Bioreactor culture of Picea mariana Mill. (black spruce) and the species complex Picea glauca-engelmannii (interior spruce) somatic embryos. Growth parameters

Somatic embryo cultures of Picea mariana and the species complex P. glauca-engelmannii were each grown in 7.5-l-capacity mechanically-stirred bioreactors containing 6 l medium (LP, von Arnold and Eriksson) with 30 mM sucrose. Growth of both species occurred with no observable signs of shear stress due to mechanical agitation. Growth kinetics were analysed using an array of parameters (settled culture volume, packed culture volume, osmolarity, conductivity, pH). These were compared with fresh weight, dry weight, and somatic embryo number in order to determine what parameters were highly correlated with growth and embryo number. Increasing the sucrose concentration from 30 mM to 60 mM resulted in an increase in biomass and total number of somatic embryos. For P. mariana a maximum dry weight of 6.3 g l-1 and 3076 embryos ml-1 occurred in LP medium with 60 mM sucrose after 10-12 days of culture. For P. glauca-engelmannii a maximum dry weight of 4.3 g l-1 and 2278 embryos ml-1 occurred in LP medium with 60 mM sucrose after 6-8 days culture. For all sucrose concentrations, fresh weight, dry weight and embryo number were closely correlated with packed culture volume and conductivity for P. mariana, and settled culture volume, packed culture volume and conductivity for P. glauca-engelmannii.