The present work looks for a knowledge of multiplícate rate and mortality index of. S. punctata to several concentrations of butachlor, propanil and gliphosate as well as to compare two different methods. On essay 1 the concentrations were a little toxic provoking low index of mortality in spite of it has occured inhibition of increasing on stronger concentrations. The essay 2 showed what, the butachlor and the propanil are more toxics than the gliphosate, with values of mortality of 100% in only 48 hours. The multiplícate rate, on this essay, was only determinated to the gliphosate, because the other herbicides were highly toxic to the species. It was checked on the comparation of the two different methods the posts used on essay 2 were more appropriate to the cultive specie and the toxic effects must be observated on considered individualy and not on whole plants.
Spirodela punctata; Butachlor; Propanil; Gliphosate; Growth