EFFECT OF LOCATION, VARIETY, COLOUR OF FLESH AND WAY OF CULTIVATION ON THE CONTENT OF ASCORBIC ACID IN POTATO TUBERS

The results of three field trials in the Czech Republic from 2004 to 2009, which reflected the trend (nonsignificant difference) to higher content of ascorbic acid (AA) on the location Přerov nad Labem with the lowest altitude and the warmest climate (the average content of 185.69 mg/kg FM) against higher locations with higher altitudes (decrease of AA content of 4.1 to 8.3%), are reported. Content of AA in tubers was demonstrably affected by the genotype of the variety; the difference in content AA between the varieties Marabel (247.59 mg/kg FM) with the highest level and Saturna (142.20 mg/kg FM) with the lowest content was 42.6%. Varieties with purple and red pulp (169.8 to 232.8 mg/kg FM) reached in 2009 comparatively the order of the same content AA as the yellowfleshed variety Agria (233.0 mg/kg FM). In the ecological cultivation of potatoes it was found out a tendency toward lower content AA when compared with conventional way of cultivation