Influence of environmental conditions and way of cultivation on the polyphenol and ascorbic acid content in potato tubers

In 1995 till 1997 field trials were conducted to study the influence of environmental conditions of regions with different altitudes, variety, year and ecological way of cultivation on total polyphenol content (in Agria and Karin variety) and ascorbic acid (in seven varieties after five months of storage) in potato tubers. In three year trials significantly higher total polyphenol content was determined (46.25 mg.100 g(-1)) in potato tubers from traditional potato regions of the Czech Republic with higher altitude (cooler and more humid) in comparison with drier and warmer regions of lower altitudes (43.50 mg.100 g(-1)). Highly significant differences of total polyphenol contents were found between two used varieties; total polyphenol content was higher in the Karin variety (52.89 mg.100 g(-1)) than in the Agria variety (36.85 mg.100 g(-1)). Variety influence was more apparent than locality influence. In potatoes cultivated in ecological way in three year period higher total polyphenol content in tubers (47.64 mg.100 g(-1)) was found than in potatoes cultivated in conventional way (43.20 mg.100 g(-1)). Our experiments have not proved dependence of ascorbic acid content on different ecological conditions of higher and lower situated regions of the Czech Republic. Significant influence on ascorbic acid content has shown the variety. In seven investigated varieties we have found the highest ascorbic acid amounts in the Impala variety (6.37 mg.100 g(-1)), the lowest levels in the Rosella variety (5.16 mg.100 g(-1)). Influence of a given year on ascorbic acid content has been manifested more significantly in comparison with that of variety. Vegetations of all three years have differed each other very significantly in ascorbic acid content when they reached the levels 4.91, 6.47 and 5.75 mg.100 g(-1) in 1995, 1996 and 1997. Ecological way of cultivation has not influenced ascorbic acid content in tubers because differences against the results obtained for potatoes cultivated in conventional way have not exceeded levels of statistical significance and there has not become evident an unambiguous trend.