Agriculture Reference
In-Depth Information
Fig. 1.1. Features used for identifying food alliums. Flowers (A), stamens (B) ('i'
indicates the inner stamens) and cross-sections of leaf blades (C) and of flower
stalks (D). Leaf and scape sections are not to scale (from Jones and Mann, 1963,
Fig. 3. Reproduced by courtesy of John Wiley & Sons Inc.).
Onion and shallot, Allium cepa L.
The onion has been cultivated for 4700 years or more and does not exist as a
wild species. Onion was probably first domesticated in the mountainous
regions of Turkmenistan and north Iran bordering the ancient advanced
civilizations of the Near East (Sumerian). Therefore, south-west Asia is
regarded as being the primary centre of domestication and variability. Other
regions of great diversity like the Mediterranean are considered secondary
centres (Hanelt, 1990; Fritsch and Friesen, 2002). The nearest wild relative in
the subgenus Cepa section Cepa is A. vavilovii (Klaas and Friesen, 2002), which
is found in the Koppet Dag mountains of Turkmenistan. It has a hollow scape
with a bubble-like swelling, but the leaves are completely flat. Recent molecular
studies have shown that A. asarense is basal to the group, which includes A.
cepa and A. vavilovii (Fritsch and Friesen, 2002). This has only very recently
been discovered at a single site in the Elburz range near Tehran. It grows on
steep, rocky slopes and the plants have semi-cylindrical leaves and a flower
stem with a bubble-like inflation. It has globose umbels of greenish brown-
tinged flowers.
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