The effect of collection date and frozen storage on the formation of embryo-like structures and elongating shoots from explants from mature Larix decidua and L. x eurolepis

Abstract

Branches were collected in the winter and early spring from a 37-year-old Larix decidua and a L. x eurolepis tree. Part of these were used immediately and the rest stored at −5 °C and −10 °C for 3 months. Primordial shoot explants were excised from stored and non-stored material and cultured on half-strength Litvay medium free of growth regulators. Storage at −5 °C promoted formation of embryo-like structures which formed shoots with elongated stems (long-shoots). The highest number of these was obtained with material collected shortly before bud break. De-needled stem sections, cut from elongating stems in early summer, produced axillary short-shoots instead of embryo-like structures.