Productivity and establishment of DRIS indexes for cultivation of potato cultivar Asterix tubers in a dystrophic Red Latosol

The potato culture has the highest relative demand for fertilizers per unit area, around 2.3 to 2.8 t ha-1. The objective of this study was to evaluate the productivity of a potato Asterix cultivar subjected to different doses of nitrogen, phosphorus, and potassium, and to establish the DRIS index according to productivity results. The experimental design was randomized blocks, with 5 rates and 4 replicates for each nutrient totalizing 20 plots per experiment. The rates of nutrients were: nitrogen (0, 70, 140, 210 and 240 Kg ha-1); phosphorus (0, 200, 400, 600 and 800 kg ha-1) and potassium (0, 150, 300, 450 and 600 kg ha-1). For leaf diagnosis by the DRIS index, 10 complete leaves of the third expanded trifoliate were collected. The DRIS standards calculations were based on populations of high productivity (or reference) and low productivity. Plants whose productivities were greater than 22 t ha-1 represented the groups of reference. It was concluded that productivity was not influenced by the P and K doses studied, with an increase in yield of tubers as a function of the N rates applied, up to the dose of 173 kg ha-1 of N. According to the DRIS index, it is possible to establish the order of limiting nutrients for failure in descending order in areas with high productivity Ca> Mn> P> S> Zn = Cu> K> N> B> Fe> Mg, and the order of limiting nutrients in areas of low productivity Ca> Cu> Mg> P> S> Mn> Zn> K> Fe = B> N. The results showed that productions above 22 t ha-1 need adjustments of the soil fertility managements.