The study looked at how the Goldspur Apple tree's gas exchange is affected by different levels of soil water. They used special equipment to measure photosynthesis and water loss in the leaves of apple trees under varying soil water conditions. The researchers found that as soil water decreased, the photosynthesis rate and water loss from the leaves also decreased. This suggests that the apple trees are sensitive to changes in soil water levels, and maintaining suitable soil water content is important for their growth and water-saving irrigation.