The Quality of Sunflower Seed Oil Changes in Response to Nitrogen Fertilizer

Abstract

Core Ideas Topdressing N increase the content of crude fat and linoleic acid in sunflower seeds. More topdressing N reduces the content of protein, oleic acid, and palmitic acid. Crude fat content significantly correlated with protein content in sunflower seeds. Sunflower (Helianthus annuus L.) has emerged as a very important crop in China due to the economic value of vegetable oil production. A 2‐yr field experiment was conducted in 2013 and 2014 to determine the effect of different N fertilizer application levels on the oil quality of a sunflower hybrid Kang Di T562 grown in the Hetao irrigation district, a sub‐arid region in China. The effects of N fertilizer were evaluated for three characteristics of oil from sunflower seeds: crude fat content (CFC), protein content, and fatty acid composition. The results showed that N fertilizer application had a significant effect on CFC, protein content, and fatty acid composition (oleic acid, linoleic acid, palmitic acid, stearic acid). When basic N fertilizer (68 kg ha−1) was used, subsequent topdressing N applications at the end of budding promoted the synthesis of protein, palmitic acid, and oleic acid in the oil of sunflower seeds, but decreased the CFC and linoleic acid content. There was a significant negative correlation between CFC and protein content (P ≤ 0.05) and between oleic acid and linoleic acid (P ≤ 0.01) in oil from sunflower seeds. There were positive and negative correlations among the main quality indices of sunflower seed. To increase the content of crude fat and linoleic acid in the oil of sunflower seeds, topdressing should not be used, or its use should be reduced, although this could reduce the content of protein, oleic acid, and palmitic acid.