LARSON, TROY and PHILIP J. VILLANI.* Augustana College, 639 38th Street, Rock Island, IL 61201. - The effects of thidiazuron on the release of foliar embryos in Bryophyllum calycinum.
Leaves on the plant of Bryophyllum calycinum produce foliar
embryos in the notches of the leaf margin. These embryos remain
dormant while the leaf is attached to the plant. However, detaching a
leaf will cause many of these foliar embryos to be released from
dormancy and develop into plantlets. The effects of thidiazuron (TDZ),
a hormone with cytokinin activity, on the release of foliar embryos
and root formation was investigated. Two centimeter explants of the
leaf margin including the notch region were removed from the leaves
and grown in tissue culture on Murashige and Skoog media supplement
with B5 vitamins and various hormones. Overall, TDZ causes
significantly more embryos to be released from dormancy compared to
the control or some concentrations of 6-Benzly-aminopurine (BAP). At
concentrations of 10-8 and 10-10 TDZ, greater
than 92% of the foliar embryos placed in culture were released from
dormancy compared to 84% or 82% on 10-6 or 10-8
BAP, respectively, or 73% on the control media. In addition, a trend
was observed that higher concentrations of TDZ causes the release of
fewer embryos than lower concentrations. TDZ at various concentrations
had little affect on the number of roots per explant unlike BAP or
2,4-D compared to the control.
Key words: asexual reproduction, Bryophyllum calycinum, Crassulaceae, foliar embryo, thidiazuron