BULB FORMATION AND FLOWER PRODUCTION IN ONION PLANTS GROWN FROM SETS

Abstract

THE dependence of bulb formation in the onion on the stimulus of long days has been well established^1,2,3,4,5 and also the interaction of day-length with temperature^3,5 ; a day-length just adequate at high temperature fails to induce bulb formation at low temperature, or leads to long delay. With regard to inflorescence emergence ('bolting') Thompson and Smith³ recorded a large temperature effect but no effect of photoperiod, a lack of response attributed by Heath⁵ to the limited range of day-length covered in that work. Heath concluded that conditions favourable to bulb formation (long days, high temperatures) are inimical to bolting and vice versa. In this communication an outline of the further analysis of this apparent antagonism is presented.