THE EFFECTIVENESS OF VARIOUS NITROGEN-SOURCES IN WHITE SPRUCE [PICEA-GLAUCA (MOENCH) VOSS] SOMATIC EMBRYOGENESIS

The effects of glutamine-based dipeptides, glutamine and casein hydrol ysate, as well as the deletion of organic nitrogen, were investigated during white spruce [Picea glauca (Moench) Voss] somatic embryogenesis . There were no differences in the fresh weight increase of the tissue masses grown on initiation medium with different combinations of orga nic nitrogen. This was also the case for subsequent growth on kinetin medium, except that glutamine alone produced a significantly lower fre sh weight increase than the other organic nitrogen combinations. Witho ut organic (i.e. with only inorganic) nitrogen in the medium, the fres h weight increase was significantly less than with organic nitrogen on both initiation and kinetin medium. No differences were found between the dry/fresh weight ratios obtained with the various nitrogen treatm ents. The number of mature embryos produced per gram fresh weight when cultured in the absence of organic nitrogen was significantly higher than that obtained in its presence. There were no differences in the t otal number of mature embryos produced in cultures grown with various organic nitrogen combinations or without organic nitrogen. There were large clone differences with respect to the number of mature somatic e mbryos per gram tissue and the total number of somatic embryos produce d. Hence, nitrogen type influences culture growth rate but not the num ber of mature somatic embryos produced. The latter was clone dependent .