Three variety of rice seed (Oryza sativa L.) BR-IRGA 410 and BR-IRGA 414 (semi-dwarf type) and Bluebelle (intermediate type) were treated with plant-growth regulator (PRO-GIBB), thus active ingredient is Gibberellic Acid (GA3) on five doses: 0,0; 0,25; 0,50; 0,75 and 1,00g GA3/50kg of seeds and proceed germination test at four constant temperatures: 15, 18, 21 and 25°C and evalued first count and germination percentage. The results allowed to conclude what the Gibberellic Acid: a) increased first count of germination in sub-optimal temperatures of germination (15 at 21°C); b) increase the percent of germination in semi-dwarf varieties in sub-optimal temperatures of germination (15 at 21°C) e, c) the dose more adequade were 1,00g GA3/50kg seeds for BR-IRGA 410 and BR-IRGA 414 variety and 0,75g GA3/50kg seeds for Bluebelle variety.