Response of Sunflower to Nitrogen Application and Water in Northern Brazil Alfisol

Decline in crop yield has been a problem in Northern Brazil region due to inherent low fertility status of the soils and water deficit of different crops. In order to study the effects of nitrogen and available soil water levels on growth and yield components of sunflower, an experiment was carried out from March to June 2010 in a semi-controlled greenhouse condition of the Federal University of Campina Grande, Paraiba, Brazil using Alfisol soil. The treatments were arranged as a completely randomized design, in a 4×4 factorial experiment (four nitrogen levels and four available soil water levels), in triplicates, total of 48 experimental units. The nitrogen levels in kg/ha were 0; 60; 80 and 100 which was added as urea; the available soil water levels were 55; 70; 85 and 100%. The results of this research indicate that nitrogen had a significant effect only on leaf area at 40 DAS and % achenes viable. The effect of available soil water on sunflower cv. Embrapa 122/V-2000 biometry and the yield showed that there were significant differences, on average, in all growth traits (stem height and diameter) at 40 and 60 DAS, in leaf number at 40 DAS, in leaf area at 40 and 60 DAS and in all production traits. The biometry and yield response to available soil water of different crops is of major importance in production planning. In this study, the maximum biometry and yield response factor of sunflower was determined at 100 % of available soil water.