What it gains and what it costs
All four methods — cuttings, layering, grafting and tissue culture — share the same advantages, because they share the same biology. This page closes vegetative propagation by setting them out together.
Advantages gained through vegetative propagation
- being able to propagate plants in which seeds do not form well;
- being able to obtain daughter plants with characteristics identical to the mother plant;
- being able to propagate plants from which fruit can be obtained quickly;
- being able to identify and propagate varieties resistant to damage by diseases and pests;
- being able to prepare varieties that withstand adverse environmental conditions.
Disadvantages of vegetative propagation
- new varieties not arising.
One disadvantage, and it is a large one
The list of drawbacks has a single entry, which makes it look small. It is not. Every plant raised vegetatively from one parent is a copy of it, so a whole plantation can have no genetic variation at all. A new disease that one plant cannot resist, none of them can resist.
This is exactly the trade-off from table 14.1, met again: speed and certainty bought with variety. Sexual reproduction — the rest of this chapter — is where the variety comes back.
Why a farmer chooses it anyway
A seed from a good mango tree does not give you that tree — it gives you a mixture of it and whatever pollinated it, and you wait years to find out what you got. A graft from that tree is that tree, and it fruits sooner. For a crop you are selling, that certainty is usually worth more than the variety.