## 3 Results
### Effects of Different Salt Concentration Treatments on Physiological Indexes of Halophytes
Figure 5: Characteristics of daily changes in Pn of halophytes under different salt concentration treatments. (**a**) Ha. (**b**) Tc. (**c**) Pa. (**d**) Daily average of net photosynthetic rate. The error bar above the graph represents the standard error. The same below. Different lowercase letters in the graphs indicate significant differences under different salt concentration treatments (\(p<0.05\)). The daily mean Pn values of the three halophytes decreased with increasing salt concentration. The daily mean values of Pn for Ha, Tc, and Pa were all highest at a salt concentration of 0 mmol\(\cdot\)L\({}^{-1}\) and were 21.55, 15.03, and 14.29 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\), respectively. Both Ha and Pa showed a significant decreasing trend (\(p<0.05\)) in the daily mean Pn at salt concentrations of 150-300 mmol\(\cdot\)L\({}^{-1}\) compared with the control. Ha decreased by 15.11%, 29.42%, 44.74%, and 57.15%, while Pa decreased by 19.62%, 34.88%, 50.31%, and 67.61%, respectively. The daily mean Pn of Tc at a salt concentration of 150 mmol\(\cdot\)L\({}^{-1}\) was not significantly different (\(p>0.05\)) from that of the control but was significantly different (\(p<0.05\)) from that of the control at salt concentrations of 200-300 mmol\(\cdot\)L\({}^{-1}\). 3.2 Characteristics of Daily Changes in Transpiration Rate (Tr) of Halophytes Under Different Salt Concentration Treatments  
As can be seen from Figure 6, the daily variation in Tr of the three halophytes was consistent with the daily variation in net photosynthetic rate and also showed a \"bimodal\" trend. Tr peaked at 11:00 and 17:00 for all three halophytes and was significantly higher at 11:00 than at 17:00. The Tr maxima of Ha were 8.23, 6.37, 5.30, 4.80, and 4 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\) at salt concentrations ranging from approximately 0 to 300 mmol\(\cdot\)L\({}^{-1}\) treatment, respectively. The Tr maxima for Tc were 9.63, 7.87, 7.24, 6.30, and 5.71 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\), respectively. The Tr maxima for Pa were 9.03, 6.73, 4.87, 4.57, and 4.03 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\), respectively. Figure 6: Characteristics of daily changes in Tr of halophytes under different salt concentration treatments. (**a**) Ha. (**b**) Tc. (**c**) Pa. (**d**) Daily average of transpiration rate. Different lowercase letters in the graphs indicate significant differences under different salt concentration treatments (\(p<0.05\)). The daily mean Tr values of all three halophytes showed a gradual decreasing trend with increasing salt concentration. The daily mean values of Tr for Ha, Tc, and Pa were all highest at a salt concentration of 0 mmol\(\cdot\)L\({}^{-1}\) and were 5.82, 7.57, and 6.21 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\), respectively. It decreased to a minimum at a salt concentration of 300 mmol\(\cdot\)L\({}^{-1}\), where Ha, Tc, and Pa decreased by 50.98, 44.51, and 55.73%, respectively, compared with the control. At salt concentrations of 150-300 mmol\(\cdot\)L\({}^{-1}\), the daily means of Tr for Ha, Tc, and Pa were all significantly different from the control (\(p<0.05\)). 3.3 Characteristics of Daily Changes in Stomatal Conductance (Gs) of Halophytes Under Different Salt Concentration Treatments  
Under the treatment of different salt concentrations, the daily change pattern of Gs of the three halophytes was shown in Figure 7, which showed a trend of increasing, then decreasing, then increasing, and then decreasing, which was basically consistent with the daily change pattern of the net photosynthetic rate. The maximum value of Gs was observed at 11:00 for all three halophytes. The maximum values of Gs for Ha were 0.81, 0.68, 0.57, 0.46, and 0.37 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\) at salt concentrations ranging from approximately 0 to 300 mmol\(\cdot\)L\({}^{-1}\) treatment, respectively. The Gs maxima for Tc were 0.73, 0.59, 0.50, 0.36, and 0.30 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\), respectively.