Abstract
For genetic improvement of the monogerm sugar beet (Beta vulgaris L.) that has double-ovule fruits, we examined the distribution of double-ovule fruits in the branching system. We also compared the percentage of double-ovule fruits before anthesis and at maturity. The higher the node position of the branch on the main stem, the higher the percentage of double-ovule fruits, and the primary branch had more double-ovule fruits than the secondary branch. The percentage of double-ovule fruits increased as the thousand grain weight increased, and the percentage in each branch decreased as the percentage in the individual decreased. The percentage of double-ovule fruits in the plant was similar to the percentage on the branch at the highest nodal position among those having secondary branches. Many double-ovule fruits were distributed in the middle part of the primary branch having secondary branches. These results suggest that the formation of double-ovule fruit is related with the developmental stage of fruits on the main stem and branches. The percentage of double-ovule fruits before anthesis was higher than that at maturity with a positive correlation. Thus the formation of double-ovule fruit before anthesis is considered to be genetically controlled before anthesis, but finally determined by the environmental conditions during ovule development after pollination.
