The effects on germination and early seedling growth of presowing true potato seed in water or gibberellic acid (GA) at 1500 ppm and of priming in -1.0, -1.25 and -1.5 MPa solutions of KNO3+K3PO4 were studied using 30, 18, 6 and 3/4 month-old seed. The influence of light during presowing on the effectiveness of treatments was also investigated. Overall, priming in the light at -1.0 MPa was the most, and GA the least successful treatment for enhancing emergence and subsequent seedling growth. Though GA increased final emergence from about 20 to 70% in the most recently harvested lot (3/4 mo), the rate and extent of final germination or emergence in this dormant seed was still much lower than that of the nondormant lots (6-30 mo), especially when the latter were primed. For all lots, dry weight per seedling was 40% lower in dormant than in nondormant seed, and 20% higher when seeds were primed at -1.0 MPa than when GA treated. In conclusion, the use of nondormant seed may be a requirement for both effective priming and sowing of potato crops via true seed. © 1989 Kluwer Academic Publishers.