Investigations on the dormancy of Fraxinus excelsior L. buds. I. Sequence of growth period, correlated inhibition and rest of shoot apex in the annual cycle

Abstract

The relation between the period of growth and the subsequent period of correlated inhibition and rest of the terminal bud on the main shoot of the 6-year-old Fraxinus excelsior trees was investigated. From July 21 to August 31, 1971, at ten-day intervals groups of 12 trees, each similar as regards the mean date of bud setting on the main shoot, were defoliated. The data of bud opening after defoliation was considered as index of the depth of dormancy. Statistical analysis demonstrated a rather strong correlation between the number of days after bud setting and the date of their opening after defoliation. The calculated regression curve reached its limit 65.4 days after bud setting, this empirically determining the duration of the period of correlated inhibition of buds of the given tree population. Rest of the terminal buds occurred, therefore, in particular trees at various. times in dependence on the date of bud setting.