Strategies modulating the level of harmful nitrogen compounds in edible potato tubers depending on the evaluation date

Due to its high daily consumption, the potato is classified as an important vegetable of the human diet. Its food safety is determined, among other things, by the content of nitrates and nitrites in the tubers. The aim of this study was to comprehensively analyze the effect of genotype, cultivation and storage technology on the concentration of nitrates and nitrites in the tubers of edible potato varieties (Gardena, Denar). Potatoes were grown using integrated and organic technology at different locations. Various variants of fertilization, protection against fungal pathogens and plant stress protection were applied. The content of nitrates and nitrites was evaluated immediately after harvest and after 6-month storage under constant conditions of temperature and relative humidity consistent with the direction of use. The content of the tested compounds was influenced by all factors of the experiment. Significant differences were found between the tested varieties. The Gardena variety was characterized by a lower propensity for nitrate accumulation compared to the Denar variety, with an average of 82.3 and 85.4 mg kg^-1 f. m., respectively. Due to more favorable weather conditions in 2020, the concentration of nitrates and nitrites was at a lower level compared to 2021 (69.2; 0.56 and 98.5; 0.75 mg kg^-1 f. m., respectively). Of the technologies used, organic cultivation proved to be the most favorable, for which location turned out to be important. The use of protection against fungal diseases and the intervention irrigation treatment contributed to a decrease in the content of the tested compounds. Long-term storage reduced the content of nitrates and nitrites by an average of 2.7% and 7.5%, respectively. It was shown that the effect of experimental factors on the content of the tested nitrogen compounds after storage was the same as after harvest. Regardless of the experimental factors, the daily intake standards for nitrate and nitrite were not exceeded.