Absorption of nutrients by two cultivars of sunflowers (Helianthus annuus L.) under field conditions: IV. Acumulation of the micronutrients

Abstract

In order to study the acumulation of the micronutrients by sunflower plants a field experiment was carried out at the Centro Nacional de Pesquisa de Soja, Londrina, PR, Brazil. Six fertilizers doses of NPK were use, but in the present paper only the doses 0-0-0 and 90-45-45 kg/ha for the cultivar Contissol and 0-0-0; 45--45-45 kg/ha for the cultivar Guayacan were examined. Samples of plants were harvested form 14 days after emergence to the end of the plant cycle. The author concluded: The maximum acumulation occur on the 88 days and the maximum rate of 56 days after emergence. The total amount of micronutrients content in the plants for a production of 1,000 kg of seeds was: Fe = 933 g; Mn = 787 g; B = 295 g; Zn = 255 g and Cu = 10 g. The exportation of micronutrients for a production of 1,000 kg of seed was: Fe = 68.8 g; Mn = 59.9 g; Zn = 59.3 g; Cu = 22.8 g and B = 12.3 g. The total quantity of the micronutrients by the seeds obey the following order: Fe >; Mn £ Zn >; Cu >; B.