Effects of Different Cultivation Treatments on Tuber Yield, Nitrogen Compound Accumulation, and Natural Storage Losses in Chip Potatoes

The yield, consumer safety, and storage stability of potato tubers depend on the interaction between the genotypic characteristics of the cultivar, its intended use, the cultivation technology applied, and storage conditions. The aim of this study was to comprehensively assess the effects of seed potato dressing with a fungicide and a biostimulant, applied individually or in combination, on total and starch yield, the content of undesirable nitrogen compounds, and the storage stability of tubers. A field experiment was conducted over three growing seasons (2021–2023) at the Agricultural Experimental Station of the University of Warmia and Mazury in Olsztyn, using a randomized split-block design with three replications. The field experiment was conducted over three growing seasons (2021–2023) at the Agricultural Experiment Station in Tomaszkowo (53°42′ N, 20°26′ E). Three potato cultivars intended for chip processing were evaluated using a randomized split-block design with three replications. The storage experiment and laboratory analyses were conducted at Bydgoszcz University of Science and Technology. Analyses were performed immediately after harvest and after six months of storage under controlled conditions (8 °C and 95% relative humidity). The novelty lies in the comprehensive evaluation of the effects of fungicide and biostimulant seed treatments on potato yield, starch production, nitrate and nitrite accumulation, and storage losses. Potato genotype had a significant effect on tuber yield and the proportion of marketable tuber yield. The highest total and marketable tuber yields were obtained from the cultivar with the longest growing season. The study demonstrated variation in total tuber yield, marketable tuber yield, and the proportion of marketable tuber yield depending on the study year, reflecting differences in meteorological conditions among growing seasons. The cultivation technology did not significantly affect total tuber yield. Numerically, the highest total tuber yield (35.81 t ha−1) was recorded following the combined application of fungicide and biostimulant, while the highest marketable tuber yield was observed after treatment with fungicide (23.40 t ha−1). The potato cultivars intended for chip processing were characterized by low nitrate and nitrite contents (49.56 and 0.49 mg kg−1 FM, respectively), not exceeding 200 mg kg−1 limit for food intended for children. After six months of storage, the contents of these harmful nitrogen compounds decreased by an average of 8%, while natural storage losses remained low, averaging 3%. The effects of the cultivation factors applied during the growing season on nitrate and nitrite contents after storage were consistent with the trends observed immediately after harvest. These findings indicate that the cultivation technology evaluated in this study can be recommended for the production of potatoes intended for chip processing. However, further research involving a larger number of cultivars, including those intended for French fry processing and table use, is needed to confirm the broader applicability of these results.