dormancy of buds of Citrus sinensis (L.) Osbeck inserted into rootstock stems: factors intrinsic to the inserted bud

Buds of sweet orange, harvested from shoots of different time of flushing and from different positions along the shoot, were used to examine whether lack of burst of inserted buds was a characteristic of the bud. Bursting of inserted buds was significantly slower in buds taken from (a) older branches (b) shoots produced under winter conditions, and (c) basal rather than apical buds on the same shoot. The slowness to burst when transferred matched a tendency to dormancy in buds on shoot segments grown in vitro, suggesting that the variation in budburst was intrinsic to the bud. Budburst was correlated with the extent of secondary bud development; the majority of buds from apical regions of the shoot had developed a secondary bud by the time of implantation, but basal buds had not. Adequate vascular connections with the host tissues were found in both burst and unburst buds.