Diurnal variation of photosynthesis and stomatal conductance along a latitudinal gradient
Light drives photosynthesis and is one of the keys to control stomata opening. At high latitudes, the midnight sun gives light throughout the diurnal cycle for extended periods. Photosynthesis is one of the major players in the carbon cycle and plant transpiration in the hydrological cycle. Transpiration is also important for the energy balance in an area, thus influencing climate. Therefore, these two processes are important parts of climate modelling.t
Laboratory study: light quality, light intensity and plant physiological activity
Stomata opening is an active process. Plants keep their stomata open when there is a need for replacement of CO2 in the internal foliar air spaces, that is when there is light to drive photosynthesis. Blue light is often shown to be the signal that controls stomata opening. This is balanced against the water availability, since plants lose water through open stomata. Drought causes plants to close stomata.
We will set up experiments simulating growing conditions in southern and northern Norway and compare the performance of plants originating from low and high latitudes.
By this, we wish to find out whether the assumptions about plant responses to their physical environment should be the same for plants adapted to growing with darkness during night and plants living at high latitudes with light also during night in the growing season.
Further, this experiment can be combined with ozone exposure, if we find that morning twilight influences daytime stomatal conductance significantly. The ones with less open stomata are then expected to be less influenced by ozone. Otherwise, we could add a drought period and study whether plants with more closed stomata are less affected. Transpiration can be affected both during day, twilight and night.
Ane Vollsnes and Anne K Brysting, July 2020.