Abstract
In the present study, three ecotypes of Xanthium strumarium L. were collected from different ecological regions, i.e., Uchalli (E-1), Sargodha (E-2), and Samundri (E-3) in Punjab province, Pakistan. All ecotypes were assessed for their salt resistance and remediation capacity at different NaCl levels (T-1 (control), T-2 (50 mM), T-3 (100 mM), and T-4 (150 mM)). Xanthium responses to varied NaCl levels were investigated for growth, anatomical, and physio-biochemical attributes. A comparative account of different attributes revealed a performance difference between three ecotypes. Biomass of all ecotypes was reduced, but the minimum reduction in biomass was noticed in E-1 as compared to other ecotypes. Comparison of control and NaCl-treated Xanthium plants indicated highest reduction (96.3%) for both chlorophyll a and chlorophyll b observed under T-4 in E-3 as compared to E-1 and E-2. Maximum increase in carotenoids was observed in E-2 (82.2%) under T-4. Shoot Na+ correspondingly increased in all ecotypes with NaCl levels and maximum Na+ in E-3. Minimum absorption of Cl- ion was observed in E-1. Osmoprotectants in three ecotypes were much higher under elevated NaCl levels than that of control plants. A significant increase in total soluble sugars was recorded in E1 (76.82%) and E2 (45.35%) as compared to E3. Additionally, significant anatomical changes in stem, leaf, and root of X. strumarium L. were observed in all three ecotypes grown under NaCl conditions. E1 ecotype showed large vascular bundle cell area (119.23%), (110.95%), (56.34%), epidermal thickness (152.21%), (187.40%), (117.28%) of leaf, root, and stem, respectively, as compared to E2 and E3 ecotypes. Similarly, E1 ecotypes showed the highest percentage increase in root sclerenchyma cell area (93.46%), stem epidermal cell area (246.66%), stem cortical cell area (114.23%), and stem sclerenchyma cell area (92.5%) as compared to E2 and E3 ecotypes. These findings endorse differential capabilities of different ecotypes of the same plant with reference to the changes in studied attributes. Overall, results indicate that X. strumarium L. withstood high NaCl stress (150 mM) and can be an eco-friendly source for the phytoremediation of saline soils. It could serve as a foundation for future research on the plant adaptability. We recommend use of this plant for restoring saline-degraded and marginal soils.