scholarly journals Towards In Vivo Monitoring of Ions Accumulation in Trees: Response of an in Planta Organic Electrochemical Transistor Based Sensor to Water Flux Density, Light and Vapor Pressure Deficit Variation

2021 ◽  
Vol 11 (11) ◽  
pp. 4729
Author(s):  
Davide Amato ◽  
Giuseppe Montanaro ◽  
Filippo Vurro ◽  
Nicola Coppedé ◽  
Nunzio Briglia ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Flux Density ◽  
Precision Agriculture ◽  
Vapor Pressure Deficit ◽  
Accumulation Rate ◽  
Xylem Sap ◽  
Water Flux ◽  
Electrochemical Transistor ◽  
Olive Trees

Research on organic electrochemical transistor (OECT) based sensors to monitor in vivo plant traits such as xylem sap concentration is attracting attention for their potential application in precision agriculture. Fabrication and electronic aspects of OECT have been the subject of extensive research while its characterization within the plant water relation context deserves further efforts. This study tested the hypothesis that the response (R) of an OECT (bioristor) implanted in the trunk of olive trees is inversely proportional to the water flux density flowing through the plant (Jw). This study also examined the influence on R of vapor pressure deficit (VPD) as coupled/uncoupled with light. R was hourly recorded in potted olive trees for a 10-day period concomitantly with Jw (weight loss method). A subgroup of trees was bagged in order to reduce VPD and in turn Jw, and other trees were located in a walk-in chamber where VPD and light were independently managed. R was tightly sensitive to diurnal oscillation of Jw and at negligible values of Jw (late afternoon and night) R increased. The bioristor was not sensitive to the VPD per se unless a light source was coupled to trigger Jw. This study preliminarily examined the suitability of bioristor to estimate the mean daily nutrients accumulation rate (Ca, K) in leaves comparing chemical and sensor-based procedures showing a good agreement between them opening new perspective towards the application of OECT sensor in precision agricultural cropping systems.

scholarly journals Diurnal In Vivo Xylem Sap Glucose and Sucrose Monitoring Using Implantable Organic Electrochemical Transistor Sensors

2020 ◽  
Author(s):  
Chiara Diacci ◽  
Tayebeh Abedi ◽  
Jeewoong Lee ◽  
Erik O. Gabrielsson ◽  
Magnus Berggren ◽  
...  
Keyword(s):  
Xylem Sap ◽  
Electrochemical Transistor

Assessing reliability of HRM sap-flow sensors under large range of vapor pressure deficit

2020 ◽  
Author(s):  
Rémy Schoppach ◽  
Daniella Ekwalla Hangue ◽  
Julian Klaus
Keyword(s):  
Vapor Pressure ◽  
Sap Flow ◽  
Vapor Pressure Deficit ◽  
Heat Waves ◽  
Linear Trend ◽  
Water Flux ◽  
Gravimetric Method ◽  
Flow Sensors ◽  
Tree Transpiration ◽  
Sap Flow Sensors

<p>Evapotranspiration (ET) is a major water flux of ecosystems and represents globally 60-80% of the incoming precipitation lost by terrestrial environments. In forested lands, tree transpiration (TR) is the dominant component of ET, yet remains challenging to measure. Over the years, sap-flow sensors have become the standard tool for quantifying tree TR and different methods based on thermal approaches have been developed. Heat ratio methods (HRM) are considered as the most reliable and accurate method to quantify absolute flows. Leading commercial brands ensure an accurate measurement of positive flows up to 100 cm hr<sup>-1</sup> but different studies have highlighted a saturation effect at high flows with threshold for accuracy remaining elusive[RS1] . Due to climate change, the occurrence, the severity and the duration of extreme events like heat waves and dry periods are expected to increase in future, so the potential for high TR rate periods will also increase. Therefore, it is crucial to determine the species-specific environmental conditions allowing a reliable measurement of TR in order to improve or understanding of eco-hydrological and physiological processes during high potential TR periods that can be crucial for vegetation survival. In this study, we tested the accuracy of HRM sap-flow sensors for beech (Fagus sylvatica) and oak (Quercus robur) tree species under extreme vapor pressure deficit (VPD) conditions in order to determine threshold for reliable measurements. In greenhouse conditions, we collected a complete and dense series of TR response to VPD between 0.7 to 8.3 kPa for potted beech and oak trees using three different methods: infrared gas analyser, gravimetric method, and HRM sap-flow sensors. Responses shown a linear trend at the low-canopy leaf level (41.5 and 45.1 mg H<sub>2</sub>O m<sup>-2</sup> s<sup>-1</sup> kPa<sup>-1</sup> respectively for beech and oak) but a bi-linear conformation at the whole plant level (1<sup>st</sup> slope = 12.04 ± 0.7 mg H<sub>2</sub>O m<sup>-2</sup> s<sup>-1</sup> kPa<sup>-1</sup> and break-point at 3.9 ± 0.07 kPa for beech trees). Sap-flow sensors using the HRM method displayed a clear inability to reliably measure flows under high VPD conditions. Thresholds of 2.25 ± 0.04 and 2.87 ± 0.14 kPa were identified as the maximum limit of method reliability for beech and oak respectively. In highly demanding environments, we suggest a bi-linear extrapolation beyond VPD threshold for better quantifying tree TR. Further experiments aiming at characterizing TR responses to VPD for a broad range of species and in different water deficit conditions are certainly needed for better understanding tree transpiration at the whole stand level.</p>

scholarly journals Responses of petiole sap flow to light and vapor pressure deficit in the tropical tree Tabebuia rosea (Bignoniaceae)

2015 ◽  
Author(s):  
Adam Roddy ◽  
Klaus Winter ◽  
Todd Dawson
Keyword(s):  
Vapor Pressure ◽  
Sap Flow ◽  
Vapor Pressure Deficit ◽  
Water Flux ◽  
Tropical Tree ◽  
Environmental Drivers ◽  
Ratio Method ◽  
Flow Rates ◽  
Leaf Level ◽  
Tabebuia Rosea

Continuous measurements of sap flow have been widely used to estimate water flux through tree stems and branches. However, stem-level measurements lack the resolution necessary for accurately determining fine-scale, leaf-level responses to environmental variables. We used the heat ratio method to measure sap flow rates through leaf petioles and leaflet petiolules of saplings of the tropical tree Tabebuia rosea (Bignoniaceae) to determine how leaf and leaflet sap flow responds to variation in photosynthetically active radiation (PAR) and vapor pressure deficit (VPD). In the morning sap flow rates to east-facing leaves increased 26 minutes before adjacent west-facing leaves. Integrated daily sap flow was negatively correlated with daily mean VPD, and sap flow declined when VPD exceeded 2.2 kPa whether this occurred in the morning or afternoon, consistent with a feedforward response to humidity. Indeed, changes in VPD lagged behind changes in sap flow. In contrast, changes in PAR often preceded changes in sap flow. The sap flow-VPD relationship was characterized by two distinct patterns of hysteresis, while the sap flow-PAR relationship displayed three types of hysteresis, and the type of VPD hysteresis that occurred on a given day was correlated with the type of PAR hysteresis occurring on that day. These patterns highlight how multiple environmental drivers interact to control leaf sap flux and that the development of sap flow sensors capable of measuring individual leaves could drastically influence the amount of data recordable for these structures.

scholarly journals Sap flow through petioles and petioles reveals leaf-level responses to light and vapor pressure deficit in the tropical tree Tabebuia rosea (Bignoniaceae)

2013 ◽  
Author(s):  
Adam Roddy ◽  
Klaus Winter ◽  
Todd Dawson
Keyword(s):  
Vapor Pressure ◽  
Sap Flow ◽  
Vapor Pressure Deficit ◽  
Water Flux ◽  
Tropical Tree ◽  
Ratio Method ◽  
Flow Rates ◽  
Leaf Level ◽  
The Difference ◽  
Tabebuia Rosea

Continuous measurements of sap flow have been widely used to measure water flux through tree stems and branches. However, these measurements lack the resolution necessary for determining fine-scale, leaf-level responses to environmental variables. We used the heat ratio method to measure sap flow rates through leaf petioles and leaflet petiolules of saplings of the tropical tree Tabebuia rosea (Bignoniaceae) to determine how leaf and leaflet sap flow responds to variation in light and vapor pressure deficit (VPD). We found that in the morning sap flow rates to east-facing leaves increased 26 minutes before adjacent west-facing leaves. Although leaves had higher integrated sap flow than their largest leaflet, this difference was not proportional to the difference in leaf area, which could be due to lower conduit area in petiolules than in petioles. In contrast to measurements on main stems, integrated daily sap flow was negatively correlated with daily mean VPD. Furthermore, leaves exhibited previously undescribed patterns of hysteresis in the sap flow-VPD and sap flow-PAR relationships. When hysteresis in the sap flow-PAR relationship was clockwise, the sap flow-VPD relationship was also clockwise; however, when hysteresis in the sap flow-PAR relationship was counterclockwise, the sap flow-VPD relationship displayed an intersected loop. These pattern differences highlight how substantially leaf-level processes may vary within a canopy and how leaf-level processes may not scale predictably to the stem level.

scholarly journals Sap Flow Dynamics and Responses to Grazing and Seasonal Changes in Soil Moisture for Acacia Ancistroclada and Comberatum Molle in a Kenyan Savanna

2020 ◽  
Author(s):  
Joseph Ondier ◽  
Dennis Otieno ◽  
Daniel Okach ◽  
John Onyango
Keyword(s):  
Soil Moisture ◽  
Vapor Pressure ◽  
Flux Density ◽  
Sap Flow ◽  
Seasonal Changes ◽  
Vapor Pressure Deficit ◽  
Livestock Grazing ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Rainfall Patterns

Abstract The Kenyan savanna, which is dominated by Acacia ancistroclada and Comberatum molle, has experienced notable changes in rainfall patterns and increased livestock grazing. A significant decrease in trees spread from 5 % to less than 1 % has been documented for the ecosystem and could be linked to the increased livestock grazing and changes in rainfall patterns, however, scientific evidence is lacking. We utilized sap flow to analyze the hydraulic responses of the prevailing trees to livestock grazing and seasonal changes in soil moisture. Environmental factors including precipitation, air temperature, soil moisture at - 0.3 m, and vapor pressure deficit were simultaneously measured. The results showed that the diurnal variation in sap flux density exhibited a single peak curve at around midday and correlated strongly with vapor pressure deficit and air temperature. Sap flux density was higher in the grazed (27.47 ± 8.65 g m-2s-1) than the fenced plots (20.17 ± 7.27 g m-2s-1). In all the plots, sap flux density followed seasonality in rainfall patterns, increasing and decreasing in wet and dry seasons respectively. The higher crown projected area was responsible for higher sap flow in the grazed plots. The diurnal variation in sap flux density showed that sap flow was coupled to the atmosphere with relatively low boundary layer resistance and the seasonal variation in sap flow was controlled by stomatal regulation. These findings point to the possibility that the dominant tree species in Lambwe are isohydric species. However, additional measurements need to be conducted on the eligibility of the species to confirm the conclusion.

Restriction threshold of vapor pressure deficit for light use efficiency varied with soil water content

2021 ◽  
Author(s):  
Dexin Gao ◽  
Shuai Wang ◽  
Zidong Li ◽  
Fangli Wei ◽  
Peng Chen ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Arid Regions ◽  
Vapor Pressure Deficit ◽  
Water Flux ◽  
Heihe River ◽  
Light Use Efficiency ◽  
Evaporative Water ◽  
Use Efficiency ◽  
Weather Stations ◽  
Using Data

<p>Understanding the constraints on light-use efficiency (LUE) created by high evaporative water demand (vapor-pressure deficit; VPD) and restricted water supply (soil moisture content; SMC) is crucial for understanding and simulating vegetation productivity, particularly in arid and semi-arid regions. However, the relative impacts of VPD and SMC on photosynthesis are unclear, as we lack a mechanistic understanding of them and their interactions. In this study, we quantified the relative roles of VPD and SMC in limiting LUE and analyzed the interactions among VPD, SMC, and LUE in China’s Heihe River Basin using data from CO<sub>2</sub> and water flux stations and weather stations along a climatic gradient. We found a threshold for VPD’s restriction of LUE; above the threshold, LUE decreased at only 3.6% to 23.1% of the rate below the threshold. As SMC decreased, however, the VPD threshold increased, and the reduction of LUE caused by VPD decreased significantly, which is more than half lower than that in moister regions. Therefore, both VPD and SMC played essential roles in LUE limitation and the resulting reduction of photosynthesis caused by water stress. A threshold also existed for heat flux and the correlation between SMC and LUE; the strength of the correlation first decreased and then increased with increasing VPD. Our results clarified the relative impacts of VPD and SMC on photosynthesis, and can improve simulation and prediction of plant productivity.</p>

Biophysical limits to responses of water flux to vapor pressure deficit in seven tree species with contrasting land use regimes

2015 ◽  
Vol 200 ◽  
pp. 258-269 ◽  
Author(s):  
Jianguo Gao ◽  
Ping Zhao ◽  
Weijun Shen ◽  
Junfeng Niu ◽  
Liwei Zhu ◽  
...  
Keyword(s):  
Land Use ◽  
Vapor Pressure ◽  
Tree Species ◽  
Vapor Pressure Deficit ◽  
Water Flux

scholarly journals Responses of petiole sap flow to light and vapor pressure deficit in the tropical tree Tabebuia rosea (Bignoniaceae)

2015 ◽  
Author(s):  
Adam Roddy ◽  
Klaus Winter ◽  
Todd Dawson
Keyword(s):  
Vapor Pressure ◽  
Sap Flow ◽  
Vapor Pressure Deficit ◽  
Water Flux ◽  
Tropical Tree ◽  
Environmental Drivers ◽  
Ratio Method ◽  
Flow Rates ◽  
Leaf Level ◽  
Tabebuia Rosea

Continuous measurements of sap flow have been widely used to estimate water flux through tree stems and branches. However, stem-level measurements lack the resolution necessary for accurately determining fine-scale, leaf-level responses to environmental variables. We used the heat ratio method to measure sap flow rates through leaf petioles and leaflet petiolules of saplings of the tropical tree Tabebuia rosea (Bignoniaceae) to determine how leaf and leaflet sap flow responds to variation in photosynthetically active radiation (PAR) and vapor pressure deficit (VPD). In the morning sap flow rates to east-facing leaves increased 26 minutes before adjacent west-facing leaves. Integrated daily sap flow was negatively correlated with daily mean VPD, and sap flow declined when VPD exceeded 2.2 kPa whether this occurred in the morning or afternoon, consistent with a feedforward response to humidity. Indeed, changes in VPD lagged behind changes in sap flow. In contrast, changes in PAR often preceded changes in sap flow. The sap flow-VPD relationship was characterized by two distinct patterns of hysteresis, while the sap flow-PAR relationship displayed three types of hysteresis, and the type of VPD hysteresis that occurred on a given day was correlated with the type of PAR hysteresis occurring on that day. These patterns highlight how multiple environmental drivers interact to control leaf sap flux and that the development of sap flow sensors capable of measuring individual leaves could drastically influence the amount of data recordable for these structures.

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