Differential Growth Response of Aspen Clones Stored at Sub-Zero Temperatures

Abstract

The potential of dormant buds for conservation of forest tree germplasm was investigated. Dormant buds along with twigs from 14 aspen (Populus tremula, P. tremuloides) and hybrid aspen clones were wrapped in plastic bags and stored at five different sub-zero temperatures (0 C, -5 C, -8 C, -18 C, and -80 C) for up to two years. In another set of experiments, only dormant buds from two aspen and two hybrid aspen clones were stored in screw-cap bottles or sealed ampules at the five sub-zero temperatures for up to two years. Before storage, some dormant buds were coated with wax and stored under vacuum. After different periods of storage, bud expiants were cultured on a screening medium to monitor the growth and differentiation of microshoots. Results of these studies show that storage potential of an aspen clone is largely determined by the storage temperature, the genotype, and the conditions of storage. Of the five temperatures tested, -80 C seemed to be the best temperature for long-term storage of dormant buds.