Phenotypes change as response to external factors such as stress and diseases. The external factors change biochemistry and physiology, and this translates into phenotypic features. Physiological phenotyping focuses on non-invasive measurements of such changes. This comprises using imaging technologies such as fluorescence and luminescence imaging, hyperspectral imaging, or NIR/IR imaging which can reveal biochemical changes in the surface proximity that are not detectable in visible light imaging. Moreover, it comprises imaging of symptomatic changes, e.g. wilting or occurrence of leaf spots or discolorations. In addition to measuring plant responses, imaging methods can be used to characterize the stress factors as such, e.g. insects feeding on plants and their movements or nematodes that colonize plant roots.
Image and data processing, particularly including artificial intelligence methods, establishes links between the measured signals and the biological properties of the samples. Applications comprise environmental stress assessments, plant pathological studies, or physiological characterization of plant varieties. Physiological phenotyping is important in plant research, for plant breeding, in climate change research, for plant health monitoring and testing, and in the development of plant treatments for improved cultivation.