Foliar dehydration tolerance of twelve deciduous tree species

The potential for foliar dehydration tolerance and maximum capacity for osmotic adjustment were compared among 12 temperate, deciduous tree species, under standardized soil and atmospheric conditions. Dehydration tolerance was operationally defined as lethal leaf water potential (ψ): the ψ of the last remaining leaves surviving a continuous, lethal soil drying episode. Nyssa sylvatica Marsh., and Liriodendron tulipifera L. were most sensitive to dehydration, having lethal leaf ψ of −2.04 and −2.38 MPa, respectively. Chionanthus virginicus L., Quercus prinus L., Acer saccharum Marsh., and Quercus acutissima Carruthers withstood the most dehydration, with leaves not dying until leaf ψ dropped to −5.63 MPa or below. Lethal leaf ψ (in MPa) of other, intermediate species were: Quercus rubra L. (−3.34), Oxydendrum arboreum (L.) D.C. (−3.98), Halesia carolina L. (−4.11), Acer rubrum L. (−4.43), Quercus alba L. (−4.60), and Corpus florida L. (−4.88). Decreasing lethal leaf ψ was significantly correlated with increasing capacity for osmotic adjustment. C. virginicus and Q. acutissima showed the most osmotic adjustment during the lethal soil drying episode, with osmotic potential at full turgor declining by 1.73 and 1.44 MPa, respectively. Other species having reductions in osmotic potential at full turgor exceeding 0.50 MPa were (in MPa) Q. prinus (0.89), A. saccharum (0.71), Q. alba (0.68), H. carolina (0.67), Q. rubra (0.60), and C. florida (0.52).