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 Vegetable Crops Research: Madison, WI
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ARS Home Midwest Area Madison, Wisconsin Vegetable Crops Research Docs





Simon: Release: B6439, B6274headline bar UNITED STATES DEPARTMENT OF AGRICULTURE                      AGRICULTURAL RESEARCH SERVICE                                   and                        THE CALIFORNIA AND IDAHO                     AGRICULTURAL EXPERIMENT STATIONS              RELEASE OF CARROT INBRED LINES B6439 AND B6274The United States Department of Agriculture, Agricultural Research Service,in cooperation with the California and Idaho Agricultural Experiment Stationsannounce the release of two new carrot inbreds for use as breeding linesand for producing market type hybrids.  These are components of the femaleparent in a high quality hybrid, [(B6439xB6274)xB6274]xB8080, to be releasedas soon as pilot production and commercial trials can be completed.  Theselines are being released now so that seedsmen can increase them for use inthe above candidate hybrid and for testing in hybrid combinations with linesof 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 theUSDA at Madison, Wisconsin.  Related seed from all three sources was groupedfor planting at Brawley.  No effort is made here to identify the exact originof seed from which the final selections were made.B6439 was derived from an open pollinated breeding population started in 1969by massing under screen, one selected F1 plant from each of eight crossesinvolving 16 maintainer inbreds.  Roots of this highly variable populationwere grown and selected in California and 10-15 roots were massed for increaseunder screen.  At the M6 generation, when a fair degree of uniformity had beenachieved, 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 additionalcycles of mass selection resulting in a cytosterile companion line at BC5and the maintainer at S1M5.  B6439 is slightly tapered, 6-8 inches long,semi-stumped, with rounded shoulders and good interior color.  The flavoris uniformly mild.  Average total carotene in Califonria-grown roots was110 ppm in 1983.B6274 originated from a cross made in 1973 between a Nantes type inbredB2340 and a selection from the open-pollinated cultivar Scarlet Nantes.Subsequent selection was made for flavor, color and the typical cylindricalroot and blunt tip of Nantes.  Six plants, grown from F3 roots selected in1976 out of Brawley row 6274, were massed under screen.  The line was advancedon an annual schedule by growing the root crop in the Imperial Valleyin the winter and the seed crop under cages the following summer.  Thestock, now at generation F3M5, is uniform for Nantes type and color.  Itstexture and flavor are comparable to the Nantes parent.  It is 5-6 inchesin length, with a rounded crown and some tendency to develop green xylem inthe crown area, a defect largely overcome in hybrids with pollen parentshaving deep orange color.Page Break Breeders seed of B6439S, B6439M and B6274M from cage isolations will bepro-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._____________________________________     ____________________________Director                                  DateCalifornia A.E.S._____________________________________     ____________________________Director                                  DateIdaho A.E.S._____________________________________     ____________________________Administrator                             DateAgricultural Research Service


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