**2. Treatment of tubers**

After breaking of dormancy, a vigorous bud is stimulated by the transfer of tubers every 7 to 10 days from the dark medium to the light (indirect) medium and back. Darkness promotes the growth and development of the internodes, while indirect light improves the vigour of the buds and induces short internodes. After treatment with dark and indirect light, when the buds are 3 cm long, the apical part is sectioned by a very sharp knife. This stimulates the formation of lateral buds and consequently the increase in the number of cuttings. After removal of the apical part, the tubers with their buds are submerged for a maximum of 10 minutes in a solution of

**Figure 6.** *Bud cutting technique (Stapes to follow).*

gibberellic acid of 12 ppm in order to improve the growth of the buds. After which the proper distance of the internodes is regulated by placing the tubers in darkness or under indirect light. Root formation can be stimulated by high relative humidity.

#### **3. Cuttings**

A small portion of the buds will have to remain on the tubers if another harvest of the bud cuttings is expected. Two to three bud harvests can be taken from each tuber if they are physiologically young.

If the tuber is to be planted, at least a harvest can be made. After removal of the tubers, the buds are sectioned into pieces of one or more nodes. Cuttings should have at least one apical bud and two small roots to ensure good growth of the new seedling. A single tuber can produce up to 40 buds, depending on the size of the tuber, the number of eyes and the management of the buds.

#### **4. Planting Bud Cuttings**

The bud cuttings are planted on a well-drained substrate (fine sand 1 mm) in tray. The apical bud should be slightly higher above the sand after first watering. Terminal cuttings grow very quickly and should therefore be planted separately from those from the base.

#### **5. Transplantation**

After about 15 days, the cuttings will have formed roots and are thus ready for transplantation. Two days before transplant a foliar application of fertilizer is desired. The transplant can be done directly in the field or in pots in the greenhouse.

• *In the field:*

The soil-cuttings contact must be optimal. At least one leaf node must be underground; this is best done by watering after transplantation. Good results are obtained when the fertilizer solution is made of a concentrated mixture of P2O5 and water.

Two to three weeks after transplant, cuttings are treated as normal potato plants. Early earthing-up must take place to maximize tuber production. The average yield of 500 gr per plant can be obtained.

• *In the pots:*

Cuttings planted in pots can be considered mother plants for the production of node cuttings. If 34 cuttings are transplanted into a large pot, they can be used for future propagation of stem cuttings, leaves or for tuber production.

#### *3.3.2.2.2 Stem cuttings*

Stem cuttings used as rapid propagation can produce 20 to 60 cuttings from each parent plant. The advantage of stem cuttings is that non-systemic diseases and nematodes can actually be eliminated because only the top part is used for propagation [18, 19]. The procedure is as follows (**Figure 7**).

**Figure 7.** *Stem Cutting Technique (Stapes to follow).*
