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 B5238 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 B5238 to provide germplasm for developing improved genotypes and producing
hybrids.

B5238 was derived from a cross made in 1980 at the University of Wisconsin
between B4367 (a dark orange Imperator-shaped inbred from an open-pollinated
synthetic consisting of fresh market varieties) and PI419042 (a Nantes-Danvers-
shaped Chinese variety, Hong Ting Hsain, which varies widely for root color).
Beginning at the F₂ generation, selection was made for dark orange color, long, blunt,
smooth root shape, small core size, and non-green shoulders. Two generations
beyond the F₂, selection was also initiated for mild, sweet flavor. The best of four
plants self-pollinated in the 1984 breeding plots produced seed for field row 5238 in
Florida and California. Now at F₂MSM₇, B5238 is the result of ten generations of
selection for root shape and color and eight generations for culinary quality. Yellow
cambium ("zone") segregants have occurred in low incidence (less than 0.3 percent)
throughout the development of B5238 with an apparent elimination of this defect at
F₂MSM₅. A 1992 evaluation of 89 F₁ hybrid plants derived from pollinating
petaloid steriles with B5238 were completely male sterile, demonstrating that B5238
is a maintainer of sterility ("B" line). B5238 tends to flower early and produce
abundant pollen and seed.

Roots of B5238 are medium long (16-20 cm), cylindrical, uniformly blunt, very dark
orange throughout, with a small core. Root surface is rough in some growing conditions.
Tops of B5238 are fairly tall and medium green with strong attachment to the root.
Carotene content of mature roots is 310 to 340 ppm (compared to 70 to 100 ppm for older
and 120 to 160 ppm for modern fresh market varieties). Flavor is mild and fairly sweet
while texture is succulent. Minimal selection for disease resistance occurred during the
development of B5238 but fair tolerance to black crown rot was exhibited in recent trials
on naturally infected California fields. B5238 has average tolerance to Alternaria leaf
blight.

Several hybrid combinations with B5238 have performed well in trials including
(B5280 x B0186) x B5238, (B5280 x B5316) x B5238, and (B5280 x B2566) x B5238 in
California and (B9304 x B5238) x HCM in Florida. Hybrids of B5238 are of the United
States fresh market type but they approach a cylindrical, blunt Nantes shape and they are
often strikingly dark orange.

Breeder's seed of B5238 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.