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Storage
To
guarantee a long-lasting and steady delivery to the market, a sufficient
part of the crop should be put in the storehouse. Pre-condition
for successful storage is, first of all, the use of suitable varieties
(s. list), especially, since in Germany the treatment with MH 30
for the prevention of sprouting has been forbidden.
Exact
trials to determine optimum storehouse conditions are not available.
According to experience in Austria, the Netherlands and Denmark,
the optimum temperature oscillates around +/- 0° C. As the onions
emit water and produce heat when they are stored, they should be
ventilated with cooling air (relative humidity 65% - 70%) from time
to time. The cooling temperature mustnīt be below -1° C, since the
freezing point of the onions is at -1,5 °C.
To
avoid the production of condensation moisture, it is of vital importance
that the temperature of the ventilation air is not higher than that
of the onions. A steady supervision of the storehouse by means of
temperature sensors is recommendable. Storehouse rot and the inclination
to sprout mean increased biological activitiy, which results in
temperature rises.
The
onions are stored in large boxes or loosely. The best method is
determined by the farm and the marketing structure. Generally, loosely
storaged onions (2 -3 m max) can be ventilated more easily and exactly.
Large boxes, on the other hand, prevent that infections are spread.
Besides, smaller quantities can be taken from the storehouse without
disturbing other parties. Without cooling measures, the storage
life generally ends in February. With sufficient cooling the onions
may be stored until April/ May.
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Onions
