EFFECT OF BIOELEMENTS (N, K, Mg) AND LONG-TERM STORAGE OF POTATO TUBERS ON QUANTITATIVE AND QUALITATIVE LOSSES PART I. NATURAL LOSSES

Storage is one of the most important and, at the same time, most difficult stages in potato production and potato economy. During long-term storage, potato tubers are affected by processes leading to quantitative changes. The present three-year field experiment (2003-2005) investigated the effect of varied mineral fertilization (N, K and Mg against the fixed P dose) and storage (3 and 6 months) on the occurrence of quantitative potato tuber losses. The research involved mid-early cultivars: Bila and Triada. The samples were stored in a storage chamber for 3 and 6 months (temperature +4 degrees C, relative humidity 95%). The present research shows that natural losses were affected by all the experimental factors. The K and Mg fertilizer doses significantly decreased the amount of fresh weight losses as compared with the control; as for potassium, the most favourable in that respect was the dose of 160 kg K(2)O ha(-1), and for magnesium - 60 kg MgO ha(-1). Nitrogen fertilization, on the other hand, demonstrated a negative effect on the amount of losses throughout the storage period. The highest fresh weight losses occurred after 6 months of storage and for the nitrogen, potassium and magnesium fertilization experiments they reached 8.9, 6.4 and 7.3%, respectively. The best storage life was reported for cv. Triada potato tubers - potassium fertilization and cv. Bila - magnesium fertilization.