Growth, production and nutrient use efficiency of sunflower cultivars under nitrogen and boron fertilization

The objective of this study was to evaluate the vegetative growth, production of achenes and efficiency of use of nutrients in sunflower crop in function of N and B fertilization under semi-arid conditions of the Brazilian Northeast. The experiment was carried out in the experimental area of the State University of Paraíba, Campus II, Lagoa Seca, PB, Brazil. The experiment followed a randomized block design with three replications in a factorial outline 2 x 4 x 4; with two sunflower cultivars (Helio 250 and Helio 251), four doses of nitrogen (30; 60; 90 and 120 kg ha-1) and four doses of boron (1; 2; 3 and 4 kg ha-1).The following parameters were analyzed: plant height, stem diameter, area and leaf area index, the mass of achenes, the mass of 250 achenes and nutrient use efficiency. The cultivars differed significantly on the vegetative growth and mass achenes. The increments of nitrogen influenced, significantly, growth and yield characteristics of the sunflower. Boron application in soil up to 4 kg ha-1 did not cause significant effect on the variables analyzed in this study. Smaller doses of nitrogen and boron provided the greater efficiencies of use of these nutrients.