Grafting is a horticultural technique that involves joining two different plants together to create a new plant with desirable characteristics. Grafting can be used to propagate rare or difficult-to-grow plants, improve disease resistance, enhance fruit quality, or create ornamental effects.
But how does grafting work? What makes two plants compatible for grafting? The answer lies in a thin layer of cells called cambium.
What is cambium?
Cambium is a single layer of cells that lies between the wood and the bark of a plant. It is responsible for producing new cells that form the secondary growth of stems and roots. Cambium can be divided into two types: vascular cambium and cork cambium.
Vascular cambium produces xylem and phloem, which are the tissues that transport water and nutrients throughout the plant. Xylem forms towards the inside of the stem, while phloem forms towards the outside. Cork cambium produces cork cells, which form the protective outer layer of bark.
Why is cambium important for grafting?
When two plants are grafted together, their vascular cambia must align and fuse together to form a continuous connection between the scion (the upper part of the graft) and the rootstock (the lower part of the graft). This allows water and nutrients to flow from the rootstock to the scion, and vice versa.
If the cambia do not match up, or if they are damaged during grafting, then the graft will fail. Therefore, it is essential to cut both scion and rootstock at an angle that exposes as much cambial surface as possible, and to join them together firmly without leaving any gaps or air pockets.
How to ensure cambial alignment?
Different types of grafts require different methods of ensuring cambial alignment. Some common types of grafts are:
- Cleft graft: A vertical cut is made in the rootstock and two scions are inserted into opposite sides of the cleft. The scions should be slightly wedge-shaped so that their outer edges contact with the rootstock’s cambium.
- Whip-and-tongue graft: A diagonal cut is made in both scion and rootstock, followed by a vertical slit in each cut surface. The scion and rootstock are then fitted together like puzzle pieces, with their tongues interlocking inside their whips.
- Bark graft: A horizontal cut is made around the circumference of a branch or trunk on both scion and rootstock. The bark is peeled back on both sides to expose their cambia. The scion is then placed on top of the rootstock’s exposed area and secured with tape or twine.
- Budding: A single bud from one plant (the budstick) is inserted under a flap of bark on another plant (the stock). The bud should be positioned so that its base contacts with
the stock’s cambium.
Regardless of which type of graft you choose, you should always seal all cut surfaces with wax or paint to prevent moisture loss and infection. You should also label your grafted plants clearly and monitor them regularly for signs of success or failure.
Conclusion
Grafting is a horticultural technique that involves joining two plant parts, a scion and a rootstock, to form a new plant with desirable characteristics. The key to successful grafting is the alignment and fusion of the cambium layers of both plant parts. The cambium is a thin layer of cells between the wood and bark that produces new growth and vascular tissues. The cambium of the scion must match as closely as possible with the cambium of the rootstock for a good graft union.
If the cambiums are not aligned, the graft will fail or be weak. Therefore, cambium is king for grafting because it determines whether a graft will succeed or not. It determines whether two plants can grow together as one. By understanding what cambium is and how it works, you can improve your chances of successful grafting and enjoy its benefits.