The use of biostimulants and cultivar selection play an important role in modern potato farming because they influence tuber yield and quality. The nutritional value and processing suitability of potato tubers are affected by their content of total protein, reducing sugars and sucrose. The aim of this study was to determine the effect of biostimulants on the content of total protein, glucose, fructose and sucrose in potato tubers (skin, flesh and whole tubers with skin), at harvest and after 5 months of storage. The experimental materials included tubers of five edible potato cultivars: Irga, Satina, Valfi, Blaue St. Galler and HB Red. During the growing season, potato plants were treated with the following biostimulants: Asahi SL, Bio-Algeen S-90, Kelpak SL and Trifender WP. Control plants were not treated with biostimulants. The total protein content of tubers was determined by the Kjeldahl method. Simple sugars and sucrose were determined by high-performance liquid chromatography. At harvest, total protein concentration was significantly higher in purple- and red-fleshed cultivars than in cream- and yellow-fleshed cultivars. An analysis of tuber parts revealed that flesh had the highest protein content. The total protein content of tubers increased during storage. Biostimulants had no significant effect on total protein concentration in tubers at harvest or after storage. The content of simple sugars and sucrose was higher in the skin, flesh and whole tubers of purple- and red-fleshed cultivars, than in cream- and yellow-fleshed cultivars. Potato tubers with colored flesh accumulated the highest amounts of total sugars. Biostimulants, in particular Bio-Algeen S-90 and Kelpak SL, contributed to the accumulation of monosaccharides and the disaccharide in potato tubers, and, in consequence, total sugars. Their concentrations in potato tubers increased during storage.

An application of biostimulants is becoming an increasingly popular operation in agriculture because they positively affect crop performance and qualitative characteristics, and prevent stress-related losses. The objective of this study was to determine the effect of an application of the following biostimulants: PlonoStart, Aminoplant, and Agro-Sorb Folium, and the herbicide Avatar 293 ZC on total carotenoids in table potato tubers. The research material consisted of tubers of two table potato cultivars, Oberon and Malaga, which were produced in a 3-year field experiment. Chemical analyses of fresh material were conducted 4–6 days following harvest. Biostimulants applied with the herbicide significantly increased the table potato tuber content of carotenoids compared to tubers obtained from unamended control plots. The highest accumulation of carotenoids was determined following an application of the biostimulant Agro-Sorb Folium, and it was higher in the tubers of cv. Oberon versus cv. Malaga. It should be added that in the available literature there is no research on the effect of biostimulants on the content of carotenoids in potato, which is the main food in the world. Carotenoids perform many important functions in the human body. They exhibit antioxidant properties, which means that they protect cells from damage, and also have a beneficial effect on the immune system. Carotenoids are substances that show an indispensable effect on the health and appearance of the skin. Regular consumption of them in the form of vegetables and fruits ensures its firmness, elasticity, smoothness, as well as a healthy appearance. The protective function of carotenoids against free radicals simultaneously contributes to slowing down the aging process. This action, in turn, translates into preventing the development of cancer or diseases of the circulatory system.

The group composition of epicuticular waxes of the five Polish varieties of Solanum tuberosum were studied by HPLC, GC, and GC/MS. Alkanes, alcohols (primary and secondary), fatty acids and ketones (terminal and internal) were identified and quantified. The quantitative compositional results were analysed by chemometrie methods such as cluster and principal component analysis. A correlation was found between Colorado potato beetle infestation and quantities of specific chemical groups in epicuticular waxes.