Tree reproduction is essential for the perpetuation of species, obtaining healthy specimens, and expanding our garden or plot. various methods of reproduction, both sexual and asexual, each with its own advantages, particularities, and the species for which it is ideal. This article provides a comprehensive, accurate, and up-to-date account of the main techniques, drawing on both traditional knowledge and the latest innovations employed by gardeners, nursery workers, and botanical experts.
Sexual reproduction: sowing seeds
The most common and natural method of reproduction in trees is from seeds. Each seed is the result of the genetic combination of its parents, so the resulting plants can differ in various aspects from the parent plant, resulting in genetically diverse populations. This can be beneficial for creating trees that are more resilient, adaptable, and less vulnerable to disease. Seed reproduction is carried out using various methods, which help overcome dormancy and improve germination.
- Direct sowing: The seeds are collected and sown directly in seedbeds or in the final location.
- Previous soaking: The seeds are soaked in water for 24 hours to soften the coating and facilitate hydration of the embryo.
- Cold stratificationWe expose the seeds to low temperatures (around 6°C) for several months in the refrigerator. This method is especially important for species from temperate climates that require a simulated winter to germinate.
- Hot stratification: Heat is used to simulate summer, preferred in species from warm climates.
- Thermal shock: This involves immersing the seeds in boiling water for a few seconds and then in room temperature water for 24 hours. It stimulates germination, especially in hard-shelled seeds.
- Scarification: Gentle sanding of the shell promotes water passage and germination.
Each species may require a different seed treatment.. For example, him coat germinates easily if the base of the bone is left in water, while others require stratification or scarification. For species such as Acacia Thermal shock is recommended, and for Acer cold stratification.
Asexual reproduction: main methods
Asexual reproduction guarantees plants identical to the mother, preserving their genetic characteristics (color, flavor, resistance). It is ideal for obtaining uniform specimens and is especially appreciated in species that do not produce viable seeds or for reproducing selected varieties.
- Cuttings: It consists of cutting a branch or stem and stimulating the development of roots through rooting hormones and humidity conditions. Cuttings can be woody, semi-woody or green-stemmed, depending on the season and the plant. It's recommended to keep them in places protected from direct sunlight until roots appear, a process that can take from a few weeks to several months depending on the species.
- LayeredIt is a propagation technique in which a branch still attached to the parent plant is partially or completely buried, stimulating root development before separating it. It can be simple, multiple, trench, or air layering, the latter being ideal for species with rigid stems or those that do not root easily from cuttings. Layering is common in ficus, jasmine, bougainvillea, and many other ornamental trees.
- Division of clumps, rhizomes, bulbs and tubers: It is common in some shrub species, but is also used in trees that sprout from the base or whose underground structure allows for fragmentation. It allows for rapid multiplication of identical specimens.
- Root cuttingsParticularly useful in species that tend to send out shoots from vigorous roots, such as ailanthus or some fruit trees.
Grafting and advanced multiplication techniques
El graft It is one of the most sophisticated asexual reproduction techniques. It consists of joining a branch (scion) of the desired variety with the trunk or branch (rootstock) of another plant. When the union is consolidated, the whole plant grows as a single organism, combining the qualities of both. It is essential in fruit trees, where the goal is to improve fruit quality or the strength of the root system.
There are various types of grafts:
- Bud graft (T or shield)
- English or cleft graft
- Side grafting and veneering
It's crucial that both the scion and the rootstock are compatible and that the cambium of both parts is in perfect contact. To learn more about these procedures, you can read how it works. the English graft.
Choosing the method according to the species and common mistakes
Each technique has its preferred species and less suitable ones. For example, conifers tend to multiply best by seed, and some fruit trees by grafting. It's important to consider:
- The state of maturity of the material: The best results in cuttings are achieved with stems in the intermediate stage (neither very green nor very woody).
- The time of year:Propagation success varies with season and climate.
- The correct use of rooting hormones and prevent drying of plant material.
- Keep tools clean and disinfected prevents the spread of diseases.
Innovative methods and current considerations
In addition to the classical methods, there are advanced techniques such as embryogenic somatic regeneration in the laboratory to obtain clonal plantations, mainly in reforestation and genetic improvement programs. On the other hand, the use of F1 hybrids or inbreeding selection may increase production, but reduces genetic diversity and long-term resistance.
The health of the root system is critical to the long-term success of the tree. The use of suitable plugs and containers It promotes the formation of strong roots, preventing the development of circular or damaged roots that will affect their adaptation to the final transplant.
The correct selection of the propagation method, its careful application, and knowledge of the specific characteristics of each species significantly increase the success of obtaining new, robust, healthy trees adapted to their environment. Both amateurs and professionals can benefit from this knowledge to maximize the beauty, productivity, and biodiversity of their garden or forestry.
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More information - Birth of a tree, part I.