Resposta da beterraba a adubação com nitrogênio, enxofre e micronutrientes em um Cambissolo Háplico

Abstract

There are few studies in Brazil aiming to calibrate fertilization of macro and micronutrients for beet in Southern Brazil. Two experiments were carried out, one in the field and another in a greenhouse with the objectives: a) under field conditions, to access the response of beet to nitrogen (N) in the presence or absence of a single rate of sulfur (S), boron (B), zinc (Zn) and molybdenum (Mo); b) in a greenhouse experiment to evaluate the response of plants to S, B, Zn and Mo. The experiment 1 was carried out in a Cambisol with 270 g/kg clay and 33 g/kg organic matter. Treatments were N rates (0, 50, 100, 150 and 200 kg/ha N) in presence or absence of fertilization with S, Zn, B and Mo in dosages of 50; 2; 1 and 0.01 kg/ ha, respectively, in a 5×2 factorial design with randomized blocks and four replications. In experiment 2 we used the same soil of experiment 1, in a greenhouse in pots of 3.0 kg soil. Six treatments were tested: (control, addition of S, of B, of Zn, or of Mo and addition of S, Zn, B and Mo) in a completely randomized design with five replications. The rates of nutrients were the same as used in experiment 1, while the remaining nutrients (P and K) were added in all treatments following the technical recommendations for the crop. At 60 days after transplantation, the plants of both experiments were collected and separated in leaves and roots for the determination of fresh and dry matter and determination of N, S, B and Zn in plant tissue. We observed a significant effect for factor N on plants reaching maximum productivity with the application of 100 kg/ha N in the presence of S, Zn, B and Mo, whose addition nearly doubled the production of roots. The experiment in the greenhouse showed that sulfur was the nutrient, after N, responsible for increasing the production observed in experiment 1.