Reassessment of Practical Subspecies Identifications of the USDA Daucus carota L. Germplasm Collection: Morphological Data
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David Spooner, Mohamed Neffati, Mohamed El Koudrim. (8/4/2014). Reassessment of Practical Subspecies Identifications of the USDA Daucus carota L. Germplasm Collection: Morphological Data. Crop Science, 54.
Abstract
The genus Daucus includes about 20 recognized
species. The most widespread and economically
important species, Daucus carota L.,
occurs on almost every continent. The cultivated
carrot, subsp. sativus (Hoffm.) Schübl. and G.
Martens, has been selected from wild populations
that are extremely diverse, especially in
the western Mediterranean. The predominant
outcrossing and the lack of sexual isolating
mechanisms among recognized infraspecific
taxa complicate the taxonomy and identification
of the wild populations, resulting in widely
different interpretations of the number of infraspecific
taxa. We measured 36 morphological
characters from multiple individuals within each
of 155 accessions of D. carota and from the
morphologically similar species D. capillifolius
(both species 2n = 18) alongside other species
for comparison (D. aureus Desf., 2n = 22; D. broteri
Ten., 2n = 20; D. involucratus Sm., 2n = 20;
and D. littoralis Sm., 2n = 20) in an experimental
field plot. Within D. carota, multivariate analyses
were able to identify only two subspecies, but
even these showed great overlap of individual
characters. Because of the ease of crossability
of wild D. carota to the domestic landraces and
cultivars and because of the taxonomic challenges,
the purpose of our study is to explore
morphological support for subspecies within
D. carota, including the phenetically similar D.
capillifolius, which is part of the same clade as
D. carota, with the long-term goal of resolving
taxonomic disagreements and developing a
practical system to classify variation within this
economically important species.