Use of Thermal Imaging and Spectral Data to Detect Water Stress in Green Bean

It is important to detect water stress before physiological activities of plants permanently change. Otherwise production might decrease dramatically. Many researches showed that thermal imaging or spectral data, collected from plant leaves or canopy, have potential to determine plant water stress. In this study, our objective was to determine water stress on green beans (Phaseolus vulgaris L. cv. Gina) using both thermal imaging technique and spectral reflectance data. In order to determine water stress of green bean, experiment were formed with four irrigation levels (100% of the water consumed (I–100), 75% (I–75), 50% (I–50), and 25% (I–25). Thermal images and spectral data were collect using infrared thermal camera and spectro–radiometer respectively. It was found that the total amount of irrigation and seasonal evapotranspiration were found between 232–681 mm and 379–804 mm, respectively. According to the classification and regression tree analysis, it was found that water stress could be better explained by thermal indices especially in I-100 level. In this study, It was concluded that there are several indices calculated both from thermal images (crop water stress indices calculated empirically (CWSIe) and based on reference surface (CWSIa)) and spectral data (Structural Independent Pigment Index (SIPI) and Normalized Difference Vegetation Index (NDVI)), could be used to determine the green beans water stress levels.