Genotype x environment interactions and heritability of tocopherol contents in canola
2004
Marwede, V. | Schierholt, A. | Mollers, C. | Becker, H.C.
Tocopherols are natural antioxidants found in all vegetable oils. They are important dietary nutrients and thus breeding for increased tocopherol content is a new and important objective in canola (Brassica napus L.). Tocopherols exist in four forms (alpha-, beta-, gamma-, and delta-tocopherol) differing in molecular structure and biological effectiveness. In the seed oil of canola, mainly alpha- and gamma-tocopherol are found with an alpha/gamma-tocopherol ratio of about 0.5. Three canola populations of doubled haploid lines were grown in three to four field environments to analyze genetic variance and genotype x environment interactions as well as heritability of tocopherols and correlations with other seed components. Significant genotypic differences occur, but large genotype x environment interactions are the major source of variation. Heritability of tocopherol was low in all three populations; the estimates ranged from 0.23 to 0.44 for alpha-tocopherol and from 0.33 to 0.50 for gamma-tocopherol. Heritability for tocopherol content is considerably lower than heritability of oil content (0.56-0.90), protein content (0.43-0.76), or glucosinolate content (0.91-0.95). No correlation between alpha- and gamma-tocopherol or between tocopherol and oil, protein, and glucosinolate content was detected. Individual tocopherols can be increased independently of each other and without affecting other major quality traits.
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