Real-Time Monitoring of Osmotic Stress via Extracellular Voltage to Identify Early-Stage Salt Stress

Overview

Soil salinization is a global issue affecting an estimated 20% of irrigated land and costing approximately $27 billion annually in lost productivity. Traditional monitoring relies on visual cues, but symptoms of salt stress only appear after irreversible cellular damage has occurred. In regions with fluctuating watering quality, this delay leads to silent osmotic stress that reduces yields before growers even notice a problem. This project investigated whether plant electrical signals, specifically variation potentials (VPs), can serve as an early indicator of osmotic stress long before visible symptoms appear. It is hypothesized that the plants' VPs would provide an early metric of osmotic stress before actual physical symptoms manifest. In a controlled grow environment (grow-tent, thermostatically controlled heat-mat, timed lights for a controlled photoperiod), multiple plant species were treated with varying molarities of NaCl (0.1M-0.4M). Their VPs were measured inside a Faraday cage (as an electromagnetic shield) with two electrodes connected to a customized noise-reducing 5x signal amplifier and recorded with an Arduino Uno. While reverse-osmosis water induced a positive voltage rise, salt treatments triggered a significant voltage decrease within minutes. This decrease was correlated with salt concentration, providing a clear electrical signal of stress more than 24 hours before the first visual signs (such as loss of leaf turgor) were apparent. By shifting the focus from visual evaluation to the plant's internal biological response, this project demonstrates a viable early-warning system for intervention before salt stress leads to permanent crop loss.

Competition history

• CSEF 2026 Plant Biology (Senior Division) · Entry S-18-12

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