Understanding the relationship between tree production and water use, as well as the main environmental and plant-related drivers of water use, is crucial for the development of production prediction models and reliable water management strategies under different climatic conditions. However, the relation between tree water use and biomass production has never been assessed throughout the entire rotation for poplar trees. Meanwhile, it remains poorly understood how the transpiration driving factors of poplars will change with stand age. Therefore, we investigated the relationship between transpiration (E) and aboveground biomass (ABM), as well as the main drivers of E for 2- to 5-year-old (2016–2019) Populus tomentosa trees under three water treatments. The annual increase in ABM depended on annually accumulated E and their relationship could be fitted with a logistic curve in each growing season (R² > 0.89). Throughout the whole rotation period, compared with the non-irrigated trees, full irrigation trees produced 59% more biomass with only 12% more E, while deficit irrigation trees attained 46% more biomass with 32% more E. The daily E had a strong exponential relationship with vapor pressure deficit (D) during years 3–5 of the rotation, and the asymptote of this relationship increased with tree age (1.6 kPa (2017), 2 kPa (2018), 2.5 kPa (2019)). The E was also strongly linearly correlated to solar radiation (R_s) for each year although with slightly weaker relationships than for D. Similar to other poplar species, P. tomentosa showed effective stomatal control on E. However, soil water content had almost no effect on E for all treatments, no matter which soil layer was considered. D and R_s were the major drivers of P. tomentosa transpiration during the growing season, even during drought periods, in the study region. Our findings will not only help to deepen the understanding of poplar water use characteristics and the underlying mechanisms, but also help to develop models for predicting the biomass production.

理解树木生产与用水之间的关系，以及与环境和植物有关的主要用水驱动因素，对于开发不同气候条件下的生产预测模型和可靠的水资源管理策略至关重要。然而，从未对杨树的整个轮作过程中的树木用水和生物量生产之间的关系进行过评估。同时，人们仍然对杨树的蒸腾驱动因子将随着林分年龄的增长而发生变化的了解仍然很少。因此，我们研究了蒸腾作用（E）与地上生物量（ABM）之间的关系，以及2至5岁（2016–2019年）毛白杨的E的主要驱动因素。树木经过三种水处理。ABM的年增长率取决于每年累积的E，并且它们的关系可以在每个生长季节拟合出logistic曲线（R ² > 0.89）。在整个旋转周期，与非灌溉树木相比，充分灌溉树木产生更多的59％的生物质仅具有12％以上ê，而充分灌溉树木获得更多46％的生物质用32％更ë。在旋转的第3-5年，日E与蒸气压亏缺（D）有很强的指数关系，并且这种关系的渐近线随着树龄的增加而增加（1.6 kPa（2017），2 kPa（2018），2.5 kPa（ 2019））。该Ë每年与太阳辐射（R _s）的线性关系也很强，尽管与D的关系略弱。与其他杨树种相似，毛白杨对E表现出有效的气孔控制。然而，土壤水分含量对几乎没有影响Ë所有治疗，无论哪个土层进行了审议。d和[R_小号是主要的驱动毛白杨研究区域在生长季节甚至干旱期间的蒸腾作用。我们的发现不仅有助于加深对杨树水分利用特征及其潜在机理的理解，而且有助于建立预测生物量生产的模型。