Nutrient enrichment is a key driver of plant diversity loss in grassland ecosystems. However， the specific pathways and mechanisms underlying species diversity reduction under different nutrient additions influence remain insufficiently understood. This study investigated the effects of nitrogen （N）， phosphorus （P）， and combined nitrogen and phosphorus （N+P） additions on alpine meadows located on the eastern edge of the Tibetan Plateau， using the natural community as a control. The main objective was to examine changes in species richness， biomass， and light transmission， and to elucidate the direct and indirect mechanisms contributing to species richness decline under these experimental treatments. The results showed as follows：（1） N was identified as the primary limiting nutrient for aboveground biomass. Both N and N+P additions significantly increased aboveground biomass （P<0.05）， primarily due to an increase in the biomass of grasses； （2） N and N+P additions significantly reduced species richness （P<0.05）， whereas P addition alone had no significant effect； （3） The mechanisms underlying the reduction in species richness under N and N+P treatments were consistent and involved both direct effects of nitrogen and indirect effects via increased aboveground biomass， which in turn reduced light availability.

Shrub encroachment， which significantly alters structure and function of grassland ecosystems， is a critical ecological issue in China. To obtain a comprehensive and quantitative understanding of the research trends on shrub encroachment research in China， this study conducted a bibliometric analysis using CiteSpace and a meta-analysis based on published literatures on shrub encroachment in China since 1970s. Research on shrub encroachment in China had developed rapidly in recent years， with a primary focus on the drivers of shrub encroachment and its impacts on soil， vegetation， and biodiversity. Studies on shrub encroachment in China had been predominantly conducted in drylands and alpine regions. Major drivers of shrub encroachment included grazing management， climate change， habitat characteristics， and fire. Shrub encroachment was found to have a negative impact on soil quality but a positive effect on community composition， as well as the structure of vegetation and microbial communities in China. The primary management techniques for shrub encroachment included grazing exclusion， grazing management， physical removal， and prescribed burning. This study provides scientific insight into the drivers， impact， and future management strategies for shrub encroachment in Chinese grassland. In the future， it is necessary to strengthen large-scale dynamic assessments of shrub encroachment across diverse grassland types， and integrate remote sensing technology to enhance the scientificity and effectiveness of monitoring and management of encroached landscape in China.

Heat shock transcription factor （HSF）， widely found in eukaryotes， are one of the most crucial transcriptional factors families in the plant resistance to heat stress. HSF has highly conserved DNA-binding domain （DBD）， which is involved in complex stress signal transduction and response networks. HSF， as a terminal component of the signal transduction chain， mediated the expression of target genes under abiotic stress. In response to stress， HSF is phosphorylated and ubiquitinated by upstream protein kinases or binds to heat shock elements （HSEs） through ABA signaling pathway to regulate the expression of downstream genes such as heat shock proteins （HSPs）， thereby improving plant stress resistance. In this study， the discovery， structure， classification， regulatory mechanism of HSF and its role in plant response to abiotic stress （extreme temperature， drought， high salinity， heavy metal， et al.） were reviewed， and the future research direction was expected to provide theoretical basis and gene resources for the genetic improvement of crop and forage stress resistance.

Leymus chinensis is an important native forage grass species in China， yet its low seed setting rate greatly constrains large-scale production and utilization. To identify the key traits influencing seed setting and to evaluate their relative contributions， this study examined 100 Leymus chinensis germplasms collected from different geographic origins. Fifteen traits closely related to seed setting were measured， including seed number， spike weight， seed weight， floret number， spikelet number， spike length， number of spike knots， vegetative plant height， reproductive plant height， leaf length， leaf width， seed setting percentage， thousand seed weight， and the number of vegetative and reproductive branches. The results showed that there was substantial genetic variation among the germplasms， with coefficients of variation for the 15 traits ranging from 10.88% to 56.05%. Correlation analysis showed that spike weight， seed number， seed weight， and thousand seed weight were significantly and positively correlated with seed setting rate， indicating their central roles in reproductive success. Multiple regression and hierarchical partitioning analyses demonstrated that seed number had the greatest contribution to seed setting rate， accounting for 31.57% of variation. Principal component analysis indicated that the first five principal components collectively explained 78.126% of the total variance. Based on a comprehensive evaluation of these traits， ten germplasms （77， 23， 24， 37， 35， 20， 57， 10， 22， 7） were identified as superior germplasms with high reproductive potential and stable performance across multiple traits.

Salt stress leads to the accumulation of reactive oxygen species （ROS） in plants， causing damage to plant cells. However， the enzymatic antioxidant system is responsible for scavenging ROS in plant cells and protecting cells from ROS damage. At present， there are few functional analyses of genes related to ROS-scavenging enzymes in alfalfa （Medicago sativa） in response to salt stress. Based on the transcriptome data of roots and leaves of salt-tolerant alfalfa cultivar （GIB） and salt-sensitive cultivar （LS） under salt stress， this study identified 28 differentially expressed genes related to ROS-scavenging. Twenty-eight genes are distributed on 19 chromosomes， belonging to five gene families： MsGST， MsPOD， MsAOX， MsGRX and MsPrdx， among which MsGST （12） and MsPOD （11） families account for the largest proportion. The physicochemical properties of ROS scavenging enzyme proteins were different among the members of each gene family. There were highly similar conserved motifs in the members of the gene family. Phylogenetic analysis showed that MsGSTUs and MsPODs were located in the branches defined by Tau and AtPERs in Arabidopsis thaliana， respectively， suggesting that they had similar evolutionary processes and similar functions.Real-time fluorescence quantitative PCR analysis showed that the expression levels of MsGSTU26， MsPOD2 and MsPOD4 genes in GIB leaves under salt stress were significantly higher than those in LS， and the promoter regions of the three genes had elements （G-box and CGTCA-motif） related to adverse stress. It indicated that the MsGSTU26， MsPOD2 and MsPOD4 genes may be involved in the regulation of the adaptability of GIB and LS to salt stress.

Grassland restoration is a critical pathway toward achieving sustainable utilization and high-quality development goals for degraded ecosystems. While scientific evaluation of restoration outcomes provides essential evidence for optimizing rehabilitation strategies， current methodologies predominantly focus on pre- and post-restoration changes in individual or limited indicators （e.g.， biomass， vegetation coverage）， with insufficient attention to comprehensive multi-indicator assessments. To address this issue， this study used factor analysis to comprehensively evaluate eight restoration approaches and nine ecological restoration effect assessment indicators for degraded grasslands in Chen Barag Banner， Inner Mongolia， aiming to identify representative community assessment indicators and suitable restoration approaches. The findings demonstrated that： （1） Three critical indicators-vegetation coverage， aboveground biomass， and community species richness-were identified as representative metrics for restoration evaluation. （2） The integrated approach combining fencing with root pruning， fertilization， and sustained management practices demonstrated superior restoration effectiveness. Our comprehensive quantitative assessment methodology exhibited both scientific rigor and practical applicability. These findings provide an evidence-based framework for evaluating and managing grassland restoration initiatives in Inner Mongolia's degraded steppes and comparable ecoregions.

The desert steppe is increasingly affected by severe degradation， and enclosure has been recognized as an effective method for restoring degraded grasslands. Therefore， understanding the effects of enclosure on plant species diversity and aboveground biomass in desert steppes is essential for grassland conservation. This study investigated the effects of different enclosure durations （3 years， 13 years， 18 years， and 20 years） on plant communitiy characteristics， species diversity， and aboveground biomass in the Siziwang Banner and Zhurihe grasslands. The results showed that aboveground biomass exhibited an increasing trend with extended enclosure duration. The important values of perennial grasses， such as Cleistogenes songorica and Stipa breviflora， gradually increased， whereas those of degradation indicator species， including Salsola collina， Convolvulus ammannii， and Neopallasia pectinata， progressively declined， or even disappeared. Vegetation height and canopy coverage increased as enclosure duration extended. In plots enclosed for 13 years， the response ratios of the dominance index， diversity index， richness index， and evenness index reached their peak values. Meanwhile， in plots enclosed for 18 years， aboveground biomass attained its maximum value. A positive correlation was observed between aboveground biomass and the response ratio of the diversity index. This study provides scientific evidence for the restoration of desert steppe ecosystems， demonstrating that enclosure measures effectively promote ecosystem recovery and enhance vegetation community structure.

Phytolith-occluded organic carbon （PhytOC）， which is a part of the organic carbon encapsulated during the silicification process in grassland plants， constitutes an important component of the grassland carbon sink. The sequestration of PhytOC is important for maintaining the dynamic balance of the carbon cycle within grassland ecosystems. However， the sequestration of PhytOC in grassland ecosystems has not received enough attention and remains insufficiently studied. In this study， we reviewed the current research progress on terrestrial ecosystem PhytOC， analyzed the formation and sequestration of plant PhytOC， the accumulation and stability of soil PhytOC， and the distribution and storage of PhytOC across different grassland types. We also discussed the impacts of human activities and global climate change on grassland PhytOC. Furthermore， the future research directions for PhytOC in grassland ecosystems were also proposed. An in-depth study of PhytOC in grassland ecosystems can provide a theoretical basis for accurately estimating the carbon sequestration potential of phytolith under the background of global climate change， and this could further enhance the carbon cycle model of ecosystems.

To clarify the impact of wind turbines on biodiversity and soil properties of grasslands， this study took a wind power area with wind turbines installed and operated for 15 years in the temperate meadow steppe of Inner Mongolia as the research area， and selected a grassland without wind turbines as the control area. The plant community， insect community， soil microorganisms， and soil physical and chemical properties in the area were investigated， and the relationships among these factors were analyzed. The results showed that compared with the grassland in the control area， the vegetation coverage， aboveground biomass， and community diversity of the grassland in the wind power area decreased significantly （P<0.05）. The number of insects in the wind power area increased significantly （P<0.05）， but the diversity of the insect community decreased significantly （P<0.05）. The number of soil fungi and community diversity in the wind power area were all significantly reduced （P<0.05）.Soil moisture content， bulk density， total nitrogen， ammonium nitrogen， alkali-hydrolyzable nitrogen， total phosphorus， and total potassium in the wind power area were all significantly reduced （P<0.05）. Correlation analysis found that there was a significant relationship between soil physicochemical properties and soil microbial communities. Overall， during the operation period of wind power stations， it will cause the degradation of grassland plant communities， the loss of soil nutrients and reduce plant diversity， and lead to a homogenization of the insect community structure.

In this study， alfalfa （Medicago sativa cv. Zhongmu No.1） was used as experimental material under mixed saline-alkali stress at concentrations of 0， 40， and 80 mmol/L （NaCl， Na2SO4， Na2CO3 and NaHCO3 molar ratios of 1∶1∶1∶1， pH 9.3）. The growth indexes， physiological indexes and the expression levels of key genes of the seedlings were measured， which provided a theoretical basis for revealing the mechanism of response to mixed saline-alkali stress. The results showed that the plant height， photosynthetic rate， effective quantum yield of PSⅡ photochemistry and the maximum quantum efficiency of PSⅡ photochemistry （Fv/Fm） in ‘Zhongmu No.1’ alfalfa seedlings were significantly inhibited with the intensification of mixed saline-alkali stress （P<0.05）. The accumulation of hydrogen peroxide， superoxide anion， and malondialdehyde gradually increased， while the activity of peroxidase， proline， and soluble sugar content all significantly increased （P<0.05）. Under 80 mmol/L mixed saline-alkali stress， the expression levels of Na+ transporter encoding genes MsSOS1， MsNHX1， and MsHKT1 were significantly induced （P<0.05）. In summary， ‘Zhongmu No.1’ alfalfa may mainly respond to mixed saline-alkali stress through the following pathways： （1） high expression of Na+ transporter genes such as MsSOS1， MsNHX1， and MsHKT1， promoting Na+ efflux， vacuolar segregation and transfer， and avoiding ion toxicity to plants caused by excessive accumulation of Na+； （2） enhance antioxidase activity and alleviate oxidative damage caused by high pH value.

To investigate salt tolerance in alfalfa （Medicago sativa） germplasm， 30 alfalfa accessions of diverse origins were subjected to salt stress （200 mmol/L NaCl） for 15 days. Responses were evaluated through changes in seedling morphology， photosynthetic parameters， and physiological indices compared to control plants （CK， irrigated with Hoagland nutrient solution）. The results demonstrated that NaCl treatment decreased plant height， leaf area， leaf relative water content， root activity， shoot dry weight， chlorophyll a， chlorophyll b， transpiration rate， stomatal conductance， net photosynthetic rate， intercellular CO₂ concentration， water use efficiency， catalase （CAT） activity， and potassium （K⁺） content relative to CK. Conversely， root dry weight， root-to-shoot ratio， stomatal limitation value， proline content， malondialdehyde （MDA） content， peroxidase （POD） activity， superoxide dismutase （SOD）， sodium （Na⁺） content， and the Na⁺/K⁺ ratio exhibited increases. Regression analysis identified stomatal conductance， root activity， root-to-shoot ratio， and Na⁺ content as critical indicators for salt tolerance evaluation. The clustering analysis based on the comprehensive evaluation value of the membership function shows that the 30 alfalfa accessions were classified into four distinct tolerance categories： high salt-tolerant， moderately salt-tolerant， low salt-tolerant， and salt-sensitive. Accessions 7254 and 7657 exhibited high salt tolerance.

Nitrogen deposition represents a critical driver of nitrous oxide （N₂O） emissions in global terrestrial ecosystems， with profound implications for climate change prediction. Although numerous studies have investigated soil N₂O emissions patterns in response to nitrogen addition， controversies persist regarding the regulatory mechanisms and driving factors. Through a meta-analysis intergrading the 87 global studies， we demonstrate that nitrogen addition significantly enhances soil N₂O emissions. This effect is particularly pronounced under high nitrogen application rate （>200 kg/hm² year）， in low-precipitation regions （≤400 mm annual rainfall）， and with short-term and moderate-term nitrogen application （≤3 years）. Our analysis identified nitrogen input level， mean annual precipitation， and ecosystem type as the dominant factors controlling global N₂O emissions， providing a scientific foundation for developing targeted emission mitigation strategies.

This study employed multivariate statistical methods， including analysis of variance （ANOVA）， principal component analysis （PCA）， correlation analysis， hierarchical cluster analysis， and membership function evaluation， to comprehensively analyze and evaluate five seed morphological traits of 329 wildrye （Agropyron cristatum） accessions conserved in the National Crop GeneBank. The objective was to establish a theoretical framework for the evaluation and innovative utilization of A. cristatum （L.） Gaertn germplasm resources. The results showed that among the five phenotypic traits examined， thousand-seed weight exhibited the highest genetic variation， with a genetic diversity index of 1.880 and a coefficient of variation of 24.56%. The average genetic diversity index for all five traits was 1.752， and the average coefficient of variation of 14.06%. PCA extracted three principal components， explaining 98.750% of the trait variation， with the first three main components contributing 65.555%， 26.162%， and 7.034% respectively， effectively preserving the core genetic information of seed traits. Correlation analysis demonstrated extremely significant positive correlations between seed length with the other four phenotypic traits （P<0.01）. Additionally， significant positive correlations were observed between seed width and both thousand-seed weight and single-seed area （P<0.01）， between thousand-seed weight and seed length-width ratio， as well as between seed length-width ratio and single-seed area. Hierarchical cluster analysis categorized the accessions into four groups： Group Ⅰ （284 accessions， moderate）， Group Ⅱ （41 accessions， small-grained）， and Groups Ⅲ and Ⅳ （two high-quality unique accessions each）. Comprehensive evaluation using the membership function identified B-288， B-243， B-233， and B-250 accessions with excellent performance in seed length， seed width， single-seed area， and thousand-seed weight. In contrast， B-152， B-143， B-128， B-149， B-141， and B-153 accessions exhibited relatively weak performance across multiple traits. In conclusion， seed length， single-seed area and thousand-seed weight were identified as the key morphological indicators contributing to the genetic diversity of A. cristatum germplasm.

Fertilization is a key strategy for restoring degraded grasslands. To identify suitable nitrogen （N） and phosphorus （P） fertilization gradients for enhancing the productivity and soil characteristics of degraded alpine meadows， a lightly degraded alpine meadow in Dangxiong County， Xizang Autonomous Region， was selected for study. A two-factor randomized block design was employed， with four nitrogen levels （N0：0 kg N/hm²， N1：60 kg N/hm²， N2：90 kg N/hm²， N3：120 kg N/hm²） and four phosphorus levels （P0：0 kg P₂O₅/hm²， P1：30 kg P₂O₅/hm²， P2：60 kg P₂O₅/hm²， P3：90 kg P₂O₅/hm²）， resulting in 16 N-P treatments combinations， with N0P0 treatment serving as the control （CK）. Grassland productivity and soil characteristics were evaluated to determine the optimal N-P combinations. The results showed that the combined application of nitrogen and phosphorus fertilizers significantly enhanced aboveground biomass compared with the control， with the N2P2 and N2P3 treatments increasing biomass by 136.9% and 111.9%， respectively （P<0.05）. The combined application also improved soil organic carbon content， particularly in the 0-10 cm soil layer， where the N2P1 and N2P3 treatments reached 15.67 g/kg and 15.26 g/kg， respectively. Available phosphorus content was highest under N2P3 treatment in both 0-10 cm and 10-20 cm soil layers， while total nitrogen content was greatest under N3P1 treatment. Grey correlation analysis of aboveground biomass and soil characteristics （0-10 cm） indicated that N2P3 treatment provided the most favorable comprehensive improvement in productivity and soil nutrient status， followed by N3P3 treatment. Therefore， the combination of 90-120 kg/hm² nitrogen fertilizer with 90 kg/hm² phosphorus fertilizer is recommended as the optimal strategy for the restoration of degraded alpine meadows in Dangxiong County， Xizang Autonomous Region.

The D27 （DWARF27） gene encodes an iron-containing β-carotene isomerase essential for strigolactone biosynthesis. In this study， the TpD27 gene was cloned from Trifolium pratense ‘Minshan’ using RT-PCR. Bioinformatics analysis revealed that the full-length coding sequence of TpD27 was 792 bp， encoding a 264-amino acid protein with a predicted molecular weight of 29.71 kDa， an isoelectric point of 8.76， and an instability index of 51.30， indicating that it was an unstable protein. Subcellular localization prediction suggested that TpD27 may be localized in the chloroplasts. The secondary structure of TpD27 was mainly composed of α-helix （33.71%） and random coil （55.68%）， consistent with its predicted tertiary structure. Phylogenetic analysis showed that TpD27 clusters closely with MtD27 from Medicago truncatula， indicating a close evolutionary relationship between the two species. Spatiotemporal expression profiling revealed tissue-specific expression of TpD27， with the highest transcript levels in flowers and the lowest in roots. Under abiotic stress conditions， TpD27 expression was significantly downregulated in response to cadmium， salt， and drought treatments. Under low-temperature stress， its expression followed a dynamic pattern： initial downregulation， subsequent upregulation， and eventual decline. The recombinant expression vector pCAMBIA2300-TpD27 was successfully introduced into wild-type Arabidopsis thaliana via Agrobacterium-mediated floral-dip transformation. Phenotypic analysis demonstrated that the transgenic Arabidopsis thaliana exhibited a significantly reduced number of branches compared to the wild-type plants.

Dof （DNA-binding with one finger） transcription factors are plant-specific regulators playing critical roles in plant response to environmental stresses. This study comprehensively identified MrDof gene family based on the genome-wide of Medicago ruthenica. We performed analyses including collinearity assessment， phylogenetic analysis， and chromosomal localization on the Dof family members. Furthermore， by integrating transcriptome data of M. ruthenica under drought stress and qRT-PCR validation， we explored the potential functions of these genes in drought stress responses. The results showed that a total of 33 MrDof genes were identified in M. ruthenica， and the number of amino acids encoded by these genes ranged from 157 to 492 aa. According to the evolutionary relationships among M. ruthenica， Medicago truncatula and Arabidopsis thaliana， these genes were classified into eight distinct groups （Group A， B1， B2， C1， C2.1， C2.2， C3， D1 and D2）. The 33 genes were unevenly distributed across nine chromosomes. Expression pattern analysis demonstrated that five genes （MrDof11， MrDof13， MrDof22， MrDof27， and MrDof30） were significantly induced by drought stress.

Warming and nitrogen deposition can affect the functions and structures of alpine meadow ecosystems on the Qinghai-Xizang Plateau. Ecological stoichiometry provides a framework to understand the biogeochemical cycling of nutrients between plant and soil. This study conducted a field experiment in an alpine meadow of Qinghai Province， to investigate the effects of different levels of warming and nitrogen deposition. The warming treatment included four levels： W0 （no warming）， W1 （air temperature increases 0.47 °C， soil temperature increases 0.61 °C）， W2 （air temperature increases 0.92 °C， soil temperature increases 1.09 °C）， W3 （air temperature increases 1.44 °C， soil temperature increases 1.95 °C）. Nitrogen application treatments included： N0 （no nitrogen application）， 16 kg N/（hm²·a）， and 32 kg N/（hm²·a）. The experiment assessed changes in carbon， nitrogen， and phosphorus contents in plant and soil， soil enzyme activity， and their stoichiometric ratios， as well as the relationship among these components. The results showed as follows： Warming significantly increased total nitrogen in the aboveground plant tissues， soil total nitrogen， soil organic carbon， the soil nitrogen phosphorus ratio， and the enzyme nitrogen phosphorus ratio. Simultaneously， it significantly decreased the carbon nitrogen ratio in aboveground plant biomass， and the carbon nitrogen and carbon phosphorus ratios of soil enzymes. Nitrogen deposition significantly increased total nitrogen in both aboveground and root tissues， soil organic carbon， soil total nitrogen， and the enzyme carbon nitrogen ratio. It significantly decreased the root carbon nitrogen ratio and enzyme nitrogen phosphorus ratio. The interaction between nitrogen deposition and warming significantly affected soil organic carbon content and the carbon nitrogen， carbon phosphorus， and nitrogen phosphorus ratios of soil enzymes. Analysis of stoichiometric homeostasis in plant tissues in responses to soil elements and enzyme activities revealed strict stoichiometric homeostasis in plant tissues under both warming and nitrogen deposition. Soil total nitrogen， soil carbon nitrogen ratio， and soil β-1， 4-xylosidase activity significantly influenced plant nutrient content and stoichiometry. In summary， short-term warming and nitrogen deposition significantly alter the stoichiometry of soil and enzyme systems in alpine meadows， which in turn influences the nutrient acquisition strategies of plants on the Qinghai-Xizang Plateau.

In order to investigate the root-specific genes regulating root growth of alfalfa （Medicago sativa），transcriptome sequencing was performed to analyze differentially expressed genes （DEGs） and their functions between the aerial parts （stems and leaves） and root system of alfalfa cultivar Zhongmu No. 1. The results showed that compared to aerial parts，a total of 15258 DEGs were identified in root system，including 5095 up-regulated and 10163 down-regulated. The GO functional annotation demonstrated significant enrichment of these DEGs in cellular process，metabolic regulation，and biocatalytic activities. KEGG pathway enrichment analysis showed significant enrichment of these DEGs in pathways related to porphyrins and chlorophyll metabolism，photosynthesis-antenna protein synthesis，and carbon fixation in photosynthetic organisms. Six candidate up-regulated genes exhibiting significant differential expression were selected for real-time quantitative PCR validation. The results indicated high concordance between their expression patterns and transcriptome sequencing data.

In the context of global climate change， the impact of extreme climate on grassland productivity has attracted extensive attention of academics and research institutions worldwide. In order to investigate hotspots in this research field and assess the state of current international research frontiers， this article exported literature data from the core database of Web of Science， and visualized with CiteSpace to analyze and summarize the status of international research on the impact of extreme climate on grassland productivity. The results demonstrated an increasing trend in research publications from 1992 to 2023 regarding the impact of extreme climate on grassland productivity， especially a rapid increase from 2019 to 2023. Collaborative teams were assembled by authors， though connections between different teams were not solid as expect. Scholars from both China and the United States have published over 200 academic papers， which leading the field of effects of extreme climate on grassland productivity. Over the past two years， Lanzhou University， Chinese Academy of Agricultural Sciences have played crucial roles in the research of effects of extreme climate on grassland productivity. A comprehensive analysis of hotspots and frontiers reveals that research in recent three years primarily focused on the impact of extreme drought on grassland productivity， as well as the legacy effects of extreme climate on grassland. Future research on grassland extreme climate should pay more attention on a thorough analysis of complex extreme climate， and elucidate the role of biodiversity and biological interactions in regulating ecosystem for the response to extreme climate events.

This research aims to investigate the effects of variations in precipitation on the ecological stoichiometry of soil organic carbon （SOC）， total nitrogen （TN）， and total phosphorus （TP） in desert steppes and to reveal the response of C， N， and P and their ecological stoichiometry to precipitation gradients in desert steppe ecosystems. The experiment was conducted in temperate desert steppe on the southern edge of Mu Us Desert， Yanchi County， Ningxia Hui Autonomous Region. Five precipitation levels， 33%， 66%， 100%， 133%， and 166% of natural precipitation （G1， G2， G3， G4， G5）， were simulated by rainout shelters and manual water replenishment. Variation patterns of SOC， TN， TP contents across soil layers （0-10 cm，10-20 cm， and 20-30 cm） were analyzed under different precipitation levels. The results indicate that： （1） When precipitation increased （G4）， the SOC， TN， and TP contents， and soil C∶P and N∶P ratios in 10-20 cm and 20-30 cm soils were significantly lower than in 0-10 cm soils （P<0.05）. However， the TP content did not respond significantly to precipitation changes. （2） With the increasing of soil layer depth， the correlation between the contents and ratios of SOC， TN， and TP within soil followed the order of 20-30 cm>10-20 cm>0-10 cm； （3） The variation in the SOC， TN， and TP contents was the highest in the 20-30 cm layer， followed by the 10-20 cm， and was the lowest in 0-10 cm. The variation of soil TP content was the least for all the three soil layers. In conclusion， precipitation changes have a significant impact on the ecological stoichiometry of soil carbon， nitrogen， and phosphorus， and the variation of carbon， nitrogen， and phosphorus in deep soil is greater. Deep soil （20-30 cm） is more responsive to precipitation changes than surface soil （0-20 cm）， indicating that the ecological stoichiometry of desert steppe soils is more sensitive to precipitation in deeper layers.

In this study， whole oilseed rape at the full-bloom period and dried rice straw were used as silage materials. Seven treatments were established： Pediococcus acidilactici， Lactobacillus buchneri， Lactobacillus acidophilus， silage mixed powder of lactic acid bacteria and cellulase， Lactobacillus plantarum， Enterococcus faecalis， and a control group （CK）. Each treatment was replicated three times. The sensory characteristics， fermentation quality， nutritional composition， and aerobic stability of the mixed silage were analyzed at 90 days of ensiling to assess the effects of different bacterial additives on silage made from oilseed rape and rice straw. The results showed that the addition bacterial agents improved sensory evaluation， increased lactic acid production and lactic acid bacterial count， and reduced pH and protein loss in the silage. The ammonia nitrogen to total nitrogen in all additive-treated groups was significantly lower than that of CK （P<0.05）， except for the groups treated with Lactobacillus acidophilus and Enterococcus faecalis. However， dry matter content in the group of silage mixed powder of lactic acid bacteria and cellulase was significantly lower than that of CK （P<0.05）. Neutral detergent fiber and acid detergent fiber levels in silage mixed powder of lactic acid bacteria and cellulase and Lactobacillus plantarum treatments were significantly lower than those in CK （P<0.05）. Based on a grey correlation analysis， the ranking of silage quality among the seven treatment groups， from highest to lowest， was as follows： silage mixed powder of lactic acid bacteria and cellulase>Lactobacillus plantarum>Lactobacillus acidophilus>Pediococcus acidilactici>Lactobacillus buchneri>Enterococcus faecalis>CK. In conclusion， the addition of bacterial agents influenced the nutritional quality and fermentation quality of mixed silage of oilseed rape and rice straw. Among the treatments， the silage mixed powder of lactic acid bacteria and cellulase exhibited the best overall performance and was the most suitable additive for preparing mixed silage from oilseed rape and rice straw.

This study investigated the effects of varying soil salinity levels on the growth and salt transport capacity of Suaeda salsa （L.） Pall. S. salsa was selected as the test species， and a barrel planting experiment was conducted with six salinity treatments： 10.21 g/kg （S1）， 20.92 g/kg （S2）， 30.29 g/kg （S3）， 40.55 g/kg （S4）， 50.36 g/kg （S5）， and a control treatment （CK） with 6.20 g/kg soil salt content. Plant growth parameters and salt transport capacity were assessed at four growth stages to identify optimal salinity conditions for S. salsa cultivation and ecological restoration in saline soils. The results showed that across all growth stages， the treatment with 20.92 g/kg soil salinity （S2） resulted in the most favorable growth performance for S. salsa， as evidenced by significantly higher plant height， stem diameter， fresh weight， and dry weight compared to other treatments. Specifically， at maturity stage， these parameters increased by 29.87%， 47.75%， 33.54%， and 19.45%， respectively， in the S2 treatment compared to CK. Increased soil salinity generally promoted stem and leaf succulence throughout the adult plant， flowering， and mature stages. Across treatments， a trend of decreasing succulence was observed from the seedling stage to the mature stage. Leaf tissue exhibited the highest salt transfer amount across all treatments， followed by stem and seed. As plants progressed through the growth stages， the ash content in all treatments decreased， likely due to dilution by increasing biomass. However， salt transfer amount continuously increased， reaching a peak at the mature stage. The S2 treatment displayed the greatest salt transfer amount （4250.41 kg/hm²）. These findings suggest that a soil salinity level of 20.92 g/kg promotes optimal plant growth status and salt transfer ability in S. salsa.

Grassland ecosystems， as one of the dominant types of terrestrial ecosystems worldwide， exhibit substantial carbon sequestration potential and play a vital regulatory role in the global carbon cycling and climate change mitigation. This article conducted a bibliometric and visualization analysis of 4，464 publications in the Web of Science Core Collection （WOS） and China National Knowledge Infrastructure （CNKI） database spanning from 1999 to 2022 by VOSviewer and CiteSpace. Current research status and development trends on carbon sequestration functions in grassland ecosystems were examined. The results revealed an increase trend in publication outputs on the carbon sequestration function of grassland ecosystems. Country distribution analysis of publications in WOS database by VOSviewer identified that China and the United States lead this research area. Institute analysis of publication by CiteSpace indicated that Chinese Academy of Sciences， the United States Department of Agriculture， and the University of the Chinese Academy of Sciences emerged as the top three in WOS database. Northwest A&F University， the University of the Chinese Academy of Sciences， and Beijing Forestry University were the most active institutes in the CNKI database. However， there is still potential for improving effective international communication and collaboration among nations and research teams. The bibliometric analysis identified three research hotspots in this field： the driving effects of climate change， human activities， and soil microbial communities on dynamics of carbon sequestration functions in grassland ecosystems；the spatiotemporal variation characteristics of soil carbon storage； and the evaluation of carbon sequestration functions in grassland ecosystems.

This study investigated the efficacy of exogenous 2，4-epibrassinolide （2，4-EBR） in mitigating saline-alkali stress during seed germination and seedling growth of quinoa （Chenopodium quinoa Willd.‘Longli 1’）. Seeds were treated with various concentrations （0， 0.05， 0.1， 0.2， 0.4， 0.8， 1.5 and 2 mg/L） of 2，4-EBR and exposed to a range of simulated saline-alkali stress conditions. Principal component analysis and membership function method were used to comprehensively evaluate the physiological and biochemical indicators of quinoa under different saline-alkali stresses and different 2，4-EBR treatments. The results demonstrated that both single salt stress and mixed saline-alkali stress significantly inhibited the germination of quinoa seeds and the growth of seedlings. Exogenous application of 2，4-epibrassinolide （2，4-EBR） at concentrations of 0.05-2 mg/L effectively enhanced quinoa's osmotic adjustment capacity， alleviated oxidative damage induced by saline-alkali stress， and thereby improved its saline-alkali tolerance. Additionally， comprehensive evaluation analysis indicated that 0.2 mg/L 2，4-EBR exhibited the optimal alleviating effect on mixed saline-alkali stress； 0.4 mg/L 2，4-EBR proved the most effective for single salt stresses （NaCl and NaHCO₃）； and 0.8 mg/L 2，4-EBR was optimal for single salt stresses induced by Na₂SO₄ and Na₂CO₃.

To investigate the growth adaptability of ten forage oat （Avena sativa L.） varieties in continuous alfalfa replanting fields in the northeastern Ordos and to identify high-quality varieties suitable for multiple cropping， ten representative forage oat varieties were selected based on preliminary screening. A randomized block design was employed to analyze and compare their growth period， agronomic performance， and nutritional quality. Partial least squares path model （PLS-PM） was further applied to examine the effects of varieties and harvest date on agronomic traits and forage quality， while the grey relational analysis method was used for comprehensive evaluation. The results showed that varieties reached the milk stage in approximately 70-80 days in the northeastern region of Ordos. Among varieties， ‘Sun God’ and ‘Yellow Oat’ exhibited significantly greater plant height （121.44 cm and 114.31 cm， respectively； P<0.05）. ‘White Oat No.7’ produced the highest hay yield （9414.79 kg/hm²）， followed by ‘Yellow Oat’ （9130.31 kg/hm²）， both significantly exceeding other varieties （P<0.05）. ‘Aiwo 256’ had the highest crude protein （CP） content （12.14% DM）， significantly higher than ‘Qingyin No.1’ and ‘Leader （Surui）’ （P<0.05）. ‘White Oat No.7’ showed significant lower acid detergent fiber （ADF） and neutral detergent fiber （NDF） contents than most varieties， except ‘Qinghai 444’ and ‘Qingyin No. 2’ （P<0.05）. Except for ‘Qingyin 2’，the potassium （K） content of ‘White Oat No.7’ was significantly lower than that of all other varieties， while its relative forage quality （RFQ） was significantly higher than those of other varieties （P<0.05）. Across harvest dates， oats harvested on September 9th exhibited significantly greater plant height， hay yield， dry-to-fresh ratio， and RFQ， while CP， ADF， and K content were significantly lower compared to earlier harvests （P<0.05）. In contrast， oats harvested on August 21st had higher CP， ADF and K contents but lower plant height， hay yield， dry-to-fresh ratio， and RFQ. Grey relational analysis identified CP， NDF， and hay yield as key indicators for evaluating forage oat productivity. Overall， ‘White Oat No.7’ and ‘Yellow Oat’ demonstrated superior performance and were recommended for re-cultivation after alfalfa cutting in the northeastern Ordos.

This research was conducted in the Stipa breviflora desert steppe of Siziwang Banner， Inner Mongolia. We established four stocking-rate treatments 0， 0.91， 1.82， and 2.71 sheep/（hm²·a） and plant community was categorized into five plant functional groups-perennial rhizomatous grasses， perennial forbs， perennial bunchgrasses， annual–biennial herbs， and shrubs/sub-shrubs. Quadrat sampling was used to measure plant height， cover， density， above-ground biomass， and species composition in August 2022. We calculated importance values and applied principal component analysis （PCA） to evaluate productivity-diversity coupling. Results showed that：（1） Species richness exhibited a hump-shaped response to stocking rate （22， 24， 22， and 21 species， respectively）， while morphological traits and productivity of the plant functional groups generally declined with increasing grazing pressure. （2） Importance-value analysis showed that the relative importance of perennial bunchgrasses increased from 40% to 68%， while their contribution to community productivity rose from 60% to 95%. PCA further indicated that productivity and diversity together accounted for 66.12% of the variance， which was primarily driven by this functional group.（3） A positive linear relationship was observed between species richness and productivity in the perennial forb group under no grazing， light grazing， and moderate grazing， whereas this relationship under heavy grazing was found in shrubs/sub-shrubs group. No other functional groups exhibited significant correlations. These results demonstrate that while stocking rate significantly alters plant functional group composition， species diversity alone is not a direct determinant of productivity， indicating complex interactions among disturbance， diversity， and productivity. Since perennial bunchgrasses play a crucial role in supporting productivity at higher stocking rates， grazing management strategies should prioritize the conservation and regulation of this functional group to ensure sustainable use and the ecological stability of the desert steppe.

To explore the effects of different grazing intensities on soil microbial biomass in alpine meadow，this study investigated the variation characteristics in soil microbial biomass and interactions between soil physicochemical properties and microbial parameters including biomass，microbial quotient，and stoichiometric ratios under no grazing （CK），light grazing （LG），moderate grazing （MG），heavy grazing （HG），and extreme grazing （EG） conditions in the alpine meadow of Tianzhu Zangzu Autonomous County on the northeastern edge of the Qinghai-Tibet Plateau. The results showed that both microbial biomass carbon （MBC） and phosphorus （MBP） reached the maximum levels under LG，which were significantly higher compared with EG condition （P<0.05）. Soil microbial biomass nitrogen （MBN） was highest under HG，followed by MG，while MBN was significantly lower under EG compared with HG （P<0.05）. Soil microbial quotient carbon （qMBC），microbial quotient phosphorus （qMBP） and the MBC∶MBN ratio were all highest under LG，whereas microbial quotient nitrogen （qMBN），MBC∶MBP ratio，and MBN∶MBP ratio were highest under MG. Soil bulk density emerged as the predominant factor influencing microbial biomass，microbial quotients，and their stoichiometric ratios. These findings indicate that both light and moderate grazing intensities benefit the accumulation of microbial biomass and promote efficient utilization and transformation of soil nutrient in alpine meadows. In contrast，extreme grazing leads to soil fertility decreasing and a reduction of microbial biomass. A win-win scenario of ecology sustainability and economic benefits will be achieved when apporiate grazing intensities adopted.

To investigate the effects of plateau zokor （Eospalax baileyi） disturbance on soil stoichiometry and plant diversity，as well as changes in their interrelationships，this study established three disturbance intensities （light，moderate，and heavy），using undisturbed grassland （without zokor mounds） as the control. We assessed plant species richness and abundance，Shannon-Wiener and Simpson’s diversity indices，and evenness，alongside measurements of soil organic carbon （SOC），total nitrogen （TN），and total phosphorus （TP） contents. Differences and variation patterns in plant diversity and soil stoichiometric traits across disturbance levels were analyzed to determine whether plateau zokor disturbance alters the relationship between soil stoichiometry and plant diversity. The results showed as follows： （1） Under heavy disturbance，SOC and TN contents were significantly lower than those at other disturbance intensities，while TP content was significantly lower under light disturbance compared to other treatments （P<0.05）. （2） The soil C∶P ratio under light disturbance was significantly higher than in all other treatments （P<0.01）. Similarly，the soil N∶P ratio was significantly higher than in both the control and heavy disturbance treatments （P<0.01）. However，no significant difference was observed in the soil C∶N ratio across treatments. （3） Plant species richness，Shannon-Wiener and Simpson’s diversity indices，and evenness all exhibited an upward trend with increasing disturbance intensity，being significantly higher than in the control （P<0.05）. （4） In the undisturbed area，species richness was positive correlated with soil C∶N and N∶P ratios；however，these relationships were not observed under zokor disturbance. Under heavy disturbance，the relationships between species diversity indices and soil N∶P and C∶P ratios were significantly affected，with positive correlation between evenness and the N∶P ratio becoming stronger. In conclusion，plateau zokor disturbance significantly influenced SOC，TP，and TN contents，promoted higher plant species diversity，and modified the relationships between plant diversity and soil stoichiometric characteristics.

The overexploitation of agro-pastoral systems has driven widespread grassland reclamation in northern China，accelerating soil carbon and nutrient depletion. However，the mechanisms underlying the responses of soil organic carbon （SOC） and its fractions to grassland cultivation remain unclear. In this study，we investigated the effects of grassland reclamation on soil physicochemical properties and SOC fractions across three representative sites in the agro-pastoral ecotone： Jianping （Liaoning），Youyu （Shanxi），and Yuzhong （Gansu）. Cultivation significantly increased soil nitrate nitrogen but reduced SOC content by 24.17%. Among SOC fractions，labile free particulate organic carbon （fPOC） decreased significantly，whereas occluded particulate organic carbon （oPOC） and mineral-associated organic carbon （MAOC） remained unchanged. Random forest analysis identified soil electrical conductivity，moisture，and the carbon-to-nitrogen （C/N） ratio as the primary regulators of SOC and its fractions. Specifically，SOC and MAOC were mainly influenced by soil electrical conductivity and moisture，while the C/N ratio was the dominant driver of SOC and fPOC dynamics. Overall，grassland cultivation selectively depleted labile carbon pools while maintaining oPOC and MAOC，a process largely mediated by shifts in soil electrical conductivity，moisture，and the C/N ratio，ultimately reshaping SOC distribution and stability.

Moisture content is a key indicator of seed quality，and its accurate and rapid determination is essential for seed grading. With the increasing use of seed coating technology in seed production and trade，traditional high （low） constant-temperature method often severely underestimated the actual moisture content of coated seeds due to the influence of coating materials. To address this issue，four coated forage species： Medicago sativa，Elymus dahuricus，Lolium perenne and Dactylis glomerata，were selected as experimental materials. By analyzing the relationship between water activity of coated seeds and the moisture content of naked seeds，a predicted model for coated seeds moisture content based on water activity was developed. The goodness-of-fit values of the prediction models for the four species were 0.9003，0.9124，0.9076，and 0.9323，respectively，with relative errors of 2.87%，4.08%，3.07% and 4.14%. These results indicated that seed water activity can serve as a reliable，non-destructive，and rapid indicator for determining the moisture content of coated seeds.

This study focused on the moderately degraded alpine meadow in the eastern part of Qilian Mountains. A gradient of microbial fertilizer application rate was applied， namely CK （no microbial fertilizer）， BIM （7.5 g/m²）， BIIM （15 g/m²）， and BIIIM （22.5 g/m²）. The effects of different microbial fertilizer application rates on soil nutrient content， microbial community structure， and diversity of degraded alpine meadow were investigated. The results show that： In 0-10 cm soil layer， the soil nutrient content with microbial fertilizer application was significantly increased （P<0.05） compared with CK， with BIIM treatment showing the greatest effect. The contents of organic matter， available phosphorus， alkali hydrolyzable nitrogen， and available potassium were increased by 6.6%， 30.52%， 18.79% and 12.02%， respectively compared with CK； With the increase of soil depth， the effect of microbial fertilizer on soil nutrient content gradually declined； At the 20-30 cm depth， except for available potassium， no significant differences were observed among the treatments for any nutrients. The analysis of soil microbial community composition and diversity indicated that the effect of any bacterial fertilizer treatment on the diversity of fungal community was not significant， whereas the species richness of the bacterial community was significantly reduced by the BIIM treatment （P<0.05）. From the compositional perspective， the functional composition of microbial community was positively influenced by increasing the relative abundance of beneficial bacteria such as Penicillium， Mortierella， Bacillus， and Ferribacterium. Correlation analysis showed that the relative abundance of most beneficial bacteria was positively correlated with soil nutrient content. The results demonstrated that the application rate of 15 g/m² for the microbial fertilizer enriched with Bacillus subtilis， Bacillus mojavensis and Pseudomonas synxantha was effective. It significantly increased the content of key nutrients in soil and improved the soil microbial community structure， which could be applied in the restoration of regional degraded alpine meadow.

In order to screen out the optimal oat mixed-sowing combinations and planting ratio in the Horqin Area， this study used mixture of oat （Avena sativa L.） with forage peas （Pisum sativum L.）， crimson clover （Trifolium incarnatum L.）， and common vetch （Vicia sativa L.） to explore the effects of different oat-legume combinations and different seeding ratios on forage growth performance， yield， and nutritional quality. The results showed that： the combinations of oat-crimson clover and oat-common vetch achieved the highest hay yield at a 5∶5 seeding ratio. In contrast， oat-forage pea at 8∶2 ratio produced the highest hay yield， with a significantly greater system productivity compared with the other mixtures. The nutritional quality of the forage mixture improved with increasing legume proportion in the seeding ratio， whereas the oat-crimson clover mixture had lower nutritional quality compared with the other two mixtures. In the grass-legume interspecific relationships， oats were the dominant species which made the largest contribution to the total forage yield. In conclusion， the combinations of oats + forage peas， oats + crimson clover， and oats + common vetch achieved relatively high hay yields at seeding ratios of 8∶2， 5∶5， and 5∶5， respectively， which were suitable for widespread planting in Horqin Region.

Soil fauna is an important part of the terrestrial ecosystem and serves as a critical biological indicator for the maintenance of the grassland ecosystem function and stability. Global climate change combined with diverse anthropogenic disturbances， have induced substantial changes of soil faunal community structure and biodiversity， and further affected soil quality and soil health. This review systematically analyzed development and current status of soil fauna in Chinese grassland ecosystem the responses of soil fauna in different grassland types to simulated warming， nitrogen addition， precipitation change and anthropogenic disturbance （grazing， mowing， enclosure， reclamation and mining） Based on the review， three research directions for further research are proposed： to strengthen the interdisciplinary research of soil fauna， to establish long-term monitoring network across spatial gradients to assess effects of climate change on soil faunal community characteristics， and to illustrate the structural and functional stability of soil faunal community in grassland ecosystem.

In order to explore the effects of litter on the plant community characteristics and functional groups of desert steppe， this research focused on Stipa breviflora desert steppe in Inner Mongolia. A field control litter experiment （including no addition （CK）， adding 83.3 g/m² litter， and adding 166.6 g/m²） was conducted on degraded steppe under overgrazing for more than a decade. The results showed that the addition of litter improved community height， coverage， density and aboveground biomass under the adding 83.3 g/m² litter treatment， and the community height， coverage and aboveground biomass increased significantly by 2 cm， 3% and 9 g/m²， respectively. Plant community indices such as Simpson dominance index， Shannon-Wiene diversity index， Pielou evenness index and Margalef richness index were also increased significantly. The addition of litter enhanced the competition of perennial bunch grasses between perennial rhizome grasses and perennial forbs. Plants adapted to the environmental changes by altering the occupancy ratio of the functional groups. The addition of 83.3 g/m² litter had a more significant effect on plant community of the desert steppe. In conclusion， the input of appropriate amount of litter can help the recovery of degraded grassland by influencing the diversity of the community and the relationship between functional groups to promote the positive growth of grassland.

This study focused on Poacceae weeds Digitaria sanguinalis and broad-leaved weeds Amaranthus retroflexus， which pose a serious threat to alfalfa fields. The allelopathic effects of six phenolic acids on seed germination （germination percentage， germination potential， germination index） and seedling growth （height and fresh weight） of the two weeds were determined to develop bioherbicides for alfalfa fields. The results indicated that： The allelopathic effects on the seed germination and seedling growth of Digitaria sanguinalis and Amaranthus retroflexus varied after treated with six phenolic acids. The phenolic acids with high concentration inhibited the seed germination and seedling growth of the two weeds， while some of the low-concentration phenolic acids showed “low-concentration promotion and high-concentration inhibition” on the seedling growth of Digitaria sanguinalis. When the concentration of the solution is 500 mg/L， the order of the allelopathic effects on Digitaria sanguinalis was： coumarin=salicylic acid>caffeic acid>ferulic acid>p-hydroxybenzoic acid>chlorogenic acid； and the order of the allelopathic effects on Amaranthus retroflexus was： coumarin=salicylic acid>ferulic acid>p-hydroxybenzoic acid>chlorogenic acid>caffeic acid. Except for caffeic acid， the inhibition of chlorogenic acid， ferulic acid， p-hydroxybenzoic acid， coumarin， and salicylic acid with the same concentration on Amaranthus retroflexus was stronger than that of Digitaria sanguinalis. The effects of the same phenolic acid varied significantly on different growth stages （germination and early growth of seedlings） of the same weed. High concentration phenolic acid Seedling growth was inhibited more compared to seed germination by high concentration phenolic acid.

To investigate the genetic variation characteristics and agronomic potential of the polycotyledon trait in alfalfa （Medicago sativa L.），this study evaluated the phenotypic diversity of alfalfa cotyledonous mutations under field cultivation. Eleven agronomic quantitative traits were assessed using the Kruskal-Wallis non-parametric test，mean analysis method，and the entropy-weight TOPSIS method. The results showed that： （1） The polycotyledonous mutation rate in the test population was 1.44%，with 29 phenotypic variation patterns were identified；（2） the B8 type （tricotyledon-one unifoliolate true leaf-normal main stem-erect branches） exhibited the highest mutation rate （41.28%），followed by the B2 type （dicotyledon-two unifoliolate true leaves-normal main stem-erect branches） at 8.74%；（3） Mean analysis indicated that differences among variant types were mainly associated with branch number and plant height；（4） The entropy-weight TOPSIS evaluation ranked the B2 type highest （score： 0.8389），followed by the B8 type （0.6297），whereas the B12 type （tricotyledon-one unifoliolate true leaf-clustered branch） scored lowest. This study provides the first systematically characterization of phenotypic diversity and agronomic polycotyledonous alfalfa variants and offers novel mutant germplasm resources for breeding innovation.

As a high-value cool-season grass species cultivated worldwide，perennial ryegrass （Lolium perenne L.） frequently faces various abiotic stresses. Fructans are the primary reserve carbohydrates in perennial ryegrass，which play a crucial role under abiotic stress conditions and significantly enhance stress tolerance. This article reviews research progress on fructan metabolism in perennial ryegrass in China and internationally，focusing on its biosynthesis and degradation pathways，as well as the regulatory mechanisms of certain biomolecules on fructan metabolism. In addition，metabolic changes and underlying mechanisms of fructans in perennial ryegrass were illustrated under various abiotic stresses including drought，low temperature，salinity，waterlogging，nitrogen deficiency，and mowing，with prospects on future research directions.

To investigate the effect of biochar coating on the drought resistance of Astragalus adsurgens， this experiment established four sand bed moisture levels （2%， 3%， 5%， and 10%， with 10% as control） and four biochar coating mass ratios （biochar∶seed at 1∶15， 1∶10， 1∶5， and 1∶3）. Germination tests conducted in the sand beds were aimed to identify apporiate drought stress simulation conditions and to determine the optimal biochar coating formulation. Effects of biochar coating on seedling emergence， seedling growth， and antioxidant enzyme activities under drought stress were also assessed. The results indicated showed that， under 2% sand bed moisture condition， which simulated drought conditions， the biochar coating treatment with at a 1∶10 mass ratio （biochar∶seed， denoted as BC1-10） significantly increased （P<0.05） seedling emergence rate， fresh weight， root length， seedling length， and antioxidant enzyme activities.

To investigate the mitigation effect of externally applied γ-aminobutyric acid （GABA） on the growth of alfalfa seedlings under drought stress， this study explored five new drought-resistant alfalfa lines （P1， P2， P3， P4， and P5） and five drought-sensitive materials （15354， 7657， 7470， 7740， and 15578）. With normal water supply as the control （CK）， drought stress was simulated using the previously screened stress intensity （-1.6 MPa PEG-6000）. Under this drought stress treatment， exogenous GABA was applied at concentrations of 0， 5， 10， and 15 mmol/L （designated as T1， T2， T3， and T4， respectively） to analyze their effects on the physiological characteristics of alfalfa seedlings. Results showed that external GABA application significantly increased superoxide dismutase， peroxidase， catalase， leaf relative water content， and root activity in alfalfa under drought stress， while the content of proline， soluble sugar， soluble protein， malondialdehyde， hydrogen peroxide， and the production rate of superoxide anion were decreased. Membership function analysis revealed the optimal alleviation of GABA on drought-stressed alfalfa under the T3 treatment， with significantly stronger mitigation effect on sensitive genotypes compared with drought-resistant lines. The results provide a theoretical basis for the rational application of GABA in drought-tolerant cultivation of alfalfa.