Plant Breeding Department, Agricultural Institute, Shumen, Bulgaria
Key words: Sugar beet, Male sterility, Monogerm, Productivity.
The majority of the commercial varieties of sugar beet in Europe are hybrids, based on monogerm diploid malesterile females and multigerm diploid and tetraploid pollinators. The aim of the present study is by testing the basic biological qualities of recently created male-sterile sugar beet lines (male sterility, monogermity, seeds germination), and the combination of productivity and technological qualities, to make an assessment of their breeding value. The diploid lines have high male sterility, combined with high laboratory seeds germination and practically full monogermity. The tetraploid lines show significantly lower levels of male sterility and germination. The diploid monogerm lines MS 0819, MS 0922 and MS 0926 combine good biological characteristics with high own productivity and technological indices. The tetraploid lines tested have better technological qualities, and the best combination of good biological and economic qualities is manifested by MS 142. The high heterosis effect levels registered for the white sugar yield from the triploid hybrids of the tested lines with multigerm pollinators are indication for the very good combining ability of the monogerm lines and a proof for their high breeding value.