Genetic analysis of tocopherol content and composition in winter rapeseed

The improvement of the nutritional value and the stability properties of ra peseed oil is partly hindered by the lack of information on the genetic con trol of tocopherols. The objectives of this investigation ware to character ize the inheritance of tocopherols by using two factorial mating designs (N orth Carolina Design II, NCII). The first (NCII-A) was produced with two se ts of nine parents each, one selected for high and the other for low total tocopherol contents. In the second (NCII-B), each set consisted of six pare nts, which were either high or low for the alpha/gamma -tocopherol ratio. P arents and F-1 hybrids from both experiments were tested under field condit ions in 1998 and 1999 using a completely randomized design with two replica tions. Only small differences were detected between mean values of parents and F-1 hybrids. General combining ability (GCA) variation in both experime nts was highly significant (P < 0.01) for all tocopherol traits. Significan t specific combining ability (SCA) effects were only detected for <alpha>-t ocopherol in NCII-A and therefore for the alpha-/gamma -tocopherol ratio. T hese results indicate that tocopherol contents and composition are controll ed mainly by genes with additive effects. Interactions of F-1 hybrids and G CA effects with the environment were significant for only tocopherol conten ts and not for tocopherol composition.