Onions and Their Storage

New Zealand Journal of Agriculture, Volume 66, Issue 2, 15 February 1943, Page 95

Onions and Their Storage

Z“VNIONS are members of the -lily ONIONS are members of the lily family ■ grown . for their bulbs, and have a more or less characteristic, odour. and flavour. They have; been cultivated for many centuries for use as vegetables for pickling and for sea-., soning for other food materials, especially sauces and soups. In the United • States of America they "are;, dried'inthe form of flakes and ground into powder for this purpose also. From a commercial standpoint onions are an important food crop, and rank in value next to potatoes, tomatoes and cabbages. There . are a number of varieties of onions grown in New Zealand, of which the most suitable for long storage is the Turbott 'or Pukekohe Longkeeper. . Onion Rots Onions are subject to disease during their growth, and also to rots, which develop during harvesting and storage. They are also subject to blemish and bruising which renders them susceptible to the . invasion of . bacteria and moulds. . ../ ■. ‘ ■■ ...' During the harvesting, - transit- and j storage of onions heck rot is a serious - onion disease, and is caused by Botry- ' tis rots, which will bring about heavy

losses if ’ the stem tissues : are not properly dried out. "'J;; ’. '.U" Trials to be carried out in the coming season at Marshlands, Christchurch, will include,forced drying with heat of- onions immediately after harvest,* to determine whether .this will control the development of neck rot and other rots during storage. . . . . Sunny, dry weather is ideal for drying onions, as . under these conditions the moisture given off by the skins and stem .. tissues, evaporates • quickly. High humidity brings about the condensation of moisture .with the added, possibility of rot development. Rainy weather is detrimental to both harvesting and drying in the field. Since decay is such' an important item in onion raising, care should be practised in destroying, diseased..bulbs and tops after harvesting. Selection For Storage Only sound, well-formed bulbs which have been, properly cured ' should go into storage for use late in the season. That part of the crop which is not of the quality for long storage, but suitcable for . immediate consumption, should be ' marketed without undue delay after harvesting and curing.

“Well ventilated crates, as illustrated on page 27 of the January issue of the “Journal of Agriculture,” are the most suitable, containers for the curing and the successful storage of onions, as they conserve storage space by permitting high stacking without causing pressure on the bulb. They also allow ample ventilation throughout the onions -if . the crates are properly stacked. Essential Factors Temperature, humidity, air circulation and ventilation are the four essential factors in the : successful storage of onions. Temperatures of 32 deg. F. and from 60 deg. F. to 95 deg. F. have been found to i retard sprouting of sound onions . during storage. When held in heat storage at 74 deg. F. and 70 per cent. , relative humidity, root growth is reduced to a minimum. * The results of a commercial trial with heat storage which was carried out at Marshlands, Christchurch, during the past season indicated that sound onions after removal into ordinary atmospheric temperatures will not readily develop sprouting or root growth, thus allowing ample time for marketing and consumption.

—A. A. POWELL,

Cool Storage

Officer, Wellington.