Where does a plant need to be chilled to induce flowering?

[mikesid]

I asked this question back in the GW forum but when I looked for it I couldn't find it. I'm wondering where exactly on a given fruit tree does it 'sense' that is is being chilled enough to break cycle and push flowers for fruiting. It seems that there must be some averaging of temps the plant must receive at a given point or area on the plant to induce flowering. My question is, can this be artificially done? I originally thought wrapping a smaller tree in cold packs and changing them frequently to see if it would have an effect. In looking for equipment for my aquaponics I found chillers that chill water for fish that require lower temps. If a system could be designed where one could wrap some sort of cooling coil around a tree for a given period would this be enought to 'trick' the plant to induce flowering? If would had a small enough Lychee tree in a pot I imagine we could throw it in a walk-in cooler set at correct temp and give it the reccomended chill hours. So why not try cooling it outside? ...Sorry sometimes I have to much time on my hands and sit around and think up crazy ideas...please entertain me and tell me your thoughts on this.....

[bsbullie]

It would originate from the ambient air temperature.  Could you change this artificially, I suppose but is it realistic for trees grown in the ground, no....especially the larger the size of the tree is.

[zands]

http://forums.gardenweb.com/forums/load/tropicalfruits/msg1214062426044.html?10

[Tropicdude]

Just curious but how much "chill" is considered a chill hour?  45F, 40F Lower?   will it work if applied all at once? meaning if you had a chance to place the plant in a large fridge or freezer.  would, lets say leaving it in there continuously for 200 hours to meet a particular fruits minimum chill requirements work? using a grow light that is.

[fruitlovers]

I asked this question back in the GW forum but when I looked for it I couldn't find it. I'm wondering where exactly on a given fruit tree does it 'sense' that is is being chilled enough to break cycle and push flowers for fruiting. It seems that there must be some averaging of temps the plant must receive at a given point or area on the plant to induce flowering. My question is, can this be artificially done? I originally thought wrapping a smaller tree in cold packs and changing them frequently to see if it would have an effect. In looking for equipment for my aquaponics I found chillers that chill water for fish that require lower temps. If a system could be designed where one could wrap some sort of cooling coil around a tree for a given period would this be enought to 'trick' the plant to induce flowering? If would had a small enough Lychee tree in a pot I imagine we could throw it in a walk-in cooler set at correct temp and give it the reccomended chill hours. So why not try cooling it outside? ...Sorry sometimes I have to much time on my hands and sit around and think up crazy ideas...please entertain me and tell me your thoughts on this.....

I knew a guy here that did exactly what you propose, and he was able to fruit temperate fruits here in the tropics. He used air conditioning equipment to cool down the soil around the trees. He told me that normally this would be prohibitive in cost, but because he was an a/c repairman he had a lot of discarded equipment sitting around to play with. I think chill hours is normally measured by ambient air temperature, but no doubt soil temperature is as important, probably even more important.

[Mike T]

Most plant sensory apparatus are in the foliage.Once there are the right cues phytohormones are made to trigger the flowering response.I have tried growing plants that prefer it coopler many times and it always ends in tears.Florda prince,brown turkey,feijoas,cold loving citrus and many other now are part of the humus and I grow plants better suited to my climate.