The productive potential of cherry cultivation is established very soon after the start of a harvest season, since there are physiological processes that define the following season, such as floral induction and differentiation, considered to be between approximately 70 and 140 days after full bloom (DDPF).
During the flowering stage, there may be differences in floral opening under normal conditions of around a week, which is enough time to determine fertilization and subsequent fruit setting. This period of time is essential to understand all the fruiting processes of cherry cultivation, since the expansion in different latitudes results in a very erratic crop and is generally attributed to environmental factors.
The fleeting life of the cherry blossom contrasts with the long period of floral development before flowering. This extensive process of pre-flowering development takes place over approximately eight months from the summer of the previous year until flowering the following spring; this is partly due to the fact that flower development stops in winter, there is a dormant period for the flowers, and growth resumes after the dormant period.
Dormancy is essential for flowering and the productive potential of an orchard. The more hours of cold the plant “absorbs”, the better it will awaken and have a better physiological and phenological development at the beginning of the season.
Flower bud differentiation occurs at a time stage towards the end of summer and beginning of autumn (approximately between 110 and 140 DDPF) depending on the climatic zone where the crop is being grown. After dormancy, differentiation, expansion and final flower development occur when temperatures rise again in spring and the phenological development of the crop begins.
As for the dormancy of the flower buds, they stop developing and enter an inactive stage called endodormancy (central phase of dormancy) where there is an adaptability to low winter temperatures. Later, once the requirements are met and the transitions of endodormancy and ecodormancy are met, there is no immediate response to activate their development and a period of warm temperatures is needed to reactivate this process after the cold hour requirements for each cherry cultivar.
“The first phase of dormancy, which is an acclimatization phase, is called ecodormancy, considering more or less that the month of May or the first three weeks of May could correspond to this acclimatization process. The second phase of dormancy, and from the physiological point of view, the most important, is called endodormancy, which in terms of dates could extend between the last week of May and the third or fourth week of June. Endodormancy is very important, since it corresponds to what we could call “the deep sleep” of the plant, where a number of hours of cold must be accumulated, and these are hours of very good quality cold. Chilean studies say that if endodormancy exceeds 200-250, perhaps 270 hours of cold in the classic model, 7.2°C is a very good indicator of dormancy or accumulation, independent of the final number of accumulations.” said Carlos Tapia, technical director of Avium.
This final dormancy process can be artificially interrupted by using exogenous agents such as chemical dormancy breakers, including hydrogenated cyanamide and some alternatives such as Erger®, Siberio®, Fiore® and Syncron®; considering the particularity of use and the objective sought depending on each situation.
“The last part of dormancy is called paradormancy and it could be understood as the month of July, which is another month of acclimatization and in theoretical and technical terms, the dormancy period theoretically ends on July 31st. However, the end of dormancy could be artificial from the management point of view since we ourselves decided to apply products that break this dormancy, such as hydrogenated cyanamide and other products that are in the same niche of action. It is very important to monitor the evolution of the cold during this dormancy period, especially in endodormancy.” Tapia added.
Finally, the expert stressed; "A good accumulation of cold is an index of fertility in the plant, it is an indicator that the plant starts off strong and with a lot of energy the following season, it is an indicator of very good flowering, homogeneous flowering, vigorous flowers, flowers ready to both promote pollen and receive that pollen, therefore it is the first technical background that we should have as a background or as a parameter to be able to check some indicators of productive potential..”
Bibliographic references
- – Carlos Tapia- Personal communication.
- – Cherries, botany, production and uses- Edited by: José Quero-García, Amy Lezonni, Joanna Pulawska and Gregory Lang.
- – DNA methylation and small interference RNAs participate in the regulation of MADS-box genes involved in dormancy in sweet cherry (Prunus avium L.) – Karin Rothkegel Evelyn Sanchez Christian Montes Macarena Greve Sebastián Tapia Soraya Bravo Humberto Prieto Andréa Miyasaka Almeida.
