caa a22 4500 477101941 CHVBK 20180405111544.0 cr unu---uuuuu 170330e19960601xx s 000 0 eng 10.1007/BF00196572 doi (NATIONALLICENCE)springer-10.1007/BF00196572 Measurement of apoplasmic and cell-to-cell components of root hydraulic conductance by a pressure-clamp technique [Elektronische Daten] [Federico Magnani, Mauro Centritto, John Grace] A pressure-clamp technique was devised for the direct measurement of cell-to-cell and apoplasmic components of root hydraulic conductance; the experimental results were analyzed in terms of a theoretical model of water and solute flow, based on a composite membrane model of the root. When water is forced under a constant pressure into a cut root system, an exponential decay of flow is observed, until a constant value is attained; when pressure is released, a reverse water flow out of the root system is observed which shows a similar exponential behavour. The model assumes that the transient flow occurs through a cell-to-cell pathway and the observed decrease is the result of accumulation of solutes in front of the root semi-permeable membrane, whilst the steady-state component results from the movement of water through the parallel apoplasmic pathway. Root conductance components are estimated by fitting the model to experimental data. The technique was applied to the root systems of potted cherry (Prunus avium L.) seedlings; average apoplasmic conductance was 15.5 × 10−9m3· s−1· MPa−1, with values ranging from 12.0 × 10−9 to 18.5 × 10−9m3· s−1· MPa−1; average cell-to-cell conductance was 11.7 × 109 m3· s−1· MPa−1, with values ranging from 8.5 × 10−9 to 15.3 × 10−9 m3 · s−1·MPa−1. Cell-to-cell conductance amounted on average to 43% of total root conductance, with values between 41 and 45%. Leaf specific conductance (conductance per unit of leaf area supported) of the root systems ranged from 2.7 × 10−8 to 5.6 × 10−8 m· s−1·MPa−1, with an average of 3.7 × 10−8 m · s−1·MPa−1. The newly developed technique allows the interaction of mass flow of water and of solutes to be explored in the roots of soil-grown plants. Springer-Verlag, 1996 Apoplasm nationallicence Hydraulic conductance nationallicence Pressure clamp technique nationallicence Prunus (water relations) nationallicence Root (hydraulic conductance) nationallicence Water relations nationallicence A Lp : root hydraulic conductance nationallicence AaLpa : root apoplasmic conductance nationallicence AccLpcc : root cell-to-cell conductance nationallicence Cs(t) : concentration of solutes in apical root compartment at time t nationallicence Jv : flow of water through the root nationallicence Jva : apoplasmic flow of water nationallicence Jv/cc : cell-to-cell flow of water nationallicence LSC : leaf specific conductance of the root system nationallicence P : root hydrostatic pressure nationallicence Pappl : applied pressure nationallicence πs(t) : root osmotic pressure at time t nationallicence πm : osmotic pressure of rooting medium nationallicence σ : reflection coefficient of root membrane nationallicence τ : time constant of cell-to-cell flow decay nationallicence Magnani Federico Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, King's Buildings, Mayfield Road, EH9 3JU, Edinburgh, UK aut Centritto Mauro Istituto Irrigazione, Consiglio Nazionale delle Ricerche, via Cupa Patacca 85, I-80056, Ercolano (NA), Italy aut Grace John Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, King's Buildings, Mayfield Road, EH9 3JU, Edinburgh, UK aut Planta Springer-Verlag 199/2(1996-06-01), 296-306 0032-0935 199:2<296 1996 199 425 https://doi.org/10.1007/BF00196572 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00196572 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Magnani Federico Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, King's Buildings, Mayfield Road, EH9 3JU, Edinburgh, UK aut NATIONALLICENCE 700 1- Centritto Mauro Istituto Irrigazione, Consiglio Nazionale delle Ricerche, via Cupa Patacca 85, I-80056, Ercolano (NA), Italy aut NATIONALLICENCE 700 1- Grace John Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, King's Buildings, Mayfield Road, EH9 3JU, Edinburgh, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 199/2(1996-06-01), 296-306 0032-0935 199:2<296 1996 199 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer