Alfalfa, as a high-quality forage resource, has high nutritional value. Due to the high phenotypic similarity among its varieties and the susceptibility to environmental influences, challenges are encountered in variety identification and breeding. In this study, 23 simple sequence repeat (SSR) markers were screened to distinguish 49 alfalfa varieties, among which 21 SSR markers showed polymorphic fragments. The results indicated that these 21 markers were highly polymorphic, with an average of 5.91 alleles per SSR marker locus and an average polymorphic information content (PIC) of 0.66, suggesting a strong discriminatory efficiency. The results of a population genetic diversity analysis showed that there was a relatively high level of genetic diversity among the tested materials. The analysis of molecular variance (AMOVA) results indicated that the genetic variation within the population of the 49 alfalfa germplasm samples was the main source of the total variation. The results of genetic distance and genetic identity analyses showed that the genetic relationship between population 1 and population 4 was the most distant, while the relationship between population 2 and population 3 was the closest. The cluster analysis results showed that samples S16 and S55 formed a separate branch; that is, there were two main genetic subgroups. These results confirm that SSR markers are effective tools for genetic characterization and precise discrimination of alfalfa varieties and have important application values in breeding, variety registration, and germplasm resource conservation.

Saline–alkali land is widely distributed worldwide, and poses significant challenges to agricultural productivity and ecological restoration, particularly in the Qaidam Basin. This study investigates the effects of intercropping and mixed sowing systems of oats (Avena sativa L.) and forage peas (Pisum sativum L.) on hay yield and soil chemical fertility in mildly saline–alkali soils of the Qaidam Basin. Through a comprehensive analysis of hay yield, soil chemical properties, and enzyme activities under different sowing methods (mixed sowing, intercropping, and monoculture) and row spacings (30, 25, 20 and 15 cm), an optimal planting pattern was identified. The 25 cm intercropping treatment produced the highest amount of fresh biomass (2242 kg hm⁻¹), with an increase ranging from 3.17% to 70.44% compared to other treatments. Additionally, this treatment led to significant reductions in soil pH and electrical conductivity (by 3.87–8.31% and 5.13–6.05%, respectively), while enhancing organic matter content and enzyme activities. The intercropping system also demonstrated higher ammonium nitrogen and available phosphorus contents compared to the mixed sowing system. Structural equation modeling revealed that row spacing indirectly influenced both hay yield and enzyme activities, with the 25 cm row spacing proving to be the most effective. A comprehensive evaluation using the TOPSIS model further affirmed that the 25 cm intercropping system significantly enhanced hay yield, soil chemical properties, and enzyme activities, making it the most suitable planting pattern for sustainable land management in the study area. Therefore, the 25 cm intercropping model not only optimizes hay yield, but also improves soil quality and ecological functions in saline–alkali land, offering valuable insights and practical recommendations for the sustainable use of saline–alkali land in the Qaidam Basin.

Interactions between species give rise to chemical pathways of communication that regulate the interactions of transboundary species. The communication between nematodes and other species primarily occurs through the regulation of chemicals, with key species including plants, insects, bacteria, and nematode-trapping fungi that are closely associated with nematodes. G protein-coupled receptors (GPCRs) play a crucial role in interspecies communication. Certain flp genes, which function as GPCRs, exert varying degrees of influence on how nematodes interact with other species. These receptors facilitate the transmission of corresponding signals, thereby completing the interactions between species. This paper introduces the interactions between nematodes and other species and discusses the role of GPCRs in these organisms, contributing to a deeper understanding of the impact and significance of GPCRs in cross-border regulation between nematodes and other species. Furthermore, it is essential to leverage GPCRs in efforts to control pests.