Factors influencing the induction of embryogenic and caulogenic callus from embryos of Piceaglauca and P. engelmanii

Abstract

Zygotic embryos of Piceaglauca (Moench) Voss from five half-sib seed families and P. engelmanii Parry from one half-sib family, collected on July 13 and 27 and August 24, were cultured in the presence of 2,4-dichlorophenoxyacetic acid, N6-benzyladenine, and sucrose ranging from 0.5 to 4% for the induction of embryogenic callus and the production of stable embryogenic callus lines. Embryogenic callus was induced from all three collections with all seedlots. The July 13 collection was two to four times more embryogenic than the later collections. Embryogenic callus was induced at all sucrose levels, but 4% sucrose was clearly inferior, whereas 1% was best overall. Factors that favored the induction of embryogenic callus also favored the production of stable embryogenic callus lines. There was a 40% decline in callus line establishment compared with embryogenic callus induction and some seed lots failed to yield embryogenic lines from the two later collections. The formation of caulogenic callus was promoted at 3 and 4% sucrose. Embryos from the August 24 collection were more caulogenic than those from the earlier collections.