Abstract
This study was carried out to clarify the effect of chilling treatment for seed-bulbs or seedlings on the bulb formation of bulbous Oxalis, i.e. O. bowieana, O. cernua, O. variabilis and O. versicolor.
The results obtained were summarized as follows:
1. When the seed-bulbs or seedlings of Oxalis were exposed to 5°or 10°C for 30 days and thereafter were grown under a daylength of 16-hour at 20°C, the plants of Oxalis turned yellow and formed the new bulbs. While those of O. bowieana, O. variabilis Lavender and O. versicolor grown without chilling treatment failed to form new bulbs.
2. When the seed-bulbs of O. variabilis Lavender and O. versicolor treated with both chilling at first and then heat treatment of 30°C or 35°C for 10 or 20 days, the development of new bulbs was suppressed though grown under a daylength of 16-hour at 20°C.
3. From these results, it may be assumed that the low temperature of 5°°C to 10°C caused the physiological state of seed-bulbs of Oxalis to be favourable for their bulb formation, but the high temperature of 30° to 35°C vanished the above-mentioned physiological state.
4. Based on the aforesaid results, both the practical method of year round culture of Oxalis by the control of the period of its bulb formation and the relationship between the development of bulbs of O. bowieana and shrinking of its contractile roots were discussed.
