Simon: Release: B951-1

UNITED STATES DEPARTMENT OF AGRICULTURE                      AGRICULTURAL RESEARCH SERVICE                                    and                 FLORIDA AGRICULTURAL EXPERIMENT STATION              RELEASE OF CARROT BREEDING POPULATION B951-1 The United States Department of Agriculture, Agricultural Research Service, and the Florida Agricultural Experiment Station announce the release of carrot breeding population B951-1 designed to provide breeders with a source from which high quality, disease resistant inbreds can be extracted. B951-1 originated from 14 inbred x inbred crosses made in outdoor breeding plots at Madison, WI in 1976.  The parents chosen for the sources of Alternaria resistance were F4 lines derived from crosses made in 1971 between high quality market-type inbreds and three open pollinated accessions from Japan, PI 261648 (Kokubu), PI 226043 (San Nai) and Imperial Long Scarlet.  The market-type parents were derived from earlier inbred x inbred crosses of diverse origin and advanced to at least F4. Selected F1 roots, grown in muck soil at Palmyra, WI in 1977, were vernalized for six weeks then grown in the greenhouse.  One healthy plant from each F1 progeny was selected for massing under a screen cage.  The seed produced was planted in October 1978 at Zellwood, FL where the plants were regularly sub- jected to high levels of inoculum of Alternariadauci from nearby crops and from alternate rows of susceptible cultivars grown to insure a continuous supply of inoculum.  Additional field and greenhouse testing has confirmed that a high level of resistance to A. dauci exists in this population. From the plants selected for Alternaria resistance, in February 1979, approxi- mately 200 with good interior color and acceptable market type were sampled for flavor.  Ten roots considered to have the best eating quality were planted at Madison, WI for increase under an outdoor screen isolator numbered 951. Two additional cycles of selection have resulted in a population with a high incidence of roots with both good flavor and Alternaria resistance.  The frequency of superior horticultural qualities is sufficient to provide a good source of improved parent lines for the development of high-quality hybrid cultivars. Seed from the third recurrent cycle of selection grown in a screen cage isolation at Madison in 1981 will be distributed on a pro-rata basis to carrot breeders and seedsmen who address a written request to C. E. Peterson, USDA, ARS, Department of Horticulture, University of Wisconsin, Madison, WI, 53706, before April 1, 1983. _____________________________________     _________________________________ Director                         Date     Administrator                Date Florida Ag. Expt. Station                 USDA, ARS

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