Simon: Release: B493, B9304

UNITED STATES DEPARTMENT OF AGRICULTURE                    AGRICULTURAL RESEARCH SERVICE                       WASHINGTON, D.C.  20250                                 with            THE WISCONSIN AGRICULTURAL EXPERIMENT STATION                      MADISON, WISCONSIN  53706               RELEASE OF CARROT INBREDS B493 and B9304 The United States Department of Agriculture, Agricultural Research Service, and with the Wisconsin Agricultural Experiment Station, announces the release of two carrot inbreds to be used as germplasm for developing improved genotypes and for genetic and physiology research. B493 was derived from a cross made in 1968 at the University of Wisconsin between B8549 (a high-solids, Imperator-shaped inbred from Long Chantenay) and B5931 (a dark orange inbred from Imperator 58 used as a parent in hybrids Spartan Sweet and Spartan Bonus).  Selection was based on improving color and Imperator shape for eight generations beyond the F2.  Beginning in the F2M3S5 generation, selection was made for harsh (turpentine-like, burning) flavor, high volatile terpenoid content, and low bisabolene content.  Fourteen sibling populations were selected for these characteristics plus continued lection to withstand inbreeding depression.  After six more generations of self-pollination plus two generations of mass pollination to increase seed supplies, B493 is in the F2M3S11M2 generation, making it suitable as a homozygous test parent in carrot genetic and physiology research.  B493 has also been tested for use in tissue culture where it produces callus and suspension cultures readily and regenerates on solid medium or in liquid culture easily.  Sucrose predominates in the free sugars stored in B493 roots.  Therefore B493 is rs/rs. Volatile terpenoid content surpasses 110 ppm (less than 1% bisabolene) whereas the carotene content of B493 ranges from 180 to 210 ppm, depending on growing conditions.  Its dark orange color and Imperator shape make it suitable for developing additional fresh market germplasm and commercial hybrids.  A petaloid (anthers transformed to petals) cytosterile counterpart ("A" line) of B493 is now at BC11. B9304 was derived from a cross made in 1972 at the University of Wisconsin between W33 (a uniformly dark orange tapered inbred derived from a cross between Hutchinson and Tendersweet) and B10138 (a dark orange Danvers-shaped inbred from Danvers 126). Dark orange color and Danvers shape was selected for four generations beyond the F2 generation.  In the F5 generation, selection for mild flavor, low volatile terpenoid content, succulent texture, and high reducing sugar content was initiated among seven sibling populations of W33xBl0l38.  After four more generations of mass pollination, B9304 was derived from one of these populations in the F5M5 generation.  B9304 roots have uniformly high reducing sugar (Rs/Rs), very low volatile

terpenoids (10-15 ppm), crisp succulent texture, Chantenay shape, and carotene content of 90 to 125 ppm, depending upon growing conditions.  B9304 has been tested for use in tissue culture where it proves to be a slow producer of callus and suspension cultures, and a difficult genotype to regenerate.  Its excellent culinary quality makes it suitable for developing additional high quality germplasm and commercial hybrids.  B9304 is a partially sterile male parent.  A petaloid (anthers transformed to petals) cytosterile counterpart ("A" line) of B9304 is now at BC7. Seed of cytosteriles B493S and B9304S, and of their maintainers B493M and B9304M will be pro-rated upon written requests received before May 1, 1987, addressed to P. W. Simon, USDA, ARS, Department of Horticlulture, University of Wisconsin, Madison, WI 53706. _____________________________________     _______________________ Director, Wisconsin Agricultural          Date Experiment Station _____________________________________     _______________________ Administrator, ARS                        Date

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