Carte sur le nombre annuel d'heures sous 7 degrés pour agriculture

[mesmsg]

Bonjour,

 

Je compte créer un verger avec certaines espèces peu communes. Certaines ont besoin d'un certain nombre de "chill hours" (nb d'heures annuelles avec des températures entre 0/1° et 7°) pour sortir de leur dormance et fructifier. Si cette notion de chill hours pour les fruitiers et bien documentée sur les sites anglophones avec des cartes comme sur le lien suivant (https://mrcc.illinois.edu/VIP/indexChillHours.html), je ne trouve rien pour la france, et d'autant moins pour la Corse ou je suis. Or, ces informations sont capitales pour mon projet.

 

Quelqu'un est il en mesure de m'aider ?

 

Merci !



Chill hours et besoin des arbres, explications en anglais: https://thegrownetwork.com/planting-fruit-trees-in-fall/

 

A fellow master gardener volunteer once told me, “All deciduous plants have chill-hour requirements.” I don’t know for sure that this is true, but for spring-flowering fruit trees and shrubs, chill hours are absolutely critical.

“Chill hours” are the number of hours air temperatures are between 32-45ºF. (There are other definitions of chill hours, but they all oscillate around this basic temperature zone.)

Early Bloom

Chill hours are basically a plant’s dormancy clock. Plants go dormant in winter to protect themselves from dying during extended cold. After a certain number of hours of moderately cold (but not freezing) temperatures, the plant’s clock says something like this:

“Well, we’ve had our 300 hours of moderate cold for this year, so winter must be over and spring must be on the way. The next time it gets warm and sunny, let’s grow some blooms so we can reproduce!”

Then, the next time there’s a warm day, the plant will bloom in response to the sensation of warmth. Given the unprecedented temperature highs and lows in winter months that are occuring in so many places, these kinds of “false positives” for spring in plants with low chill-hour requirements are becoming more prevalent.

Because we transport trees around the world, we can easily put a tree with a 300-chill-hour timer in a zone that has 1,200 chill hours each year. When we do, that plant will almost always try to flower too soon. Those blooms will usually die when the normal cold weather returns a couple of days later.

Eventually, that poor plant will succumb to sadness over its repeated failures to reproduce (or it will just freeze to death).

Never Bloom

Now, if you tried to plant a tree that needed 1,500 chill hours in an area that only has 1,200 a year, you’d get a different problem. Instead of setting blooms and losing them to cold, you’d never even get blooms. That tree would also be likely to die from reproductive frustration or heat exhaustion.

If you have planted fruit trees or shrubs that should be producing and are not, and you’ve never even seen blooms, check the chill-hour requirements for your variety. Then, find the chill-hour calculator for your region and find out if you met the requirements.

If you can’t find a chill-hour calculator for your area, check with your agricultural or extension office.

Goldilocks Chill Hours

If you want good fruit production, you need to match a plant’s chill hours to your average chill hours. With climate change upon us, this will sometimes mean that you won’t get fruit in an extremely cold or hot winter. However, matching average chill hours is still a better goal than not considering them at all.

[mesmsg]

Je viens de trouver des informations sur un modèle créé par Georges Nissen pour l'australie qui permet de se baser sur la moyenne des temperatures pour le mois (ou les deux mois) le(s) plus froid(s) et de comparer sur les courbes du modèle pour obtenir le nombre d'unités de froid. Cela me donne déjà une idée...

 

https://practicalprimate.com/chill-hours/

 

Il faut savoir que certains considère entre 0 et 7° car les températures sous 0 ne participeraient pas à la dormance. Et il y a encore des méthodes plus compliquées et dynamiques de calcul dans certains Etats aux USA.