Spectral and thermal response of Heliconia psittacorum species to induced water stress

Abstract

An important limitation in agricultural production is stress resulting from water deficit. Flower production and postharvest life both decrease in Heliconia psittacorum affected by water stress. Remote sensing provides tools for estimating the water status of plant species using spectral information in the visible and infrared range. This paper presents a study of reflectance in the 350-800 nm range and the response in the thermal infrared of leaf tissue under different irrigation regimes. For the measurement of reflectance, an OceanOptics® Micro-Spectrometer was used, while for the thermal infrared measurements, a FLIRE40® camera was used. Three irrigation regimes were established: T1: 100% field capacity (FC), T2: 50% FC, and T3: 10% FC. Significant differences were found between treatment T1 and treatments T2-T3 in the water stress index (CWSI) and stomatal conductance index (GI). The reflectance around 800 nm decreased for T2 and T3. Significant differences were obtained between T1 and T2-T3 in the maximum of the first derivative of the reflectance between 700 and 750 nm. It was found that, in the range 350-800 nm, the thermal indices were better indicators of the water status of the Heliconia species than the spectral indices.

Keywords

• thermal índices
• spectral reflectance
• water déficit
• vegetation indices.