Phytotoxic effect of plant extracts from asteraceae on germination of echinocloa crus-galli growth

In Egypt Echinocloa crus-galli is one of the most successful yield-limiting weeds in the rice fields that its control mostly relies on herbicides. Plant species Nauplius graveolens, Picris asplenioides, Reichardia tingitana and Urospermum picroides were collected from naturally growing population in coastal (Deltaic Mediterreanean coast) and inland desert WadiHagul of Egypt. The phytochemical analysis of the selected species in the present study showed that, they contain relatively high contents of tannins, saponins, flavonoids, alkaloids and phenols. At 500 µg/ml the scavenging activity of Nauplius graveolens, Picris asplenioides, Reichardia tingitana and Urospermum picroides extracts were 14.3%, 6.25%, 7.73% and 4.14, respectively. The allelopathic effect of the extracts from the different tested species exhibited reduction of Echinochloa crus-galli seed germination. Also, the allelopathic activities of different extracts of the four species significantly inhibited shoot and root growth of Echinochloa crus-galli at both low and high concentrations.