Achenes germination of sunflower lines (Helranthus annuris L.) treated with ethephon is presented. Four different maintainer lines were treated with five concentrations of ethephon (2.0ml.l-1, 3.0ml.l-1, 4.0rnt.l-1, 5.0mt. l-1, 6.0 ml.l-1 ). Plants were treated before flowering and open-pollinated. The percentage of viable, abnormal, and non-viable germs was determined, with a strong genotypical reaction being observed. It was possible to rank the lines by sensitivity to ethephon. The optimal achene number per plot can be determined based on characters of germination of genotypes.