Water relations in sweet cherries ( Prunus avium L.) on sour cherry rootstocks ( Prunus cerasus L.) of different compatibility

Abstract

During the 1985 growing season, leaf water potential (LWP) and leaf conductance were measured on the following graft combinations: Prunus avium cultivar ‘Sam’ on: (1) P. cerasus cultivar ‘Weiroot’ clones; (2) P. acida; (3) P. avium F 12 1 . In addition, measurements were taken on P. cerasus seedlings. The diurnal course of LWP generally parallelled inversely the evaporative demand of the atmosphere. The most negative values of LWP were observed in the P. cerasus seedlings, followed by ‘Sam’/F 12 1 , ‘Sam’/ P. cerasus clones and ‘Sam’/ P. acida. Delayed incompatibility in graft combinations on P. cerasus and P. acida rootstocks were noted by severely wilted leaves. These however showed less negative LWP (up to 1.0 MPa difference at noon) than turgescent leaves of the same combination. Low transpiration rates of the wilted leaves provided evidence for nearly closed stomata. Resistance to water flow in association with the graft was not found.