1. UNI Plant Physiology 2010www.uni.edu/berg The Maple Syrup Story V. Berg UNI Plant Physiology

2. UNI Plant Physiology 2010www.uni.edu/berg How maple trees give us sap for syrup. Original idea by Mother Nature (a great biophysicist). Experimental work by Dr. Mel Tyree (then at University of Toronto, now with the US Forest Service).

3. UNI Plant Physiology 2010www.uni.edu/berg The key experiment that explained what was going on took place in Dr. Mel Tyree’s lab on a small island in Ontario. Based on this, he proposed a mechanism to explain how maple sap rises, providing us with a liquid that turns into money for Vermonters, and into maple syrup for the rest of us.

4. UNI Plant Physiology 2010www.uni.edu/berg : What every Vermonter knows Sap flows in the early spring Need nights below freezing Need days above freezing Need hole bored into xylem (wood) of tree to get sap out via pipe or tubing You need to boil the excess water from 30 gallons of sap to get one gallon of maple syrup Maple sap has a lot of sugar (and flavors)

5. UNI Plant Physiology 2010www.uni.edu/berg What we didn’t understand Why we needed cold nights Why we needed warm days What made the sap rise into the trunk

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8. UNI Plant Physiology 2010www.uni.edu/berg The big surprises Sap moved up into the trunk at night Pressure in the trunk went up in the day This was a whole new idea Now, how to explain it? What follows is the proposed mechanism, which is generally accepted today.

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15. UNI Plant Physiology 2010www.uni.edu/berg What we now know On freezing nights –Ice forms between cells, “attracting” water –Sap rises in xylem to replace water in cells On thawing days –Ice melts –Liquid water flows back into cells & sugary xylem –Pressure increases in xylem –Sap flows out the hole into the pipe into the bucket into the sugar shack into the bank account

16. UNI Plant Physiology 2010www.uni.edu/berg Why maple? Maple sap (xylem) has lots of sugars Starch stored in roots for winter Moved up in spring to use for growth High concentration in early spring All members of Acer genus –Acer saccharum (sugar maple) –Other maples (Acer sp.) –Box elder tree (Acer negundo)

17. UNI Plant Physiology 2010www.uni.edu/berg Thanks Thanks for viewing this presentation. If you have any errors To report, or any suggestions, please email me at bergv@uni.edu.