Effect of Temperature on Bulb- and Tuber-Formation in Bulbous and Tuberous Crops

IV. On the Pupa Formation in Freesia Corms at Various States of Dormancy

Abstract

In the previous paper the present writer reported that the physiological states for corm formation in freesia were induced by the chilling treatment at about 10°C for seed corms or seedlings. This study was carried out from 1970 to 1973 in order to clarify whether dormant corms or cormlets produce pupas by the chilling treatment.
In this experiment, corms and cormlets (cultivar‘Rijnveld′s Golden Yellow’) of various dormant states were treated periodically with the low temperatures of 5°or 9°C for 30 to 45 days and then were stored in the thermostat or pan of moist sand at 20°C.
In the lots of dormant corms or cormlets, the pupa formation, i.e. new corm formation was scarcely ever recognized. After the emergence from dormancy the effect of the chilling on pupa formation tended to increase, and the percentage of pupa-formation and the size of new corm increased. Therefore, it is sure that in the deep dormant corms the physiological state for corm formation was not induced by the chilling treatment, but that was induced in the corms the dormancy of which had become lighter. The aforesaid phenomena in corm formation of freesia resemble to vernalization in flower formation.