University of Helsinki: Chlorophyll fluorescence, the light from photosynthesis, illuminates our view of plant function

Chlorophyll, the green pigment found in plants and algae, emits faint red and far-red light when illuminated during photosynthesis. This so called chlorophyll-a fluorescence conveys information about the instantaneous rate of photosynthesis, which provides an “optical window” that tracks plant functional and health status.

Although methods to measure and interpret chlorophyll-a fluorescence at the leaf and subcellular levels have been around for decades, it is only recently that chlorophyll fluorescence (known as solar-induced fluorescence, SIF) can be estimated and imaged at the ecosystem and regional scales.

Cutting edge SIF measurements are conducted with hyperspectral optical sensors mounted on towers, drones, aircraft, and even satellites. For example, the FLuorescence EXplorer (FLEX) satellite mission from the European Space Agency is scheduled for launch in 2024 and will provide global maps of SIF at a resolution of a few hundred meters.

These developments pave the way to multiple scientific and commercial applications in plant ecophysiology, ecology, biogeochemistry, as well as precision agriculture and forestry.

“Excitingly, SIF opens up spatial and 3D photosynthesis studies in the field. This will help to resolve long standing research questions related to the photosynthetic dynamics of the different parts of a plant or ecosystem in real world conditions. SIF can also be applied in physiological phenotyping and pre-visual stress detection, which is a powerful tool for next-generation forest and crop management practices,” says