The aim of this study has been to determine the relationship between the supply of potato with mineral magnesium during potato growth and the content of selected nutrients: magnesium, ascorbic acid and total protein in tubers after harvest and after storage. The vitamin C content was assayed with the Tillmans method, in line with standard PN-90/A-75101/11. The content of total protein was calculated from the content of nitrogen multiplied by 6.25, assayed with the Kjeldahl method on a Büchi Labortechnik B-324 apparatus, after mineralization in concentrated sulphuric acid (VI). The magnesium content was determined in the dry weight in potato tubers after mineralization and using atomic absorption spectrophotometry. An attempt has been made to present model determination of daily consumption of total protein, vitamin C and magnesium, assuming that the daily consumption of potato tubers equalled 300 g per capita. The data were compared with the RDA (Recommended Dietary Allowance). We have found that the content of magnesium after harvest ranged from 1.61 g kg-1 to 1.80 g kg-1 with an average of 1.69 g kg-1. The content of ascorbic acid ranged from 210 to 224 mg kg-1 with an average of 218 mg kg-1 and total protein – from 9.13 to 9.91 g kg-1 with an average of 9.51 g kg-1 in fresh weight of the tubers, and they were similar to data found in the literature. The following findings can be reported: 1. the magnesium fertilisation applied during potato growth increased the content of the nutrients in tubers; 2. after 3 and 6 months of tuber storage, the content of ascorbic acid became considerably decreased, but the magnesium applied reduce the loss; 3. potato tubers had the highest nutritive value when magnesium sulphate was applied at a dose of 80 kg MgO ha-1.

25.2.2020