Agriculture Reference
In-Depth Information
to study the effects of pre- and post-harvest factors on
onion bulb dormancy.
DIVERSITY OF STORAGE METHODS
How onions, shallots and garlic are stored varies enor-
mously with local conditions, and every situation from
domestic storage in bunches in a warm kitchen to indus-
trial scale bulk storage holding thousands of tonnes of
onions, with controlled temperatures and humidity and
even with CA, can be found somewhere among onion-
producing nations. Currah and Proctor (1990) found that in
many tropical countries, onions were usually marketed at
once after harvest, and that on-farm storage was not prac-
tised at all; in other places, onions may be stored out of
doors in sacks or under trees, or even left in the ground
during the hot dry season. When onions are to be stored,
they are often first lifted and field cured (i.e. left to dry in
the open or under a leafy covering in the field, or in sacks)
if the weather is suitable (i.e. dry and warm), or may be
dried further under cover of a shed or barn before being put
into storage on the farm. Many types of tropical on-farm
onion storage are illustrated or described in Brice
et al
.
(1997).
The prices obtainable at a particular time affect onion
marketing strategies: very high prices encourage onion
farmers to lift a crop early or even green so to take
advantage of prices which they know will fall rapidly once
the maincrop comes in. In areas such as the Mount Elgon
region in Kenya, for example, farmers leave the onions in
the ground and only lift them when prices are right. The
onions then have their tops cut off, are very roughly dried
in the open, after being collected from the field in sacks,
and are sold as rapidly as possible. Such onions are not
expected to keep beyond a month after lifting, since
they have received virtually no curing and have been cut
across a fleshy region of the neck, allowing pathogens to
enter freely. Many start to sprout again at once. Even nor-
mally good storage varieties do not withstand such rough
treatment. But as onions are produced all year round in
Kenya from rain-fed as well as irrigated regions, the main
job of the marketing authority is simply to ensure consistent
supplies to the cities at a reasonable price.
In areas where onion storage is traditionally practised,
the storage crop usually consists of maincrop onions
which come in at a time when the price has gone down to
uneconomic levels due to temporary oversupply. In
economic terms, the market for onions is inelastic, with a
constant requirement from consumers for the product
throughout the year, and the market cannot absorb more
than a small excess over normal demand without the price
falling fast, often to less than the cost of production.
Therefore, farmers, grower cooperatives, marketing boards
or onion merchants make arrangements to take the onions
GARLIC STORAGE EXPERIMENTS
Several garlic storage experiments have recently been
reported, mostly from Europe, Argentina and East Asia. In
Poland, a study on the effect of storage up to nine months
of local garlic ecotypes and the cv. Mera was carried out.
Most of the ecotypes showed an increase in dry matter
with storage duration. Total sugars increased until the
middle of the period and then declined again. Storage at
4°C was most effective in retaining dry matter content and
total sugars, but losses of L-ascorbic acid occurred in low
temperature storage (Nurzynska-Wierdak 1998).
In Argentina, recent work in Mendoza province, which
has a dry climate (about 50% RH), established that for
short-term storage (three months or less) storage in the field
or in store was probably adequate for garlic cv. Colorado,
whereas for longer periods, a cold store at 0°C or -3°C gave
superior quality for up to nine months of storage, with no
sprouting when the lower temperature was used (Giménez
et al
.1998). Another group in Argentina studied the effect
of irradiation on garlic bulb quality and reported that treat-
ment at 0.4 Gy/s at 30 days post-harvest had beneficial
effects on quality through its influence on water content
and the movement of solutes between organs during stor-
age (Pellegrini
et al
. 2001). In Taiwan, experiments on a
wide range of storage temperatures determined that at 5°C,
10°C or 15°C, garlic sprouted early and losses were severe,
whereas at 35°C or at 1°C the garlic could be stored for ten
months. However, shelf life after storage was shorter when
the garlic had been stored at the lower temperature, due to
rapid sprouting, whereas storage at 35°C was followed by
an acceptable shelf life of ten days at 20°C (Wang & Horng
2001). Park
et al
. (2000) in the Korean Republic investi-
gated different clipping treatments (no clipping, or trim-
ming at 5 or 10 cm above the neck) and ambient versus 0°C
storage temperatures on garlic cv. Eusung. Nonclipped
bulbs stored under ambient conditions lost the most weight
after 7.5 months in storage. The low-temperature storage
treatment resulted in less weight loss and sprouting.
Clipping treatments also reduced sprouting. Ambient
conditions, however, were satisfactory for short-term stor-
age (Park
et al
. 2000). J.K. Lee (personal communication,
2003) in the Korean Republic reported that computer-
controlled cold stores are commonly used now for storing
'southern' types of garlic. Korean consumers use a lot of
garlic for the production of the salted vegetable pickle
kimchi
, as well as in cooking many other popular dishes.
Annual consumption is about 8 kg per year per person.
