The study looked at how alfalfa plants in Beijing change their photosynthesis throughout the day. They found that the plants have two peaks in their photosynthesis, with a dip in the middle of the day. The rate at which the plants release water and take in carbon dioxide follows a similar pattern to their photosynthesis. The plants' stomata, tiny openings on their leaves, also play a role in this process. Overall, the midday drop in photosynthesis is mainly due to factors other than the stomata.