Plastic coverings on the environment of agricultural greenhouses

ABSTRACT Adequate thermal comfort for plant growth in protected environments is associated with properties of translucent coverings. This study investigated the influence of three types of plastic films (diffuser, transparent, and milky) at three agricultural greenhouses in Fortaleza city, CE, Brazil. The objective of this study was to analyze air temperature and relative air humidity conditions, seeking recommendations to optimize plant growth performance in greenhouses. Ten monitoring stations were distributed, three for each plastic covering and one external; readings were taken 2 m above the ground level, using temperature and relative air humidity sensors (SHT31). Data were collected from July 11 to July 27, 2023, with readings every 5 min (totaling 12 readings per hour) and subsequently processed through linear regression. The tested coverings resulted in different temperature and relative air humidity during early morning hours (1 and 5%). The comparison between diffuser and transparent, and diffuser and milky films showed differences at 5 and 1%, respectively, while transparent and milky films did not show differences. The diffuser film exhibited lower temperature variations throughout a 12-hour period. The diffuser covering provided the lowest temperatures and smaller variations throughout the day, which was significantly different from milky and transparent films during warmer hours. These results provide valuable information for optimizing conditions in agricultural greenhouses, contributing to sustainable and efficient practices in protected cultivation.