The purpose of this study was to observe the genetic variation of quantitative and qualitative traits and to determine important genetic parameters, including better-parent heterosis and the degree of dominance of hybrids over their parents, and their application in breeding programs. A randomized complete block design was conducted using 42 potato hybrids and 4 control cultivars with 3 replications over 2 years at the Ardabil Agricultural and Natural Resources Research Station. The highest coefficients of genotypic and phenotypic variation were related to the number of main stems per plant and the number of tubers per plant. General heritability was estimated to be between 2.27% for the days to maturity and 98.36% for the percentage of dry matter. The general heritability for tuber yield was 84.88%. The heritability and GAm were high and interconnected for the following traits: number of main stems per plant, the number of tubers per plant, tuber yield and percentage of tuber dry matter. The highest heterosis for tuber yield was observed in the LK5 hybrid from the ♀Caesar ×Luta♂ cross (66.77%) and the highest heterosis for percentage of tuber dry matter was observed in the LS7 hybrid from the ♀Savalan × Luta♂ cross (39.30%). The tuber yield of the 12 hybrids from the ♀Caesar ×Luta♂ cross indicated 58% overdominance, 33% partial dominance, and 8% reduction by dominance. The tuber yield of the 13 hybrids from the ♀Savalan ×Luta♂ cross showed 15% overdominance, 47% partial dominance, and 38% reduction by dominance, while the 12 hybrids from the ♀Caesar × Savalan♂ cross exhibited 8% overdominance, 42% partial dominance, and 50% reduction by dominance.

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