## 3 Results
### Effects of Different Salt Concentration Treatments on Physiological Indexes of Halophytes
The maximum values of Gs for Pa were 0.57, 0.40, 0.32, 0.27, and 0.20 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\), respectively. The daily mean values of Gs for the three halophytes decreased with increasing salt concentration. The daily means of Gs for Ha, Tc, and Pa were all highest at a salt concentra  
Figure 7: Characteristics of daily changes in Gs of halophytes under different salt concentration treatments. (**a**) Ha. (**b**) Tc. (**c**) Pa. (**d**) Daily average of stomatal conductance. Different lowercase letters in the graphs indicate significant differences under different salt concentration treatments (\(p<0.05\)). tion of 0 mmol\(\cdot\)L\({}^{-1}\) and were 0.54, 0.41, and 0.34 mmol\(\cdot\)m\({}^{-2}\cdot\)s\({}^{-1}\), respectively. Compared with the control, the daily mean values of Gs for Ha, Tc, and Pa at salt concentrations ranging from approximately 150 to 300 mmol\(\cdot\)L\({}^{-1}\) showed a significant decrease (\(p<0.05\)). Ha decreased by 19.70%, 33.95%, 46.17%, and 59.72%, respectively. Tc was reduced by 12.37%, 26.59%, 38.73%, and 48.21%, respectively. Pa was reduced by 22.66%, 38.74%, 51.05%, and 67.83%, respectively. 3.4 Characteristics of Daily Changes in Intercellular Carbon Dioxide Concentration (Ci) in Halophytes Under Different Salt Concentration Treatments  
Under different salt concentration treatments, the daily changes in Ci in the three halophytes showed a \"W\" trend of decreasing, then increasing, and then increasing, with the lowest values occurring at 11:00 and 17:00, respectively (Figure 8). The Ci of Ha decreased to a minimum of 219 mmol\(\cdot\)mol\({}^{-1}\) at 11:00 under the treatment with a salt concentration of 0 mmol\(\cdot\)L\({}^{-1}\). In contrast, the Ci of Ha was minimized at 17:00 under salt concentration treatments ranging from approximately 150 to 300 mmol\(\cdot\)L\({}^{-1}\): 172.33, 121.33, 280, and 315.33 mmol\(\cdot\)mol\({}^{-1}\), respectively. Similarly, the lowest values of Ci for Tc and Pa were observed at 17:00 under the treatment with salt concentrations ranging from 0\(\sim\)300 mmol\(\cdot\)L\({}^{-1}\). The lowest values of Ci for Tc were 244, 184.67, 145, 118.67, and 274.33 mmol\(\cdot\)mol\({}^{-1}\), respectively. The lowest values of Ci for Pa were 174, 150.33, 107.67, 239.67, and 270.67 mmol\(\cdot\)mol\({}^{-1}\), respectively. Figure 8: Characteristics of daily changes in Ci of halophytes under different salt concentration treatments. (**a**) Ha. (**b**) Tc. (**c**) Pa. (**d**) Daily average of intercellular carbon dioxide concentration. Different lowercase letters in the graphs indicate significant differences under different salt concentration treatments (\(p<0.05\)). With the increase in salt concentration, the daily mean Ci values of the three halophytes showed a trend of decreasing and then increasing. Ha and Pa were minimized at a salt concentration of 200 mmol\(\cdot\)L\({}^{-1}\), whereas Tc was minimized at a salt concentration of 250 mmol\(\cdot\)L\({}^{-1}\). Compared with the control, the daily mean values of Ci for Ha showed a significant (\(p<0.05\)) decrease at salt concentrations of 150-200 mmol\(\cdot\)L\({}^{-1}\) by 13.89% and 33.86%, respectively. A significant increasing trend (\(p<0.05\)) was observed at salt concentrations of 250-300 mmol\(\cdot\)L\({}^{-1}\), which increased by 12.71% and 27.97%, respectively. Notably, although the daily mean values of Ci at salt concentrations of 150 mmol\(\cdot\)L\({}^{-1}\) for Tc and Pa were reduced compared with the control, the difference was not significant (\(p>0.05\)). The daily mean Ci values of Tc at salt concentrations of 200-250 mmol\(\cdot\)L\({}^{-1}\) showed a significant (\(p<0.05\)) decrease compared with the control, by 25.67% and 35.33%, respectively. A significant increasing trend (\(p<0.05\)) was observed at a salt concentration of 300 mmol\(\cdot\)L\({}^{-1}\), which increased by 13.16%. The daily mean Ci of Pa showed a significant (\(p<0.05\)) decrease of 39.18% at a salt concentration of 200 mmol\(\cdot\)L\({}^{-1}\) treatment compared with the control.