UNITED STATES DEPARTMENT OF AGRICULTURE
AGRICULTURAL RESEARCH SERVICE
WASHINGTON, D.C.  20250

with

THE CALIFORNIA AGRICULTURAL EXPERIMENT STATION
DAVIS, CALIFORNIA  95616

and

THE FLORIDA AGRICULTURAL EXPERIMENT STATION
GAINESVILLE, FLORIDA  32611

and

THE WISCONSIN AGRICULTURAL EXPERIMENT STATION
MADISON, WISCONSIN  53706

RELEASE OF CARROT INBRED B6333 GERMPLASM

The Agricultural Research Service, United States Department of Agriculture, the
California Agricultural Experiment Station, the Florida Agricultural Experiment Station
and the Wisconsin Agricultural Experiment Station announce the release of a carrot
inbred B6333 to provide germplasm for developing improved genotypes and producing
hybrids.

B6333 was derived from a cross made in 1983 at the University of Wisconsin between
B748 (a blunt Imperator-shaped inbred developed from Nantes and fresh market
varieties) and a selected plant from a complex population derived from B5986 (a dark
orange Imperator-shaped inbred, and several European Nantes parents. Beginning at
the F₂ generation, selection was made for dark orange color, long, blunt, smooth root
shape, and single tops. Two generations beyond the F₂, selection was also initiated for
mild, sweet flavor. The best of three plants self-pollinated in the 1985 breeding plots
produced seed for field row 6333 in Florida and California. Now at F₂MSM₄, B6333
is the result of six generations of selection for root shape and color and four generations
for culinary quality. B6333 is a maintainer of sterility ("B" line) and a cytosterile
counterparent ("A" line) is now at BC₄ in the Wisconsin Wild cytoplasm. B6333 is an
excellent seed producer.

Roots of B6333 are medium long (17-21 cm), slightly tapered, and very dark orange
throughout. Root surface is smooth. Tops of B6333 are of average height and color with
some tendency toward multiple tops, although this characteristic is masked in hybrids.
Carotene content of mature roots is 230 to 250 ppm (compared to 70 to 100 ppm for

Carrot Inbred B6333, p. 2

older and 120 to 160 ppm for modern fresh market varieties). Flavor is very mild and
sweet. Minimal selection for disease resistance occurred during the development of
B6333 but good resistance to beet leafhopper-transmitted virescent agent was exhibited
in recent trials on naturally infected California fields. B6333 has average tolerance to
Alternaria leaf blight.

Several hybrid combinations with B6333 have performed well in trials including
(B6439 x B6333) x B5280 in California and (B5280 x B2566) x B6333 and (B6439 x
B6274²) x B6333 in Florida. Hybrids of B6333 are of the United States fresh market
type.

Breeder's seed of B6333 will be prorated upon written requests before April 1, 1994,
addressed to P.W. Simon, USDA, ARS, Department of Horticulture, 1575 Linden Drive,
University of Wisconsin, Madison, WI 53706.

When this germplasm contributes to a new cultivar, it is requested that appropriate
recognition be given to its source.