Sweet potato cultivars were studied to see how different amounts of water affected their growth and water use efficiency. The researchers found that the sweet potato plants used water more efficiently when they were given 75% of the recommended amount. The plants also grew more leaves when given more water, with the best growth seen at 100% of the recommended amount. The plants had lower leaf water potential and less growth when they didn't get enough water. Overall, the study showed that the relationship between soil moisture and plant growth is important for managing irrigation effectively.