Heterosis and Genetic Variances and their Implications for Breeding Improved Varieties of Spring Beans (<em>Vicia faba</em> L.).

Handcrosses were made in a factorial manner with 24 Vicia faba inbred lines in three sets, each between four male and four female parents. The resulting 48 hybrids, their parental inbreds and three commercial varieties were grown in performance trials during the years 1985-87 with three replications at one location. Yield and yield components were recorded on single plant basis. The average superiority of the hybrids above the control varieties was 26 % in plant yield. The best crosses outyielded the controls by more than 50 %. However, a few inbred lines also reached the yield level of the controls. The average heterosis was significant for all characters except for maturity date. In plant yield the average heterosis was 75 %, ranging between 34 % and 148 % in the various cross combinations. The highest average heterosis of 110 % was observed in yield at the lateral stems. In all characters the best inbreds were superior to the lower hybrids and in some characters even equal to the average of the hybrids. A strong positive relationship was found for all characters between hybrid performance and midparent value and between the per se performance of the inbreds and their general combining ability. Genotypic differences between the hybrids as well as between the inbreds were highly significant. Most of the variability between the hybrids in all characters were attributed to general combining ability with only little evidence for specific combining ability. In the discussion the results are evaluated according to the choice of the breeding category of the partial allogamous faba bean species. [ABSTRACT FROM AUTHOR]