Physiological Adaptation of Three Halophytes from the Same Ecological Habitat and Analysis of their Supporting Soil

Objectives This study was conducted to investigate the physiological adaptations and metabolic responses of three halophytes: Pulicaria undulata , Tamarix nilotica , and Lycium shawii —during their flowering stage under abiotic stress conditions in Sabkhat Al-Awshaziyah. The study aimed to assess the physical and chemical characteristics of the rhizosphere soils associated with these species. Material and Methods Rhizosphere soil samples were collected from around each species and analyzed for their physical properties, including soil texture and hydraulic conductivity, as well as chemical properties such as cation exchange capacity (CEC) and organic matter (OM) content. To understand plant responses to salinity stress, several physiological and biochemical parameters were measured, including leaf area, total carbohydrate content, photosynthetic pigments (chlorophyll and carotene), and antioxidant enzyme activities (peroxidase and polyphenol oxidase). Results The rhizosphere soils were predominantly sandy. Soils associated with L. shawii and P. undulata showed a medium-coarse texture, while those of T. nilotica were fine sandy. Hydraulic conductivity values were relatively high, ranging from 23.33 to 27 cm h -1 . Overall, soil fertility was low, as reflected by CEC and OM values. The highest CEC was recorded in T. nilotica soil, reaching 12.3 Meq/100 g in the subsurface and 11.27 Meq/100 g at the surface, whereas L. shawii exhibited the lowest values at both depths. Organic matter content followed a similar trend, with T. nilotica showing the highest percentages (0.83% at the surface and 0.74% in the subsurface). In contrast, P. undulata and L. shawii displayed comparable but lower OM values. Regarding physiological traits, T. nilotica had the smallest leaf area (0.66 cm 2 /plant) but accumulated the highest carbohydrate content (31.5%). L. shawii recorded the lowest carbohydrate level (16.8%). Pigment analysis revealed that P. undulata contained the highest levels of chlorophyll and carotene. In terms of antioxidant activity, peroxidase activity was highest in L. shawii (477.33 u/g fresh weight/h), while P. undulata showed the greatest polyphenol oxidase activity (38.94 u/g fresh weight/h). Conclusion The results demonstrate that the studied halophytes employ different adaptive strategies to cope with saline stress. T. nilotica appears to benefit from relatively better soil conditions and higher carbohydrate accumulation, P. undulata maintains stronger photosynthetic pigment levels, and L. shawii exhibits enhanced antioxidant enzyme activity. Collectively, these findings highlight the ecological significance and practical value of these species as potential candidates for the conservation and rehabilitation of saline areas.