Propagation of Ornamental Plants
5(3): 113-118, 2005
THE INFLUENCE OF ENVIRONMENT, MEDIA, AND ZEROTOL ON FORCING AND IN VITRO ESTABLISHMENT OF SOFTWOOD SHOOTS FROM LARGE STEM SEGMENTS OF ACER SACCHARINUM L. AND FRAXINUS PENNSYLVANICA MARSH.
Faheem Aftab¹², Katayoun Mansouri¹ and John E. Preece¹*
¹Department of Plant, Soil and Agricultural Systems, Southern Illinois University, Carbondale, IL 62901-4415, USA, *Tel: +618-453-1796, *Fax: +618-453-7457,
² Current Address: Department of Botany, University of the Punjab, Q. A. Campus,
The objectives of this research were to study the effects of three environments (lab, mist, or fog), four media (perlite, vermiculte, 1 perlite : 1 vermiculite (by volume), or a control (empty flats) and hydrogen dioxide (Zerotol) treatments on shoot forcing and subsequent transfer of explants to in vitro conditions. Stem segments from field-grown trees were cut into 40 cm lengths before being placed horizontally in flats with the media treatments. Stems in half of the flats under mist and fog were drenched weekly with Zerotol (0.18% H2O2). In a separate study, Acer saccharinum (silver maple) was forced under intermittent mist and drenched weekly with Zerotol at 0, 0.090, 0.108, 0.135, 0.180, 0.270, or 0.540 % H2O2. Shoots (≥ 4 cm long) were harvested and nodal and shoot tip explants were surface disinfested and placed in vitro on DKW medium with 10-8 M thidiazuron plus 10-6 M indolebutyric acid. Species did not interact with environment, media, or Zerotol treatment, and silver maple produced a mean of 6 shoots per stem segment, while green ash produced a mean of 1.2 shoots. There was a significant interaction among perlite, vermiculite and environment, with the most shoots (6.7/stem segment) produced under mist in the perlite/vermiculite mix. Silver maple explants from the lab had only 4% microbial contamination, whereas 68% of explants from fog and 92% of explants from mist were contaminated. When forcing was under fog, in perlite, and drenched with Zerotol, explants had a 43% rate of contamination. In a separate study, when silver maple stems were placed under mist and drenched weekly with 0.18% H2O2, 46% (18 of 39 explants) established cleanly in vitro. Contamination was higher with misted explants that were drenched with higher or lower concentrations of Zerotol. This demonstrates that it is possible to force softwood shoots under mist or fog and establish some explants in vitro without microbial contamination.
Key words: Epicormic shoots, hydrogen dioxide, green ash, silver maple, thidiazuron, tissue culture