An automatic and portable Wiltmeter leaf turgor measurement device

• We present an automatic Wiltmeter system to obtain leaf turgor estimative.
• The automatic Wiltmeter presented correlation R2 > 0.9 when compared to a reference instrument.
• Automatic Wiltmeter can be used to periodically measure leaf turgor pressure during several days.
• Automatic Wiltmeter can be used in ecophysiology or irrigation scheduling.

The Wiltmeter is a non-invasive device that provides estimates of leaf cell turgor pressure in the field. It can be used for the quantification of the hydration of leafy vegetables and as supplementary method to gauge the irrigation scheduling efficiency. It also enables direct inferences about the occurrence of water stress on plants. The traditional non-automated Wiltmeter, however, requires careful and tiring procedures and it is also subjected to interference of the operator handling. In that way, the automatic and portable Wiltmeter herein described presents some improvements to make the instrument more robust, easier and practical. Fully automatic and portable versions of the Wiltmeter, prepared with a load cell and a FSR force sensor are described and compared to a reference non-automated instrument. The proposed automatic Wiltmeter has shown a correlation R2 greater than 0.9 and curve slope close to one in both prototypes when compared to a reference non-automated Wiltmeter, showing that the new automatic Wiltmeter is a practical and reliable device for non-destructive leaf turgor studies and analysis, which even can be set to perform stand alone periodic measurements.