EN
It is commonly believed that intensive nitrogen fertilization, while increasing the yield, simultaneously causes depreciation of the crop's quality. Potential accumulation of nitrates and solanine i.e compounds harmful to the consumers creates additional concern. The results obtained in our studies of many years show that systematic increase of yield affected by bigger and bigger doses of nitrogen fertilizers is not accompanied by significant relations among the particular components of nitrogen compounds. The concentrations of nitrates and solanine increased considerably but did not reach values which, according to compulsory international standards, should be considered harmful. Nitrogen fertilization not only did not modify the vitamin C content in potato tubers but-on the contrary-caused a significant increase its concentration in many studied cultivars.