Plantlet formation in black and white spruce. I. In vitro techniques

Abstract

A comparative study on plantlet formation in black (Piceamariana (Mill.) B.S.P.) and white (Piceaglauca (Moench) Voss) spruce led to the development of similar in vitro systems. Buds were induced on epicotyl explants on Schenk and Hildebrandt's mineral salts containing sucrose and equimolar concentrations of benzylaminopurine and 6-(γγ-dimethylallylamino)-purine. Transfer to cytokinin-free medium allowed for secondary, shoot formation. Shoot elongation and development required a medium with reduced sucrose and containing conifer-derived charcoal. Preparation for rooting involved further culture in charcoal-free medium. For rooting, shoots were dipped in a sterilized rooting powder containing indolebutyric acid and placed in sterile vermiculite containing half-strength mineral salts, sucrose, and charcoal. Roots could also be formed under nonsterile conditions. Shoot formation had a higher optimum temperature and longer photoperiod requirements than rooting. The above sequence of manipulations can produce ca. 40 plantlets per seed within 170 days in culture.