Determining mid-day stem water potential from sap flow measurements

2018 ◽  
pp. 179-184
Author(s):  
O. Ahiman ◽  
A. Naor ◽  
S. Friedman ◽  
S. Cohen
Keyword(s):  
Water Potential ◽  
Sap Flow ◽  
Stem Water Potential ◽  
Flow Measurements ◽  
Stem Water ◽  
Sap Flow Measurements

Examination and parameterization of the root water uptake model from stem water potential and sap flow measurements

2012 ◽  
pp. n/a-n/a ◽  
Author(s):  
Yuting Yang ◽  
Huade Guan ◽  
John L. Hutson ◽  
Hailong Wang ◽  
Caecilia Ewenz ◽  
...  
Keyword(s):  
Water Potential ◽  
Water Uptake ◽  
Sap Flow ◽  
Root Water Uptake ◽  
Stem Water Potential ◽  
Flow Measurements ◽  
Stem Water ◽  
Sap Flow Measurements

Relationships Between Climatic Variables and Sap Flow, Stem Water Potential and Maximum Daily Trunk Shrinkage in Lemon Trees

2006 ◽  
Vol 279 (1-2) ◽  
pp. 229-242 ◽  
Author(s):  
M. F. Ortuño ◽  
Y. García-Orellana ◽  
W. Conejero ◽  
M. C. Ruiz-Sánchez ◽  
O. Mounzer ◽  
...  
Keyword(s):  
Water Potential ◽  
Sap Flow ◽  
Climatic Variables ◽  
Stem Water Potential ◽  
Stem Water

Diurnal and inter-day hysteresis of species-specific stomatal conductance from sap-flow measurements illustrates hydraulic-stress responses strategies of trees

2020 ◽  
Author(s):  
Gil Bohrer ◽  
Theresia Yazbeck ◽  
Ana Maria Restrepo Acevedo ◽  
Ashley M. Matheny
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Land Surface ◽  
Sap Flow ◽  
Stress Recovery ◽  
Flow Measurements ◽  
Surface Models ◽  
Stem Water ◽  
Species Specific ◽  
Sap Flow Measurements

<p>Modeling of plant hydraulics is at the forefront of development in vegetation and land-surface models.  Numerical tools that consider water flow within the conductive system of plants, and particularly trees, have been developed and used in studies of hydraulic strategy and consequences of hydraulic behavior for drought tolerance. Several established land-surface models such as ED2, CLM, and E3SM have recently developed “hydro” versions and are ready to extrapolate the consequences of including tree hydraulic behaviors into large scale and global simulations. At the core of any plant hydrodynamic model is the assumption that stomatal conductance is dependent on xylem water potential. Further, “plant hydro” models assume that the effect of soil moisture on stomatal conductance is not direct but cascades through depletion of xylem water content in dry soil conditions.</p><p>We use observations of sap flow, soil moisture, and evapotranspiration at a mixed forest in the University of Michigan Biological Station (UMBS) at the footprint of the US-UMd flux tower to characterize the onset and advancement of hydraulic stress and post-stress recovery. We define stress by observing tree-level decrease of stomatal conductance during sunny days as soil-moisture deficit progresses. We use the Penman-Monteith (PM) formulation to calculate stomatal conductance given observed atmospheric forcing: air temperature, humidity, net radiation, soil heat flux, and aerodynamic resistance. Such PM-based approach effectively decouples changes in evapotranspiration due to atmospheric forcing vs. changes due to decreased stomatal conductance. Multiple years of sap-flow measurements in tens of trees of multiple species allow us to identify the species-specific characteristics of the onset of stress, and the hysteretic dynamics of stomatal conductance. The daily hysteresis indicates the severity of stress. Longer-term inter-day hysteresis of the relationship between noon-time stomatal conductance and soil moisture, before and after rain have alleviated the moisture stress, indicates species-specific strategies of hydraulic-stress recovery. Recovery time is related to the degree of stress, and can vary between a nearly reversible state and 1 to 2 days of recovery, to a long recovery of several days. We find large differences between species in the sensitivity to stress and in the strength of coupling between stem water content and stomatal conductance. These are consistent with the hydraulic strategy of the trees along the an/isohydric continuum.    </p><p>Identifying the hydraulic characteristics of water stress and direct observations of the coupling between stem water storage, conductance, and transpiration provide key observations with which to tune hydrodynamic models and allow process-based functional-type parameterization of stomatal conductance that accounts for tree hydrodynamics and hydraulic stress recovery.   </p>

scholarly journals Root growth, water uptake, and sap flow of winter wheat in response to different soil water availability

2017 ◽  
Author(s):  
Gaochao Cai ◽  
Jan Vanderborght ◽  
Matthias Langensiepen ◽  
Andrea Schnepf ◽  
Hubert Hüging ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Water Potential ◽  
Soil Water ◽  
Sap Flow ◽  
Root Density ◽  
Soil Types ◽  
Flow Measurements ◽  
Physically Based ◽  
Sap Flow Measurements ◽  
Water Treatments

Abstract. How much and where water is taken up by roots from the soil profile are important questions that need to be answered to close the soil water balance equation and to describe water fluxes in the soil–plant–atmosphere system. Physically-based root water uptake (RWU) models that relate RWU to transpiration, root density, and water potential distributions have been developed but far less used or tested. This study aims at evaluating the simulated RWU of winter wheat by the empirical Feddes–Jarvis (FJ) model and the physically-based Couvreur (C) model for different soil water conditions and soil textures against sap flow measurements. Soil water content (SWC), water potential, and root development were monitored non-invasively at six soil depths in two rhizotron facilities that were constructed in two soil textures: stony vs. silty with each three water treatments: sheltered, rainfed, and irrigated. Soil and root parameters of the two models were derived from inverse modeling and simulated RWU was compared with sap flow measurements for validation. The different soil types and water treatments resulted in different crop biomass, root densities and root distributions with depth. The two models simulated the lowest RWU in the sheltered plot of the stony soil where RWU was also lower than the potential RWU. In the silty soil, simulated RWU was equal to the potential uptake for all treatments. The variation of simulated RWU among the different plots agreed well with measured sap flow but the C model predicted the ratios of the transpiration fluxes in the two soil types slightly better than the FJ model. The root hydraulic parameters of the C model could be constrained by the field data but not the water stress parameters of the FJ model. This was attributed to differences in root densities between the different soils and treatments which are accounted for by the C model whereas the FJ model only considers normalized root densities. The impact of differences in root density on RWU could be accounted for directly by the physically-based RWU model but not by empirical models that use normalized root density functions.

scholarly journals Water economy by Italia grapevines under different irrigation treatments in a Mediterranean climate

OENO One ◽  
2007 ◽  
Vol 41 (3) ◽  
pp. 131
Author(s):  
Aziz Ezzahouani ◽  
Charles Valancogne ◽  
Paolo Pieri ◽  
T. Amalak ◽  
Jean-Pierre Gaudillère
Keyword(s):  
Water Supply ◽  
Root Zone ◽  
Water Status ◽  
Practical Interest ◽  
Capture Efficiency ◽  
Stem Water Potential ◽  
Flow Measurements ◽  
Stem Water ◽  
Sap Flow Measurements

<p style="text-align: justify;"><strong>Aims</strong>: A study was conducted to compare traditional vineyard irrigation (TI) using one drip emitter per vine, and partial root zone drying irrigation (PRD) using two drip emitters per vine (one per each vine side), at 2 rates of water application (controlled deficit (TI4 and PRD4) and non limiting (TI8 and PRD8)).</p><p style="text-align: justify;"><strong>Methods and results</strong>: Individual vine transpiration and vine water status were estimated from sap flow measurements by a stem heat balance method and midday stem water potential. The quality of the harvest was not significantly changed by the treatments. However, the vegetative growth was lower for the low irrigation rate treatments (TI4 and PRD4) and the PRD8 (compared to TI8). The total amount of water transpired by the vines during the season was estimated to 147 l/m2 without water limitation. A limiting water supply (TI4) lessened vine water use and improved the fraction of supplied water trapped by the vines (81 % for TI4 and 66 % for TI8). PRD decreased the transpiration of the vines, but also the efficiency of use of irrigation water.</p><p style="text-align: justify;"><strong>Significance and impact of study</strong>: Limited water supply saved water and improved the water capture efficiency by the roots of the vines. PRD irrigation saved water but the vine water capture efficiency was lower, limiting the practical interest of the method.</p>

scholarly journals The Effect of Irrigation Rate on the Water Relations of Young Citrus Trees in High-Density Planting

2021 ◽  
Vol 13 (4) ◽  
pp. 1759
Author(s):  
Said A. Hamido ◽  
Kelly T. Morgan
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Soil Salinity ◽  
Planting Density ◽  
Stem Water Potential ◽  
Irrigation Rate ◽  
Biological Stress ◽  
Stem Water ◽  
Water Contents ◽  
Soil Water Contents

The availability and proper irrigation scheduling of water are some of the most significant limitations on citrus production in Florida. The proper volume of citrus water demand is vital in evaluating sustainable irrigation approaches. The current study aims to determine the amount of irrigation required to grow citrus trees at higher planting densities without detrimental impacts on trees’ water relation parameters. The study was conducted between November 2017 and September 2020 on young sweet orange (Citrus sinensis) trees budded on the ‘US-897’ (Cleopatra mandarin x Flying Dragon trifoliate orange) citrus rootstock transplanted in sandy soil at the Southwest Florida Research and Education Center (SWFREC) demonstration grove, near Immokalee, Florida. The experiment contained six planting densities, including 447, 598, and 745 trees per ha replicated four times, and 512, 717, and 897 trees per ha replicated six times. Each density treatment was irrigated at 62% or 100% during the first 15 months between 2017 and 2019 or one of the four irrigation rates (26.5, 40.5, 53, or 81%) based on the calculated crop water supplied (ETc) during the last 17 months of 2019–2020. Tree water relations, including soil moisture, stem water potential, and water supplied, were collected periodically. In addition, soil salinity was determined. During the first year (2018), a higher irrigation rate (100% ETc) represented higher soil water contents; however, the soil water content for the lower irrigation rate (62% ETc) did not represent biological stress. One emitter per tree regardless of planting density supported stem water potential (Ψstem) values between −0.80 and −0.79 MPa for lower and full irrigation rates, respectively. However, when treatments were adjusted from April 2019 through September 2020, the results substantially changed. The higher irrigation rate (81% ETc) represented higher soil water contents during the remainder of the study, the lower irrigation rate (26.5% ETc) represents biological stress as a result of stem water potential (Ψstem) values between −1.05 and −0.91 MPa for lower and higher irrigation rates, respectively. Besides this, increasing the irrigation rate from 26.5% to 81%ETc decreased the soil salinity by 33%. Although increasing the planting density from 717 to 897 trees per hectare reduced the water supplied on average by 37% when one irrigation emitter was used to irrigate two trees instead of one, applying an 81% ETc irrigation rate in citrus is more efficient and could be managed in commercial groves.

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