KAUFMANN, M.R., Department of Plant Sciences, University of California, Riverside, California, 92502, United States
LEVY, Y., Department of Plant Sciences, University of California, Riverside, California, 92502, United States

Seven‐month‐old rough lemon (Citrus jambhiri Lush.) seedlings were subjected to high‐ and low‐humidity treatments (vapor pressure deficits of 8.0 and 19.6 mbar) for 3 weeks. Half of each group was well supplied with water and half was subjected to a series of three drying cycles in which xylem pressure potential fell to below −25 bar. The relationship between leaf conductance and xylem pressure potential was similar during each drying phase and was unaffected by atmospheric humidity. Several days elapsed after rewatering before normal stomatal opening occurred. When all the plants were subsequently kept well watered, leaf conductances decreased as the leaf‐to‐air vapor pressure difference was increased. However, the conductances of previously stressed plants were lower than those of unstressed plants, and consequently previously stressed plants had lower transpiration rates. Copyright © 1976, Wiley Blackwell. All rights reserved