Simon: Release: B8080

UNITED STATES DEPARTMENT OF AGRICULTURE                        AGRICULTURAL RESEARCH SERVICE                                         and                             THE FLORIDA AND WISCONSIN                        AGRICULTURAL EXPERIMENT STATIONS                         RELEASE OF CARROT INBRED LINE B8080 The United States Department of Agriculture, Agricultural Research Service, in cooperation with the Florida and Wisconsin Agricultural Experiment Stations announce release of the market-type carrot inbred B8080 for direct use as a parent in hybrid cultivars and as a source genotype to use in breeding for flavor, high carotene and disease resistance.  A high quality hybrid, B6274 BC1x B8080, will be released as soon as pilot production and commer- cial trials can be completed.  This line is released now to permit seedsmen to build up a supply of stock seed and to begin testing B8080 in experimental hybrids. B8080 was derived from a cross, made in 1972 at the University of Wisconsin, between plants selected from inbred B2158 and the Japanese cultivar, Kokubu (PI 261648).  Line B2158 was released in 1976 as the pollen parent in hybrid Candy Pack.  Kokubu was first identified as a source of resistance to Alternaria leaf blight (Alternariadauci) in field exposure tests at Belle Glade, Florida in February, 1970.1/  Resistant selections from that test, grown through the seed cycle at Madison, WI, became the source of Alternaria resistance in crosses with B2158 and several other advanced maintainer lines. Roots of B8080 are 7-8 inches long, slightly tapered to a semi-blunt tip. Color is deep orange exterior and interior with little contrast between xylem and phloem and no tendency to develop a light cambium zone.  The orange color extends down into the tap root.  In the seed cycle the plants are vigorous and produce abundant pollen.  It has produced good seed yields on a wide range of seed parents.  The development of a cytosterile companion line has not been completed.  All of the backcross progenies have been 100% male sterile demonstrating that B8080 is the maintainer (M) type. In F2 and subsequent generations the B2158 x Kokubu progenies segregated for better color and higher carotene content than either parent.  Selection through F3 and M1 was based entirely on color and other visible character- istics.  In the last four cycles the roots from plants having Alternaria resistance at Zellwood, FL were selected for flavor by a simple taste test and finally for carotene content by laboratory analysis of samples taken from individuals roots which were then planted for seed production in breeding plots and cages at Madison.  This selection sequence resulted in combining good flavor with resistance to Alternaria leaf blight and high carotene _______________ 1/Field tests for Alternaria resistance were conducted by J. O. Strandberg, University of Florida, Research and Extension Center, Sanford, FL.

-2- content.  Average carotene levels in roots grown in California were 190 ppm in B8080, 85 in Imperator 58 and 66 in Scarlet Nantes.  Since there is still significant root to root variability for carotene content the recurrent selection program will be continued until a stable, high carotene level is achieved.  As improvements are made new stocks will be distributed on request to replace the original. Breeders seed of B8080 grown in screen cages will be pro-rated to seedsmen and breeders upon written request addressed to C. E. Peterson, USDA, ARS, Department of Horticulture, University of Wisconsin, Madison, WI  53706, before September 1, 1983. _____________________________________     ___________________________________ Director                                  Date Florida A.E.S. _____________________________________     __________________________________ Director                                  Date Wisconsin  A.E.S. _____________________________________     ___________________________________ Administrator                             Date Agricultural Research Service

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