g soil (w/w) per pot. Weed seeds were sown in the pots and seedling emergence was observed. C. rotundus did not significantly affect wild beet germination percentage, but negatively affected those of canary grass and barnyard grass particularly at 40 and 80% extract concentration. The extracts also inhibited seedling length and fresh weight of canary grass and barnyard grass particularly at 40 and 80% concentration. In the glasshouse, barnyard grass was the most susceptible to allelopathy by C. rotundus residues, followed by canary grass and wild beet. Seedling emergence inhibition and reduction in weed dry matter were higher with tuber than leaf residues. Foliage residues reduced the dry weight of wild beet by 91 and 70% of the control at 6 and 12 g, respectively. The crop residues showed lower reduction in the dry weight of wild beet than the other 2 weed species. C. rotundus tuber and foliage contained different flavonoids and phenolic compounds: rutin, kaempferol, quercetin, myricetin, p-hydroxybenzoic, chI orogenic acid and ferulic acids.
