Potato crops need high investment for its establishment. Among the inputs responsible for the high crop cost, fertilizers and seeds stand out. We identified the effect of fertilizer doses and tuber seed size on growth, yield and profitability of potato crop. The experiment was carried out in a commercial potato field at Guarapuava, Paraná state, Brazil, beginning on December 2010. The treatments were 0, 2, 4 and 6 t ha-1 of mineral fertilizer (main plot) and potato seeds of type I and III (sub plot), arranged in a split-plot with three blocks. The analyzed characteristics were main stem length, number of stems, leaf area index, fresh weight and number of tubers at 24, 41 and 57 days after emergence, and marketable yield, number of tubers and maximum technical and economical doses of fertilizers at harvest. There was no significant interaction between fertilizer doses and potato seed tuber size for any analyzed characteristic. The doses of fertilizer influenced all the analyzed plant characteristics, where, in general, the higher dose resulted in higher values of the characteristics. However, the dose of fertilizers had low effect on the number of stems, which was the most influenced characteristic by the seed size; it was higher in plants from seed type I. The size of tuber seeds did not influence tuber yield. Tuber yield increased with increasing doses of fertilizer up to the dose of 4.2 t ha-1, but the maximum economic efficiency was achieved with 3.5 t ha-1 of fertilizer. It is concluded, therefore, that the use of 3.5 t ha-1 of fertilizers and potato-seed type III resulted in the best economic option for the growers.
Solanum tuberosun; fertilization; leaf area index; production; tubers
