This research was aimed at counting the concentration of macronutrients throughout the onion, cv Superex, established by direct seeding. The experiment was conducted at Rio Doce farm, between the counties of Itobi and São José do Rio Pardo, state of São Paulo, Brazil (21°37'16"S and 46°53'15"W). The macronutrients N, P, K, Ca, Mg, and S as well as plant dry matter content were evaluated in plant samples taken at 30, 50, 70, 90, 110, and 150 days after seeding (DAS). The maximum dry matter content in the bulb and in the aerial part were reached at 150 DAS and were, respectively, of 4.70 and 17.86g plant-1. The aerial part and the bulb contributed respectively with 20 and 80% of the whole mature plant dry matter. The macronutrients were accumulated in the plant in the following order: K>N>Ca>S>Mg>P. The onion plant accumulated 202.43; 31.23; 295.28; 172.42; 35.20 e 73.47 mg of N, P, K, Ca, Mg, and S, respectively, and exported 67%, 85%, 68%, 57%, 56% and 81%, respectively, of N, P, K, Ca, Mg and S accumulated for the plant.
Allium cepa L.; growth; plant nutrition; cropping system
