*3.3.2.2.3 Leaf bud cuttings*

As with stem cuttings, the use of leaf bud cuttings as a rapid propagation technique eliminates non-systemic pathogens from the soil and tubers [20, 21]. The procedure is as follows (**Figure 8**).

#### **1. Selection of the mother plant**

The first step in the production of leaf bud cuttings is to choose a healthy and suitable mother plant. The mother plant should be cultivated under the conditions of a long photoperiod (long days) and then kept for 10 to 15 days in short photoperiod (short days) before cutting to induce tuberization. A plant that begins senescence (when the basal leaves are mature) is ready to cut the cuttings of leaf buds.

#### **2. Cutting**

The best cuttings yield comes from the central part of the plant. Those coming from the lower part of the plant produce smaller micro-tubers, the cuttings of the top parts produce few micro-tubers and tend to produce aerial roots and buds.

After removing the stems from the base of the plant, they are cut (main stems) into cuttings of leaf buds of 13 cm, depending on the cultivar. In the centre of the

**Figure 8.** *Cutting technique of leaf buds (Stapes to be followed).*

cuttings, a node should be present with an undifferentiated bud and a leaf. Approximately 70100 cuttings can be produced per plant.

#### **3. Cultivation of cuttings**

Leaf bud cuttings are planted with part of the stem in a well-drained substrate (fine sand, 1 mm), with the bud below and the leaf above the surface.

The cuttings are planted in line 57 cm apart, depending on the size of the leaves, and their leaves should be covered with sand more or less completely. Cuttings and sand substrate should be well in contact. Irrigation should be done carefully with very fine water droplets. When the light intensity is high, shading can be provided. The temperature in the greenhouse should be relatively low, about an optimum 20°C.

#### **4. Harvest**

After one or two weeks, the germs begin to develop. When all the leaves have died (46 weeks after planting, depending on the cultivar and temperature), the micro-tubers are harvested. Generally, 1 micro-tuber is harvested by cutting, but sometimes 2 can be obtained. As a result, 80120 tubers are harvested from a single-parent plant. The typical size of tubers produced in 31 days is between 0.5 and 1.0 cm (0.2–1.0 gr).

By the technique of leaf buds, more than 1000 tubers can be produced on 3 m<sup>2</sup> .

#### **5. Storage of Micro-tubers**

Micro-tubers can be stored for 46 months at 4°C and relative humidity of 90% after which the dormancy period is generally over.
