Cotton plants in an oasis region were studied to see how they use water and sunlight to grow. The researchers found that in late June, the plants were better at photosynthesis and used more water compared to early August. The plants were most active during the day and didn't slow down in the middle of the day. In August, the plants didn't do as well because there was less water in the soil and the leaves were getting old. Overall, the plants were efficient in using water to make food through photosynthesis.