REST PERIOD OF RHODODENDRON FLOWER BUDS .I. EFFECT OF BUD SCALES ON ONSET AND DURATION OF REST

Shortly after flower differentiation, Rhododendron flower development is interrupted by a rest period. The results reported here show that the onset and duration of rest depended upon the presence of the flower bud scales. When the scales were removed before the onset of rest, the flowers continued to elongate and attained anthesis. Intact buds stopped growing and remained in rest for at least four months. Scale removal after the onset of rest terminated the rest period, though there was a lag phase before the flowers began to elongate. The duration of the lag phase was related to the time of scale removal. The scales prevented flower development in situ, on detached stems and in vitro.The results further show that the rest period of each flower bud was independent of the rest period of adjacent flower buds and that the resting terminal flower buds correlatively inhibited the growth of the lateral vegetative apices. The correlative inhibition was eliminated by removing the terminal flower bud or by breaking the rest period of the flower bud. © 1968 Oxford University Press.