I am still interested in whether increasing root temperature could help newly planted container citrus adapt more quickly. I was reading an article from Citrus Industry, Nov. 2011 which referred to temperatures. What do you think?


"From these data, it is clear that the
tree roots experienced very few hours
above the 81° F threshold for maximum growth. If these trees were newly
transplanted liners, one could imagine
it would take them longer to root into
the new containers and reach budding size than if the container media temperatures were warmer.
The slower growth that can occur
in response to cool root temperatures
as depicted in Figure 1 is the result
of different physiological interactions
within. Root conductivity decreases
as temperature decreases. Thus, at
the same soil moisture content, a tree
with cool roots will be able to take up
less water over a given period of time
than one with warm roots. And, by
extension, nutrient uptake will also
be lower, which could lead to wasted
fertilizer that ultimately increases
production costs. "

I have a large heat table (an old 250-gal. dye vat tank) that presently has a Lemonade tree, 2 Saint Michael Paperrind Orange trees, 2 Dekopon trees, 2 Xie Shan satsuma trees, and 2 Black Twig lime trees placed on top of it. The tank is attached to a heating source, which can raise the water temperature as high boiling 212-F. I have the tank set to keep the root zone of the above container trees at 81-F. Further, I have the greenhouse set to maintain a constant day time air temperature between 79 - 84-F,. and a night time temperature of 55-F. Lastly, I also have the the heat table trees receiving extended light, using a HID lamp, until 10:30 PM every night. Thus these trees are root heated, foliage heated, and light extended. This procedure, produces five growth flushes per year, and occasionally even a sixth flush of new growth. Without doing this extra treatment, a citrus tree normally would give only one main flush in the spring, an a small lesser second flush later in the summer. Therefore, the treated trees grow three times faster, than normal grown citrus trees. Lastly, I have recently purchase an order of Harpin proteins, to be used as a protein foliage spray. Harpin Proteins have shown to promote strong plant growth, increase root mass, additional plant stamina, greater tree vigor, and even helps manage disease. This protein project is going to be a highly interesting time. - Millet

Hello Millet
The Harpin protein did not sell in France. I'm not convinced of its efficacy on citrus, but I am interested in your future trials.
Here are some links I found on the subject:
http://www.actahort.org/books/727/727_69.htm
http://www.epa.gov/opp00001/chem_search/reg_actions/registration/fs_PC-006506_30-Jan-02.pdf
http://puyallup.wsu.edu/~Linda%20Chalker-Scott/Horticultural%20Myths_files/Myths/Harpin.pdf

Do you have documents that led you to this method?
“I have the tank set to keep the root zone of the above container trees at 81-F. Further, I have the greenhouse set to maintain a constant day time air temperature between 79 - 84-F”
thank you

Bouladou, thank you for the three links, I read them all. I have been aware for some time of the product Messenger, a first generation Harpin Protein. I also have been aware of Messenger's failures and successes. The Harpin protein that I am applying is not the product Messenger, rather it is a second generation Harpin protein. My aims are only to find its efficacy on white fly control particularly on greenhouse tomatoes of which I have seven vines growing, and also mealy bug and aphid on citrus. As a side efficacy project, the products ability to produce additional growth and vigor of citrus trees. Time will tell. Whatever, the results the trials will be interesting.

As for documentation on heating citrus roots, and foliage, plus lengthening photo period, to promote citrus growth, you can find it in any number of literature and books on citrus - Millet

Millet,

When measuring root temps, does it matter where you take the temp? On ARPCs, for example, you can take temp pretty much anywhere. Would you need to take temps on the bottom, middle and top of the pot?

Thank you!