In the horticulture and nursery industry, “plant cutting" is a phrase that is frequently used. It can be confusing when it comes to understanding what it means.
According to Wikipedia, "plant cutting" can be used as a noun which refers to is a piece of the source plant that is used in horticulture for vegetative propagation.
"Plant cutting" is also a technique for propagating a plant. A piece of the source plant called a “cutting” is dipped in hormone powder then placed in growing media so it can grow into a plant in its own right. The "cutting" produces new roots and stems and then becomes a new plant. The whole process is called "plant propagation".
In this article, "plant cutting" or "cutting" refers to the process and we are going to explore how to automate this process of placing (plant) cuttings into trays that can be reproduced from asexual vegetative reproduction
Other plants can develop underground stems which are called rhizomes. Rhizomes produce new plants at a distance from the parent. Tubers (e.g. potatoes) and bulbs (e.g. onions) could also have underground stems that can grow into new plants.
When it comes to making new plants using asexual reproduction, nurseries grow plants from cuttings taken from a parent shrub. What horticulturists do is snip a young shoot off a plant, dip it in rooting hormone and then place the cutting in a mixture of sand & potting mix or alternatively into a plug. The plant cutting grows roots quickly and then it can be potted up and transferred outdoors.
According to NC Cooperative Extension Resources, in terms of propagating woody ornamental plants, propagation by stem cuttings is the most commonly used method.
It is very important to maintain high humidity around the cutting during the propagation process.
Production nurseries usually place cuttings in plastic or foam trays/cells. These are commonly covered by clear plastic stretched over a wire frame to keep the humidity at a high level while reducing water loss from the cuttings. Having holes in the bottoms of the trays is a must to help with drainage.
The research study "Raising native plants in nurseries: basic concepts" illustrates that depending on when the cuttings are collected, there are 3 types of cuttings used in nursery practices:
Step 1: The cutting of the parent plant
Parent plants are used for obtaining newly grown branches, which can then be used for producing cuttings. The task should be done very quickly - cutting the shoot then placing the cutting in the substrate to minimising the loss of water.
Step 2: The stem cuttings
After the parent branches have been cut, each new cutting includes at least one leaf node, near the base of the cutting is needed for producing the new roots. Same as with step 1, hydration is very important so soaking them in water sometimes is necessary.
Step3: The removal of the leaves
The leaves from the stem on the basal part of the cutting should be removed, to prevent the leaves from being inserted or coming into contact with the substrate, which may cause some problems to the new plants
Step 4: The plant hormone subministration
In this step, the cutting basal part is to be immersed in a plant growth substance so the formation of roots can be promoted.
Step 5: The insertion of the cutting in the substrate
The final step is to put each cuttings in a cell of multi cells tray. A substrate is used in the cells to promote rooting and to prevent roots from breaking off.
The 5 steps above to reproduce young plants in nurseries is usually done manually by staff, to reduce costs, improve production efficiency and quality, automation needs to be introduced.
There is research presently being done overseas and prototypes are being developed to automate the plant cutting process. Take ornamental plants as an example:
The ornamental plants automatic cutting process would be as below: the automatic process looks like this:
The technical solution proposed to automate cuttings into trays is innovative, with the advancement of modern technolgy, robotics and more research it will be only a matter of time before this process is fully automated.
In the mean time there has been various egonomic cutting benches and work stations developed to make the manual process more efficient and easier.