In vitro propagation of Araucaria cunninghamii and other species of the Araucariaceae via axillary meristems.
Stem segments with 3-5 leaf axils, excised from the upper portion of the main stem of 2-yr-old A. cunninghamii seedlings, produced orthotropic buds from the concealed axillary meristems when cultured on a basal medium (BM) of half-strength Murashige and Skoog (MS) inorganic salts, the medium level of growth factors and amino acids of deFossard, 20 g/litre sucrose and 6.5 g/litre agar. This procedure was also successful with A. balansae, A. bidwillii, A. columnaris, A. hunsteinii, A. luxurians, A. montana, A. rulei, A. scopulorum and Agathis robusta and with stem segments from orthotropic coppice shoots of 20-yr-old A. cunninghamii trees. The A. cunninghamii explants were highly sensitive to cytokinin; 1 and 10 µsmallcap˜M 6-benzylaminopurine [benzyladenine] caused the formation of distorted buds and total inhibition of bud development respectively. Lower concn. did not noticeably influence bud formation or development. Reculturing the stem segments after the excision of the initial shoots led to a low rate of multiplication. New buds developed in the leaf axils of that part of the initial shoot which remained attached to the primary stem explant. Shoots derived from seedling and coppice cultures of A. cunninghamii and seedling cultures of Agathis robusta rooted in vitro on BM + 0.1-10.0 µsmallcap˜M IBA, but with only 5-20% success. Up to 80% rooting was obtained if both A. cunninghamii shoot types were cultured on modified BM (quarter-strength MS salts, 10 µsmallcap˜M IBA, no agar) for 2 wk, before being transferred to a mixture of non-sterile peat and perlite or vermiculite and perlite and maintained at RH 90-95%. Plantlets were subsequently transferred to normal greenhouse conditions and then to the field with less than 5% mortality.