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Horticulture Principles and Practices

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FIGURE 10–11 The basic elements<br />

in a graft union: a rootstock<br />

<strong>and</strong> scion.<br />

Scion<br />

Graft<br />

Rootstock<br />

FIGURE 10–12 Methods for<br />

making an approach graft.<br />

Make slanting<br />

cuts in opposite<br />

directions<br />

Wedge<br />

together<br />

Tie <strong>and</strong><br />

seal<br />

OR<br />

Remove bark in<br />

parts to be united<br />

grafting is not feasible. The produce harvested from the plant reflects only the<br />

characteristics of the scion parent <strong>and</strong> not both stock <strong>and</strong> scion. The scion serves<br />

only as ground support.<br />

10.8.1 HEALING OF A GRAFT JUNCTION<br />

A graft is successful if healing is complete <strong>and</strong> vascular transport restored between the<br />

scion <strong>and</strong> stock. It is critical that the tissues in the two parts be correctly aligned—xylem<br />

for xylem <strong>and</strong> phloem for phloem. Healing starts with the production of callus<br />

(undifferentiated cells) by mitosis <strong>and</strong> occurs in the cambium region of the two parts.<br />

Next, some of the cells differentiate to form new cambium tissue to join the old in the<br />

two parts (Figure 10–13). This stage is followed by further differentiation of cells to form<br />

vascular tissue, which completes the repair of the cuts <strong>and</strong> allows for uninterrupted<br />

vascular transport.<br />

322 Chapter 10 Asexual Propagation<br />

10.9 WHEN TO USE GRAFTING<br />

Grafting may be used for relatively simpler <strong>and</strong> more routine propagation of plants <strong>and</strong><br />

for more complicated <strong>and</strong> specialized repair of damaged plants.

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