The Impact of Long-Term Dry-Season Irrigation on Eucalyptus Tree Height Growth: Insights from Leaf Photosynthesis and Water Conduction

Tree height is a crucial characteristic of plant ecological strategies and plantation productivity. Investigating the influence of dry-season irrigation on the tree height growth in Eucalyptus plantations contributes to a deeper understanding of precise improvement and sustainable development in such plantations. We conducted a field experiment in a Eucalyptus plantation with three-year fertilization and five-year dry-season irrigation to compare their effects on height growth rate during wet vs. dry seasons. Our findings revealed that long-term dry-season irrigation significantly increased the height growth rate of Eucalyptus urophylla x E. grandis by improving leaf hydraulic conductivity and photosynthetic rate during the dry season. However, in the wet season, the tree height growth rate in the fertilization treatment outperformed the other treatments significantly. Interestingly, we also found that leaf photosynthetic capacity contributed more to accelerating height growth than water conduction within the leaves. By examining the differences in leaf structural and functional traits, our results shed light on the impact of long-term dry-season irrigation on the height growth of E. urophylla x E. grandis plantations. Furthermore, this research provides both theoretical and empirical evidence supporting the application of dry-season irrigation and the potential for further enhancing plantation productivity in seasonally arid areas.