Maximizing photosynthesis under strong light fluctuations

Photosynthesis is the motor for plant growth, and depends heavily on light. The intensity of sunlight on a leaf can fluctuate a lot from minute to minute. Previous research in tomatoes shows that with a rapid transition from low light to intense light, it takes the plant more than 10 minutes before the photosynthesis process reaches the max efficiency level that is possible at that high intensity. This inertia is not constant, but depends on a number of factors, such as light level, CO2, temperature and air humidity. Model calculations show that if there was no inertia, photosynthesis on an annual basis would be at least 10 percent higher.

The goal of this project is to increase the utilization of (sun) light by reducing the slowness of photosynthesis by smartly switching on and off LED lighting, in interaction with setpoints for CO2, temperature and air humidity. This way photosynthesis can be greatly increased during short periods of high light intensity. Furthermore, energy can be saved by turning off lights during and immediately after the period with high light intensity, as the light utilization is extremely low then.

This three-year project includes the following four research goals:

1. Screening different crops: The slowness of photosynthesis is established in five crops. The choice of crops is tomato, cucumber, rose, chrysanthemum and a pot plant. A number of varieties are also examined per crop.

2. Slowness of photosynthesis in relation to climate factors: In one of the crops the slowness of photosynthesis is measured under different climate conditions and a simulation model for inertia of photosynthesis is made.

3. Sensor for photosynthesis inertia: A method is developed to use existing fluorescence sensors to monitor the slowness of photosynthesis. The simulation model from project 2 will also be linked to the sensor in order to continuously determine the inertia and to indicate how the efficiency of light utilization can be improved by adjusting lighting (and climate).

4. Assessment of energy-efficient lighting strategy: A standard lighting regime is compared with a strategy that takes into account the inertia of photosynthesis.

Philips is contributing €21,000 to this project. Wageningen University will submit this proposal to NWO/TTW (Netherlands Organization for Scientific Research), and two postdoc researchers and a HBO researcher will be appointed to this project. The total project budget will be in the hundreds of thousands of euros. NWO is expected to provide a definite answer to the proposal around summertime.

Source: Kas als Energiebron