caa a22 4500 397522339 CHVBK 20180308164636.0 cr unu---uuuuu 161202e199511 xx s 000 0 eng 10.1093/jxb/46.11.1701 doi (NATIONALLICENCE)oxford-10.1093/jxb/46.11.1701 A critical re-examination of pressure-volume analysis of conifer shoots: comparison of three procedures for generating PV curves on shoots of Pinus resinosa Ait. seedlings [Elektronische Daten] [William C. Parker, and Stephen J. Colombo] Prediction of water relations attributes for red pine (Pinus resinosa Ait.) derived from pressure-volume (PV) curves varied depending on which of three methods was used. The sap expression method entailed the enclosure of a shoot in a pressure chamber and expression of xylem sap by applying a constant selected pressure until sap flow ceased, at which point xylem water potential and shoot weight were measured. A sap expression PV curve was formed by aggregating pairs of water potential-weight measurements, each pair supplied by one of 25 shoots. The repeat pressurization method involved repeatedly measuring xylem water potential and shoot weight on a single shoot drying on a laboratory bench. Repeat pressurization PV curves were constructed from data provided by a single shoot. The composite method utilized single measurements of xylem water potential and shoot weight on 25-30 different shoots ranging in relative water content from about 1.0 to 0.5 achieved by bench drying. Composite PV curves were constructed from aggregate data supplied by a population of shoots. There was close agreement in all PV attributes generated using repeat pressurization and sap expression methods. In contrast, with the composite PV method, there was a fundamental difference in the slope of the linear region of the PV curves, causing osmotic potentials at full turgor and turgor loss to be more negative, and relative water content at turgor loss to be lower and symplast fraction to be higher. Comparison of composite and repeat pressurization PV curves over the same ranges in water content did not eliminate differences in derived water relations attributes. Differences in water potential isotherms related to the PV procedures used suggest that prolongedor repeated exposure to gas at high pressure may introduce errors in the estimation of water relations attributes. © Oxford University Press RESEARCH PAPERS nationallicence Pinus resinosa nationallicence pressure chamber nationallicence pressure volume nationallicence tissue water relations nationallicence Parker William C. Ontario Forest Research Institute, Box 969, 1235 Queen St. E., Sault Ste. Marie, Ontario P6A 5N5, Canada aut Colombo and Stephen J. Ontario Forest Research Institute, Box 969, 1235 Queen St. E., Sault Ste. Marie, Ontario P6A 5N5, Canada aut Journal of Experimental Botany Oxford University Press 46/11(1995-11), 1701-1709 0022-0957 46:11<1701 1995 46 exbotj https://doi.org/10.1093/jxb/46.11.1701 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jxb/46.11.1701 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Parker William C. Ontario Forest Research Institute, Box 969, 1235 Queen St. E., Sault Ste. Marie, Ontario P6A 5N5, Canada aut NATIONALLICENCE 700 1- Colombo and Stephen J. Ontario Forest Research Institute, Box 969, 1235 Queen St. E., Sault Ste. Marie, Ontario P6A 5N5, Canada aut NATIONALLICENCE 773 0- Journal of Experimental Botany Oxford University Press 46/11(1995-11), 1701-1709 0022-0957 46:11<1701 1995 46 exbotj Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford