Drought is a serious threat to cotton growing. This study aims to evaluate effect of hydropriming on seed germination of two varieties of cotton, STAM 129A and STAM 190, under drought stress. Seeds are primedfor3, 6, 9, 12, 15 and 18 hours. The germination test was carried out in 90 mm Petri dishes, at 0, -3, -6 and -9 bar adjusted by PEG-6000, and lasted 7 days. Germination percentage (GP), mean germination time (MGT), germination index (GI) and the relative PEG injury rate (RPIR) was then calculated. The results show that drought stress damage on seed germination was significantly reduced by priming seeds for 12 hours for both cotton varieties. Under drought stress, 12H-hydropriming increased the GP by 206.25% for STAM 129A and 179.26% for STAM 190. Germination, previously nil at -6 bar and -9 bar for unprimed seeds, becomes possible with priming and better with 12H-hydropriming. Increases of 250.76% and 289.55% of GI for respectively STAM 129A and STAM 190 are noted, when MGT did not vary significantly from the control. RPIR was reduced 35.89 % for STAM 129A and 27.10 % for STAM 190.Thus, seed hydropriming of STAM 129A and STAM 190 for 12 hours can be recommended to maintain germinative vigor whatever rainfall conditions may arise.
