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 B7322 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 B7322 to provide germplasm for developing improved genotypes and producing
hybrids.

B7322 was derived directly from the genetically diverse, dark orange carrot population,
B951-1 having resistance to Alternaria leaf blight. Beginning in 1979 at the fifth
generation of mass selection for dark orange color and long, blunt root shape (M₅), seven
of the highest carotene, sweetest roots selected from a population of several hundred were
sib-mated. In both 1980 and 1981, one of ten sib-mated populations (3 to 4 plants each)
selected for high carotene content, sweet non-harsh flavor, and orange petioles was
chosen to advance this elite stock. In 1982 through 1986 one of three or four selected
populations was chosen for advance in breeding plots. The best 1986 selection was
grown in field row 7322 in Florida and California. Now at M₁₃, B7322 is the result of
eight generations of selection for root shape, color and culinary quality. B7322 is a
maintainer of sterility ("B" line) and a petaloid cytosterile counterpart ("A" line) in the
Cornell cytoplasm is now at the BC₅ generation. B7322 tends to flower early and
produce abundant pollen and seed.

Roots of B7322 are long (18-23 cm), cylindrical, with a slight taper, and very dark orange
throughout. Root surface is rough in some growing conditions. Tops of B7322 are of
average height and dark green with orange petioles and strong attachment to the

root. Carotene content of mature roots is 175 to 200 ppm (compared to 70 to 100 ppm for
older and 120 to 160 ppm for modern fresh market varieties). Flavor is mild and sweet.
Minimal selection for disease resistance occurred during the development of B7322 but
fair black crown tolerance was exhibited in recent trials on naturally infected California
fields. B7322 has average tolerance to Alternaria leaf blight and some susceptibility to
powdery mildew.

Several hybrid combinations with B7322 have performed well in trials including
(B2302 x B6366) x B7322 and (B3475 x B4367) x B7322 in California and (B5280 x
B6366) x B7322 in Florida.

Breeder's seed of B7322 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.