Approximately 75% of avocado trees in Indonesia are cultivated from seed. The consequence of this phenomenon is that the quality of the avocado tree is diminished, as fruit production exhibits considerable variability in terms of size, shape, and taste.
The application of top working or grafting techniques can result in the production of avocado trees with uniform fruit size and high quality. The time required for avocado trees resulting from top working to begin bearing fruit is approximately two to three years, in contrast to trees without top working, which takes between four and five years to produce fruit.
Top working is a process whereby rootstock seedlings are combined with avocado tree scion seedlings. In top working, the rootstock seedling is a mature avocado tree with a robust root system and a trunk with a diameter of 5-30 cm. The scion seedlings are selected from superior avocado species with high productivity, averaging 50 kg/tree. These include the long green avocado species. The results of top working become apparent after a period of two to three years.
Two methods of top working are bark grafting and cleft grafting.
A. Bark Grafting
Bark grafting is a technique applied in the cultivation of avocado trees whose bark is relatively easy to peel and the tree is not particularly old. The following steps are involved:
a. Avocado trees with a diameter of 5-30 cm are cut to a height of 60-75 cm from the ground.
b. At the cut mark, a 5-7 cm long downward bark incision is made.
c. The entry of the selected species is cut 10 cm long. Both sides of the base are pointed.
d. The entry is joined to the tree by opening the bark incision and inserting it inside. Three incisions are made. Each connected entry is reinforced using a rafia rope. The open portion of the trunk may be coated with wax or paraffin.
e. To prevent precipitation and direct solar radiation, the tree is covered with cement paper or plastic. To maintain adequate air circulation within the enclosure, holes are created on both sides.
B. Cleft Grafting
Cleft grafting is a technique employed on avocado trees exhibiting characteristics such as large trunks, advanced age, and bark that are challenging to remove.
a. The procedure begins with the tree being cut at a height of 60-70 cm from the ground. A gap measuring 3 cm is then created in the cut.
b. The selected species is then introduced into the tree through a 10 cm long incision. The lateral surface of the base is shaped and tapered to the dimensions of the stem opening.
c. The entry is connected to the tree by inserting it into the opening. It is recommended that the connection be reinforced with a rafia rope. The exposed portion of the trunk is then coated with wax.
d. To prevent direct exposure to rain or sunlight, the tree is subsequently covered with cement paper and plastic. To maintain adequate air circulation within the enclosure, holes have been created on both sides.
