LAUSR

The objective of this three-year study was to evaluate the effect of foliar application of dedusted potassium sulphate and chelated forms of microelements on the contents and accumulation of zinc (Zn), copper (Cu), manganese (Mn) and iron (Fe) as well as on the quality parameters of potato tubers at the stage of full maturity. Four treatments were analysed, including the control, where only nitrogen, phosphorus and potassium fertilisation was applied. Consistent with the experimental design adopted, other trials included: (I) Double foliar treatment with potassium sulphate in the combined dose of 8.6 K kg ha −1 (SOP); (II) double foliar treatment with micronutrients: 12 g Zn ha −1 , 12 g Cu ha −1 , 300 g Mn ha −1 and 500 g B ha −1 (Micro) and (III) combined application of SOP and Micro on two scheduled terms (SOP + Micro). Two potato varieties were tested: The French fries variety Zorba and the crisps variety Hermes. The experiment was arranged in a randomised complete block design with four replicates for each potato variety. Both the two-fold foliar spray with micronutrients and the treatment combined with the application of potassium sulphate resulted in the enhanced content and accumulation of the elements examined. The significant effect of the experimental factor was especially visible for the content and uptake of manganese and iron. Moreover, a highly significant relationship was determined between the tuber contents of protein and starch. The tuber quality parameters were most significantly conditioned by manganese and iron for the French fries variety and by zinc, copper and manganese for the crisps variety.