M. Uosukainen
In preeding woody perennials the cloning of selected material is often time consuming and technically difficult. The purpose of this research was to find tissue culture methods to speed up breeding programmes and to make it possible to propagate the selected clones round the year without any preconditioning of mother material.

Material was collected directly from trial fields and from Arboretum Mustila. The motherplants were 10 – 50 years old. Different medias, mainly Murashige-Skoog medium and its modifications were tested. The influence of cytokinins and gibberellic acid was examined. No auxins were used in the medias.

In most plants the establishment of meristem-tip culture was succesful when only 1/10 of MS macro- and microelements were used. Higher salt concentrations killed the tissues and caused browning in surviving tissues. After the first medium the established cultures tolerated higher salt concentrations. Zeatin (trans isomer) 1 – 2 mg/l gave the best results in establishing the cultures of Rhododendron sp. (70 clones). Vaccinium sp. (5 species), Pieris floribunda and Hydrangea sp. (5 clones). Kinetin, 1 – 2 mg/l, together with GA3, 1 mg/l, gave the best results in the culture of Philadelphus lewisii and 2 mg/l BA was the best cytokinin for Forsythia ovata ( 7 clones ).

The succeeding in the establishment of the cultures was both dependent on the location of the bud on a shoot and on the skill of an assistent. When all of the buds were used, only 10–30 % of cultures succeeded but when the buds were selected, about 80 % of the preparates succeeded. The cultures were well established and started rapid proliferation after the second or the third division on the proliferation medium. This phase took about six months from the beginning. The difficulties in the sterilization of the shoots were the major problems with Philadelphus lewisii and with such hairy species as Rhododendron smirnowii.

According to the results obtained in this research it is possible to start the tissue culture of woody perennials without preconditioning of motherplants. This result is of great value for the work done in collecting and maintenance of material for gene banks. The plants propagated by tissue culture are more vigorous than their mostly over aged mother plants.

DOI: 10.17660/ActaHortic.1987.212.6

Acta Horticulturae