Effects of Different Tree Ages on Leaf Water Potential and Photosynthetic Characteristics of Populus euphratica

【Objective】 to reveal the effects of different tree ages on leaf water potential and photosynthetic characteristics of Populus euphraticain Xinjiang. 【Methods】 The leaf water potential and photosynthetic parameters of Populus euphraticaat two tree ages (3 and 5 years) were chosen for analysis. 【Results】 (1) The diurnal process of leaf water potential of two tree ages of Populus euphraticashowed a "V" shape in general, and the younger the tree age, the weaker the photosynthetic capacity and the higher the leaf water potential; (2) The changes of photosynthetic factors were also different with different tree ages. The daily mean values of intercellular CO₂ concentration, stomatal conductance and water use efficiency of 5-year-old Populus euphraticawere significantly higher than those of 3-year-old Populus euphratica(P< 0.05); (3) The leaf water potential of Populus euphraticaat two tree ages in the rapid growth period was significantly positively correlated with the transpiration rate of physiological factors (P< 0.01), and both showed the weakening of photosynthesis caused by stomatal constraints. 【Conclusion】 The changes of leaf water potential of Populus euphraticaat two tree ages vary with different tree ages, and the diurnal variation characteristics of photosynthesis of Populus euphraticaat different tree ages are not significant. In general, with the increase of tree age, the photosynthetic capacity of Populus euphraticais improved, and the water use efficiency and productivity of Populus euphraticaare higher.