Studies on the effects of ionizing radiation for extending the storage lives of onions

Experiments with ionizing radiation for extending the storage lives ot onions are described and compared with the available literature on the subject. The aim was to form a general picture of the effects of ionizing radiation applied to onions on the basis of the multitudinous environmental and physiological conditions influencing the results. All that contributes to optimal growth, uniform maturation, and pood storage conditions will improve the results. Only first-class market oniode should be used for irradiation as even apparently negligible deviation trom that category will increase the rot during storage. It was found very important to use strains of cultivars with a specially good storability. The best results were obtaiaed with irradiation shortly after lifting when the onions are in the deepest state of rest. At that time only 6-12 krads were necessary to inhibit, but not to prevent, the onions from sprouting. At the above conditions the effect on the incidence of rot will be small, but all deviations from them may result in an increase in both sprouting and rot. Doses above the optimal for sprout inhibition causes an increase In storage rot and may promote a transitory, p«i»»»«l> UVt< sprouting rate within 1-2 months after the application. Small bulbs sprout faster than larger ones. Discoloration of the growth centre of irradiated onions may often occur, but with great variation between strains of cultivars and from one bulb to another. The cause has not been elucidated, but some explanations are given. Generally the discoloration should not make the onions objectionable for most kinds oiuse. The total loss by respiration and transpiration in the whole storage period was greatest in the non-irradiated, but in the first months of storage, until the tiprouting accelerates, the loss was greatest in the irradiated onions. The culinary value was practically unchanged.