Leaf osmotic potential of Eucalyptus hybrids responds differently to freezing and drought, with little clonal variation

Abstract

Concentrations of solutes, and thus leaf osmotic potential (Ψπ), often increase when plants are subject to drought or sub-zero (frost) temperatures. We measured Ψπ and concentrations of individual solutes in leaves of 3-year-old Eucalyptus camaldulensis Dehn., E. globulus Labill., E. grandis W. Hill ex Maid, and 29 hybrid clones on a site subjected to both summer drought and winter frost. We sought to characterize seasonal and genetic variations in Ψπ and to determine whether Ψπ or leaf turgor is related to bole volume increment. Leaf osmotic potential at full turgor (Ψ π(100)) was 0.7 MPa more negative in winter than in late summer, and this trend was uniform across genotypes. Soluble carbo..