Twenty sunflower seed lots were subjected to accelerated aging at 42ºC and 100% relative humidity for periods of 0, 24, 48, 72, 96, and 120 hours. The objective was to determine the exposure time which best discriminated the lots as to the germination response after aging. Results showed that seed lots were quite different concerning the degree of resistance to the unfavorable conditions of accelerated aging, even those with comparable initial percentages of germination. The initial standard germination test was not appropriate to show differences among lots. The 72 hour exposure period was the best for discriminating lots with higher percentages of germination, and the 48 hours exposure period was the best for lots with lower percentages of germination (less than 50%).
germination; vigor; sunflower; Helianthus annuus L.