Extend winter dormancy by refrigerating and keeping the apex of a tree in the dark
Image credit: Istockphoto
Darko SavicJan 11, 2022
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A system that refrigerates the apexes of fruit trees in orchards, thereby preventing the plants from coming out of winter dormancy too early. Turn it off only after the danger of frost has passed.
Early spring is often interrupted by a brief round of snow and frost in the northern hemisphere. The trees that come out of winter dormancy early are damaged by this. They cannot bear fruit that year. This means no cherries, plums, apricots, in entire regions.
How it works
Firstly, let me say that this needs to be experimented with. I'm not sure whether keeping the apex of a tree at a freezing temperature and in the dark would actually prevent the plant from coming out of winter dormancy. I suspect it might, based on this:
"After bud dormancy is broken by adequate chilling, apically produced growth-promoting hormones move down the branches and stem and provide the stimulus for initiation of seasonal cambial growth."
So, what if we refrigerate and keep the apex in the dark, until the danger of frost has passed? It would generally need to be done only for a brief period of 1 to 3 weeks when it looks that spring has arrived, but a freezing rain/snow is still posible.
Peltier elements and liquid cooling
Similarly to how the light bulbs are hung in this image below, cooling units would be hung to power all the tree tops in an orchard.
Each cooling unit would consist of:
a silicone tube that is wrapped around the apex area of a tree
a miniature pump that circulates the liquid coolant through the tube
a peltier element that cools the liquid on one side, and radiates excess heat on the other
a thermostat that keeps the unit running only when the temperatures are above freezing
A small water cooler, pwered by a peltier element:
Such a cooling unit would be the size of an old light bulb. It would be mounted just under the apex of each tree. A tube coming out of the cooler would wrap around the apex. An antifreeze type of liquid would circulate througout the tube, keeping the apex at around freezing temperature. A dark hood would be pulled over the entire apex area, keeping the sun away to additionally prevent the apex from producing the necessary hormones that cause the breakage of winter dormancy.
Depending on how many trees there are in an orchard, the Installation would take some time. But a day's worth of work saves a season worth of fruit.
Theodore T. Kozlowski, Stephen G. Pallardy, in Growth Control in Woody Plants, 1997 - https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/bud-dormancy