Absorption of nutrients by two cultivars of sunflower plants (Helianthus annuus L.) under field conditions: I. Macronutrients concentration

Abstract

In order to find out the absorption of the macronutrients during the growth of sunflower plants, a field experiment was carried out at the Centro Nacional de Pesquisa de Soja/EMBRAPA, Londrina, PR, Brazil. This soil used is classified as Latossolo Roxo (Eutrustox). The following doses of fertilizer were used: 0-0--0; 1-1-1; 2-1-1; 1-2-1; 2-2-1; 2-0-0 (NPK) , being 0 = zero, 1 = 45 kg/ha; 2 = 90 kg/ha (N, P2O5, K2O). The population of plants were calculated in 62,500 plants/ ha, with a spacing of 0,80 m between the lines. The authors concluded: - The lowest concentration of the nutrients occured near the period of maximum dry matter production (88 days), - For leave diagnoses the following levels may be use: N = 3.60%; P = 0.39%; K = 3.41%; Cu = 2.43%; Mg = 0.59%; and S = 0.20%.