PERFORMANCE OF DOUBLED HAPLOID POPULATIONS SEGREGATING FOR LINOLENIC ACID LEVELS IN SPRING RAPESEED

Linolenic acid (18:3) is a trienoic fatty acid known as the unstable c omponent of canola oil contributing, upon oxidation, to undesirable od ors and flavors of oil. The environmental sensitivity and complex inhe ritance of the trait make the breeding for lower 18:3 content difficul t, A. 2-yr, two-location study was carried out using a doubled haploid (DH) population of rapeseed lines (Brassica napus L. or Brassica rapa L.) varying for 18:3 content in order to characterize these lines agr onomically and assess the magnitude of environmental variation of the 18:3 content. Correlation analyses between 18:3 and other fatty acids as well as various agronomic and quality traits were performed to dete rmine possible correlated responses associated with breeding for low 1 8:3 canola. Decreasing the 18:3 content was significantly associated w ith later flowering and maturity, higher oil, and lower protein conten t but not with yield, lodging, and plant height, Orthogonal contrasts comparing the low with intermediate and high 18:3 containing DH lines showed no yield disadvantage of the low 18:3 DH lines for one location in 1 yr. Environmental influence on tate 18:3 content was larger betw een tile gears than between locations in 1 yr. Because of environmenta l sensitivity, and correlation between low linolenic acid content and later maturity, it may bat preferable to use molecular markers linked to the low 18:3 content alleles to select for low linolenic canola at the seedling stage.