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 B6366 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 B6366 to provide germplasm for developing improved genotypes and
producing hybrids.

B6366 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 951-1 (an Alternaria leaf blightresistant breeding population). Beginning
at the F₁ generation, selection was made for dark orange color and long, smooth root
shape, orange cambium and small core size. Two generations beyond the F₂, selection
for mild, sweet flavor was also initiated. The better of two plants self-pollinated in the
1985 breeding plots produced seed for field row 6366 in Florida and California. Now at
F₂MSM₆, B6366 is the result of nine generations of selection for root shape and color
and six generations for culinary quality. B6366 is a maintainer of sterility ("B" line) and
a petaloid cytosterile counterpart ("A" line) in the Wisconsin Wild cytoplasm and now at
BC₆. B6366 is a fair producer of seed.

Roots of B6366 are long (17-21 cm), fairly blunt, dark orange throughout, especially the
core. Root surface is very smooth with a tendency for growth cracks under stressful
conditions. Tops of B6366 are of medium height and dark green. Carotene content of
mature roots is 180 to 200 ppm (compared to 70 to 100 ppm for older and 120 to 160

Carrot Inbred B6366, p. 2

ppm for modern fresh market varieties). Flavor is sweet. B6366 has average tolerance to
Alternaria leaf blight.

Several hybrid combinations with B6366 have performed well in trials including
(B6439 x B6274²) x B6366 in Florida and California as well as combinations with
B6366 as a component of the seed parents (B2302 x B6366) and (B5280 x B6366) with
several pollinators. Hybrids involving B6366 are of the United States fresh market type
and generally smooth.

Breeder's seed of B6366 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.