Allelopathic effects of Datura stramonium L. on rice and Echinochloa colonum

The effect of fresh fruit extract and seed extracts of Datum stramonium in aqueous methanol, chloroform and diethyl ether was studied in vitro and in pot culture on the germination and seedling growth of rice ev. Kranti and its major weed Echinochloa colonum. In in-vitro studies datura fresh fruit extract of 10 % and 20 % concentrations (w/v) significantly reduced the germination, root and shoot growth of seedlings of both the test species. However, these were found more toxic to E. colonum than rice. Seeds soaked in fruit extracts (1, 5, 10 and 20 %) for 24 h and sown in pots did not influence the plant height at 30 DAS (days after sowing) but soaking in 20 % extract significantly reduced the dry weight in rice and E. colonum. Aqueous methanol fraction of datura seeds completely inhibited the germination of E. colonum and significantly reduced the root and shoot growth of rice followed by diethyl ether and chloroform extracts. Foliar spray of aqueous methanol fraction on 20 days old test plants, drastically reduced the dry weight both in rice and E. colonum, the former being more severely affected, but the height at 30 DAS was not affected.