Cluster mulberry plants were studied under different soil moisture conditions to understand their photosynthesis and water use efficiency. The researchers found that the plants had two peaks in photosynthesis rates during the day, with the highest values occurring under normal soil moisture. Water use efficiency was highest in the morning and decreased throughout the day. Stomatal conductance and photosynthesis decreased under drier conditions, indicating that water availability affects plant growth. Overall, the study shows that cluster mulberry plants adjust their photosynthesis and water use efficiency based on soil moisture levels.