Abstract
We studied the aqueous extracts of different organs (root, stem, leaf and fruit) of colocynth (Citrullus colocynthis (L.) Schrad. to control ryegrass (Lolioum rigidum Gaudin), major weed in barley (Hordeum vulgare L.) crop. We found strong decrease in barley germination (83.3 to 46.7 %) and seedling number (85 to 65 %) due to competition from ryegrass. The fruits and leaves extracts of colocynth at 5 % concentration and all organ extracts at 10 % concentration completely inhibited the ryegrass seed germination. Phytochemical analyses showed that glycosides, alkaloids and cucurbitacins were the most abundant metabolites in fruits and leaves of colocyhnth extracts. These allelochemicals have high allelopathic potential to inhibit the ryegrass seed germination. According to soil sorption/desorption of colocynth allelochemicals results, this study suggested that colocynth extracts, can be field-sprayed one month prior to barley sowing to control noxious weeds i.e. the colocynth extracts may be suggested as promising biological material for ryegrass control.