Crotalaria incana L. y Leucaena leucocephala Lam. (Leguminosae): especies indicadoras de toxicidad por hidrocarburos de petróleo en el suelo

this study assesses the toxic effects produced by a gleysol molic soil contaminated with crude oil on seedlings of two species of legumes. a phytotoxic impact index (iif) was generated, which includes five parameters measured by relative rates of impact (irif(x)) for variables; emergency, height, root length, aboveground biomass and root biomass. bioassays were conducted under a completely randomized design with three replications under semi-controlled conditions, to assess the sensitivity of leucaena leucocephala and crotalaria incana at different concentrations of htp (total petroleum hydrocarbons). effects were highly significant (p ≤ 0.01) with increasing concentrations of htp in substrate. the emergence of l. leucocephala was 29 % lower with 80 000 mgkg-1 htp, while c. incana decreased 30 % with 32 000 mgkg-1 htp respect to control. both species showed a five-day delay in the emergence of seedlings when exposed to high levels of htp. a significant decrease in the accumulation of dry matter (dm) at concentrations above 20 000 mgkg-1 htp was observed in both species. the respective iif declined of 50 % with 80 000 and 25 000 mgkg-1 tph, but l. leucocephala had no significant effect with 10 000 mgkg-1 tph. finally, the ec50 in l. leucocephala, is presented with 80 000 mgkg-1 tph whereas in c. incana this parameter is noted from 25 000 mgkg-1 tph.