Bud development in Sitka spruce. I. Annual growth cycle of vegetative buds and shoots

Abstract

Vegetative apices of Picea sitchensis (Bong.) Carr. were studied throughout the annual growth cycle. Apices became mitotically active late in March and the shoot axis and leaf primordia elongated causing the bud to swell. New axillary apices were initiated in mid-April and the terminal apex and new axillary apices initiated bud scales until early in July. Vegetative bud burst occurred early in June and shoot elongation was completed by mid-July. The end of shoot elongation coincided with the onset of leaf initiation. The change from bud-scale to leaf initiation was characterized by a period of increased mitotic activity and rapid apical growth. About half of the final number of leaves were initiated during the early period of rapid leaf initiation. The remaining leaf primordia were initiated more slowly over the next 3 months. Buds became dormant by mid-November.

Structure and development of vegetative buds, from the lower crown of Picea abies

“…No autumnal phase of bud scale initiation was previously noted in the genus Picea (eg, Owens and Molder, 1976;Harrison and Owens, 1983). Assuming that those observations were exact, this would make Picea abies an exception.…”

“…In winter, the ratio is 0.4 and it increases to 0.5-0.6 in midAugust. (Lewis and Dowding, 1924;Korody, 1938;Camefort, 1956;Anikeeva and Minina, 1959;Fraser, 1966;Schüepp, 1966;Owens and Molder, 1976;Owens et al, 1977; Pillai and Chacko, 1978;Tompsett, 1978;Harrison and Owens, 1983;Skupchenko, 1984;and …”

Mid-winter ultrastructural changes in the vegetative embryonic shoot of Norway spruce [Picea abies (L.) Karst.]

“…With respect to the morphological and anatomical structure, the analysed winter embryonic shoots of Norway spruce did not differ from those described by other authors in this species and in other species of the genus Picea [5,8,13]. However, considerable differences in starch content and cell ultrastructure could be observed between the two dates of collection.…”

“…Some information on the microscopic structure of spruce buds has been published (e.g. [5,8,13]), but most of it does not concern Norway spruce. Thus the knowledge of changes in the structure and ultrastructure of embryonic shoot is still insufficient.…”

Reduced height of short day induced bud scale complex may partly explain early bud burst in Norway spruce seedlings

“…Bud formation and development have been well studied in several tree species, especially on adult trees (Owens and Molder 1976;Owens et al 1977;Sutinen et al 2009Sutinen et al , 2012. In conifer seedlings, the phenology of buds has also been studied for example in Douglas-fir (Pseudotsuga menziesii (Mirb.)…”