A guide to understanding and measuring photosynthetic induction: considerations and recommendations

Photosynthetic induction is the leaf-level process by which a plant assimilates CO₂ from the atmosphere once exposed to a change in light intensity after a period of darkness or shade. In the field, photosynthetic induction can take place hundreds of times in a single day in response to rapid fluctuations in the light environment due to cloud cover, wind, solar angle, and neighbourly shading. In general, the speed of photosynthetic induction is broadly regulated by two main components: the diffusional limitations of CO₂ reaching the sites of carboxylation; and the biochemical limitations associated with the assimilation of CO₂. Quantifying these limitations and exploring genetic diversity can lead to the optimization of photosynthetic efficiency, and consequently, increased plant productivity. Growing numbers of studies have shifted away from characterizing photosynthesis in steady-state light environments in preference to understanding photosynthetic induction under more realistic, dynamic light environments. In this guide, we aimed to promote consistency between studies and facilitate comparison of results with and cross species by: discussing best practice when designing an experiment focussed on measuring photosynthetic induction; providing resources for analysing photosynthetic induction data; and identifying gaps in our collective knowledge relating to photosynthetic induction.