# Effect of Planting _Portulaca oleraca_ L. on Improvement of Salt-Affected Soils
## 1 Introduction  
Soil salinization has emerged as a globally escalating environmental crisis that threatens agricultural sustainability and food security [1]. Current estimates indicate that approximately 1 billion hectares of land worldwide are affected by salinization, with this figure continuing to rise at an alarming rate [2]. In recent decades, the rapid advancement of urbanization has led to a large amount of cultivated land becoming occupied, resulting in continuous reduction in cultivated land area, which undoubtedly brings huge pressure to food production [3]. For China, a country with scarce land resources, a small cultivated land area, and a wide distribution of salt-affected soil, saline-alkali land management is an important measure to ensure national food security from a strategic height and an important link to alleviate the contradiction between people and land and promote the sound and rapid development of the national economy [4, 5]. Conventional amelioration approaches, including hydraulic engineering measures and chemical amendments, have demonstrated limited effectiveness in addressing salinization challenges [6, 7, 8]. These traditional methods are frequently constrained by high implementation costs, operational complexity, and the potential for secondary environmental contamination. In contrast, the utilization of salt-tolerant plants for phytoremediation represents a promising alternative strategy. This phytoremediation approach offers distinct advantages through its cost-effectiveness, environmental compatibility, and potential economic returns from cultivated species. As such, it embodies a sustainable, eco-friendly, and economically viable solution for saline-alkali soil reclamation and can be widely applied worldwide for the restoration of such degraded lands [9]. Studies have demonstrated that certain halophytic species can absorb saline ions from salt-affected soils and enhance both the physicochemical properties and structural characteristics of saline soils [10, 11]. Purslane, _Portulaca oleraca_ L, is an herbaceous plant belonging to the Portulacaceae family that exhibits strong stress resistance (including tolerance to salinity, drought, and poor soil conditions), high photosynthetic efficiency, minimal susceptibility to pests and diseases, and low requirements for pesticides and fertilizers [12, 13]. It is widely distributed across the globe. Under suitable temperature and light conditions, _P. oleraca_ develops a unique high-yield growth pattern due to its C4 photosynthetic advantage, strong regenerative capacity, and efficient resource utilization [14]. With a short growth cycle, _P. oleraca_ can trigger an axillary bud regeneration mechanism by retaining 2-3 basal nodes during harvesting, resulting in multiple regenerative branches and allowing for repeated harvesting. In recent years, studies have revealed that _P. oleraca_ possesses significant potential for the remediation of saline-alkali soils. _P. oleraca_ demonstrates the ability to grow normally under certain levels of salt stress, exhibiting strong salt tolerance [15, 16]. Remarkably, it can absorb salts from the soil and thrive and complete its life cycle even in high salt-affected conditions [17]. Nevertheless, the studies on _P. oleraca_ have primarily focused on its physiological traits, with limited exploration of its role as a dominant species for ecological restoration in salt-alkali land. The effects of planting _P. oleraca_ in the ecological remediation of coastal salt-affected soils remain poorly understood. Therefore, the objectives of this study were to (1) determine _P. oleraca_ capacity of salt removal in coastal saline soils with different salinity concentrations, (2) compare its effects on the physicochemical properties of salt-affected soils, and (3) further clarify its phytoremediation potential in saline-alkali lands.