fotoinhibioituminen

Fotoinhibioituminen, or photoinhibition, is a process where the rate of photosynthesis decreases under high light conditions. This phenomenon occurs when the light energy absorbed by the photosynthetic apparatus exceeds the capacity of the plant to utilize it for carbon fixation. Consequently, excess light energy can lead to damage within the photosystems, particularly photosystem II (PSII).

The damage typically involves the disruption of the D1 protein, a key component of the PSII reaction center. High light can cause photooxidative stress, where reactive oxygen species (ROS) are generated, further contributing to the damage. Plants have evolved various mechanisms to cope with photoinhibition. These include non-photochemical quenching (NPQ), a process that dissipates excess absorbed light energy as heat, and the repair of damaged PSII components.

Photoinhibition can have significant implications for plant productivity, especially in environments with fluctuating light intensities. While moderate light levels are essential for photosynthesis, prolonged exposure to supra-optimal light can reduce growth rates and biomass accumulation. Understanding photoinhibition is crucial for optimizing agricultural practices and predicting plant responses to changing environmental conditions. The severity of photoinhibition depends on factors such as light intensity, duration, temperature, and water availability.