Abstract

This study aimed to evaluate the effect of increasing N rates as ammonium sulfate combined with three irrigation rates on leaf P and K concentrations in 10 blueberry (Vaccinium spp.) cultivars grown in pots with a substrate. Four increasing N rates (0%, 100%, 200%, and 300%) and three irrigation rates (70%, 100%, and 130% of the water requirement) were evaluated on leaf P and K concentrations previous to a winter break of 10 blueberry cultivars grown in pots with a substrate. Overall, the P values were within normal ranges reported for some cultivars of blueberries; however, K values were higher than those reported in other studies, except for "Blue Ribbon." Treatments affected leaf P and K concentrations, and the N application was usually positively correlated with the leaf P concentration and negatively correlated with the leaf K concentration. The P and K concentration values ranged from 0.05 to 0.26% and 0.61 to 2.70%, respectively.The highest P and K values were obtained with the N fertilization treatments N 200% and N 0%, respectively; in general, these values were significantly higher with 70% of the water requirement. At the N 100% fertilization rate, all cultivars reached an adequate leaf P concentration, except cv. Blue Ribbon. On the other hand, the different irrigation rates mainly affected leaf P concentration, and, in five of the evaluated cultivars, there was no effect of irrigation on leaf K concentration.