In vitro establishment, shoot multiplication, and rooting of Pinus strobus, Pseudotsuga menziesii, and Thuja occidentalis 'Hetz Wintergreen'

Tissue culture propagation or micropropagation is an important new technology used to clone herbaceous and woody angiosperm plants. This technology would have great potential if it could be applied to mature conifers. The research objectives of this study were to improve disinfestation, axillary shoot proliferation and in vitro rooting of Pinus strobus (white pine), Pseudotsuga menziesii (Douglas fir) and Thuja occidentalis 'Hetz Wintergreen'.The disinfestation of conifers was improved using a solution of 0.1% w:v mercuric chloride when compared to a 20% v:v commercial bleach solution. The mercuric chloride solution used on white pine and Douglas fir seeds significantly reduced microbial contamination without changing seed germination percentage. Contamination was also reduced for newly expanded shoots of field grown Douglas fir trees, when shoots were covered with 65:35 polyester:cotton broadcloth bags prior to spring growth and disinfestation.Two cytokinins, thidiazuron (TDZ) and benzyladenine (BA), were used to promote axillary shoot proliferation of Douglas fir and white pine. The number of Douglas fir axillary shoots increased the most when 0.1 micromolar TDZ was utilized. Concentrations of BA as high as 5 micromolar did not affect the number of axillary shoots produced of Douglas fir. The number of axillary shoots of white pine was stimulated by both TDZ and BA. Excellent axillary shoot proliferation (16.5 shoots at 60 days) for white pine was achieved using 0.1 micromolar TDZ plus 5 micromolar BA, but shoots failed to elongate. The number of basal axillary shoots was found to be the best parameter to evaluate the effect of NAA and BA on shoot proliferation of Thuja occidentalis 'Hetz Wintergreen'. Axillary shoot multiplication was best with 10 micromolar BA and 0.1 micromolar NAA.Antigibberellins, ancymidol and flurprimidol, were used to promote in vitro rooting on microshoots of the three conifer species. Ancymidol was found to simulate white pine rooting more than flurprimidol. No effect was observed for Douglas fir microshoots treated with antigibberellins. Ancymidol used on Thuja occidentalis 'Hetz Wintergreen' microcuttings increased rooting percentage, root number, root area, and root length.U of I OnlyETDs are only available to UIUC Users without author permissio