Acceso usuarios
The adequate fertilization management strongly depends on the knowledge of plant demands of mineral elements. In this context, an experiment was carried out in 2010 and 2011, in Guarapuava, Paraná State, Brazil, in order to estimate the nutritional needs of pear cultivars Cascatense and Tenra in an organically managed orchard. At the end of each vegetative cycle, in early autumn, plants were removed from the soil, separated in parts (roots, trunk, branches and leaves), and analyzed for mineral content. The fruits from 2010/2011 harvest were collected in January 2011 and were also analyzed. For both cultivars, the highest content of N, Ca, Mg and S, on permanent parts, were found in the trunk. The amounts of N, K and Mg extracted by the fruits cv. Tenra were higher than those from cv. Cascatense. The mineral contents of leaves were different between cultivars. The minimum nutrient amounts of N, P, K, Ca, Mg and S annually immobilized by the permanent parts of the pear trees were, respectively, 13,763.4; 1,228.4; 7,197.2; 819.4; 2,261.2 and 1,267.4 g ha-1. The minimum nutrient amounts of N, P, K, Ca, Mg and S exported by the fruits were, respectively, 913.3; 113.3; 1,211.7; 52.3; 65.0 and 112.5 g per ton of fruits.
