Abstract
Water and solute flows in the coupled system of xylem and phloem were modeled together with predictions for xylem and whole stem diameter changes. With the model we could produce water circulation between xylem and phloem as presented by the Münch hypothesis. Viscosity was modeled as an explicit function of solute concentration and this was found to vary the resistance of the phloem sap flow by many orders of magnitude in the possible physiological range of sap concentrations. Also, the sensitivity of the predicted phloem translocation to changes in the boundary conditions and parameters such as sugar loading, transpiration, and hydraulic conductivity were studied. The system was found to be quite sensitive to the sugar-loading rate, as too high sugar concentration, (approximately 7 MPa) would cause phloem translocation to be irreversibly hindered and soon totally blocked due to accumulation of sugar at the top of the phloem and the consequent rise in the viscosity of the phloem sap. Too low sugar loading rate, on the other hand, would not induce a sufficient axial water pressure gradient. The model also revealed the existence of Münch “counter flow”, i.e., xylem water flow in the absence of transpiration resulting from water circulation between the xylem and phloem. Modeled diameter changes of the stem were found to be compatible with actual stem diameter measurements from earlier studies. The diurnal diameter variation of the whole stem was approximately 0.1 mm of which the xylem constituted approximately one-third.
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References
Bancal P, Soltani F (2002) Source–sink partitioning. Do we need Münch? J Exp Bot 53:1919–1928
Daudet FA, Lacointe A, Gaudillere JP, Cruiziat P (2002) Generalized Münch coupling between sugar and water fluxes for modelling carbon allocation as affected by water status. J Theor Biol 214:481–498
Ferrier JM, Tyree MT, Christy AL (1975) The theoretical time-dependent behavior of a Münch pressure-flow system: the effect of sinusoidal time variation in sucrose loading and water potential. Can J Bot 53:1120–1127
Génard M, Fishman S, Vercambre G, Huguet JG, Bussi C, Besset J, Habib R (2001) A biophysical analysis of stem and root diameter variations in woody plants. Plant Physiol 126:188–202
Hari P, Mäkelä A, Korpilahti E, Holmberg M (1986) Optimal control of gas exchange. Tree Physiol 2:169–175
Hari P, Keronen P, Bäck J, Altimir N, Linkosalo T, Pohja T, Kulmala M, Vesala T (1999) An improvement of the method for calibrating measurements of photosynthetic C02 flux. Plant Cell Environ 22:1297–1301
Hubbard RM, Ryan MG, Stiller V, Sperry VS (2001) Stomatal conductance and photosynthesis vary linearly with plant hydraulic conductance in ponderosa pine. Plant Cell Environ 24:113–121
Irvine J, Grace J (1997) Continuous measurements of water tensions in the xylem of trees based on the elastic properties of wood. Planta 202:455–461
Knoblauch M, van Bel AJE (1998) Sieve tubes in action. Plant Cell 10:35–50
Kockenberger W, Pope JM, Xia Y, Jeffrey KR, Komor E, Callaghan PT (1997) A noninvasive measurement of phloem and xylem water flow in castor bean seedlings by nuclear magnetic resonance microimaging. Planta 201:53–63
Lalonde S, Tegeder M, Thorne-Holst M, Frommer WB, Patrick JW (2003) Phloem loading and unloading of sugars and amino acids. Plant Cell Environ 26:37–56
Mauseth J (2003) Botany: an introduction to plant biology, 3rd edn. Jones & Bartlett, Boston
Mencuccini M, Grace J, Fioravanti M (1997) Biomechanical and hydraulic determinants of tree structure in Scots pine: anatomical characteristics. Tree Physiol 17:105–113
Milburn JA (1996) Sap ascent on vascular plants: challengers to the cohesion theory ignore the significance of immature xylem and recycling of Münch water. Ann Bot 78:399–407
Minchin P, Thorpe MR (1987) Measurement of unloading and reloading of photoassimilate within the stem of bean. J Exp Bot 38:211–220
Morison KR (2002) Viscosity equations for sucrose solutions: old and new 2002. In: Proceedings of the 9th APCChE Congress and CHEMECA 2002, Paper # 984
Nobel PS (1991) Physicochemical and environmental plant physiology, 4th edn. Academic, San Diego, CA
Offenthaler I, Hietz P, Richter H (2001) Wood diameter indicates diurnal and long-term patterns of xylem water potential in Norway spruce. Trees 15:215–221
Pate JS, Jeschke WD (1995) Role of stems in transport, storage, and circulation of ions and metabolites by the whole plant. In: Gartner B (ed) Plant stems physiology and functional morphology. Academic, San Diego, CA, pp 177–204
Pedersen O, Sand-Jensen K (1997) Transpiration does not control growth and nutrient supply in the amphibious plant Mentha aquatica. Plant Cell Environ 20:117–123
Perämäki M, Nikinmaa E, Sevanto S, Ilvesniemi H, Siivola E, Hari P, Vesala T (2001) Tree stem diameter variations and transpiration in Scots pine: an analysis using a dynamic sap flow model. Tree Physiol 21:889–897
Phillips RJ, Dungan SR (1993) Asymptotic analysis of flow in sieve tubes with semipermeable walls. J Theor Biol 162:465–485
Press WH, Flannery BP, Teukolsky SA, Wetterling WT (1989) Numerical recipes in Pascal: the art of scientific computing. Cambridge University Press, Cambridge, UK
Salleo S, Assunta Lo Gullo M, De Paoli D, Zippo M (1996) Xylem recovery from cavitation-induced embolism in young plants of Laurus nobilis: a possible mechanism. New Phytol 132:47–56
Salleo S, Lo Gullo M, Trifiló P, Nardini A (2004) New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis. Plant Cell Environ 25:1065–1076
Schultze ED (1991) Water and nutrient interactions with plant water stress. In: Mooney HA, Winner WE, Pell EJ (eds) The book, response of plants to multiple schemes. Academic, San Diego, CA, pp 89–101
Sevanto S, Vesala T, Perämäki M, Nikinmaa E (2002) Time lags for xylem and stem diameter variations in Scots pine tree. Plant Cell Environ 25:1071–1077
Sevanto S, Vesala T, Perämäki M, Nikinmaa E (2003) Sugar transport together with environmental conditions controls time lags between xylem and stem diameter changes. Plant Cell Environ 26:1257–1265
Sheehy JE, Mitchell PL, Durand JL, Gastal F, Woodward FI (1995) Calculation of translocation coefficients from phloem anatomy for use in crop models. Ann Bot 76:263–269
Siau JF (1984) Transport processes in wood. Springer-Verlag, Berlin Heidelberg New York, 211 p
Smith KC, Magnuson CE, Goeschl JD, DeMichele DW (1980) A time-dependent mathematical expression of the Münch hypothesis of phloem transport. J Theor Biol 86:493–505
Sperry JS, Pockman WT (1993) Limitation of transpiration by hydraulic conductance and xylem cavitation in Betula occidentalis. Plant Cell Environ 16:279–287
Taiz L, Zeiger E (1998) Plant physiology, 2nd edn. Sineaur, Sunderland, MA
Tanner W, Beevers H (2001) Transpiration, a prerequisite for long-distance transport of minerals in plants? Plant Biol 98:9443–9447
Thompson VM, Holbrook M (2003a) Application of a single-solute nonsteady-state phloem model to the study of long-distance assimilate transport. J Theor Biol 220:419–455
Thompson NM, Holbrook NM (2003b) Scaling phloem transport water potential equilibrium and osmoregulatory flow. Plant Cell Environ 26:1561–1577
Thompson VM, Holbrook M (2004) Scaling phloem transport: information transmission. Plant Cell Environ 27:509–519
Tyree MT, Christy AL, Ferrier JM (1974) A simpler iterative steady state solution of Münch pressure-flow systems applied to long and short translocation paths. Plant Physiol 54:589–600
Van Bel AJE (2003) The phloem, a miracle of ingenuity. Plant Cell Environ 26:125–149
Vesala T, Haataja J, Aalto P, Altimir N, Buzorius G, Garam E, Hämeri K, Ilvesniemi H, Jokinen V, Keronen P, Lahti T, Markkanen T, Mäkelä J, Nikinmaa E, Palmroth S, Palva L, Pohja T, Pumpanen J, Rannik Ü, Siivola E, Ylitalo H, Hari P, Kulmala M (1998) Long-term field measurements of atmosphere–surface interactions in boreal forest combining forest ecology, micrometeorology, aerosol physics, and atmospheric chemistry. Trends Heat Mass Momentum Transfer 4:17–35
Vesala T, Hölttä T, Perämäki M, Nikinmaa E (2003) Refilling of a hydraulically isolated embolised vessel: model calculations. Ann Bot 91:419–428
Zimmermann MH (1983) Xylem structure and the ascent of sap. Springer-Verlag, Berlin Heidelberg New York, 143 p
Zwieniecki MA, Melcher PJ, Holbrook N (2001) Hydraulic properties of individual xylem vessels of Fraxinus americana. J Exp Bot 52:257–264
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We thank Magnus Ehrnrooth foundation and Academy of Finland (projects #200731 and #55107) for research funding.
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Hölttä, T., Vesala, T., Sevanto, S. et al. Modeling xylem and phloem water flows in trees according to cohesion theory and Münch hypothesis. Trees 20, 67–78 (2006). https://doi.org/10.1007/s00468-005-0014-6
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DOI: https://doi.org/10.1007/s00468-005-0014-6