The paper presents the variability analysis of some quantitative characteristics, that is of tuber yield, starch content and yield, dry matter content and yield and vitamin C content in selected edible potato varieties. Reciprocal relations of variance components calculated and their percentage share in the total variability were a measure of variability evaluation for the characteristics examined. Moreover, the variability of the characteristics was characterised by means of the classical variability coefficient. It has been found that tuber yield and vitamin C content variability was determined mainly by the interaction effects of years and the factors examined, as well as the experimental error. The respective values were as follows: 44.3% and 34.7% for tuber yield, and 42.2% and 46.2% for vitamin C. The starch content was in 47.5% modified by the effects of the main factors (including 35.0% for years) and the error effect (39.0%). A similar interaction was observed in the case of dry matter content variability, but the error was 52.4%. Starch and dry matter yields were determined mainly by interaction effects of the years and the examined factors (40.7% and 39.9%, respectively) as well as the experimental error (32.2% of the total variability for both traits). The highest changes expressed as the values of the coefficient of variation were found for tuber yield, dry matter yield and starch yield.

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