Adventitious Root Formation in Stem Cuttings of Quercus bicolor and Quercus macrocarpa and Its Relationship to Stem Anatomy

Abstract

<jats:p>This study investigated the relationship of stem anatomy to differences in rooting ability between <jats:italic>Quercus bicolor</jats:italic> Wild. and <jats:italic>Quercus macrocarpa</jats:italic> Michx. cuttings. <jats:italic>Quercus bicolor</jats:italic> cuttings were found to have a significantly greater proportion of parenchymatous gaps in the sclerenchyma sheath over a 9-week period compared with <jats:italic>Q. macrocarpa</jats:italic> cuttings. In <jats:italic>Q. macrocarpa</jats:italic>, the percentage gap was generally low, coinciding with the low percentage rooting observed in this species. Percentage rooting correlated well (r<jats:sup>2</jats:sup> = 0.75) with the percentage parenchymatous gap in the perivascular region of <jats:italic>Q. bicolor</jats:italic> cuttings. The problems with accepting this relationship as causal are stated in the discussion. Untreated cuttings showed normal stem organization: a dermal tissue system that included the initial stages of phellem formation, a cortex, and a ring of closely arranged vascular bundles in early stages of secondary growth. The locations of the five distinct lobes of the pith were coordinated with the locations of root primordia. Callus growth was first detected in the cortex (i.e., external to the fiber bundles), followed by proliferation within the phloem, opposite the lobes of the pith, 8 to 12 days after cuttings were treated with indole butyric acid (6000 mg·L<jats:sup>−1</jats:sup> dissolved in 50% v/v ethanol in water). By 14 to 16 days, root primordia had developed within the proliferative tissue in the secondary phloem. In both species, root primordia penetrated parenchymatous gaps in the fiber sheath directly, the fiber bundles being displaced laterally as the roots increased in size.</jats:p>

Topophysis in Corymbia torelliana × C. citriodora seedlings: adventitious rooting capacity, stem anatomy, and auxin and abscisic acid concentrations

“…S2 cuttings) all had similar rooting, vigour, lignification and sclerification to each other and to apical-node ortet cuttings, regardless of their previous point-of-origin within the ortet. A continuous ring of sclerenchyma is often formed exterior to the site of adventitious root formation as the stem develops (Pohio et al 2005;Hartmann et al 2011) and rooting capacity is sometimes negatively associated with the continuity or number of cell layers of this ring (Maynard and Bassuk 1996;Pacholczak et al 2006;Amissah et al 2008). This does not establish a direct causal relationship between sclerification and reduced rooting capacity, as adventitious roots can emerge through breaks in the sclerenchyma that form during root or stem growth, and cuttings of difficult-to-root species often fail to form root primordia irrespective of their sclerenchyma development (Amissah et al 2008;Hartmann et al 2011).…”

In Vitro Propagation of Oriental White Oak Quercus aliena Blume

“…However, it is very difficult to vegetatively propagate most oaks by cutting, and the rooting ability decreases significantly with the age of oak tree, though grafting, cutting back, and etiolation are usually adopted to improve rooting [19,20]. Micropropagation from shoot tips or nodal explants is an efficient way to produce uniform quality oak clones with desired traits and is helpful for further improvement through genetic transformation [21].…”

Micropropagation of Eucalyptus camaldulensis for the production of rejuvenated stock plants for microcuttings propagation and genetic fidelity assessment

“…However, in this study cells in phloem region including ray parenchyma cells present in outer radius of xylem were involved in root primordium formation. In Quercus stem cuttings, root primordia had developed within the proliferative tissue of the secondary phloem region (Amissah et al 2008) (Fig. 4).…”