Drought and salinity are considered to be the major limiting factors for plant growth in desert areas. Halophytes can maintain their growth in extreme salt environments. However, few studies have linked the photosynthetic characteristics of halophytes with their anatomical structures and leaf water potential to jointly explain the effects of drought and salt on leaf internal water use efficiency (WUEi). For this reason, two different halophytes, Nitraria sibirica and Alhagi sparsifolia, were selected to analyze the leaf physiological traits in response to different water and salt gradients. The analysis further revealed the influence of soil water and salt content and anatomical characteristics on plant photosynthesis. The results showed that the leaf water potential, morphology, anatomical parameters, and photosynthetic parameters of the two plants in different habitats showed significant species-specific physiological responses. The value of WUEi of N. sibirica was negatively correlated with net photosynthetic rate (Pn), stomatal conductance (Gs), tightness of palisade tissue (CTR), and soil factors, while the WUEi of A. sparsifolia was positively correlated with Pn, Gs, and CTR. The indirect effects of soil salinity and soil moisture on WUEi were also found to be species-specific. This study will help to improve the understanding of the ecological adaptability of plants to water and salt stress and provide a theoretical basis for clarifying the drought tolerance and salt tolerance adaptation strategies of halophytes in arid areas.

Anabasis aphylla is a salt and alkali resistant shrub grows in arid and semi-arid areas, which is also a constructive species of desert soil. To reveal the population structure and genetic diversity in populations of A. aphylla, a total of 106 samples were used as experimental materials for sequencing by specific-locus amplified fragment sequencing. In total, we obtained 300105 SNP which had high consistency. Phylogenetic tree of A. aphylla result showed there was a certain difference between these samples, which can be divided into two groups. The Shanon–Wiener index of A. aphylla was 0.4440 and the Nei diversity index was 0.2854. AMOVA analysis showed there was genetic differentiation among the seven groups to a certain level. The genetic diversity analysis showed the genetic variation of A. aphylla mainly from groups. This study provides a reference for further comprehensive study of the genetic structure and evolutionary adaptation of A. aphylla.