Characterizing Crop Responses to Background Ozone in Open-Air Agricultural Field by Using Reflectance Spectroscopy

We examine the spectral signatures and foliar biophysical and biogeochemical properties of different soybean cultivars that are known to be sensitive in varying degrees to background concentrations of ozone (O₃). Specifically, the potential of plant biophysical variables from leaf reflectance spectra, including chlorophyll index, photochemical reflectance index, and leaf area index, to detect foliar O₃ damage is explored. The study was conducted at an agricultural test site located in Maryland Heights, Missouri, during the summer of 2014 where five different soybean cultivars were planted. Our results show that the soybean cultivars demonstrated different sensitivity to background O₃ as demonstrated by spectral indices and plant biophysical measurements. The outcome of this research has potential implications for development of space-based observation of large-scale crop responses to O₃ damage, as well as for biotechnological breeding efforts to improve O₃ tolerance under future climate scenarios, as background O₃ concentrations are expected to increase through the twenty-first century.