Potato onion (Multiplier onion) 495
30.1 Introduction
Onion is an important crop worldwide and is cultivated commercially in more than
100 countries. Onions and garlic are the most important bulb vegetable crops grown
in India, and onion is the only vegetable where India figures prominently in world
production and export (Singh and Joshi, 1978), with India being second only to
China in terms of area under onion and production.
Alliums are among the oldest cultivated plant species. References to edible alliums
can be found in the Bible, the Koran, and in the inscriptions of the ancient civilizations
of Egypt, Rome, Greece and China. They are mentioned as a source of food for the
builders of the great pyramid of King Cheops, and the Israelites wandering in the
desert after the exodus from Egypt bemoaned the lack of appetizing onions. The
botanical classification of alliums has recently been reviewed and summarized by
Hanelt (1990) and the comments here are largely based on this account, together with
the well-known earlier summary by Jones and Mann (1963). The Alliaceae have been
included in both the Liliaceae and the Amaryllidaceae by different authorities, but
they are now regarded as a separate family. There are more than 500 species within
the genus alliums. The best-known feature of the alliums is their characteristic smell
and taste.
Cultivated types of Allium cepa fall into two broad horticultural groups, the common
onion group and the aggregatum group (Hanelt, 1990). Members of the common
onion group are grown mostly from seed. They form large single bulbs, and constitute
the vast bulk of the economically important varieties. The bulbs of the Aggregatum
group are smaller than the common onion because they rapidly divide and form
laterals, hence forming clusters of bulbs. Jones and Mann (1963) distinguished two
bulb-forming sub-groups: multiplier or potato onions, and shallots. The multiplier or
potato onions divide into between three and 20 bulbs which are wider than they are
long. These are usually propagated vegetatively. The commercial importance of the
Aggregatum group varies between countries. Multiplier onions are cultivated in domestic
gardens in Europe, North America, The Caucasus, Kazakhstan and the south-east of
30 Potato onion (Multiplier onion).............................................................
U. B. Pandey, National Horticultural Research and Development
Foundation, India