Low-Cost Solar Radiation Measurement for the Estimate of Carbon Uptake Rate of Plants

This study presents a flexible Internet of Things (IoT) monitoring system suitable for gas sensing, applicable to the pervasive experimental assessments of CO2 concentrations, particularly in relation to plant respiration and chlorophyll photosynthesis. Beyond CO2 measurement, the system incorporates the monitoring of other parameters meaningful for photosynthesis and possible plants stress factors, such as solar radiation intensity, temperature and water vapor concentration. Concerning the solar radiation monitoring, two low-cost sensing techniques are proposed based on the measurement of the short circuit current of a monocrystalline silicon photovoltaic (PV) panel and on CdS light dependent resistors (LDRs). A preliminary experimental campaign for the measurement of global and diffuse radiation is performed outdoors and the outcomes are compared with the acquisitions of a commercial pyranometer. Then, tests are performed in the laboratory with an experimental setup envisaging a closed accumulation chamber housing some plants exposed to diffuse radiation, with the final goal of monitoring the CO2, temperature and water vapor changes inside the chamber and of providing a rough assessment of the mean daily CO2 uptake of the plants under test.