Biennial sugar beets capable of flowering without vernalization treatment.

A biennial sugar beet (Beta vulgaris) generally takes two years to flower and complete its life cycle. In year one, the plant grows vegetatively and then enters a cold winter period. In year two, the plant grows reproductively and initiates flowering under long-day conditions. Among biennial beets that grow vegetatively in outdoor field conditions, two test strains were preliminarily found to flower early under 24-h daylength conditions without being exposed to cold temperatures. To confirm the this phenomenon's genetics, crossings between the test strains and normal biennials yielded hybrid derivatives of F₁, F₂, and BC₁F₁, and bolting rate was investigated both in an outdoor field under natural daylength conditions and in a greenhouse with an artificial 24-h daylength. The test strains and hybrid derivatives did not bolt in the outdoor field, similar to the biennial control strains. This enables assessment of important agronomic traits, such as yield, which cannot be evaluated using an annual control strain in which all plants are bolted. However, under 24-h daylength conditions, the test strains bolted without vernalization treatment, unlike the biennial control strains, but similar to annuals. Hybrid derivatives' bolting rates suggest that the flowering characteristics of the test strains are mainly controlled by a single dominant gene. The flowering characteristics and the hypothetical responsible gene were named 'BLOND' and 'Bd', respectively. Because seed production in BLOND is estimated to take at least four months, similar to that of the annual beet, BLOND's bolt rate may be applicable for the speed breeding of sugar beets. [ABSTRACT FROM AUTHOR]