Effects of Genotype and Nitrogen Availability on Grain Yield and Quality in Sunflower

Sunflower (Helianthus annuus L.) conventional (CONV) and high oleic (HO) genotypes differ in yield and quality. Nitrogen affects grain yield, quality, and by-products protein concentration. The objective was to evaluate the effect of genotype and N on grain yield, oil (O-G) and protein (P-G) concentration in grain and in by-products ( P-M). The effect of genotype was evaluated in Exp. 1 with 7 CONV and 7 HO hybrids, at two planting dates (PD early and late). The effect of N (Exp. 2) was evaluated in 10 locations (3 with CONV and 7 with HO), under six N rates (0, 30, 60, 90, 120, and 150 kg N ha(-1)). We determined yield, O-G, P-G and P-M. For the early PD of E-1, yield was higher in HO than CONV genotypes (3822 kg ha(-1) vs. 3495 kg ha(-1)). In Exp. 2, N increased yield in 50% of the locations (HO: 586; CONV: 597 kg ha(-1)). In Exp. 1, genotype did not affect O-G, but P-G was higher in HO than in CONV ones (18.0 vs. 16.8%, respectively). In Exp. 2, N did not affect O-G, but increased P-G in both types of genotypes. Consequently, P-G/O-G ratio increased with N rates. The higher P-G, was also reflected in higher P-M (44.0% HO and 38.8% CONV, respectively). Increases of 2.5% points in P-G resulted in increases of 5.6 in P-M. Therefore, the application of N would allow obtaining high yields and P-G without detrimental effects on O-G, improving the quality of grains and by-products.