Differential competitive and allelopathic ability of Cyperus rotundus on Solanum lycopersicum, Solanum melongena and Capsicum annuum

A 2-year greenhouse and laboratory study was conducted to investigate the competition and allelopathy between Cyperus rotundus L. and Solanum lycopersicum L., S. melongena L. and Capsicum annuum L. All crops showed low ability to withstand competition of C. rotundus and this was the reason for the reduction of their total fruit number and fruit yield by 81%–94% and 86%–96%, respectively. The aqueous extracts from C. rotundus plant parts decreased the seed germination and root length of all vegetable cultivars, indicating supplementary allelopathic activity of C. rotundus on all vegetables. The low correlation coefficient between the total fruit yield of the cultivars grown under weed-free conditions and total fruit-yield reduction due to C. rotundus interference indicates clearly that the yielding ability of the cultivars is not related with their tolerance to C. rotundus interference.