It was attempted to determine and characterize selected quality characteristics of edible potato sold in the trade network of Siedlce by means of the variability and relationship analyses. The research material consisted of potato samples of tubers harvested during three successive years, bought once a month from October to June in five shops in Siedlce. The starch content and peeling productivity (both expressed as percentages) were determined in all samples. Moreover, an organoleptic evaluation of outer and inner characteristics of potato tuber quality was done. It was found that, apart from the regularity of tuber shape and depth of eyes, all the characteristics met the quality requirements defined by the standards. The highest variability was characteristic of the culinary and usable type, starch content and average tuber weight, which proves that the potatoes provided by suppliers vary greatly. The research carried out showed that many significant and highly significant relationships found between the quality characteristics of potato tubers were determined by the years, months and purchase places. Variation in the relationships between the examined characteristics in individual months and shops as well as a marked variation in years resulted from genetic (varietal) differences and physiological changes taking place in tubers, being modified by the storage conditions.

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