Adenium, also called a desert rose, is a favorite of gardeners. Adeniums that are propagated from seeds may not be the same as the mother plant owing to cross-fertilization of its flowers. Another method of propagation is to develop a new plant from cuttings, thus retaining the characteristics of the original plant. However, doing so may not lead to the development of a great caudex, the attractive feature of the plant. The commercial method of propagation relies on grafting, combining the advantages of seed-grown plants and those propagated by cuttings. The grafting technique ensures propagation of the same kind of plant with a good caudex.
Normally, two types of grafting techniques are followed:
* V-cut or Wedge graft
* Flat-cut graft
- Root Stock: Mature, healthy adenium plants at least a year old are used as stock. The stem which will bear the graft should be slightly woody, having a thickness of about half to three-fourths of an inch. The rootstock should be in its active growth period. In Northern India, this period lies between late February to October, March and September being the best months for grafting.
- Scion: The cutting from the plant to be propagated is called the scion. The scion too should be from a plant in its active growth period. The chosen stem may not be as woody or mature as the rootstock. Its thickness should be roughly equal to or less than the stock.
- Sharp Cutter: A thin blade knife or a cutter is needed for cutting the stock and scion.
- Clear, plastic strip: An approximately 1″ by 5″ strip is taken from a clearplastic sheet.
- Clear plastic bag: To protect the graft and maintain humidity within it.
- Tape and tying material: Needed for securing the stock with the scion and securing the plastic bag.
- Disinfectant: Alcohol can be used to disinfect the tools.
The process for V-cut or Wedge graft
The steps for grafting are:
- The stem of the rootstock is cut at least 3-4 inches from the base. If it is a single stem, a horizontal cut is made 3-4 inches above the caudex. A sharp, disinfected or new cutter is used to make this cut. Thereafter, a cut is made down the middle of the stem to a depth of about one inch. This slit is then given a sharp V shape to accommodate the scion. There is no need to wipe the sap oozing from the cut, thus avoiding contamination.
- The base of the scion is cut to form a symmetrical wedge, after estimating the length required for fitting it in the V-cut of the rootstock. For wedge graft, a longer length of scion can be used as compared to flat-cut graft.
- The scion is then inserted into the V cut of the stock.
- The graft junction is then wrapped firmly with the clear, plastic strip like a bandage and tied with tape or tying material.
- The graft is covered with a clear, plastic bag and tied loosely at the base to allow air circulation.
- The grafted plant is then kept in a shaded area for about two weeks. If the graft is successful, new sprouts start appearing on the scion. The covering is then removed.
- After tiny leaves start appearing, the plant can be gradually shifted to full sunlight. The plastic strip wrapped around the joint can be removed after another 3-4 weeks.
- Any shoots that appear from the rootstock are removed with a sharp tool.
The process for flat-cut graft
The steps for grafting are:
- Cut an Adenium scion that is around 1″ to 2″ in length with a sharp, disinfected tool. It may have1-2 nodes along its length. If the branch is long, it can be cut into several pieces to serve as scions. One should not touch the freshly cut wounds of both the stock and scion to avoid infection. The top and bottom parts of the scion should be marked.
- The stem of the rootstock is cut at least 3-4 inches from the base or if it is a single stem, a horizontal cut is made 3-4 inches above the caudex. The cut should be clean and as flat as possible.
- Now the scion is placed on top of the stock branch with the correct orientation. That is, the top side of the scion should remain so after placing it on the stock.
- Neat cuts of both the scion and stock will ensure that there are no bumps and ridges on the surface and hence no air gaps.
- Place a clear, clean plastic strip over the scion and pull down the ends tightly past the grafting point.
- The ends of the strip are then secured tightly with tying material around the rootstock branch. Now the scion becomes firmly tied to the stock branch.
- The entire graft is then covered with a clear bag and tied loosely at the base. This will protect the scion as well as maintain humidity while the graft heals.
- The grafted plant is kept in shade for about two to three weeks or till the scion shows signs of sprouting.
- The clear bag is then removed and the plant gradually moved into full sunlight.
Identifying a Successful and a Failed Graft
A successful graft will heal and sprout a new set of leaves over some time. On the other hand, a failed graft will show signs of rot. The scion will become yellow, soft and mushy indicating it could not receive water and nutrients from the stock.
Precautions to be followed for a successful graft are:
- The tools should be clean and disinfected to avoid any infection.
- The stock and scion should have maximum surface area contact.
- The graft should be left undisturbed to heal and join.