<![CDATA[Vapour pressure deficit (VPD) has gained recognition as a physiologically superior microclimate control variable in controlled-environment agriculture, yet no quantitative VPD characterisation exists for emersed cultivation of variegated Anubias barteri var. nana 'Pinto'. This study characterises the VPD microclimate of an ebb-and-flow cyber-physical incubator equipped with an MLX90614 infrared radiometric sensor, two calibrated DHT22 humidity sensors, a DS18B20 nutrient solution sensor, and an ESP32-S3 microcontroller. A 5.36-hour passive commissioning session yielded 1,884 valid data rows at a 10-second logging interval. The mean baseline was 0.703 ± 0.022 kPa, falling within the upper portion of the reference envelope inferred from available literature on emersed Anubias acclimatisation. Indoor relative humidity was identified as the dominant VPD driver (r = −0.695, R² = 0.483), while air temperature showed negligible association (r = −0.008), supporting mist actuation as the appropriate primary control strategy. The MLX90614 recorded a consistent radiometric offset of ΔT_rad = −1.61 ± 0.10 °C relative to indoor air temperature, reflecting the composite FOV average of cooler evaporative surfaces; the resulting was 0.327 kPa (32%) lower than the air-temperature-only estimate, demonstrating that the choice of surface temperature reference has a material effect on the computed VPD. A persistent ambient VPD gradient of +0.540 kPa was documented throughout the session, quantifying the continuous moisture gradient from the incubator interior to the ambient environment. These results establish a quantitative VPD baseline for emersed Anubias cultivation, define the construct validity boundaries of the sensor suite, and provide the empirical foundation for a companion closed-loop Fuzzy-PI VPD controller.]]>
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