The measurement of water deficits in broadleaf plants

Summary A review of past work and a comparison of the well-known disk technique with Stocker's whole leaf method for determining water deficit of some hardwood trees reveals confusion in existing terms and methods. The water relations of leaf disks cut from broadleaf trees cannot be assumed to be the same as whole leaves, since the excised disk usually requires more water per unit weight to saturate. Stocker's term wasser defizit (WD) and the whole leaf method, when modified to allow shorter equilibration schedules, remain the best way to express and measure water deficits in forest trees.