Propagazione in vitro e produzione di semi sintetici di Metrosideros excelsa

To induce multiple shoot formation on nodal segments of M. excelsa the Murashige and Skoog (MS) medium, augmented with different concentrations of 2- isopenthenyladenine (2iP) and indole-3-acetic acid (IAA), either singly or in combinations, was tested. In the following experiment, equal molar concentrations of four cytokinins [2iP, kinetin, zeatin, N6-benzyladenine (BA)] in combination with equal molar concentrations of three auxins [IAA, a-naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA)] were tested for ability to induce axillary shoot development. The highest rate of proliferation was induced on MS medium with 1.96 ìM 2iP and 1.14 ìMIAA. Different auxins at equal molar concentrations were tested to determine the optimum conditions for in vitro rooting. The best results were accomplished with IAA at 5.71 M. Seventy percent of the microshoots rooted ex vitro in bottom heated bench after 2 weeks. Rooted microshoots were successfully established in soil. The possibility to produce M. excelsa synthetic seeds was also tested. Shoots were encapsulated in calcium alginate beads. Forty-four percent germination was accomplished after 13 days on MS agar medium.