The purpose of the study was to determine the effect of the doses of N applied to treat new potato varieties on the content of dry matter, starch, total amount of sugars, and the reducing sugar in potato tubers. The experiments were conducted on four potato varieties: Bard, Lord, Cedron, and Kuba. The experimental field with Bard and Lord varieties (which were planned for direct consumption) was treated with three doses of N: 40, 80, and 120 kg of N/ha, while the Cedron and Kuba varieties were treated with two doses of N: 100 and 140 kg of N/ha. In the potato tubers investigated, the following parameters and the content of the following components were determined: dry matter, starch, total amount of sugars, and the reducing sugar. The potato varieties for direct consumption showed a lower dry matter and starch content, whereas the total amount of sugars in them, as well as the content of reducing sugar were higher if compared with the potato varieties planned for production of chips and dehydrated products. Higher doses of N used for the Lord variety resulted in a lower content of dry matter and starch in the potatoes, and higher doses of N used for the Bard, Lord, and Cedron varieties increased the total amount of sugars and the content of reducing sugar in potato tubers of these varieties. As for the Kuba variety, no changes in the total amount of sugars and in the content of reducing sugar were stated.
potatoes, doses of N, reducing sugars, total amount of sugars, starch, dry matter