Dormancy of Fagus sylvatica L. buds III. Temperature and hormones in the evolution of dormancy in one-node cuttings

The evolution of the growth potential of Fagus sylvatica L. buds in the autumn-winter period (September-March) was analysed. One-node cuttings (of apical, median and basal buds, and small buds at the base of the branch) were taken from one-year old shoots removed from adult beech plants (at Vallombrosa in the Tuscan Apennines) and placed in climatic chambers with a 12-h photoperiod and temperatures of 15degrees and 25degreesC. They were treated either with water or gibberellin and kinetin solutions. The trend in sprouting was followed, for all types of buds, for 60 days. The months of September and October constituted the period of entry into dormancy, which then reached a peak at the beginning of November. In December, the phase of rapid dormancy removal was already present. Restriction and subsequent widening of the thermic interval compatible with growth, establishment and later removal of the basitonal habitus were the characterising elements in the autumn-winter evolution. Kinetin had null or slightly inhibiting effects in all the examined period. Gibberellin did not modify the behaviour of buds approaching dormancy, whereas they strongly stimulated growth in the period of rapid dormancy removal, and exerted moderate effects in the subsequent period of slow residual dormancy removal.