How does flower differentiation and the dormancy stage affect the productive potential of cherry orchards?

How does flower differentiation and the dormancy stage affect the productive potential of cherry orchards?

Productive potential of the cherry cultivar is established very soon after the start of the harvest season, this is because physiological processes exist that define the next season, such as flower induction and differentiation.

Productive potential of the cherry cultivar is established as soon as the harvest season starts, since there are physiological processes that exist defining the next season like flower induction and differentiation, considered to be approximately 70 to 140 days from full bloom (DFFB).

In the blooming stage there may be differences that exist in the flower aperture in normal conditions of around a week, time that is enough to determine the fertilization and later fruit setting. This time period is essential to understand the fructification processes of the cherry cultivar since in the expansion of different latitudes the results are an erratic crop that is generally attributed to environmental factors. 

The fleeting life of a cherry flower contrasts to the long period of flower development before the bloom. This lengthy development process prior to the bloom is carried out during the approximate eight months since the summer of the previous year until the bloom of the following spring; this is due partially to the fact that the development of flowers stops in the winter, there is an inactive time of the flowers, and growth resumes after the dormancy period.

Dormancy is essential to flowering and to the productive potential in the orchard. While more hours of cold are “absorbed” the plant will have a better awakening and a better physiological and phenologic development at the beginning of the season.

The differentiation of the flower bud is produced in a stage of time towards the end of summer and beginning of autumn (approximately between 110 and 140 DFFB) depending upon the climatic zone in which it is being cultivated. After dormancy, the differentiation of the expansion and the final development of the flower occur when the temperatures rise again in spring and the phenologic development of the crop begins.

Regarding the latency of flower buds, these quit developing and enter an inactive stage known as endodormancy (central phase of dormancy) where there is adaptability to lower winter temperatures. Afterwards, once the requirements are met and the endodormancy and ecodormancy transitions are not an immediate response in order to activate development and that a warm period of temperatures is needed to reactivate said process after the requirements of cold hours for each cherry crop.

“The first phase of dormancy that is an acclimation phase is called ecodormancy considering more or less that the month of May and the first three weeks of May could correspond to this process of acclimation. The second phase of dormancy, and from the physiological point of view the most important, is called endodormancy and the ending dates could extend to between the last week of May and the third or fourth week of June. Endodormancy is very important, since it belongs to what we might call the plant’s “deep sleep” where a number of cold hours have to accumulate and they must be very good quality cold hours. It is said in Chilean studies that if in endodormancy 200-250 or maybe 270 hours of cold are surpassed in the classic model of 7.2°C it is a very good indicator of dormancy or independent accumulation of the final accumulation number” pointed out Carlos Tapia, Technical Director of Avium.

This final dormancy process may be interrupted artificially through the use of exogenous agents like chemical dormancy breakers, among which are hydrogen cyanamide and some alternatives like Erger®, Siberio®, Fiore® and Syncron®; considering the particularity of use and the objective looked for depending upon each situation.

 “This last part of dormancy is called paradormancy and could be understood as the month of July which is another month of acclimation and that in theoretical and technical terms to say that the dormancy period theoretically ends on July 31, however, the term of dormancy could be artificial from the point of view of management from the time that we ourselves decide to apply product breakers of this dormancy like hydrogen cyanamide and other products that are included in the same niche of action. It is very important to follow up on the cold evolution in this time of dormancy primarily in the endodormancy.” added Tapia.

Finally the expert emphasized; “a good cold accumulation is a plant fertility index, it is an indicator for the plant to begin the next season with lots of strength and energy, it is an indicator of good blooming, homogeneous flowering, flowers with vigor, flowers that are ready to promote pollen as well as receive pollen, therefore it is the first technical background that we should have as background or as a parameter to be able to check some indicators of productive potential.” 

Bibliographical 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 Sánchez Christian Montes Macarena Greve Sebastián Tapia Soraya Bravo Humberto Prieto Andréa Miyasaka Almeida.

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