title: Variation in water relations characteristics of terminal shoots of Port-Orford-cedar (Chamaecyparis lawsoniana) seedlings.
abstract: We measured water relations attributes of the terminal shoots of 3-year-old Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murr.) Parl.) seedlings that represented its geographic range. Pressure-volume curves were developed and osmotic potentials at full (psi(sf)) and zero turgor (psi(sz)), relative water content at zero turgor, and an index of tissue elasticity (IE) were calculated for 38 families during early, mid- and late summer at an inland nursery, and for 12 of these families during mid- and late summer at a coastal nursery. Compared with other conifer species, psi(sz) was high (-1.4 to -1.5 MPa) and declined in seedlings at both nurseries as the season progressed. Both IE and osmotic amplitude (psi(sf)-psi(sz)) increased during the season. Osmotic potential at zero turgor was lower and osmotic amplitude greater in seedlings at the inland nursery than at the coastal nursery. Correlations of water relations attributes with geographic location of the seed sources were weak and usually not significant. High elevation southern sources exhibited smaller differences in psi(sz) between nurseries than low elevation northern sources. The small differences in water relations attributes among sources and between nurseries suggest that some may be of marginal physiological importance; however, sources that produced larger seedlings appeared to be less desiccation tolerant. We conclude that, when moving genotypes during reforestation, decisions based on patterns in tree size and timing of growth will account for these small differences in water relations.
authors.affiliation: Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Zobel
authors.forename: L
authors.initials: L
authors.lastname: Riley
authors.forename: J H
authors.initials: JH
authors.lastname: Kitzmiller
authors.forename: R A
authors.initials: RA
authors.lastname: Sniezko
mesh_terms: D029780:Chamaecyparis / Q000502:physiology*; D018520:Plant Shoots / Q000502:physiology*; D012621:Seasons; D014197:Trees / Q000502:physiology*; D014867:Water / Q000502:physiology
chemical_list: D014867:Water