Journal Article

Collection of Xylem Sap at Flow Rate Similar to in vivo Transpiration Flux

Jiansheng Liang and Jianhua Zhang

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 38, issue 12, pages 1375-1381
Published in print January 1997 | ISSN: 0032-0781
Published online January 1997 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029132
Collection of Xylem Sap at Flow Rate Similar to in vivo Transpiration Flux

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We have explored a method to collect xylem sap using a Scholander pressure chamber for potted plants. Intact root system in pots which fitted the pressure chamber was pressurised at a pneumatic pressure numerically equal to the absolute value of shoot water potential. The rate of xylem flow obtained from the stem stump under such pressure was found similar to the rate of transpiration before detopping. The rate of pressurised flow from detop-ped roots was linearly related to the pressure applied in both well-watered and soil-dried plants. The osmotic concentration of the xylem sap was negatively related to the rate of volume flow, suggesting the necessity to collect xylem sap at in vivo flow rate if original solute concentration is to be evaluated. The concentration of ABA in the xylem sap, however, did not show such a relationship with water flux. Both well-watered and soil-dried plants showed the concentration of ABA in xylem sap largely stable with a range of volume flow rate, indicating a linear relationship between the rate of ABA delivery through xylem and that of volume flow. We also compared the concentrations of ABA in xylem sap sequentially collected from pressurised roots with that from detached shoots of the same plants. The concentration of ABA in the initial saps from shoots showed to be similar to that from roots. However, a decrease in the concentration of ABA in the xylem sap collected from detached leaf or twig was observed when more volume of sap was collected, which might also be dependent on the plant species and the volume of xylem vessels concerned.

Keywords: Leucaena leucocephala; Xylem ABA]; Xylem flux; Xylem sap sampling; Xylem solutes; Zea mays

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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