- Unlike other fruit species, the breaking of their vegetative buds in normal situations is later than all floral stages, that is, all reproductive stages of the flower.
- It is important to ensure a dynamic balance between production and vegetation so that production levels are sustainable over time..
The cherry tree is a species that behaves in a particular way from the point of view of its physiological and vegetative development. One of the main characteristics that differentiate it from other fruit species is that the breaking of its vegetative buds in normal conditions is after all the floral stages, that is, after all the reproductive stages of the flower. Therefore, although it can be recognized that there is green material or unfolded leaves in full flower, perhaps a little before full flower, it is not until 7 or perhaps 10 days after the full flower stage that the start of the actual vegetative activity can be visibly recognized.
It is important to understand that all the phenological states of bract breaking, exposed bouquet, beginning of flower, white bud with full flower and even petal fall are phases in which the vegetative activity of the cherry tree is not working together with the reproductive processes and that most likely these flowering states are in some way using all the reserves that the plant was able to store in the previous post-harvest period, the previous summer.
Once the vegetative activity of an orchard that is more than two years old has begun, it lasts approximately from full bloom to 70 days later. Why does it last 70 days or does vegetative development last 70 days? There are two important reasons. The first is an ecological reason and has to do with the change of season, with the summer solstice which is between December 20-22, the days begin to shorten and the plant receives this as an ecological signal in which it begins the creation of wood, secondary growth, and the beginning of the lignification of the material that it was able to develop in the previous 70 days. This is called in fruit physiology and is described as cold tolerance, since this process is what ensures that the plant when it enters the pre-dormancy and dormancy states can tolerate low temperatures and not produce damage to the wood mainly due to cold.
The other important reason for the physiology of the plant is that approximately 70 days after full flower, an important process called floral induction begins, which is a biochemical signal to the vegetative buds that indicates that they could transform into flower buds, not in the flower induction process, but in the subsequent process called floral differentiation.
If a month can be determined for each of these processes, the month of flower induction is December and the month of flower differentiation is January, where there are morphological changes in floral differentiation, flower buds can be seen at the bases of one-year-old wood and young shoots on two-year-old wood. These two reasons explain the importance of these shoots having this development. Within this development that lasts approximately 70 days there are two phases, an ascending phase in terms of growth rate and a descending phase. The ascending phase lasts from full flower of about 30-40 days where vegetative growth, vegetative development is very strong and in the second phase, the last 30 days approximately of these 70, the development rate is quite low.
It is necessary to understand that regardless of the rootstock that is had, be it from the weakest or most fertile rootstocks, Gisela series, today what we know best is Gisela 5-Gisela 6, we are getting to know Gisela 12, considering it a good alternative for our country and on the other hand, in terms of vigor, a Colt or MaxMa 60. Regardless of the vigor of the rootstock or the capacity to generate wood of each of the rootstocks, annual wood, each of the rootstocks has the same 70 days of vegetative development available.
“It is very important to take into account that medium to weak rootstocks, such as the Gisela series and probably MaxMa 14, which are in less fertile soil in poorer areas, have a much greater challenge to recover vegetatively every year compared to more vigorous rootstocks such as Colt or MaxMa 60. This has a lot to do with the nutritional proposal that one makes each year. If I have to analyze it from that point of view of how I recover the orchard, it is obvious that the less vigorous rootstocks have to carry or demand a quantity of nitrogen annually to develop their structure much more than a Colt, out of necessity, but not only the amount of nitrogen that one could incorporate into the system, but also proportionally how it should be placed. It is important in a concrete example that a highly productive Gisela 6 orchard has a significant amount of nitrogen available within the first 30 days or 40 days DDPF to ensure the ascending phase of vegetative growth development. However, in Colt at the other extreme, such as MaxMa 60 at the other extreme, it is often not so necessary and there are many cases in which nitrogen is not needed because they can easily develop this vegetative growth without any problem.” said Carlos Tapia, director of Avium.
A dynamic equilibrium must be ensured in this balance between production and vegetation so that it is optimal for high levels of sustainable production over time. That is to say, with a weak rootstock, juvenility must always be enhanced to support its production and in a vigorous orchard, consideration must be given to not allowing vegetative growth to exacerbate annually and fighting against the juvenility of that plant to enhance the reproductive states and the maturation states that are needed to achieve a high productive potential.
“It is essential to understand this balance and to understand that the vegetative condition or vegetative development has a beginning and an end and it is important to understand that this end occurs within the season. It must be taken into account that when a water deficit is done in post-harvest, it has no impact on the objective, which is to slow down or stop vegetative growth because it has already stopped for 70 days DDPF and the post-harvest will begin 90-100 days after full flower, therefore, it has no direct impact on that. It is necessary to consider the different nutritional models for each of the situations in terms of vigor and not only soil, but also foliar, considering that root growth, as we have explained, does not begin before the soil temperature is 14° and that will not happen before the first week of October.” the expert added.
