Stimulation of the regeneration capacity of tree shoot segment explantsin vitro

Abstract

Regeneration abilities of buds on shoot segment explants isolated from adult trees of oak (Quercus robur), aspen (Populus tremula), black locust (Robinia pseudacacia), Japan pagoda tree (Sophora japonica), and English walnut (Ailanthus glandulosa) were studied during the growing season. Optimum BAP concentrations for the regeneration of oak bud meristems were dependent on the date of sampling. Axillary shoots could be induced from winter and summer buds of oak and aspen on Dustan and Short media supplemented with activated charcoal and BAP at concentrations from 0.5 to 2 mg 1^-1. More intensive rooting of segments of newly formed shoots was observed on MS medium diluted to one half and supplemented with 2 % sucrose and 0.2 mg 1⁻¹ of IBA.Populus tremula formed longer axillary shoots on DS media supplemented with 0.5 mg 1⁻¹ of BAP and 1 mg 1⁻¹ of GA₃.

Regeneration capacities of black locust, Japan pagoda tree, and English walnut were higher. In addition to the induction of multiple shoots from buds, shoots could also be obtained from calluses formed on basal segment parts. Asparagine and glutamine at a concentration of 25 mg 1⁻¹ stimulated the percentage of differentiated stems on callus surface. Inhibitory effects of substances which accumulated in buds in the second half of the growing season could be reduced by means of pulse treatments in 50 mg 1⁻¹ BAP solutions or using short-term dipping into 0.1 % AgNO₃ solution.