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United States Department of Agriculture

Agricultural Research Service

Simon: Release: B6439, B6274
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                 UNITED STATES DEPARTMENT OF AGRICULTURE
                      AGRICULTURAL RESEARCH SERVICE

                                   and

                        THE CALIFORNIA AND IDAHO
                     AGRICULTURAL EXPERIMENT STATIONS


              RELEASE OF CARROT INBRED LINES B6439 AND B6274


The United States Department of Agriculture, Agricultural Research Service,
in cooperation with the California and Idaho Agricultural Experiment Stations
announce the release of two new carrot inbreds for use as breeding lines
and for producing market type hybrids.  These are components of the female
parent in a high quality hybrid, [(B6439xB6274)xB6274]xB8080, to be released
as soon as pilot production and commercial trials can be completed.  These
lines are being released now so that seedsmen can increase them for use in
the above candidate hybrid and for testing in hybrid combinations with lines
of their own origin or from other sources.

In the early generations the responsibilities for producing seed, from plants
(roots) selected at Brawley, were divided among three cooperating programs:
University of California-Davis, the Idaho Experiment Station, Parma, and the
USDA at Madison, Wisconsin.  Related seed from all three sources was grouped
for planting at Brawley.  No effort is made here to identify the exact origin
of seed from which the final selections were made.

B6439 was derived from an open pollinated breeding population started in 1969
by massing under screen, one selected F1 plant from each of eight crosses
involving 16 maintainer inbreds.  Roots of this highly variable population
were grown and selected in California and 10-15 roots were massed for increase
under screen.  At the M6 generation, when a fair degree of uniformity had been
achieved, 63 plants were self-pollinated and crossed to cytosterile testers.
At Brawley, California in March 1976 row 6439, the best of these S1 lines,
was selected for increase.  It has been advanced through five additional
cycles of mass selection resulting in a cytosterile companion line at BC5
and the maintainer at S1M5.  B6439 is slightly tapered, 6-8 inches long,
semi-stumped, with rounded shoulders and good interior color.  The flavor
is uniformly mild.  Average total carotene in Califonria-grown roots was
110 ppm in 1983.

B6274 originated from a cross made in 1973 between a Nantes type inbred
B2340 and a selection from the open-pollinated cultivar Scarlet Nantes.
Subsequent selection was made for flavor, color and the typical cylindrical
root and blunt tip of Nantes.  Six plants, grown from F3 roots selected in
1976 out of Brawley row 6274, were massed under screen.  The line was advanced
on an annual schedule by growing the root crop in the Imperial Valley
in the winter and the seed crop under cages the following summer.  The
stock, now at generation F3M5, is uniform for Nantes type and color.  Its
texture and flavor are comparable to the Nantes parent.  It is 5-6 inches
in length, with a rounded crown and some tendency to develop green xylem in
the crown area, a defect largely overcome in hybrids with pollen parents
having deep orange color.
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Breeders seed of B6439S, B6439M and B6274M from cage isolations will be
pro-rated to seedsmen and breeders upon written request to C. E. Peterson,
USDA, ARS, Department of Horticulture, University of Wisconsin, Madison,
WI 53706, by September 1, 1983.








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Director                                  Date
California A.E.S.




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Director                                  Date
Idaho A.E.S.




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Administrator                             Date
Agricultural Research Service


Last Modified: 8/10/2004