How strongly does the time of day affect the dynamic response of photosynthesis to light intensity fluctuations?

In nature and in greenhouses, plants are often exposed to highly fluctuating light environments, causing their rates of photosynthesis to respond dynamically. Since faster responses of plants to light intensity fluctuations can result in faster growth and yield, this type of research has become a “hot topic” in photosynthesis research and crop production. To compare different genotypes, researchers often characterize how quickly photosynthesis can respond to a step increase in light intensity. However, this may also differ depending on when the measurement is conducted: we have data suggesting that the time of day can have strong effects on the rapidity of the photosynthesis response to a light intensity change. This change of magnitude and rapidity of the response during the day has been observed before, but there is still no identified mechanism describing this process. Therefore, more data are needed to characterize this time of day effect in major horticultural crops (e.g. tomato, cucumber, sweet pepper, lettuce) and to pinpoint which processes influence it. In this project, you get the chance to conduct a detailed study on the time of day effects on the dynamics of photosynthesis in one or several major horticultural crops, and on the processes and limitations underlying any changes throughout the day.

Used skills

• Gas exchange measurements,
• Possibly chlorophyll a fluorescence measurements,
• Data analysis

Interested in doing a BSc or MSc thesis at HPP? Please contact the HPP student coordinator Katharina Hanika.