ChileanJAR

Seed yield and achene oil yield are the main determinants for N application rates rather than seed composition. Nitrogen plays a critical role in producing unsaturated fatty acids (oleic and linoleic acids), which are the main factors determining sunflower oil quality (Helianthus annuus L.). Studies were conducted on the effect of N fertilization on seed yield, achene oil yield, and quality parameters of sunflower hybrids for two successive years (2010 and 2011) in a split plot arrangement under a randomized complete block design. The hybrids (Hysun-33 & S-278) and N levels (0, 75, 150, and 225 kg ha^-1) were allotted in main and sub-plots, respectively. Increasing N levels resulted in steady increases in yield, protein contents and linoleic acid, whereas oil contents and percentage of oleic acid responded negatively during both years. At the same time, crop oil yield was positively related to increased N supply with higher achene yield (AY). Palmitic acid varied from 5.27 to 6.42 % and stearic acid ranged from 2.27 to 2.95%. Hybrid S-278 exhibited significantly (P < 0.05) higher AY (3380 kg ha^-1), oil content (42.11%) than Hysun-33 (2968 kg ha^-1 and 40.75%, respectively), while the opposite was true for protein content. Oil yield varied in response to N fertilizer, with a range of 34 to 37% providing the best quality traits in both seasons.