Components of the Production and Chemical Composition of Safflower Seeds as a Function of Nitrogen Fertilization

Abstract

Aims: The objective of this study was to evaluate the effects of nitrogen fertilizer application on the direct and indirect productive components of safflower. Study Design: The treatments were arranged in randomized blocks, with four replicates, and consisted of five doses of nitrogen (N): 0, 50, 100, 150 and 200 kg.ha-1, in the form of urea (45% N), which was manually incorporated into the soil 30 days after plant emergence. Place and Duration of Study: Sowing was carried out under field conditions on a small rural property in the municipality of Toledo-PR, Brazil. The experiment was conducted in between May and October 2018, totaling 158 days. Methodology: Morphometric parameters were evaluated at the full flowering stage, and the yield and chemical composition of the achenes were assessed during physiological maturation of the plants. Data were analyzed using analysis of variance (ANOVA) at the 5% significance level. Regression equations were fitted to the means of the quantitative variables. Results: The results showed that safflower grain yield was strongly influenced by the application of N-urea, with the maximum yield at a dose of 120 kg.ha-1 N. A joint analysis of the regression equation for N-urea application and grain yield, and the prices of N and safflower grains used, revealed that the most economical dose was 70 kg.ha-1 N, which provided the maximum profit per unit area. There was a positive linear correlation between grain yield and protein content (r = 0.51). Stem diameter, aerial dry biomass, grain yield, number of branches, and floral chapters per plant increased with N application, indicating that safflower culture responds positively to nitrogen fertilization. Conclusion: We conclude that sustainable use of nitrogen fertilizer using the maximum economic efficiency dose, can contribute to better plant health and, at the same time, reduce production costs.