| UNITED STATES DEPARTMENT OF AGRICULTURE|
AGRICULTURAL RESEARCH SERVICE
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 Alternaria dauci 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
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