In Vitro Rooting and Subsequent Survival of Two Clones of a Cold-tolerant Eucalyptus grandis × E. nitens Hybrid

Abstract

<jats:p>Multiple shoots of two <jats:italic>Eucalyptus grandis</jats:italic> Hill ex Maid. × <jats:italic>E. nitens</jats:italic> (Deane &amp; Maid.) Maid. clones (GN121 and GN107) generated from axillary buds were used for in vitro rooting studies. The highest rooting rates in clones GN121 (75%) and GN107 (65%) were achieved on modified 1/4-strength Murashige and Skoog (MS) (1962) medium (Ca<jats:sup>2+</jats:sup> and Mg<jats:sup>2+</jats:sup> levels as for 3/4-strength MS), 0.5 μ<jats:sc>m</jats:sc> IBA, 0.4 μ<jats:sc>m</jats:sc> biotin, 0.2 μ<jats:sc>m</jats:sc> calcium pantothenate, 0.04 <jats:sc>m</jats:sc> sucrose and 0.4% (w/v) Gelrite®. The optimal culture conditions were an initial 72-h dark incubation period followed by a 16-hour photoperiod at a photosynthetic photon flux density (<jats:italic>PPFD</jats:italic>) of 37 μmol·m<jats:sup>-2</jats:sup>·s<jats:sup>-1</jats:sup> and 23 °C day/21 °C night for 7 days, after which the <jats:italic>PPFD</jats:italic> and temperature were increased to 66 μmol·m<jats:sup>-2</jats:sup>·s<jats:sup>-1</jats:sup> and 27 °C day/21 °C night for 18 days. Plantlets were acclimatized with survival rates of 78% for GN121 and 58% for GN107 after 28 days. Chemical name used: indole-3-butyric acid (IBA).</jats:p>

Micropropagation of Metrosideros excelsa

“…After 6 wk of culture, the simultaneous presence of IAA and 2iP at 1.14 and 1.96μM, respectively, promoted the highest shoot multiplication (3.8 shoots per explant). Synergistic effect of cytokinins and auxins in axillary shoot proliferation has been also reported in Rosa roxburghii (Ma et al 1996), in rootstock selections of Pirus communis and Pirus betulifolia (Yeo and Reed 1995), in Eucalyptus grandis x E. nitens (Mokotedi et al 2000), and in Myrtus communis (Ruffoni et al 1994). The best result in terms of shoot length was also obtained from the medium augmented with 1.14μM IAA and 1.96μM 2iP, although the effectiveness of this treatment did not differ significantly from that of the medium deprived of growth regulators and from that of the other media containing 2iP alone (3.92 or 15.68μM 2iP) or in combination with IAA (1.14μM IAA and 15.68μM 2iP).…”

“…There are other reports of IAA and IBA being effective in stimulating adventitious root formation in other Myrtaceae such as Myrtus communis (Ruffoni et al 1994;Scarpa et al 2000), Eucalyptus ficifolia (de Fossard and Bourne 1976), Eucalyptus grandis X E. nitens (Mokotedi et al 2000), Eucalyptus globules, and E. saligna (Foçaga and Fett-Neto 2005). The present study also demonstrated the superiority of IAA and IBA over NAA in the induced development of adventitious root formation.…”

Analysis of differences in field performance of vegetatively and seed-propagatedEucalyptusvarieties I: survival and leaf gas exchange

“…0239/4820) located 5 km from the experimental site (Figure 1). Micropropagated saplings of a clone of E. grandis × E. nitens were produced in our laboratory (Mokotedi et al 2000) whilst macropropagated E. grandis × E. nitens of the same clone, as well as seed-propagated E. grandis and E. nitens of comparable age, were obtained from Mountain Home Nursery (Mondi Business Paper, Hilton, Pietermaritzburg). After acclimatisation, all plantlets were maintained in their containers according to standard…”

Auxin stability and accumulation during in vitro shoot morphogenesis influences subsequent root induction and development in Eucalyptus grandis

“…In terms of micropropagation, axillary bud proliferation is generally the preferred choice (reviews by Jones and Van Staden 1997;Watt et al 2003;de Assis et al 2004) and, together with some specific mini-cutting techniques (e.g. Schwambach et al 2008), the only viable method for the propagation of difficult-to-root clones (Yasodha et al 2004;Mokotedi et al 2000;George et al 2008).…”

“…In particular, roots of micropropagated plants established just below the soil surface as a few I-beam shaped roots, whereas seedling plants developed numerous T-beam shaped roots, which were significantly more resistant to uprooting than the micropropagated ones (Mokotedi et al 2010). That study employed the standard, routinely-used protocol in our laboratories, adapted for the clone for maximum multiplication, elongation, rooting and acclimation yields, with specific PGRs for each of the in vitro stages (Mokotedi et al 2000). The results from that field work may, therefore, be explained by the influences of the supplied phytohormones pre-and post-rooting.…”