A trial was conducted in 1990, 91 and 92 at Federal University of Rio Grande do Sul, in Porto Alegre, RS, Brazil, to investigate the effects of herbicides applied at the reproductive period of jimsonweed (Datura stramonium). Two imidazolinones (imazaquin and imazethapyr) and two sulfonylureas (chlorimuron and metsulfuron), which were tested for their effect on the number of seeds produced, seed viability and seed germination. All compounds applied at flowering stage, except half rate of metsulfuron, reduced by more than 75% the number of seeds produced. Herbicide applications at flowering stage reduced seed production by 76% in comparison with plants sprayed at grain filling stage. Jimsonweed seed viability was not affected by the treatments. Herbicides applied during jimsonweed reproductive stage reduce its survival by decreasing seed production.
Reproductive characteristics; seed viability; late applications; Datura stramonium; seed germination