© 1990 Heron Publishing—Victoria, Canada
Drought adaptations and responses in five genotypes of Fraxinus pennsylvanica Marsh.: photosynthesis, water relations and leaf morphology
M. D. Abrams, M. E. Kubiske and K. C. Steiner
School of Forest Resources, Ferguson Building, The Pennsylvania State University, University Park, PA 16802, USA / Received October 10, 1989
Summary
Genotypic variation in photosynthesis and plant water relations during drought, and in leaf and seedling morphology were examined
in greenhouse-grown Fraxinus pennsylvanica Marsh. (green ash) from five populations located along an east–west transect from New York State to South Dakota. During
a 17-day drought, South Dakota seedlings, from the most xeric habitat, maintained the highest net photosynthesis and leaf
conductance, and New York seedlings, from the most mesic habitat, exhibited the lowest net photosynthesis and leaf conductance.
All populations except New York adjusted osmotically during the 17-day drought, by the end of which New York seedlings had
the highest osmotic potentials at full and zero turgor. Tissue elasticity increased in New York seedlings, but decreased in
Nebraska seedlings during the drought. Leaves of South Dakota seedlings were the most xerophytic. They were smaller in area
and greater in thickness and specific mass than leaves of other sources. Leaves of New York seedlings were thinner than those
of the other genotypes and among the largest. Seedlings from South Dakota were smaller than those of the other populations.
