The domestication of fruit trees has received much less attention than the rest of the crop plants. In particular, very little is known about the reproduction of fruit trees. Environmental changes limit the reproductive activity of trees in their natural habitats, resulting in poor and irregular productivity.
Fruit trees can reproduce with different methods, some more suitable than others. Varying depending on the species in question.
Reproduction of fruit trees by seeds
Basically, a seed is a miniature plant that has not yet developed (the embryo) and is surrounded by a protective layer (the testa). They are generally small in size and are suitable for surviving the low temperatures of winter.
Many people mistakenly believe that fruit trees grow from seeds, but in reality the seeds of a fruit produce a new variety that is a hybrid of two plants.
Some seeds, when planted, a tree grows, but they never bear fruit or it can take up to 10 years to give a fruit that is not edible. There are exceptions that tend to have very little variation, even in seed-grown trees, such as papaya seedlings and some types of citrus trees.
Obviously the new plant will be of the same type, but its portions of fruits may not look the same as those of the ascending tree. This occurs because the plant is “heterozygous”. The propagation of fruit trees should be vegetatively by grafting or budding methods.
The seeds of all the fruits of common trees; such as apple, peach, pear and cherry, require a cooling period before germinating and forming new plants. The cooling period occurs after the fruit is ripe (dormancy). During this period, the embryo develops normally until it is mature. This is achieved by subjecting the seeds to a cold process.
Reproduction of fruit trees by grafting
There are big differences between the reproduction of grafted fruit trees and those grown on seeds.
A reliable way to ensure that desired characteristics are maintained on subsequent fruit trees is through grafting. Grafting involves taking a chip cut from the desired parent tree and physically placing it on a compatible rootstock. The variety and rootstock grow together, as the tree heals. All saplings are removed from the rootstock and the stem of the parent tree is allowed to grow into the new tree, thus maintaining its parental identity.
This process is called “asexual reproduction” and is a cloning of the original tree. In fact, humans have cloned fruit trees for thousands of years, even if it seems surprising. Cloning began when it was discovered that by taking the wood of a fruit tree (the stem), it could be grafted onto the wood of a mature tree (the rootstock).
Since only one parent is involved in this process, the grafted tree will be true to its name, and the true tree will name the true fruit.
Coupling consists of placing a single vegetative shoot on one side of the rhizome and bandaging until it heals. The results of the graft will be a real tree.
A grafted tree is consistent and has the following characteristics:
- It blooms and bears fruit at a certain time.
- It is resistant to disease or extreme cold.
- Their fruit can be expected to be of good size, quality and variety.
Reproduction of fruit trees in vitro
In vitro culture, or micropropagation of fruit trees, is a method of reproduction used by professionals. This is done in a laboratory under special conditions to encourage its development.
The procedure involves taking an embryo (any part of the plant, including a portion of the stem) and growing it in a test tube. Inside the tube is placed a liquid substance with sufficient nutrients.
The culture must be carried out under conditions that favor its development, with the appropriate and sterilized instrumentation. These utensils consist of:
- Autoclave. Where pressure and temperature are sterilized and controlled
- Test tube. Works as a culture medium
- Laminar flow chamber. Where the plant is handled
- Cultivation chamber. It is a room with adequate conditions of light, humidity and temperature
The process of placing the trees on the market, they must be acclimatized in different environments. After leaving the laboratory, they must go to a greenhouse, so that they finally reach the open air.
The advantage of reproducing fruit trees in vitro is that seeds can be germinated that under normal conditions would be impossible. In Spain there are about 30 laboratories dedicated to the in vitro cultivation of plants and trees.
Reproduction of fruit trees by cuttings
The reproduction of fruit trees by cuttings is one of the simplest techniques, it is not necessary to be an expert horticulturist to achieve it.
The process is very simple, only a good clean and sharp cutting instrument is required. In some cases rooting hormone is needed to boost root growth.
When is the best time to take the cutting? Really the cut will depend on the type of plant that is spreading. Generally the plants will root well with a cut of softwood, when new growth occurs. Semi-soft cuttings are acquired in the summer, and hardwood cuttings are from very mature plants.
For reproduction from cuttings should be used a healthy, healthy and well-hydrated plant. As for cutting, use a very sharp blade to avoid damage, both to the original plant and to the rooting edge.
A soilless medium is the best mixture to start fruit tree cuttings. The medium should be loose, well drained and have enough oxygen movement for the newly formed roots. Perlite and vermiculite are a good basis for root development.
Plant the cut with the cut end buried in pre-moistened media by 2.5 to 3.8 centimeters. Place a plastic bag over the container and place it in a semi-illuminated area with temperatures 13 to 24 C.
The pouch should be opened daily to stimulate air circulation. Check the roots in two weeks. Some plants may be ready and others will take a month or more.
Reproduction of fruit trees by layering
The terrestrial or aerial layering is an artificial system of reproduction of fruit trees. The method is to make possible the appearance of roots. This will be achieved by means of heat, moisture from the prepared earth and incisions.
With the layering a new fruit tree will be formed with identical qualities of the original tree.
But not all fruit trees are suitable for testing this type of reproduction, although it is true that in most it works.
Terrestrial layering. It is a simple method that consists of accumulating soil around the plant, then cutting the protruding part of the plant, in order to facilitate the formation of roots.
Aerial layering. Basically it consists of removing the part of the bark of the tree, in order to facilitate the formation of mammies that take root. Once the roots are seen, the branch is cut and transplanted.
Robert Asprin, APD is a non-dieting Accredited Practicing Dietitian passionate about inspiring positive changes in eating and lifestyle behaviors to help improve health while nurturing relationships with food and body.