The effect of nitrogen and potassium fertilizer doses and planting densities were evaluated in bulb classification of two onion cultivars. The treatments were arranged in factorial 2 x 4 x 4 x 4, respectively correspondent by cultivars (Optima and Superex), nitrogen (0; 50; 150 and 150 kg ha-1 of N), potassium (0; 75; 150 and 225 kg ha-1 of K2O) and planting density (60; 76; 92 and 108 plants m-2). The experimental design was of randomized blocks, with four replications The fertilizers ammonium nitrate and potassium chloride were employed to provide N and K, respectively. The nitrogen and potassium application reduced to near to zero the incidence of non-comercial bulbs in both cultivars. The largest percentage of bulbs measuring 50 to 70 mm was reached with 60 plants m-2 and application of 150 kg ha-1 of N, mainly for cv. Superex. Cultivar Superex presented the largest quantity of double bulbs, with the application of 150 kg ha-1 of N (17% of the total bulbs produced) and plant population of 60 plants m-2 (22% of the total bulbs).
Allium cepa L.; fertilization; plant population
