In this study, the effects of exogenous abscisic acid (ABA) on the growth and physiolo-gical characteristics of Machilus yunnanensis seedlings were examined under well water supply conditions (70%-75% field capacity, FC) and different drought stress conditions, i.e., light drought stress (50%-55% FC) and severe drought stress (30%-35% FC), respectively. The results showed that drought stress reduced leaf relative water content, plant height, and total biomass of seedlings significantly decreased, as well as net photosynthetic rate and maximal photochemistry efficiency (Fv/Fm), but enhanced root/shoot and malondialdehyde contents (MDA). Exogenous ABA improved the adaptability of seedlings under drought stress, especially under severe drought stress, with leaf relative water content being improved 21.0%. Plant height and biomass allocation were improved by exogenous ABA under drought, while root/shoot was improved by 1.1 times compared with the well watered plants. The accumulation of MDA was decreased, the activities of CAT and SOD were significantly increased, and the proline content was increased 6.7 times by exogenous ABA under drought. Exogenous ABA application alleviated the negative effect of drought on photosynthetic organs, reduced the decrease of net photosynthetic rate and stomatal conductance under drought, and enhanced Fv/Fm value. The results suggested that exogenous ABA treatment could enhance the resistance of M. yunnanensis to drought stress.A 9-year-old poplar plantation was cultivated by drip irrigation and furrow irrigation in the sandland of ancient Yongding River in Daxing District of Beijing. Soil moisture sensors were set up in main soil layers (20, 40, 60 and 80 cm) with most roots distributed. The intelligent collector was used to monitor soil moisture in real time to investigate soil moisture dynamics and forest productivity under different irrigation patterns. The results showed that after a single effective drip irrigation and furrow irrigation, the vertical depth of wet body formed along the tree row was 72 cm and 143 cm, and the cross-sectional area of wet body was 0.41 and 2.71 m2, respectively. The amount of irrigation was 79.20 and 776.47 m3·hm-2 respectively, with the latter being 9.8 times of the former. The duration was almost the same (11 d) when soil moisture went down to the level of slight water deficit (the soil moisture content=70% of field moisture carrying capacity) in the 0-40 cm layer where poplar absorption roots mainly distributed. From April to October 2019, total irrigation amount of three times furrow irrigation in May, July and September was 2329.41 m3·hm-2, and that of drip irrigation was 1425.60 m3·hm-2, 18 times in total. There were 109 days during which poplar trees suffered moderate water deficit (the soil moisture content ≤60% of field moisture carrying capacity) under furrow irrigation, whereas no moderate water deficit happened under drip irrigation during the whole growing season. Annual increment of standing volume was 38.92 m3·hm-2 under drip irrigation, which was 1.5 times of that under furrow irrigation (25.43 m3·hm-2). Our results suggested that different irrigation resulted in significant difference in productivity of poplar plantation.To explore the water consumption characteristics of trees, the thermal dissipation probe technology was used to monitor sap flow of Populus bolleana in east sandy land of Yellow River, from July to November in 2017. Microclimate variables were monitored. We analyzed the diurnal and seasonal variations of water consumption, and proposed the models for water consumption with back propagation neural network (BPNN) and Elman neural network (ENN) based on fuzzy rules. Results showed that the average sap flow rate of P. bolleana was 4.98 g·cm-2·h-1 in growing season (July to October), with solar radiation (Rs), temperature (T), vapor pressure deficit (VPD) and relative humidity (RH) as the main factors affecting sap flow. Due to the influence of meteorological factors, water consumption was characterized by obvious seasonal variation, with that in summer (July-August) being 1.4 times of that in autumn (September-October). BPNN and ENN models based on fuzzy rules were used to simulate water consumption of P. euphratica. The optimal parameter calibration of two models explained more than 80% of the total variation, which indicated that these two models could more accurately simulate water consumption. Compared with the BP neural network model, the simulated results of ENN model showed that the relative error was reduced by 27.0%, RMSE was reduced by 24.3%, Nash-Sutclife efficiency coefficient increased by 67.9%, R2 was higher than 0.80. The ENN model performed better than BPNN model with a higher efficiency and goodness of fitness. ENN model effectively improved the simulating accuracy of water consumption. Therefore, it could be used as an optimal model to estimate water consumption of P. bolleana in east sandy land of Yellow River.We evaluated the adaptability of Granier's empirical formula in the measurement of trunk sap flow in Populus tomentosa. The thermal diffusion probe method (TDP) was used to mea-sure sap flow rate, and the whole tree weighing was simultaneously measured for each tree. We compared results from the Granier empirical formula with that from the whole tree weighing to find out whether Granier formula had any error in measuring the trunk sap flow of P. tomentosa. The transpiration rate by the whole tree weighing method and the temperature difference coefficient K by the thermal diffusion method were fitted with power exponential regression to establish a corrected Granier formula. Compared with the transpiration rate measured by the whole tree weighing method, sap flow rate calculated by the Granier empirical formula was underestimated by 67.7%. Therefore, a calibrated Granier correction formula of P.  https://www.selleckchem.com/products/terephthalic-acid.html  tomentosa was established Fd=0.0135K0.6952(R2=0.77). The calculated result from this calibrated formula was only 3.4% lower than the transpiration rate estimated with the whole tree weighing method, which showed good consistency. Thus, the calculation of the P. tomentosa sap flow rate should be corrected when using the Granier empirical formula.