*Article* **Growth Stage-, Organ- and Time-Dependent Salt Tolerance of Halophyte** *Tripolium pannonicum* **(Jacq.) Dobrocz.**

**Agnieszka Ludwiczak 1,\*, Anna Ciarkowska 2, Ahmad Rajabi Dehnavi 1,3, Stefany Cárdenas-Pérez <sup>1</sup> and Agnieszka Piernik <sup>1</sup>**


**Abstract:** *Tripolium pannonicum* (Jacq.) Dobrocz. is a member of the diverse group of halophytes with the potential for the desalination and reclamation of degraded land. The adaptive processes of *T. pannonicum* to salinity habitats are still not well recognized. Therefore, we evaluated the effect of NaCl (0, 200, 400, and 800 mM) on: (1) two plant growth stages, (2) the activity of antioxidant enzymes and concentration of H2O2 and the proline in roots, stems, and leaves, and (3) the effect of long- and short-term salt stress on physiological responses. Germination, pot experiments, and a biochemical analysis were performed. The effective *T. pannonicum*'s seed germination was achieved in the control. We demonstrated that halophyte's organs do not simply tolerate high-salt conditions. The activities of APX, POD, and catalase observed at 400 mM and 800 mM NaCl were varied between organs and revealed the following pattern: root > leaves > stem. Proline was preferentially accumulated in leaves that were more salt-tolerant than other organs. Salt stress enhanced the activity of antioxidant enzymes and concentrations of salinity stress indicators in a time-dependent manner. Our study has indicated that salt tolerance is a complex mechanism that depends on the growth phase, organs, and duration of salinity exposure. The results have potential for further proteomic and metabolomic analyses of adaptive salt tolerance processes.

**Keywords:** salinity; halophytes; *Tripolium pannonicum*; proline; hydrogen peroxide; antioxidant enzymes
