Variability Associated With Leaf Water Potential in Red-Osier Dogwood in Field and Growth Chamber Environments

Sources of variability associated with pressure chamber measurements of leaf water potential (Pleaf) made on a single clone of red-osier dogwood, Cornus sericea L. (Cornus stolonifera Michx.), were assessed by the nested analysis of variance method in both growth chamber and field environments. Variation among plants was significant in the field, but not in the growth chambers. Sampling from different branches on the same plant had no effect on Pleaf, but the point of insertion or node from which a leaf was taken significantly affected Pleaf. In the field environment a stress gradient was associated with node position with leaves from upper nodes under more stress than those from lower nodes. Under growth chamber conditions, there was no consistent stress gradient. Diurnal variability in Pleaf followed daily atmospheric demand in well-watered dogwood plants.