Evaluation of thermal and optical properties measurements of paspalum in modular green roof in a tropical environment

Abstract

The objective was to evaluate the use of thermal and optical properties measurements in the characterization of the genus Paspalum for use on green roofs in a tropical environment. The experiment was conducted at the Universidade Federal Rural de Pernambuco – UFRPE from May to June 2019. The number of sixteen Paspalum accessions with prostrate and upright growth habits was evaluated. In a simulated modular green roof were evaluated: Soil-Adjusted Vegetation Index (SAVI); leaf (L) and canopy (C) temperature by thermometry (TM); and by thermography (TG). The determination coefficient (R2) between SAVI and the coverage area are of 0.84, with green matter (R2 = 0.73) and dry matter (R2 = 0.56). No significant difference was observed between the accessions for leaf temperature measure by TM and TG, and for canopy TM. Nevertheless, significant difference to canopy TG were observed, with lower canopy temperatures in accessions with upright growth habit than those with prostrate habit. The relationship between the techniques showed high values of determination coefficient to TML with TGL (R2 = 0.85) and TMC with TGC (R2 = 0.91). Given the above, the SAVI can be used to estimate the coverage area capacity (CC). Leaf and canopy temperatures can be used as an indication of water deficit in Paspalum accessions, using both the infrared thermometer (more accessible) and the thermographic camera. Canopy thermography can also be used to evaluate the thermal performance of green roofs. Thermographic images indicated that Paspalum accessions of upright growth habits may provide better thermal comfort.