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 B7262 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 B7262 to provide germplasm for developing improved genotypes and producing
hybrids.

B7262 was derived from a cross made in 1983 at the University of Wisconsin
between a purple root with yellow core selected from a true-breeding purple-rooted
S₃ population (third generation of consecutive self-pollinations) derived from
PI173686 (a Turkish introduction highly variable for root color and shape) and
B10138 (a dark orange Danvers-shaped inbred from Danvers 126). Beginning at
the F₂ generation, selection was made for deep purple outer phloem, for dark
orange core, cambium, and inner phloem and for long, blunt, smooth root shape,
small core size, and ample seed production. Two generations beyond the F₂,
selection was also initiated for mild, sweet flavor and reduced tendency to initiate
early flowering (late bolting). In the F₃ and F₄ generations, several hundred roots
were visually evaluated and 16 or 21 roots (respectively) were self-pollinated in
each cycle. The best of nine F₅ plants self-pollinated in the 1986 winter
greenhouse nursery produced seed for field row 70262 in Palmyra, Wisconsin.
Now at F₅M₅, B7262 is the result of nine generations of selection for root shape
and color and seven generations for culinary quality. B7262 is a maintainer of
sterility ("B" line) and a petaloid cytosterile counterpart ("A" line) in the Cornell
cytoplasm is now at BC₅. B7262 tends to flower early and produce fairly abundant
pollen and seed.

Roots of B7262 are medium long (15-19 cm), cylindrical, and slightly tapered with very
dark purple outer phloem with orange inner phloem, cambium, and xylem and a small
core. Root surface is rough in some growing conditions. Tops of B7262 are fairly tall,
vigorous, and medium green with strong attachment to the root and tendency for early
bolting. Purple coloration is also evident in leaves (especially early in development),
nodes, anthers, and petals. The purple flower color may be useful as an ornamental
especially since the petaloid sterile has a double whorl of persistent petals. Carotene
content of mature roots is 100 to 130 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. B7262
has average tolerance to Alternaria leaf blight and is susceptible to powdery mildew.

Several hybrid combinations with B7262 have been evaluated in Wisconsin, California,
and Florida trials. Purple root pigmentation is a monogenic dominant trait but
penetrance and expressivity varies between hybrids with B7262. Best uniformity for
purple root color occurs in (B2566 x B7262) and (B9304 x B7262). Up to 40 percent
pale purple roots occur in (B7322 x B7262) and (B4367 x B7262). Commercial
development of purple-rooted carrot hybrids may require several purple-rooted inbred
components with this trait.

Breeder's seed of B7262 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.