Propagation of plantlets from leaf callus of Betula pendula f. purpurea

Abstract

A sub-culturable callus line was obtained from young leaf blades of Betula pendula f. purpurea on a new medium combination (N 7) supplemented with casein hydrolysate (1 g l −1). Shoot differentiation was especially stimulated when casein hydrolysate was omitted and the medium contained zeatin or zeatin riboside (5 or 10 mg l −1) and a low level of auxin (NAA or NOA, 0.1 or 0.2 mg l −1) or no auxin. Rooting of shoots was confirmed later on the same medium or on an inorganic agar medium without any growth regulator. The seedlings could be transferred into pots containing peat-humus soil mixture, cultivated in a greenhouse and planted out of doors in May–June. They grew well and were able to winter out of doors in south and mid-Finland.