NOTE ON THE DETERMINATION OF LEAF WATER‐POTENTIAL

Publisher Website
Google Scholar
Abstract
Summary: A simplified modification of the micro‐osmometer of Macklon and Weatherley (1965a) for the determination of depressions of water‐potential in leaves, ΔW (DPD), is described.The apparent minimum ΔW of 31/2 atm for non‐transpiring water‐culture plants of Ricinus communis reported by Tinklin and Weatherley (1966) is considered further. Evidence is provided that this is in fact a zero value, the level recorded being due to the errors induced by water loss on sampling and by water uptake by continued growth of tissue during determinations. However, a simple subtraction of 31/2 atm from all ΔW values is not proposed as there are indications that a threshold AH’may exist above which continued growth does not occur, so that higher ΔW records will approach more closely the true value.