Bud dormancy in Fagus sylvatica L. I. Chilling and photoperiod as factors determining budbreak

Abstract

ABSTRACT Bud dormancy release was studied in one- and two-year-old seedlings of two Italian provenances (Camaldoli and Pacentro) of Vagus sylvatica. From the beginning of autumn, seedlings were exposed to different periods of chilling and then placed in controlled environment chambers with long day (LD) and short day (SD). Bud sprouting and relationships among buds in renewal bud growth were examined and relative thermal time calculated. By October, buas were already dormant, and there was no relevant growth of seedlings which were kept for six months under SD and LD conditions. Thermal time, percentage sprouting and mean time to budburst varied consistently with the amount of winter chilling up to 700h < 5°C, when a plateau was reached. Under these conditions daylength did not influence sprouting, which appeared to be, instead, determined by temperature. With shorter exposure to chilling, LD significantly stimulated sprouting. Results also show different growth potentials for the different (based on structure and/or position) types of buds.