Abstract

Allelopathy refers to an ecological phenomenon where there is plant-plant interference through release of organic chemicals (allelochemicals) in the surrounding soil environment as water leachates or root exudates. Crop residues produce allelochemicals that may inhibit seed germination of many weeds. In this study, I assessed the effect of aqueous extracts of three crop residues (radish, rocket and rhodes) on final germination percentage and germination rate of four desert plants recorded as weeds in the United Arab Emirates farms (Coelachyrum piercei (Benth.) Bor, Plantago ovata Forssk., Sporobolus arabicus Boiss. and Tephrosia apollinea(Delile) DC.). Residues of the two crucifers (radish and rocket) were more effective in inhibiting seed germination of the four species. Up to 4% of rhodes grass extracts showed insignificant effects on the seed germination. Both C. piercei and P. ovatewere more sensitive to allelopathic effect (their germination was greatly inhibited), butS. arabicus and T. apollinea were more resistant to the extracts. The suppressive ability of the two crucifers’ residues would be of environmental importance if integrated in weed management programmes.

Key words: Crop residues, radish, rhodes, rocket, seed germination, weeds.