The study of proliferation of cambium and parenchyma of branches from trees in culturesin vitro

Abstract

Proliferation of the cambium and parenchyma of branches from 34 tree species was studied by means of tissue culturesin vitro. The formation of callus tissue, the seasonal activity of cambium, the effects of indole-3-acetic acid on the reactivation of cambium and the polarity of callus formation were investigated. Various tree species are characterized by a different capacity for callus formation; in the majority of species, however, the reaction of cambium takes place in culturesin vitro. Some species produce callus from the cortex and the pith of branches and the lenticels simultaneously with the reactivation of cambium. Growth of callus tissue was maximal in winter, adequate in spring before budding occurred and later decreased greatly. During the summer the growth-rates increased again and in the autumn were close to those encountered during the winter. Some species are characterized by a similarly intensive cambial proliferation throughout the whole year. Indole-3-acetic acid (IAA) in the cultivation medium had various effects on the growth of callus tissue in the species examined. A series of species initiated meristematic foci in callus tissues that gave rise to roots (more frequently on media with added IAA) or to buds and stems. The position of the sections in the medium (whether the apical end was placed upwards or downwards) had no great effect on the polarity of callus formation. Some species produced callus tissue at both ends of sections.