THE EFFECTS OF VARIED SOIL AND FOLIAR MINERAL FERTILIZATION LEVELS IN THE PRODUCTION OF HIGH-STARCH POTATOES

The objective of this study was to determine the effect of varied (280 and 420 kg NPK ha –1 ) soil and foliar application of mineral fertilizers (Basfoliar 12-4-6, ADOB Mn, Solubor DF) on the yield and qualitative traits of late-maturing potato variety Jasia. An exact, two-factorial field experiment was conducted by the randomized split-plot method, in four replications, in the years 2004–2006 in the Masurian Lakeland. The total yield of potato tubers, the content and yield of starch, and the grain size fractions of starch were determined in the study. The applied fertilizers, regardless of their rates, had no significant effect on the total yield of potato tubers and starch yield. The starch content of potatoes was affected by soil fertilization. An increase in the rate of mineral fertilizers from 280 to 420 kg NPK ha –1 caused a decrease in starch content. Large starch grains (> 40 μm in diameter), which enable to reduce the overall loss during the removal of starch from the potato pulp, dominated in the experimental material.