Breeding for Improved C 18‐Fatty Acid Composition in Rapeseed (Brassica napus L.)

Besides increases in grain yield, it has been possible to achieve marked quality improvements (0‐ and 00‐types) in rapeseed. At present, various types of oil‐composition are desired, depending on the final purpose or usage. Results of selection of genotypes with improved C18‐fatty acid composition in 00‐rape materials will be presented. Selected inbred lines were used for experiments under varying environmental conditions (i. e. temperature and light regimes) in the phytotron and open field. In the course of these experiments two lines with reduced C18: 3‐levels (2.5–5.8%) combined with high oleic‐content (73–79%) could be selected. In the offspring of different cross combinations including these lines and high linoleic selections, further improvements of C18 fatty acid composition have been achieved. Large non‐heritable variances were found for all C18‐fatty acids on the basis of random seed samples (h 2 = 0.88–0.93). A quotient is described which allows an estimation of enzyme activities during C18‐fatty acid biosynthesis. Its usefulness for the selection of suitable parents for respective breeding programmes is discussed.