The celebration is slowly beginning in the cherry orchards. While in the central area the plants are showing some signs of green tips and swollen buds, in some warm areas with forced management that allows for early harvests, the beginning of the first flowers can already be seen.
Regardless of the phenological state of the different areas and varieties, if there is already activity in the orchards it is because the plants are metabolizing, and this process this season is mainly the result of the reserves that the plant has and the actions that were technically carried out in post-harvest.
The entire metabolism of flower development, the process of floral opening, subsequent pollination, such as
an external process to the entire physiological process, must be accompanied by a series of cultural and nutritional management in the first part of the season, that is, between the phenological states of swollen bud and full flower (80 percent of open flowers).
In this first part, all activity, or 90 percent of it, is due to reserves. The soil temperature is low and root development is practically non-existent, with growth of the root structures only becoming evident at a soil temperature of 14-15 ºC and this, at least in the central zone, will only occur in the first or second week of October.
The outcome of the season, which is about to begin, is conditioned, in part, by the nutritional decisions that are made from a technical point of view. During the first part of fruit development, from full flower to 25 to 30 days after full flower (DDPF), the process of cell division that marks the success or failure of future fruit formation is recognized. However, in this period of time, and according to many scientific and technical reports, cell division can occur before the full flower process, and it has even been established that division can begin from the exposed bouquet forward, when the flower bud has already broken, is completely green and is exposed to the environment, a state that the Americans call “popcorn”; From there onwards it can be established that the plant's metabolism is in favor of dividing its cells and forming the fruit in the best way.
What to do in such moments? There are two very specific lines; first, biostimulation, considering that its exaggeration from the vegetative point of view is not so correct. It is worth remembering that cherry trees are species that are programmed to express themselves first in a reproductive way, developing flower buds, and then in vegetative ones, that is, it is a species that first flowers and then develops its vegetative bud in order to unfold its leaves.
On the other hand, one of the essential nutrients that the plant needs, once it begins to function metabolically, is calcium; this does not easily reach the structures in the aerial part via water through the soil, because there is no flow that allows this calcium to be distributed and rise to the different points.
Now, according to research carried out by Avium over several years, it has been possible
establish that early season calcium applications are very effective; early
from exposed bouquet, through white bud, beginning of flower, full flower, petal fall and even jacket fall. Through internal research it has been shown that early calcium applications in these phenological states are much more effective than late calcium applications, from full flower onwards, with fruit formed, in addition, and furthermore no major differences have been seen when more than these 5 or 6 applications are applied in advance; these foliar calcium applications greatly influence the nutritional condition of the fruit based on calcium.
In parallel, Avium has researched and developed with other institutions, considering applications of natural products that promote the synthesis of cytokinins that can have a positive action when applied early in the season; that is, from exposed bouquet to full flower, it can be exposed bouquet, white bud, or full flower or, definitely, white bud and full flower as extreme moments in phenology.
There are also cytokinin promoters such as some algae extracts or commercial products that promote the natural development of the plant; it should be remembered that cytokinin is the phytohormone that participates most in cell division, always accompanied by others such as auxins in second place and gibberellins in third place. These actions are independent of the decision to later incorporate, if justified, a synthetic cytokinin to further enhance fruit development in the second stage from (full flower to 10-15 DDPF).
In conclusion, the two cultural and technical actions that should be done early are the incorporation of calcium from very early phenological stages, from the exposed bouquet; there is a lot of scientific and technical development and support that indicates that there is an early absorption by the plants, which should be taken advantage of. In addition, there are the applications of natural cytokinin promoters of the plant that are a benefit for the entire metabolic and physiological development of the initial floral stages in order to improve the condition of the fruit applied very early in the season.
In addition to technical and cultural management, external factors must be taken into account, mainly climatic ones; a couple of days of good temperatures are enough to generate a substantial advance in the phenological states; on the other hand, it is necessary to reiterate that special care must be taken with frost events, mainly between swollen buds and exposed bouquets, considering that the greatest damage from cold (>-0.5 degrees Celsius for more than half an hour) occurs in these early phenological states, over other more advanced ones. This ultimately implies being prepared for frost control, in order to avoid complications in a season that is approaching in leaps and bounds and that is full of challenges.
