Abstract:Stomatal regulation is a key mechanism for plants adapting to changes in water condition. Therefore, it is important to understand the response of stomatal behavior in Populus euphratica seedlings to varying sediment type and groundwater depth, since its recruitment habitats are characterized by great heterogeneity in space for soils and in time for groundwater. This study was carried out at the Akesu National Station of Observation and Research for Oasis Agro-ecosystem in 2020. P. euphratica seedlings were grown in lysimeters to examine the interaction effects between soil texture and groundwater depth on stomatal behavior. Each factor included 3 treatment levels, sandy soil (S1), sandy loam (S2), clay loam(S3) for soil texture, and 30 cm (W1), 60 cm (W2), 90 cm (W3) below soil surface for groundwater. Stomatal conductance (GS), stomatal conductance slope (g1) and stomatal limitation to photosynthesis (LS) under each treatment were obtained during growing season. Our results showed that:(1) GS was not significantly different between groundwater depths under the same soil texture, but different between soil textures under the same groundwater depth, with the GS values for S2 and S3 higher than S1 under W1, S1 and S2 lower than S3 under W2, and decreasing from sandy soil to clay soil under W3. (2) The largest g1 was found under W1 regardless of soil texture, while the differences between soil texture varied with groundwater condition, with the largest g1 occurring at S1, followed by S3 and S2 under W1 and W2, and under W3, the largest value occurring at S3, followed by S2 and S1, respectively. (3) There was no significant differences in LS between groundwater levels under S1 and S3, while the LS values of W2 and W3 were significantly higher than W1 under S2. The differences in LS between soil texture varied with groundwater condition, with the values in S2 and S3 significantly higher than S1 under W1, and under W2 and W3, the largest occurring in S2, followed by S3 and S1, respectively. In conclusion, the response of stomatal behavior in P. euphratica seedlings to groundwater depth was mediated by soil texture, which can be attributed to the effects of soil texture on the development of root system and the vertical distribution of soil water. Thus, soil texture may be a major factor that affects plant-water relationship in early life history for P. euphratica.