Response of potato cultivars to increasing levels of NPK
ABSTRACT Potato cultivation has the capacity to respond to higher fertilization levels than other crops. However, the exaggerated fertilization can result in increased production cost and promote nutritional imbalance of the plant, in addition to contamination of the environment. Thus, the aim of this work was to evaluate the response of potato cultivars, bred and introduced to increasing levels of NPK, in relation to yield, specific gravity, and fry color. The experiment was carried out in Haplustox soil, in Canoinhas - SC, Brazil, in the spring season of 2014. The treatments consisted of four doses of NPK 04-14-08 fertilizer applied at 0, 3, 6, and 9 t ha-1. The experiment was conducted in a completely randomized block design (RCBD) replicated three times. Treatments were arranged in a split-plot design with cultivars as main plots and NPK doses as sub-plots. At 120 days after planting, the characters evaluated were analyzed statistically by variance analysis and polynomial regression. It was found that with increasing doses of NPK fertilizer, there is an increase in the number and size of the tubers produced; however, it does not alter the specific gravity of tubers, but there was improvement in the fry color, except for BRS Ana that had lighter fry color. The cultivars developed for local conditions, BRS Ana and BRS F63 Camila, were more productive than the introduced cultivars, Agata and Asterix, both at higher and lower doses of fertilizer. BRS F63 Camila was the most responsive cultivar to increase of fertilizer. Depending on the cultivar, the maximum technical viability estimated was the maximum tested value of 9 t ha-1 of NPK in the formula 04-14-08, as in the case of BRS F63 Camila. However, the maximum economic viability estimated ranged from 5.77 to 9.00 t ha-1.