An improved sensor for precision detection of<i>in situ</i>stem water content using a frequency domain fringing capacitor

Zhou, Haiyang; Sun, Yifei; Tyree, Melvin T.; Sheng, Weifan; Cheng, Qiang; Xue, Xian; Schumann, Henrik; Lammers, Peter Schulze

doi:10.1111/nph.13157

Cited by 29 publications

(22 citation statements)

References 37 publications

(55 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Development of species‐specific equations describing the relationship between probe output (apparent dielectric permittivity) and stem water content are also important to the accurate determination of stem water content (Wullschleger et al, 1996; Hernández‐Santana and Martínez‐Fernández, 2008). Zhou et al (2015) developed a new frequency domain inner fringing capacitor sensor for measuring the stem water content of crops.…”

mentioning

confidence: 99%

Monitoring of Stem Water Content of Native and Invasive Trees in Arid Environments Using GS3 Soil Moisture Sensors

Saito

Yasuda

Sakurai

et al. 2016

Vadose Zone Journal

View full text Add to dashboard Cite

Dielectric soil moisture sensors have the potential for nondestructive and real-time monitoring of the stem water content (q st ) of living trees. This study was conducted to investigate the water use characteristics of trees in drylands through monitoring of q st using newly developed capacitance sensors (GS3). The plants used for data collection were Prosopis juliflora (Sw.) DC. (mesquite, invasive) in Sudan and Tamarix ramosissima Ledeb. (tamarisk, invasive) and Prosopis pubescens Benth.(screwbean mesquite, native) in the United States. The GS3 probes were installed into the trunks of two trees for each species. Stem-specific calibration equations and temperature calibration equations were derived through laboratory experiments and analysis of field observation data. The temperature calibration equations reduced inappropriate variations of q st caused by daily fluctuations in stem temperature, suggesting that these are essential for correct interpretation of monitoring data of q st in arid environments. The q st of the mesquite trees in Sudan clearly increased after heavy rainfall events and started decreasing when the soil water content became close to the wilting point. These findings indicate that mesquite trees use soil water in rainy seasons, even though they are generally considered to use groundwater through deep tap roots. The q st of neither species in the United States responded clearly to rainfall events, indicating that they depend on shallow saline groundwater. The q st of the tamarisk decreased monotonically throughout the monitoring period, apparently in response to feeding damage caused by the tamarisk leaf beetle (Diohabda sp.), which had been released for biological control of tamarisk.

show abstract

mentioning

confidence: 99%

Monitoring of Stem Water Content of Native and Invasive Trees in Arid Environments Using GS3 Soil Moisture Sensors

Saito

Yasuda

Sakurai

et al. 2016

Vadose Zone Journal

View full text Add to dashboard Cite

show abstract

“…The principle of our measurement circuit is often used in the field of frequency-domain dielectric sensors [20,21,22,23,24,25], and the measurement apparatus is as shown in Figure 1a. The appearance of the corn ear is as shown in Figure 1c.…”

Section: Methodsmentioning

confidence: 99%

Nondestructive In Situ Measurement Method for Kernel Moisture Content in Corn Ear

Zhang

Fan

et al. 2016

Sensors

View full text Add to dashboard Cite

Moisture content is an important factor in corn breeding and cultivation. A corn breed with low moisture at harvest is beneficial for mechanical operations, reduces drying and storage costs after harvesting and, thus, reduces energy consumption. Nondestructive measurement of kernel moisture in an intact corn ear allows us to select corn varieties with seeds that have high dehydration speeds in the mature period. We designed a sensor using a ring electrode pair for nondestructive measurement of the kernel moisture in a corn ear based on a high-frequency detection circuit. Through experiments using the effective scope of the electrodes’ electric field, we confirmed that the moisture in the corn cob has little effect on corn kernel moisture measurement. Before the sensor was applied in practice, we investigated temperature and conductivity effects on the output impedance. Results showed that the temperature was linearly related to the output impedance (both real and imaginary parts) of the measurement electrodes and the detection circuit’s output voltage. However, the conductivity has a non-monotonic dependence on the output impedance (both real and imaginary parts) of the measurement electrodes and the output voltage of the high-frequency detection circuit. Therefore, we reduced the effect of conductivity on the measurement results through measurement frequency selection. Corn moisture measurement results showed a quadric regression between corn ear moisture and the imaginary part of the output impedance, and there is also a quadric regression between corn kernel moisture and the high-frequency detection circuit output voltage at 100 MHz. In this study, two corn breeds were measured using our sensor and gave R2 values for the quadric regression equation of 0.7853 and 0.8496.

show abstract

“…Most of the volume change of stems is in the bark rather than in the wood, and the volume changes of whole stems are less than 0.03% versus several percentages for the volume of bubble collapse, which will happen independently of stem volume change (Irvine and Grace, 1997). Even in crop species, the volume change of stems is much smaller than the water content changes (Zhou et al, 2015). The traditional way to deal with the rehydration kinetics or change in k h with time is to measure the rehydration rate of the stem with no applied pressure and then correct the flow rate measured with an applied pressure for the rehydration rate (Hacke et al, 2000;Torres-Ruiz et al, 2012).…”

Section: Best Estimation Of Bubble Pressure and Other Implicationsmentioning

confidence: 98%

Stem hydraulic conductivity depends on the pressure at which it is measured and how this dependence can be used to assess the tempo of bubble pressurization in recently cavitated vessels.

2015

Self Cite

View full text Add to dashboard Cite

Cavitation of water in xylem vessels followed by embolism formation has been authenticated for more than 40 years. Embolism formation involves the gradual buildup of bubble pressure (air) to atmospheric pressure as demanded by Henry's law of equilibrium between gaseous and liquid phases. However, the tempo of pressure increase has not been quantified. In this report, we show that the rate of pressurization of embolized vessels is controlled by both fast and slow kinetics, where both tempos are controlled by diffusion but over different spatial scales. The fast tempo involves a localized diffusion from endogenous sources: over a distance of about 0.05 mm from water-filled wood to the nearest embolized vessels; this process, in theory, should take ,2 min. The slow tempo involves diffusion of air from exogenous sources (outside the stem). The latter diffusion process is slower because of the increased distance of diffusion of up to 4 mm. Radial diffusion models and experimental measurements both confirm that the average time constant is .17 h, with complete equilibrium requiring 1 to 2 d. The implications of these timescales for the standard methods of measuring percentage loss of hydraulic conductivity are discussed in theory and deserve more research in future.Vulnerability curves (VCs) have been used as a measure of drought resistance of woody plants, and many methods have been used and evaluated to construct VCs (Cochard et al., 2013). Vessels cavitate in response to increasing drought stress and immediately fill with a mixture of water vapor and air. Henry's law of gas solubility in water demands that, eventually, the air pressure in an embolized vessel will equal atmospheric pressure provided that the surrounding water pressure remains low enough. Most presumed, until recently, that the air pressure builds up to atmospheric pressure in 10 to 20 min (Sperry and Tyree, 1988;Tyree and Zimmermann, 2002). In contrast, research has shown that dissolving of air bubbles in stem takes many hours (10-100) depending on water pressure applied and stem diameter Yang and Tyree, 1992), but how long it takes to fully embolize a vessel remains unknown. Recently, cavitron methods have been developed to estimate average bubble pressure by measuring the impact of the water tension on stem hydraulic conductivity when the water pressure adjacent to a bubble changes, causing bubble expansion or compression (Wang et al., 2014b(Wang et al., , 2015.Subatmospheric bubble pressure in vessels makes the measurements of hydraulic conductivity of stems, k h , inaccurate when measured at or near atmospheric pressure, because bubble collapse will cause an increase in k h as shown by traditional measurements (Table I; Tyree Yang and Tyree, 1992) and modern cavitron methods (Wang et al., 2015). Intuitively, if embolized vessels have subatmospheric air pressure, then the air bubbles ought to collapse in volume as the surrounding water tension increases to zero (atmospheric pressure). A collapsing air bubble will result in a vessel partly filled ...

show abstract

An improved sensor for precision detection ofin situstem water content using a frequency domain fringing capacitor

Cited by 29 publications

References 37 publications

Monitoring of Stem Water Content of Native and Invasive Trees in Arid Environments Using GS3 Soil Moisture Sensors

Monitoring of Stem Water Content of Native and Invasive Trees in Arid Environments Using GS3 Soil Moisture Sensors

Nondestructive In Situ Measurement Method for Kernel Moisture Content in Corn Ear

Stem hydraulic conductivity depends on the pressure at which it is measured and how this dependence can be used to assess the tempo of bubble pressurization in recently cavitated vessels.

Contact Info

Product

Resources

About