title: Drought until death do us part: a case study of the desiccation-tolerance of a tropical moist forest seedling-tree, Licania platypus (Hemsl.) Fritsch.
abstract: Studies of the desiccation tolerance of 15-month-old Licania platypus (Hemsl.) Fritsch seedlings were performed on potted plants. Pots were watered to field capacity and then dehydrated for 23-46 d to reach various visible wilting stages from slightly-wilted to dead. Root hydraulic conductance, k(r), was measured with a high-pressure flow meter and whole-stem hydraulic conductance, k(ws), was measured by a vacuum chamber method. Leaf punches were harvested for measurement of leaf water potential by a thermocouple psychrometer and for measurement of fresh- and dry-weight. L. platypus was surprisingly desiccation-tolerant, suggesting that most species of central Panama may be well adapted to the seasonality of rainfall in the region. The slightly-wilted stage corresponded to leaf water potentials and relative water contents of -2.7 MPa and 0.85, respectively, but plants did not die until these values fell to -7.5 MPa and 0.14, respectively. As desiccation proceeded k(r) and k(ws) declined relative to irrigated controls, but k(ws) was more sensitive to desiccation than k(r). Values of k(ws) declined by 70-85% in slightly-wilted to dead plants, respectively. By comparison, k(r) showed no significant change in slightly-wilted plants and fell by about 50% in plants having severely-wilted to dead shoots.
authors.affiliation: USDA Forest Service, PO Box 968, Burlington, VT 05402, USA. MelTyree@aol.com
authors.forename: Melvin T
authors.initials: MT
authors.lastname: Tyree
authors.forename: Gustavo
authors.initials: G
authors.lastname: Vargas
authors.forename: Bettina M J
authors.initials: BM
authors.lastname: Engelbrecht
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Kursar
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D003890:Desiccation; D004190:Disasters; D010176:Panama; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D018547:Plant Stems / Q000187:drug effects / Q000502:physiology; D018526:Plant Transpiration / Q000187:drug effects / Q000502:physiology; D019685:Rosales / Q000187:drug effects / Q000502:physiology*; D013696:Temperature; D014329:Tropical Climate; D014867:Water / Q000494:pharmacology* / Q000502:physiology
chemical_list: D014867:Water