Canopy conductance (g_c) is the key parameter to quantify eco-hydrology processes. Salinity stress is one of the most important abiotic stresses to growth of crops in arid and semi-arid areas. Understanding the influence of salinity on stomatal movement and accurately describing g_c under salt stress are of great significance to quantify agro-hydrology processes affected by salt. Therefore, we measured stomata conductance (g_s) of sunflower leaves at different growth stages and soil salinity conditions in two consecutive years. At the same time, the evapotranspiration above canopy and the dynamic changes of soil moisture and salinity in root zone were continuously monitored. It was found that under the same meteorological conditions, leaf g_s decreased with the increase of soil salt content. Relatively, g_s was more sensitive to salt at seedling and maturity stages than at budding and flowering stages. Furthermore, an empirical formula describing the effect of soil salinity on g_s was added to the Jarvis multi-factor multiplication g_s model, which used leaf area index (LAI) as a parameter to express the salt tolerance of different growth stages. Effective LAI was used to upgrade the model from leaf scale to canopy scale. g_c calculated by Penman-Monteith equation using the farmland canopy evapotranspiration measured by the eddy covariance system was used to evaluate the applicability of model. The results showed that the model could simulate g_c well on both the half-hour and the daily average scale. Nash-Sutcliffe efficiency coefficient of the daily average scale model was about 0.65, and determination coefficient of the simulation results of different scales in two years were all above 0.66. Our findings could improve the understanding of influence of salinity on stomatal movement in such areas and provided a basis for simulating canopy evapotranspiration and photosynthesis under salt stress.

冠层电导 ( g _c ) 是量化生态水文过程的关键参数。盐分胁迫是干旱和半干旱地区作物生长最重要的非生物胁迫之一。了解盐度对气孔运动的影响并准确描述盐胁迫下的g _c对于量化受盐分影响的农业水文过程具有重要意义。因此，我们测量了气孔导度（g _s) 连续两年不同生长阶段和土壤盐分条件的向日葵叶片。同时，持续监测冠层以上的蒸散量和根区土壤水分和盐度的动态变化。发现在相同气象条件下，叶片g _s随土壤含盐量的增加而减小。相对而言，g _s在幼苗和成熟阶段比在萌芽和开花阶段对盐更敏感。此外，在 Jarvis 多因子乘法g _{s 中}添加了描述土壤盐分对g _s影响的经验公式该模型以叶面积指数（LAI）为参数来表达不同生长阶段的耐盐性。使用有效 LAI 将模型从叶尺度升级到冠层尺度。用涡度协方差系统测得的农田冠层蒸散量通过Penman-Monteith方程计算得到的g _c用于评价模型的适用性。结果表明，该模型能够模拟g _c在半小时和每日平均规模上都很好。日均尺度模型的Nash-Sutcliffe效率系数约为0.65，两年不同尺度模拟结果的决定系数均在0.66以上。我们的研究结果可以提高对盐度对这些地区气孔运动影响的理解，并为模拟盐胁迫下的冠层蒸散和光合作用提供基础。