2.2. Field experiments method
All potatoes were cultivated according the same method: as a pre-crop cereals or green-manure; fertilisation with 35 t/ha manure in the autumn supplemented with phosphate and potassium (magnesium) fertilisers (dose with regard to the supply of nutrients in the soil): nitrogen (120 kg/ha) of soil in preparation for spring. Experimental area: 13.950 m2 (2 lines of 32 clusters, i.e. 1.5 m × 9.30 m = 64 clusters on the plot); ties of planting: 0.75 m (spacing) × 0.29 m (distance of plants); seedlings: size 35–45 mm, sprouting, and 15 kg for a location for each cultivar. Cultivation: harrowing and pre-emergence herbicide application, potting; protection with regard to weeds and pests registered products; monitoring of vegetation: the final number of clusters on a plot and condition of the plants in flower (height, uniformity, coverage, total state); harvest: each part separately with findings yield per plot; sampling: 25 kg. Experiments were performed in three replicates. Uniform-size potatoes were selected from each cultivar before starch isolation.