Zuchtmethodische Entwicklungen - Nutzung von Heterosis bei Fababohnen.
1994
Link W. | Ederer W. | Kittlitz E. von
Improving yield stability at a high yield level is the obvious approach for plant breeders to improve the agronomic value of faba beans (Vicia faba L.). The improvement of yield stability using homozygous inbred lines was not found to be promising. On the other hand, heterogeneity and heterozygosity led to a marked improvement of both, yield level and stability. Mid-parent heterosis for yield amounted to at least 50%. Presently, no hybrid varieties are available, hence, these phenomena should be exploited in synthetic varieties. This recommendation was the background to study the reproductive biology of faba beans. Both traits, autofertility and degree of cross-fertilization, showed a high genetic variation and moderate to high heritability. Heterosis was positive for autofertility, and negativ for degree of cross-fertilization. At the level of inbred lines, the two traits are not correlated. At the F1-level, the correlation was r=-0.66. It could be shown that already with a low number of lines being available as components of potential synthetics, the best synthetic will outyield the best line. This advantage increases with increasing number of lines. Yield of synthetics could not be adequately predicted from the yield of their components. The prediction was improved, if the performance of the polycross-progenies of the lines was used additionally. Polycross-progenies showed to be very attractive test units in faba bean breeding. Two items were analyzed theoretically. First, the genotypic composition of a partially allogamous population in equilibrium was elucidated. The population is composed of groups of genotypes with contrasting degrees of inbreeding coefficient.
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