MACRONUTRIENT UPTAKE RATE of SUNFLOWER CROP (Helianthus annuus L.).

The study aimed to establish curves of macronutrients accumulation in sunflower crop. Thus, an experiment was conducted in field on Typic Hapludox, located at the experimental farm of Embrapa Soja in Londrina/PR. The plots consisted of 14 lines with 25 m length and 0.70 m width, resulting in a total area of 245 m2. Each plot was replicated four times. The fertilization seeding was 300 kg ha^-1 of 05-20-20, before sowing. Fertilization was split in two applications of 25 + 1 kg ha^-1 N and B, respectively, which the first application was applied at 21 and the second at 35 days after sowing. It was used the hybrid BRS-191 and the final plant density was 40.000 plants ha^-1. Plant samples were collected at each interval of 14 days after emergence and share in different parts as petioles, leaves, stems and, when applicable, chapter and achenes. After drying, each plant part was weighed and ground in order to determine the content of N, P, K, Ca, Mg and S. From the levels of these nutrients and dry mass of each plant, it was obtained the curves of accumulation. It was found that for obtaining yield higher than 3000 kg ha^-1, the hybrid BRS 191 drew about 150, 24, 286, 116, 42 and 24 kg ha^-1 of N, P, K, Ca, Mg and S, respectively, showing a following order of extraction: K> N> Ca> P = S. In addition the relation to the exportation, the nutrients order was: N> P = K> S = Mg> Ca. Therefore, special attention should be given to keep adequate supply of N, K and Ca, due to high demand of these elements by sunflower crop.