GROWTH CORRELATIONS IN EUONYMUS JAPONICUS THUNB. (CELASTRACEAE)

Euonymus japonicus Thunb. is an evergreen shrub with a periodic growth pattern consisting of several growth flushes per year. In each growth flush, 9–11 nodes are added to the stem length. The nodes formed at the beginning of a growth flush are short and bear scale-like leaves. In the middle, the nodes are longer and become shorter again toward the end of the growth flush. The growth of E. japonicus was inhibited when the plant was maintained at a day/night temperature of 17/12°C. Growth inhibition by low temperature was counteracted by gibberellin treatment. The results of experiments carried out with specially prepared single-or two-stem plants proved the existence of a growth inhibition gradient along the stem in every growth flush. Growth of new lateral shoots was more vigorous on the proximal regions of the stem produced by earlier growth flushes than on the distal regions produced by newer flushes. The presence of unpruned stems bearing an apical bud caused growth inhibition on the short and long pruned stems of the same plant. However, there was no growth inhibition when the apical bud was removed.