Effect of nitrogen fertilisation on protein content, total fatty acid content and composition of barley ( Hordeum vulgare L. ) grains

The impact of N‐fertilisation level on protein content, total fatty acid (TFA) content and major fatty acid composition of barley grains (cv. Eldorado), grown in a replicated field trial, was investigated. Increasing amounts of N‐fertiliser, applied at several stages during the growing season, resulted in a higher protein content and a very slightly lowered TFA content in the grains. Protein and TFA contents were negatively correlated ( r =‐0.4685). Minor changes of fatty acid composition were found in the decrease of the oleic acid (C18:1) proportion ( r =‐0.8376) and in the increase of the palmitic acid (C16:0) proportion ( r =0.7273). The stearic acid (C18:0) and the linoleic acid (C18:2) proportions were also affected, however, no significant linear correlations with the total N‐fertiliser level were obtained. The slow increase in the linolenic acid (C18:3) proportion ( r =0.5674) was too small, compared to the residual variance, to be significant. TFA content was positively ( P <0.001) correlated with the oleic acid proportion, and negatively ( P <0.001) with the palmitic acid proportion. These data suggest that the application of higher amounts of N‐fertiliser slightly decreases the total fatty acid content of barley grains, probably due to a decreased synthesis of oleic acid, precursor of the unsaturated C18 fatty acids. The result is a relative increase in palmitic acid.