## 1 Introduction  
Salinization is one of the main causes of land desertification and land degradation. At present, salinization has become a global ecological and resource problem and a major ecological crisis facing mankind [1]. According to FAO statistics, saline soil is distributed in more than 100 countries and regions around the world, and the total area of saline soil in the world has reached 954 million hm\({}^{2}\). In the above total saline soil area, Oceania accounts for about 37.5%, Asia for about 33.3%, America for about 15.4%, Africa for about 8.5%, and Europe for about 5.3% [2]. With climate change and the unsustainable development and utilization of resources by human beings, the area of salinized land is gradually expanding. At present, the area of salinized land worldwide is increasing at a rate of 1-1.5 million hm\({}^{2}\) per year. The salinized land in China accounts for 10.38% of the total salinized soil area worldwide. The saline land in the northwest region alone accounts for 69.03% of the total saline land area in China, accounting for a large proportion [3]. Salinization has become one of the main limiting factors of ecological construction in northwest China, which seriously restricts the development and utilization of agricultural and forestry resources in this area. Many scholars from different countries have conducted extensive research on soil salinization. In the last century, [PERSON] et al. found that groundwater and arid climate play an important role in the formation of saline soil [4]. [PERSON] et al. analyzed the salinized soil in eastern Greece and found that the salt content of the soil could be reduced using the pipe drainage method [5]. [PERSON] et al. improved the saline soil in northern Iran through deep tillage measures and found that although the vertical distribution of soil salt was changed after deep tillage, the overall soil salt did not decrease [6]. Many studies have found that planting halophytes is an economical and effective method for improving land salinization [7]. Researchers in India and African countries have successfully cultivated many salt-tolerant plants by planting and developing them on saline soil and successfully applied them to land salinization improvement [8]. [PERSON] not only cultivated halophytes with strong salt tolerance but also successfully improved land salinization in southern Australia using halophytes [9]. There are about 1560 species of halophytes worldwide, among which there are 300-400 species of halophytes with certain economic value. There are many kinds of halophytes, but the types of halophytes differ due to variations in environmental factors such as soil and climate in different regions. On the basis of previous studies, [PERSON] classified halophytes into three different types according to the transport, storage, and secretion characteristics of salt ions in halophytes: eulabolophytes, recreeolabolophytes, and pseudohalophytes, with each type of halophyte having a unique morphological structure and physiological functions [10]. Photosynthesis and physiological functions are fundamental to ensuring yield formation in the process of plant growth and development. When soil salinization occurs, plants will be subjected to osmotic stress, which will inhibit photosynthesis and the physiological functions of plants [11]. [PERSON] et al. found that salt stress clearly inhibited the photosynthesis of _Morus alba_ seedlings [12]. Different halophytes differ in sensitivity and tolerance to salt, and the effects of salt stress on their photosynthetic characteristics and physiological characteristics also differ [13]. For example, [PERSON] et al., focusing on the Yinbei area in Ningxia, found that salt stress has a great influence on photosynthesis and the physiological function of _Festuca ovina_ but little influence on _Helianthus annuus_ as a whole [14].