PARADe: A low-cost open-source device for photosynthetically active radiation (PAR) measurements

Abstract

In agriculture, proximal in-field information is crucial for a precise management of crop growth. A low-cost, miniaturized and innovative device, named PARADe (PAR Acquisition Device), is designed for in-field photosynthetically active radiation (PAR) acquisition. It combines an affordable PAR line quantum sensor (PAR/LE, SOLEMS) and an open source development platform (microcontroller) based on Arduino Integrated Development Environment. The quality of the measurement of the PARADe acquisition chain has been validated. The calibration is done by comparison (R2=0.99) with a robust acquisition chain composed of a certified PAR sensor (PQS1, Kipp and Zonen) and a data-logger (CR1000 Campbell Scientific). The accuracy of PARADe measurements is evaluated through three indicators, relative error, RMSE and normalized RMSE. They demonstrate that the PARADe system has certain operating limitations especially for low solar angles (sunset and sunrise) due to the choice of a line quantum sensor. This does not affect the accuracy and reliability of the results, but indicates that the PARADe device is specifically adapted to collect daily cumulative PAR values.