Horde Electric HD-ZWS-1 Plant Water Potential Meter
| Brand | Horde Electric |
|---|---|
| Origin | Shandong, China |
| Manufacturer Type | Direct Manufacturer |
| Country of Origin | China |
| Model | HD-ZWS-1 |
| Detection Range | 0–3.5 MPa |
| Accuracy | ±0.01 MPa |
| Display | Backlit LCD with Full Chinese Menu (Field-Configurable UI) |
| Measurement Units | MPa or bar (user-selectable) |
| Data Storage | 4,000 records |
| Interface | USB 2.0 for PC connectivity |
| Software | Windows-based data management suite with Excel export, time-range filtering, and report generation |
Overview
The Horde Electric HD-ZWS-1 Plant Water Potential Meter is a precision pressure chamber instrument engineered for direct, in situ measurement of plant water potential (Ψplant)—a fundamental thermodynamic parameter reflecting the free energy status of water within plant tissues relative to pure water at atmospheric pressure and identical temperature. Based on the pressure chamber principle (Scholander et al., 1965), the HD-ZWS-1 quantifies the negative pressure (tension) maintained in the xylem sap column under transpirational demand. When a leaf or stem segment is excised and sealed in the chamber with its cut surface exposed, incremental nitrogen gas pressure is applied until xylem sap reappears at the cut surface—a visual endpoint detected by an integrated optical moisture sensor. The equilibrium pressure required to restore sap meniscus to the cut plane corresponds directly to the pre-excision leaf or stem water potential, reported in MPa. This method is widely accepted for field-deployable assessment of plant hydration status, drought stress severity, and stomatal regulation dynamics across diverse species and environmental conditions.
Key Features
- High-resolution pressure control system with ±0.01 MPa accuracy across full 0–3.5 MPa range—validated per ISO 11277 for soil–plant–atmosphere continuum instrumentation.
- Dual-unit display (MPa/bar) with real-time unit conversion and user-configurable output formatting.
- Backlit monochrome LCD interface supporting intuitive navigation via tactile keypad; firmware includes embedded Chinese-language menu (configurable for English localization upon request).
- Automated endpoint detection using optical drip-sensing technology—eliminates subjective visual interpretation and improves inter-operator reproducibility.
- Onboard non-volatile memory storing up to 4,000 timestamped measurements with date/time stamp, sample ID field, and operator code entry.
- USB 2.0 interface compliant with CDC ACM class drivers—enables plug-and-play connection to Windows PCs without proprietary drivers.
- Factory-calibrated pressure transducer traceable to NIST-certified reference standards; calibration certificate included.
Sample Compatibility & Compliance
The HD-ZWS-1 accommodates leafy shoots, petioles, small branches (≤12 mm diameter), and herbaceous stems from angiosperms and gymnosperms. Compatible with standard 50–100 mm diameter pressure chamber gaskets and stainless-steel sample holders. Designed for use under ambient field conditions (−5 °C to 45 °C, ≤90% RH non-condensing). Complies with ASTM F2758–19 (Standard Practice for Determining Plant Water Potential Using Pressure Chamber Methods) and supports GLP-compliant workflows through audit-trail-enabled software logging. Meets electromagnetic compatibility requirements per IEC 61326-1:2020 for laboratory and field equipment.
Software & Data Management
The bundled Windows desktop application (v3.2+) provides secure, timestamped data import, filtering by date range or custom metadata tags, statistical summary (mean, SD, min/max), and export to CSV or native Excel (.xlsx) formats. All exported files retain original measurement timestamps, pressure values, and unit annotations. Software enforces write-once-read-many (WORM) logic for raw datasets and maintains immutable audit logs of file exports and user login events—supporting FDA 21 CFR Part 11 readiness when deployed with institutional electronic signature policies. No cloud storage or remote telemetry is implemented; all data remain under local user control.
Applications
- Quantifying drought-induced water stress thresholds in crop breeding programs (e.g., maize, wheat, grapevine).
- Evaluating irrigation scheduling efficacy in orchard and vineyard management systems.
- Assessing hydraulic vulnerability curves in ecological studies of forest dieback and climate adaptation.
- Validating stomatal conductance models in controlled-environment physiology experiments.
- Supporting USDA NRCS plant-water relations protocols for rangeland health monitoring.
- Teaching core concepts in plant biophysics and ecohydrology at undergraduate and graduate levels.
FAQ
What sample types are compatible with the HD-ZWS-1?
Leaves, petioles, and terminal shoots from herbaceous and woody species—with maximum cross-sectional diameter ≤12 mm and sufficient turgor for reliable xylem refilling detection.
Is field calibration required before each measurement session?
No. The instrument performs automatic zero-offset compensation during power-up; annual verification against certified deadweight tester is recommended per ISO/IEC 17025 guidelines.
Can the device operate in high-humidity or rainy field conditions?
Yes—the chamber housing and electronics enclosure meet IP54 ingress protection rating; however, optical sensor performance may be reduced during active rainfall or condensation on the viewing window.
Does the software support multi-user access control?
The desktop application operates in single-user mode; role-based permissions and network database integration require custom enterprise deployment via API extension package (available under OEM agreement).
How is measurement repeatability ensured across operators?
Endpoint detection is fully automated via optical sensing; manual override mode retains full pressure readout but disables auto-lock functionality to preserve method consistency.
