Absorption of nutrients by two cultivars of sunflower plants (Helianthus annus L.) under field conditions: III. Acumulation of the macronutrients

Abstract

In order to study the acumulation of the macronutrients at the Centro Nacional de Pesquisa de Soja, Londrina, PR, Brazil. The soil used is classified as Latossolo Roxo (Eutrustox). The following doses of fertilizers were use :0-0-0; 1-1-1; 2-1-1; 2-2-1; 2-0-0 (NPK); being 0=0 kg/ha ; 1 = 45 kg/ha; 2=90 kg/ha (N, P2O5, K2O). For the cultivar 'Contissol' the doses 0-0-0 and 90-45-45 kg/ha were choose and 0-0-0; 45-45-45 kg/ha at intervals of 14 days after the emergence of plants. The authors concluded: The maximum acumulation os nutrients occur near the 87 days after the emergence. The Maximum rate of acumulation occur at the 55 days after the emergence. The total amount of nutrients content in the plants obey the following order: K >; N >; Ca >; Mg >; P >; S. The maximum acumulation of the macronutrients for a production of 1,000 kg os seeds was K = 141 kg; N = 94 kg; Cu = 68 kg; Mg = 23 kg; P = 14 kg and S = 5 kg. The exportation of the macronutrients correspondent to a production of 1,000 kg of seeds were: N = 31.5 kg; K = 9.5 kg; P = 5.3 kg; Mg = 3.0 kg; Ca = 2.3 kg and S = 1.0 kg.