In the field experiment conducted in 1997–2000 the influence of certain agrotechnical factors on the yielding and quality of potato tubers was examined. The experiment was performed on good complex rye soil of the 5th quality land class. The experiment was set up in the arrangement of split-block-split-plot and in four repetitions. The four factors were analysed, i.e. the number of crossings (P1 – 2, P2 – 5, P3 – 8); the cultivars (O1 – Irga, O2 – Ekra); row-spacing (R1 – 62 cm, R2 – 82 cm, R3 – 102 cm); nitrogen fertilisation (N1 – 60 kg ha-1, N2 – 90 kg ha-1). The aim of the research was to determine changes in the directions of tuber quality of chosen potato cultivars grown under varying soil compaction, varying row-spacing and with a two-level nitrogen fertilisation. Special attention was paid to the starch content, elements of the crop structure, and skin diseases occurring on tubers. The analysis of the results revealed that the application of a wider row-spacing caused the increase in an average tuber weight, a grater proportion of big tubers and the increase in the starch content. Additionally, a negative influence of the crossings number increase on the proportional occurrence of big tubers (crop fragmentation) was observed. Significantly the highest starch content was found in the plots with the mean number of crossings (P2 – 5). It was also found that a higher nitrogen fertilisation level was the reason for the significantly higher average tuber weight and for the increase in the proportion of big tubers in the yield. The features of the cultivar itself seemed to be a significant factor. Regardless of other agrotechnical
factors and weather conditions, Irga cultivar had a significantly higher average tubers weight and a greater occurrence of very big tubers (over 60 mm) and big ones (50–60 mm), while Ekra cultivar had a higher starch content in its tubers and a lower infection of the tubers by Rhizoctonia solani (a greater number of healthy tubers).