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.

Polycomb group (PcG) proteins, which are important epigenetic regulators, play essential roles in the regulatory networks involved in plant growth, development, and environmental stress responses. Currently, as far as we know, no comprehensive and systematic study has been carried out on the PcG family in Medicago truncatula. In the present study, we identified 64 PcG genes with distinct gene structures from the M. truncatula genome. All of the PcG genes were distributed unevenly over eight chromosomes, of which 26 genes underwent gene duplication. The prediction of protein interaction network indicated that 34 M. truncatula PcG proteins exhibited protein–protein interactions, and MtMSI1;4 and MtVRN2 had the largest number of protein–protein interactions. Based on phylogenetic analysis, we divided 375 PcG proteins from 27 species into three groups and nine subgroups. Group I and Group III were composed of five components from the PRC1 complex, and Group II was composed of four components from the PRC2 complex. Additionally, we found that seven PcG proteins in M. truncatula were closely related to the corresponding proteins of Cicer arietinum. Syntenic analysis revealed that PcG proteins had evolved more conservatively in dicots than in monocots. M. truncatula had the most collinearity relationships with Glycine max (36 genes), while collinearity with three monocots was rare (eight genes). The analysis of various types of expression data suggested that PcG genes were involved in the regulation and response process of M. truncatula in multiple developmental stages, in different tissues, and for various environmental stimuli. Meanwhile, many differentially expressed genes (DEGs) were identified in the RNA-seq data, which had potential research value in further studies on gene function verification. These findings provide novel and detailed information on the M. truncatula PcG family, and in the future it would be helpful to carry out related research on the PcG family in other legumes.

Insufficient forage is a significant factor limiting the development of animal husbandry in high-altitude pastoral areas. This study aims to identify suitable high-quality forage Triticale (x Triticosecale Wittmack) varieties for cultivation in the Qaidam Basin and determine their optimal harvest period. Seven triticale varieties were selected as experimental materials, and their production performance and nutritional quality were comprehensively analyzed at four different growth stages [booting stage (BTS), heading stage (HDS), flowering stage (FLS), and milk stage (MKS)] in 2024 and 2025, utilizing Pearson correlation analysis, PCA, and TOPSIS methods. The results indicated that as the reproductive period progressed, plant height, dry matter yield, and dry matter content exhibited a continuous increase. In contrast, indicators such as stem diameter, number of green leaves, and fresh biomass yield initially increased before subsequently declining. The MKS soluble sugar content (SS) and relative feed value (RFV) were the highest, crude protein (CP) and crude ash content (CA) decreased, the neutral detergent fiber content (NDF) and the acid detergent fiber (ADF) content reached their peak in the HDS. The relative forage quality (RFQ) reached its peak during the flowering period. Comprehensive analysis showed that the top five rankings are QSM-8 > JSM-3 > QSM-1 > JSM-2 > QSM-7. In the Qaidam Basin, the optimal harvest period from the FLS to the MKS ensures both high yield and good nutritional quality, making it suitable for promotion in the Qaidam Basin region and similar ecological zones.

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.

Oats (Avena sativa L.) are forage grasses moderately tolerant to saline-alkali soil and are widely used for the improvement and utilization of saline-alkali land. Using the oat varieties collected from the Qaidam Basin as experimental materials, based on the analysis data of the main agronomic traits, quality, and soil physical and chemical properties of different oat varieties at the harvest stage. The hay yield of Molasses (17,933.33 kg·hm⁻²) was the highest (p < 0.05), the plant height (113.59 cm) and crude fat (3.02%) of Qinghai 444 were the highest (p < 0.05), the fresh-dry ratio (2.62), crude protein (7.43%), and total salt content in plants (68.33 g·kg⁻¹) of Qingtian No. 1 were the highest (p < 0.05), and the Relative forage value (RFV) of Baler (122.96) was the highest (p < 0.05). In the 0–15 cm and 15–30 cm soil layers of different oat varieties, the contents of pH, EC, total salt, Ca²⁺, Mg²⁺, and HCO₃⁻ showed a decreasing trend at the harvest stage compared to the seedling stage, while the contents of organic matter, total nitrogen, Cl⁻, and SO4²⁻ showed an increasing trend. The contents of K⁺ and Na⁺ maintained a relatively balanced relationship between the seedling stage and the harvest stage in the two soil layers. Qingtian No. 1, Qingyin No. 1, and Molasses all rank among the top three in terms of production performance and soil physical and chemical properties, and they are the oat varieties suitable for cultivation in the research area.

(1) Background: This study used the cold-tolerant cultivar “Daye No. 3” (DY) and the cold-sensitive cultivar “Longdong” (LD) as plant materials to study the metabolic changes in plant hormones in alfalfa (Medicago sativa L.) under cold stress. (2) Methods: The targeted quantitative detection of phytohormones in alfalfa was carried out by liquid chromatography–tandem mass spectrometry (LC-MS/MS) technology. Principal component analysis (PCA), orthogonal signal correction, and partial least squares discriminant analysis (OPLS-DA) were used to investigate sample classification and screen differential metabolites. (3) Results: The results showed that 17 differential metabolites were detected. Seven metabolites showed common changes in the two cultivars after low-temperature stress induction. The levels of tryptamine, N-jasmonoylisoleucine, trans-zeatin riboside, isopentenyladenine riboside, cis-zeatin riboside, and gibberellin A7 were decreased, while N6-isopentenyladenine levels increased. In addition, compared with the LD variety, DY had more metabolite changes in response to low-temperature stress. Abscisic acid and trans-zeatin were elevated, whereas IAA-alanine, dihydrozeatin riboside, and indole-3-carboxaldehyde showed reduced concentrations. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that differential plant hormones were more active in plant hormone signal transduction, zeatin biosynthesis, and tryptophan metabolism pathways. In addition, a total of 12 metabolites in these three pathways showed common changes under cold stress. (4) This study identified significant metabolomic differences between two alfalfa genotypes under stress. It highlighted key pathways and provided new insights into the metabolic changes of alfalfa under cold-stress conditions.