TY - JOUR

T1 - Modelling the impact of heterogeneous rootzone water distribution on the regulation of transpiration by hormone transport and/or hydraulic pressures

AU - Huber, Katrin

AU - Vanderborght, Jan

AU - Javaux, Mathieu

AU - Schroeder, Natalie

AU - Dodd, Ian C.

AU - Vereecken, Harry

PY - 2014/11

Y1 - 2014/11

N2 - A simulation model to demonstrate that soil water potential can regulate transpiration, by influencing leaf water potential and/or inducing root production of chemical signals that are transported to the leaves.Signalling impacts on the relationship between soil water potential and transpiration were simulated by coupling a 3D model for water flow in soil, into and through roots (Javaux et al. 2008) with a model for xylem transport of chemicals (produced as a function of local root water potential). Stomatal conductance was regulated by simulated leaf water potential (H) and/or foliar chemical signal concentrations (C; H + C). Split-root experiments were simulated by varying transpiration demands and irrigation placement.While regulation of stomatal conductance by chemical transport was unstable and oscillatory, simulated transpiration over time and root water uptake from the two soil compartments were similar for both H and H + C regulation. Increased stomatal sensitivity more strongly decreased transpiration, and decreased threshold root water potential (below which a chemical signal is produced) delayed transpiration reduction.Although simulations with H + C regulation qualitatively reproduced transpiration of plants exposed to partial rootzone drying (PRD), long-term effects seemed negligible. Moreover, most transpiration responses to PRD could be explained by hydraulic signalling alone.

AB - A simulation model to demonstrate that soil water potential can regulate transpiration, by influencing leaf water potential and/or inducing root production of chemical signals that are transported to the leaves.Signalling impacts on the relationship between soil water potential and transpiration were simulated by coupling a 3D model for water flow in soil, into and through roots (Javaux et al. 2008) with a model for xylem transport of chemicals (produced as a function of local root water potential). Stomatal conductance was regulated by simulated leaf water potential (H) and/or foliar chemical signal concentrations (C; H + C). Split-root experiments were simulated by varying transpiration demands and irrigation placement.While regulation of stomatal conductance by chemical transport was unstable and oscillatory, simulated transpiration over time and root water uptake from the two soil compartments were similar for both H and H + C regulation. Increased stomatal sensitivity more strongly decreased transpiration, and decreased threshold root water potential (below which a chemical signal is produced) delayed transpiration reduction.Although simulations with H + C regulation qualitatively reproduced transpiration of plants exposed to partial rootzone drying (PRD), long-term effects seemed negligible. Moreover, most transpiration responses to PRD could be explained by hydraulic signalling alone.

KW - Soil-root modelling

KW - R-SWMS

KW - Hormonal signalling

KW - Stomatal conductance

KW - Partial rootzone drying

KW - ABSCISIC-ACID

KW - SOIL-WATER

KW - STOMATAL CONDUCTANCE

KW - XYLEM SAP

KW - DRYING SOIL

KW - ABA CONCENTRATION

KW - PLANTS

KW - SHOOT

KW - GROWTH

KW - ROOTS

U2 - 10.1007/s11104-014-2188-4

DO - 10.1007/s11104-014-2188-4

M3 - Journal article

VL - 384

SP - 93

EP - 112

JO - Plant and Soil

JF - Plant and Soil

SN - 0032-079X

IS - 1-2

ER -