Abstract
1. In this study, the authors observed the phy-siological changes in onion bulbs when stored under different gaseous conditions and different humidities for 4 months after the sprouting period. The experiments were carried on from 1952 to 19 54 at room temperature in the laboratory of the University of Osaka Pref.
2. The storage conditions were as follows;
(a) Onion bulbs were enclosed simply in desiccators: In this case, both percentage of CO2 and humidity in the vessel were rapidly increased, a rapid decrease of O2 concentration also being found at the same time.
(b) Enclosed with CaCl2 in desiccators: CO2 accumulation in the vessel was somewhat less than (a) and the relative humidity was measured as low as 40_??_50%.
(c) Enclosed with soda-lime in desiccators: CO2 given off by respiration was completely absorbed in soda-lime, the relative humidity being as low as (b) and O2 concentration finally decreased to 0.9% after the storage for 4 months.
3. It was found that onions stored under the, condition (a) brought about the functional disorder, a half of samples showing internal break down at 50 days after they were enclosed, and all bulbs disintegrated after 4 months. Under the condition (b), the percentage of disintegrated bulb was less than (a). It seems that the dry condition caused the inhibition of metabolic activities of onion bulbs to some extent.
4. Under the condition (c), a few onions sprout-ed at early period, but most onions were kept in good condition for 4 months storage period (Oct._??_Feb.). There was a very little decrease of total sugar and ascorbic acid content in bulbs during the storage, showing that the metabolism of onion bulbs was extremly suppressed under such environment.
When onions were removed from the condition (c) to normal air at early period, sprouting com-menced in a short time, but the sprouting ability was not kept after the storage for 4 months.
After the storage period exceeded 4 months, it was also found that even under the condition (c), the functional disorder like (a) and (b) occurred. Further, all onions which kept at 20°C throughout the storage period showed the functional disorder at 4 months after they were enclosed, notwith-standing O2 concentration remaining 3.7_??_4.2%.
5. Judging from the result given above, it seems that such environmental condition as 40_??_50% relative humidity and about 1% O2 concentration result in prolonging the storage period of onion as long as 4 months over ordinary storage period, at natural temperature condition prevailing in temperate zone.
