|MadSci Network: Botany|
I would not expect water temperature to have a major effect on water uptake by a celery stalk unless you went to extremes. If the water temperature is below freezing (0 degrees C) and the water freezes solid, it would obviously prevent water uptake. The xylem vessels through which water flows in the celery stalk or petiole are dead. Water flow through the xylem vessels is driven by evaporation from the leaf blade stomata. This is termed transpiration. It seems unlikely that hot water in the container would be able to damage the living cells in the celery leaf blades because the upward flow is slow enough that the water would cool before it reached the leaf blades. The living cells in the part of the celery stalk in the container could be damaged or killed by a high water temperature. That might have indirect effects on water uptake if the contents of the dead cells clogged the xylem. Cut flower stems are often clogged by growth of microbes in the vase water. An increase in air temperature will probably increase transpiration. You may be confusing temperature effects on celery stalk transpiration with the common concept of Q10. The Q10 is the factor that the rate of a chemical reaction increases for every 10 degree Celsius rise in temperature. The Q10 usually ranges from 2 to 5. Water flow in xylem is not a chemical reaction so Q10 does not apply. References Celery Stalk Transpiration Transporation of Water in Plants Q10
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