Utilizing a Greenhouse Activities Streamlining System Towards Accurate VPD Monitoring for Tropical Plants

Plants from places with tropical climates need higher humidity than those native to arid regions. Most greenhouse crops prefer relative humidity between 70% and 80% [1]. However, the ideal relative humidity also depends on the temperature and plants require a higher humidity when the temperature is high and a lower humidity when it is low. Nonetheless, instead of relative humidity, the more accurate way to express the driving force of water loss from a leaf is Vapor Pressure Deficit (VPD). Its value is independent of temperature. VPD is the difference between the amount of moisture in the air and how much moisture the air could potentially hold when it is saturated. The objective of this study is to monitor air VPD in a tropical lowland shelter-house or greenhouse. A custom-designed real-time Data Acquisition system with an Arduino based microcontroller, touch screen panel and sensors for monitoring aerial parameters and soil moisture were developed, calibrated and tested. The watering system, lighting control system, ventilation and the temperature sensors are the main fundamental components of the Greenhouse prototype which bring controllable factors to monitor and manipulate the VPD, thus, giving lighting and comfort to the general atmosphere. The effectiveness of the unmanned control system were tested and monitored apropos to manual scenario and processes of maintaining an acceptable greenhouse atmosphere. The prototype was successfully used for VPD monitoring and prediction based on temperature, moisture and relative humidity inputs. In a week test, the gathered data were statistically analyzed and different means from a normal distribution were rejected at any significant level. The result of this study can be used in further studies such as decision support systems' database for controlling and maintaining tropical lowland plant production environments.