Alfalfa （Medicago sativa L.） is a globally important leguminous forage crop， widely cultivated and utilized due to its high biomass yield， nutritional value， strong adaptability， and excellent palatability. Flowering time is a critical stage in alfalfa growth cycle， directly affecting forage yield and quality. However， variations in environmental factors and genetic characteristics often lead to significant differences in flowering time， which in turn affecting its production， cultivation， management， and harvesting efficiency. In recent years， significant progresses have been made in the field of molecular biology， revealing the regulatory mechanisms of flowering gene expression was influenced by photoperiod， temperature and hormones. However， in China， the research on alfalfa flowering time regulation remains insufficient， with challenges including weak basic research， outdated breeding techniques， and inconsistent flowering periods among cultivars. This review summarizes the recent advances in the regulation of alfalfa flowering time， explores the ecological factors and genetic mechanisms influencing flowering， and proposes future optimization strategies for breeding and cultivation management. The aim is to provide theoretical support and practical guidance for high-yield， high-quality alfalfa breeding and sustainable utilization.

To investigate the responses of alfalfa root morphological traits to phosphorus supply， a total of 31 plant materials were selected comprising 30 varieties of Medicago sativa L. and one variety of Medicago falcata L.， and three levels of phosphorus addition treatments were set up at P₅ （5 mg·kg^-1 KH₂PO₄）， P₂₀ （20 mg·kg^-1 KH₂PO₄）， and P₅₀ （50 mg·kg^-1 KH₂PO₄）. To screen low phosphorus tolerant alfalfa varieties with high phosphorus use efficiency， we measured the aboveground and belowground biomass and root morphological indices for the 31 alfalfa varieties. The results indicated that the aboveground and belowground biomass of alfalfa were lowest under P₅ treatment. With increasing phosphorus supply， the aboveground biomass of alfalfa significantly increased， reaching its highest level under the P₅₀ treatment. Under the P₂₀ and P₅₀ treatments， the root biomass of alfalfa was significantly higher than that under P₅， but there was no significant difference between P₂₀ and P₅₀. However， the root morphology showed significant variation among different varieties. Among them， ‘HD’‘Algonguin’‘Magna Graze II’ and ‘Longmu 801’ had higher biomass than other varieties， and exhibited greater root morphological plasticity with higher root length， root volume， root surface area， and root diameter， which demonstrated tolerance to low phosphorus condition. The results provide a scientific basis for optimizing alfalfa cultivation and improving phosphorus fertilizer utilization efficiency.

This study aimed to explore the changes and linkages of plant community species diversity and niche under different grazing intensities in （Leymus chinensis） meadow steppe， providing a basis for rational utilization of grassland resources. Taking plant communities in Leymus chinensis meadow steppe under six grazing intensities， including no grazing （G₀=0 cow.AU·hm^-2）， light grazing （G₁=0.23 cow.AU·hm^-2）， light-moderate grazing （G₂=0.34 cow.AU·hm^-2）， moderate grazing （G₃=0.46 cow.AU·hm^-2）， moderate-heavy grazing （G₄=0.69 cow.AU·hm^-2）， and heavy grazing （G₅=0.92 cow.AU·hm^-2）， as research materials， we conducted plant community surveys and calculated diversity indices and niche indices. The results showed that diversity indices first increased and then decreased with increasing grazing intensity， peaking at moderate grazing. The species importance values changed significantly， where the dominant position of Leymus chinensis was replaced by Carex duriuscula as the important values gradually decreased. The importance value was positively correlated with niche breadth， and the correlation was the strongest under light-moderate grazing and moderate grazing. The niche overlap value first increased and then decreased， while the interspecific competition pressure remained stable under light-moderate grazing and moderate grazing. Therefore， controlling the number of grazing livestock based on the niche breadth and overlap value of species could help stabilize the grassland ecosystem and facilitate the sustainable utilization of grasslands.

In order to explore the photosynthetic physiological differences of oat ear organs and flag leaves under drought stress， a pot experiment was conducted using Avena sativa L.‘Kona’ as the experimental material. Drought stress was initiated after the first flower bloomed. Chlorophyll contents， photosynthetic enzyme activities， soluble sugar and starch contents in flag leaves and ear organs were measured at 0， 7 and 14 days after drought stress treatment. The results showed that the chlorophyll content in the glumes was higher than that of the flag leaves， while the chlorophyll content of the lemmas was lower. Drought stress significantly reduced the enzyme activities of Rubisco， PEPC， and PEPCK in the flag leaves， while it had no significant influence on the activities of Rubisco in glumes and PEPCK， NADP-ME， NAD-ME activities in both ear organs. In addition， the activities of Rubisco， PEPC and PEPCK in the glumes were significantly higher than those in the flag leaves. Drought stress significantly increased the soluble sugar and starch contents in the flag leaves， while had no significant influence on sugar contents in both ear organs. To sum up， the flag leaves of ‘Kona’ oats responded more sensitively to drought stress， while the ear organs， especially the glumes， maintained better stability.

To investigate the impact of compound drought and hot events （CH） on the productivity and phenology of forage oats （Avena sativa L.） in Shuozhou， and to explore how the accumulated temperature requirements during the growth period of forage oats should be adjusted for coping with such events， this study utilized validated APSIM （Agricultural Production System sIMulator）to conduct simulation analysis at six sites in Shuozhou within baseline and future scenarios in combination with climate model. Based on APSIM model validation （2023 aboveground biomass Normalized Root Mean Square Erro： 9.19%， 2022—2023 soil moisture NRMSE： 25.69%） and scenario simulations， the results indicate that future climatic hazards in Northern Shanxi will be intensified. By the 2070s， the frequency， duration， and intensity of CH would generally increase with a decreasing trend from east to west. This led to a reduction in forage oat yield of 2046.2 kg·hm^-2 during CH-occurring years compared to the multi-year average. Furthermore， the durations from emergence to initial flowering and from initial flowering to full flowering were prolonged by 0.97 days and 0.26 days， respectively. However， optimizing cultivar selection based on site-specific climate conditions could increase forage yield by 1.95% to 23.65%.The results of this study could provide a theoretical basis for forage oats production to cope with CH， and offer some guidance for breeding strategy and field management of forage oats in the future.

Carex breviculamis is an important native species that is water-saving and drought resistant， with advantages such as long green period， shade tolerance， and high fruiting rate. However， in the actual harvesting process， the problem of seeds easily falling off limits the mechanization of seed harvesting and large-scale production applications. In order to explore the function of SH4 gene in the process of seed-shattering in C. breviculmis and further use gene editing technology to create new germplasm resistant to seed shattering， the CbSH4 gene was cloned and the gene editing target was screened. The CbSH4 encoded 319 amino acid residues， was a hydrophilic protein， and was most closely related to Carex littledalei， containing a highly conserved Myb4 DNA-binding domain， which belonged to a typical MYB transcription factor. The transient expression results of Nicotiana benthamiana showed that CbSH4 protein was localized in the nucleus and cytoplasm. The real-time fluorescence quantification results showed that the relative expression level of CbSH4 in the spike was significantly higher than that in the roots and leaves， and it was expressed in the abscission zone at different developmental stages. At the same time， in order to achieve efficient gene editing in C. breviculmis， three specific targets were designed in this study， and sgRNA1 was obtained by sgRNA transcription and screening in vitro with a cleavage efficiency of 58.3%， which could be used for subsequent gene editing of C. breviculmis. In this study， CbSH4 was successfully cloned and the preliminary functional analysis was completed， and the high-efficiency gene editing targets were screened， which provided a basis for the creation of new germplasm with low seed shattering.

To explore the molecular regulatory mechanisms of Pvrboh5 expression， this study constructed a yeast one-hybrid library from P. vaginatum （Paspalum vaginatum Swartz） using Gateway technology and screened the upstream regulatory factors of Pvrboh5. Salt-treated stolons of P. vaginatum ‘Sea Isle 2000’ were used as experimental material. The promoter sequence of Pvrboh5 was amplified by PCR and subsequently ligated into the yeast one-hybrid bait vector pBait-AbAi， the construct was named as pPvrboh5-AbAi. This construct was then transformed into the Y1H Gold yeast strain to generate the recombinant bait strain. Concurrently， the yeast one-hybrid library was constructed using Gateway technology. Following mRNA isolation and purification， three reading-frame double-stranded cDNAs were synthesized. Primary libraries were constructed via BP reaction， followed by the generation of high-quality secondary libraries through LR reaction. Finally， transcription factors interacting with Pvrboh5 were identified by screening the P. vaginatum yeast cDNA library. The results showed that transcriptional autoactivation of the pPvrboh5-AbAi/Y1H Gold bait strain was effectively suppressed at an AbA concentration of 100 ng·mL^-1. In the screening experiment， a total of 18 proteins that bind to the Pvrboh5 promoter were identified. These findings provide a theoretical foundation for further elucidating the regulatory mechanisms of the Pvrboh5 gene.

Bermudagrass has important application value in landscaping and ecological restoration because of its strong drought resistance， saline-alkali resistance， and developed rhizomes and stolons. However， the molecular mechanism of its response to alkaline salt stress is still unclear. The WRKY gene family plays an important role in plant growth， development and defense against biotic and abiotic stresses， but it has not been fully identified in bermudagrass. Therefore， based on genomic data， this study systematically identified the physical and chemical properties， chromosome distribution， cis-acting elements， gene structure， conserved motifs and phylogenetic trees of WRKY gene family members in bermudagrass. At the same time， based on transcriptome data， the expression pattern of its family members under alkaline salt stress was analyzed. The results showed that 129 WRKY transcription factors were identified in the bermudagrass genome and named according to their location on the chromosome. Phylogenetic analysis was carried out by comparing with Arabidopsis WRKY protein， and the above transcription factors were divided into three families ： I， II and III， which were unevenly distributed on 18 chromosomes with the largest number of chromosomes 7 （22）.Collinearity analysis showed that fragment replication mainly drove the evolution of CdWRKYs in bermudagrass. Based on the transcriptome data， 11 differentially expressed CdWRKYs under alkaline salt stress were screened out. The qRT-PCR analysis showed that the expression levels of CdWRKY59， CdWRKY81， CdWRKY113 and CdWRKY126 reached the peak at 3 h， and their expression folds were 99.6-312.3 times than the control. It is speculated that these WRKY family members might play an important role in alkaline salt stress tolerance. The results of this study analyzed the role of WRKY genes in the response of bermudagrass to alkaline salt stress， and laid a foundation for further functional analysis of WRKY gene family.

Arbuscular Mycorrhizal Fungi （AMF） play an important role in maintaining the function of grassland ecosystems. Grazing is one of the main utilization modes of grasslands， which has a profound effect on the symbiotic relationship between plants and AMF. However， the regulatory effects of grazing on the Stipa breviflora-AMF symbiosis and its driving mechanisms remain unknown. This study， conducted in the S. breviflora grassland of Inner Mongolia， examined the effects of different grazing intensities—no grazing， light grazing （LG）， moderate grazing （MG）， and heavy grazing （HG）—on the AMF colonization rate in S. breviflora roots. The results revealed a significant decline in the AMF colonization rate with increasing grazing intensity. The colonization rates were 65.89%， 59.89%， 52.89% and 41.33% under different grazing intensities， respectively. Spore density and hyphal length density decreased with increasing grazing intensity. In addition， increased grazing intensity led to longer total root length and smaller root diameter in S. breviflora， along with higher soil density and pH but lower soil organic carbon and available phosphorus. However， soil moisture and nitrate nitrogen content peaked under light grazing. Soil nitrate nitrogen and available phosphorus were identified as the primary factors influencing the reduction in AMF colonization. In conclusion， grazing negatively affects AMF colonization in desert steppes by decreasing nitrogen and phosphorus nutrient effectiveness in the soil. This study provides empirical data and theoretical insights that support the development of sustainable grazing management strategies to maintain the health and resilience of desert steppe ecosystems.

To investigate the mechanisms of the effects of different frequencies and intensities of freeze-thaw cycles on the soil carbon mineralization process and the characteristics of stable carbon isotope （δ¹³C） fractionation in alpine swamp meadows， this study focused on the soil of alpine swamp meadows on the Qinghai-Tibet Plateau. Two freeze-thaw intensities （-15 to 15℃ and -10 to 10℃， a total of 15 freeze-thaw cycles） and a control group at 10℃ were established. A 15-day indoor continuous monitoring experiment was conducted to compare the dynamics of carbon mineralization and changes in δ¹³C. The results showed that low-intensity freeze-thaw cycles significantly inhibited the rate of carbon mineralization， causing a decrease of 7.67%. In contrast， high-intensity freeze-thaw cycles significantly promote the cumulative carbon mineralization， with an increase of 2.70%. The differences among treatments were relatively small after the first 3 freeze-thaw cycles， but the growth rate of carbon mineralization significantly slowed down under the low-intensity treatment after the third cycle. The δ¹³C values under different freeze-thaw intensities ranged from -21.49‰ to -28.03‰， which showed -15-15℃>10℃>-10-10℃， and showed a trend of first decreasing and then increasing with the increase of freeze-thaw frequency. Redundancy analysis （RDA） showed that ammonium nitrogen （NH₄⁺-N） and microbial biomass nitrogen （MBN） were the key factors regulating carbon mineralization and isotope fractionation. Under the -15-15℃ treatment， δ¹³C values were significantly positively correlated with nitrate nitrogen （NO₃^--N）. In contrast， under the -10-10℃ treatment， the carbon mineralization rate was significantly negatively correlated with MBN and significantly positively correlated with microbial biomass carbon to microbial biomass nitrogen ratio （MBC/MBN）. Additionally， its stable isotopes were significantly positively correlated with NH₄⁺-N and MBC/MBN. Overall， the reduced freeze-thaw intensity significantly inhibits soil carbon mineralization processes and causes changes in microbial metabolic pathways. It is crucial to pay attention to the long-term impacts of the continued weakening in freeze-thaw intensity on the carbon sequestration function of alpine wetlands.

In this experiment， the effects of single application of organic fertilizer and mixed application of organic fertilizer on the restoration of degraded natural mowing land were evaluated from the perspective of vegetation-soil-microorganism. The natural mowing land in Altay Mountains was used as the object of study. Three fertilization measures， single application of organic fertilizer （M）， mixed application of organic fertilizer and biological fertilizer （M+NY）， mixed application of organic fertilizer and compound fertilizer （M+NPK）， were used to explore the responses of grassland vegetation-soil-microorganism to fertilization. The results showed that fertilization significantly increased grassland community height， biomass， soil organic matter content， available nitrogen， available phosphorus， available potassium content and electrical conductivity （P<0.05）， and significantly reduced soil pH value （P<0.05）. There were significant differences in the richness of 5 phyla in soil bacteria （P<0.05）， and there were significant differences in the richness of 2 phyla in soil fungi （P<0.05）. The grey system correlation degree showed that compound fertilizer + organic fertilizer had the best effect on promoting vegetation growth， improving soil nutrients and increasing the number of microorganisms， and had a rapid recovery effect on the vegetation-soil-microbial system of reseeding natural mowing land. The results of the experiment provide theoretical basis， data support and technical support for the production and restoration of organic fertilizer single application and organic fertilizer mixed with other fertilizers in reseeding natural mowing land.

Botanical illustrations， often hailed as “botanical portraits” play an indispensable role in publications by serving as the finishing touch that communicates scientific essence and aesthetic value of plants. China emerges as the earliest practitioner of botanical illustration globally， with records dating back to the Tang Dynasty. The earliest alfalfa illustration appears in Zhu Su’s Jiuhuang Bencao from the early Ming Dynasty， representing the world’s first documented alfalfa drawing. Approximately a century later， Liu Wentai’s Bencao Pinhuijingyao featured similar alfalfa illustrations. Through investigation， both Zhu Su and Liu Wentai's depictions are identified as Medicago sativa； Li Shizhen’s Bencao Gangmu introduced distinct alfalfa illustrations， which textual evidence is confirmed as Medicago hispida. By the late Qing Dynasty， Wu Qijun’s Zhiwu Mingshi Tukao presented three differentiated alfalfa illustrations： alfalfa （M. sativa）， wild alfalfa type I （Medicago falcata）， and wild alfalfa type II （M. hispida）. Through textual research and literature collection， this study conducted critical analysis of 11 alfalfa illustrations from nine Ming-Qing botanical treatises. By integrating the visual representations with their textual explanations and contemporary botanical findings on Medicago species， it has essentially clarified the species identification of alfalfa depicted in Chinese botanical illustrations from the Ming and Qing dynasties.

To investigate the growth and metabolic adaptability of alfalfa （Medicago sativa L.） under saline-alkali soil conditions， this experiment used ‘Zhongmu No.3’ alfalfa cuttings as the test material. Set up neutral salt stress （NaCl+Na₂SO₄） and alkaline salt stress （Na₂CO₃+NaHCO₃） treatments， with three gradient levels for each： light （0.3% soil salinity）， moderate （0.6%）， and severe （0.9%）. After 15 days of stress， the growth physiological indicators of plant leaves and roots were measured. The results showed that alfalfa exhibited significant growth and physiological responses under saline-alkali stress. With increasing stress intensity， growth parameters under neutral salt treatment reached the lowest level under severe stress treatment （NS）， whereas alkaline salt treatment exhibited a gradual decrease in growth parameters as treatment intensity escalated. The sodium ion （Na⁺） content in the leaves and roots significantly increased under different treatments. The content of malondialdehyde （MDA） in the leaves significantly rose under moderate （NM） and NS neutral salt stress treatments； meanwhile， the MDA content in both roots and leaves significantly increased under various alkaline salt stresses. The proline （Pro） content in the roots significantly increased under different stresses， while the activity of superoxide dismutase （SOD） first increased and then decreased as the stress level rose. This study reveals the growth and metabolic adaptation mechanisms of alfalfa under saline-alkali stress， providing research references for the breeding of salt-tolerant varieties.

In order to study the adaptability of Sorghum sudanense to salt stress， 10 varieties of Sorghum sudanense with different salt tolerance grades were used as materials and treated with different concentrations of NaCl solution at the germination stage to study the morphological indexes physiological characteristics， and leaf anatomical structure changes. The results showed that salt stress had a significant effect on the morphological indexes of S. sudanense， especially under high salt concentration. In addition， salt stress could significantly increase the contents of malondialdehyde， proline and soluble protein in S. sudanense leaves. With the increase of salt concentration， the activities of peroxidase and superoxide dismutase in salt-tolerant materials continued to increase， while the activities of the two enzymes in salt-sensitive materials increased first and then decreased. Salt stress significantly increased the thickness of midvein， thickness of vascular bundle， thickness of bulliform cells and thickness of lower epidermal cell of high-sensitivity S. sudanense leaves， and significantly decreased the thickness of midvein， thickness of leaf and thickness of vascular bundle of high-sensitivity S. sudanense leaves. Principal component analysis （PCA） was used to screen proline， thickness of vascular bundle， thickness of leaf and thickness of upper epidermal cell as the key indexes for salt tolerance screening of S. sudanense.

To select suitable high-quality oat varieties for cultivation in the Qinghai Lake area， ten introduced oat （Avena sativa L.） varieties were evaluated for yield and related traits， and the structural equation modeling was employed to analyze the key factors that affecting yield. The results showed that ‘Model’ and ‘Esker’ had relatively short growth periods （132 and 125 days， respectively）. ‘Monida’ exhibited superior plant height （61.93 cm） and hay yield （12 672.60 kg·hm^-2）. ‘Baler 2’ and ‘Haymaker’ performed better in leaf area and leaf perimeter. ‘Everleaf’ had the highest leaf area index （5.29） and， together with ‘Forage’， produced more spikelet whorls （6.22）. ‘Model’ had the highest thousand-grain weight （42.68 g）. And ‘Haymaker’ achieved the highest seed yield （9963.06 kg·hm^-2）. Random forest analysis indicated that the leaf area and grain weight per spike had significant effects on seed yield， while structural equation modeling revealed that yield was jointly regulated by both the direct effects of variety and the indirect effects mediated through the leaf area index. Overall evaluation suggested that ‘Haymaker’ had remarkable advantages and could be recommended as the dominant oat variety for the Qinghai Lake area.

To identify salt-tolerant germplasm resources of Agropyron cristatum， this study subjected 31 germplasm samples to salt stress treatment with a soil salt content of 0.9%. Chlorophyll fluorescence parameters （phi2， NPQt， qL， Fv/Fm， Fo， Fm， Y（NPQ）， Y（NO）， and Y（II）） and physiological indicators （MDA， Pro， SS， and POD） were determined， and their salt tolerance was comprehensively evaluated using correlation analysis， principal component analysis （PCA）， and cluster analysis. The results showed that the coefficient of variation of the measured indicators of 31 samples ranged from 0.03 to 0.99. PCA indicated that the contribution rates of the top four principal components were 43.152%， 22.847%， 9.746%， and 8.882%， respectively. Cluster analysis suggested that the first group had higher photosynthetic efficiency and POD activity， and lower MDA content； the second group had moderate photosynthetic rate； the photosynthesis and physiological indices of the third group were severely affected. Based on PCA and cluster analysis， combined with changes in physiological responses， six salt-tolerant Agropyron germplasm （20-02， 20-03， 20-06， 20-08， 20-11， 20-17） were screened， most of which belonged to A. latissimum. In conclusion， the salt-tolerant germplasm obtained in this study could be used as the candidate materials for the breeding of new varieties of Agropyron， and also provide germplasm resources for the exploration of excellent salt-tolerant genes.

Based on the concept and practice of grassland livestock equivalent and “Standard sheep unit”， this paper defines the “Standard rodent unit” and explores its practical significance in grassland rodent survey， monitoring and pest control management. Referring to “Standard sheep unit” conception and the research progress of grassland rodents prevention and control in recent years， we analyzed the measurement indicators for relevant rodent standard unit and the methodologies for calculating rodents food equivalents. The definition of “Standard rodent unit” was as follows， based on the common weight of the average grassland rodents， one unit represents the daily loss caused by a 100 g rodent species consuming， cutting and storing 50 g fresh grass （about 50 % of its body weight）， which converts to 10 g of dry grass （assuming a moisture content of 20 %）. Eighty rodent units are equivalent to one standard sheep unit， with conversion of different rodents based on their weight differences. A preliminarily measurement relationship among “rodent-grass-livestock” at the level of forage intake was established， which will provide standard and basis for quantifying the foraging and food equivalents of different herbivores.

Shrub encroachment in grasslands， intensified by climate change and anthropogenic activities， represents a substantial threat to the health of grassland ecosystems. This underscores the pressing need for effective and precise biomass monitoring methodologies. The present study was carried out in the shrub-encroached grasslands of the Xilingol League， to investigate optimal above ground biomass （AGB） estimation model by utilizing unmanned aerial vehicle-based LiDAR and hyperspectral data validated against field measurements. Stepwise multiple linear regression， support vector machine， and random forest algorithms were employed for analysis. The results demonstrated a robust correlation between AGB and both LiDAR-derived mean canopy height and hyperspectral reflectance within the red-edge spectral region. Hyperspectral data demonstrated superior accuracy to LiDAR for herbaceous AGB inversion （R²=0.87 vs. 0.24）， whereas LiDAR performed better than hyperspectral data for shrub AGB inversion （R²=0.58 vs. 0.47）. Data fusion significantly improved the model performance， with the random forest model integrating features from both LiDAR and hyperspectral data achieving R² values of 0.88 and 0.64 for herbaceous and shrub AGB， respectively. The related findings offer critical scientific support for the sustainable utilization and precise management of shrub-encroached grasslands.

Microbial necromass carbon （MNC） constitutes a significant component of soil organic carbon （SOC） and plays a vital role in maintaining and enhancing carbon sequestration capacity of grassland ecosystems. The temperate grasslands of northern China represent a crucial component of global grassland ecosystems， but systematic understanding of their microbial necromass carbon content and its driving factors remains limited. To address this gap， this study established transects along a natural rainfall gradient from east to west in Inner Mongolia， covering three grassland types： meadow grassland， typical grassland， and desert grassland. Soil amino sugar content was measured using the biomarker method. By integrating climate and soil characteristics， the study systematically analyzed the distribution of soil microbial necromass carbon and its driving factors. Results indicate that the average microbial necromass carbon content in topsoil is 10.65 g·kg^-1， comprising 4.79 g·kg^-1 bacterial necromass carbon and 14.80 g·kg^-1 fungal necromass carbon. Structural equation modeling reveals that microbial necromass carbon is primarily regulated by annual mean temperature， dissolved organic carbon， and pH. These findings deepen our understanding of the distribution patterns and driving mechanisms of microbial necromass carbon in northern China's temperate grasslands， providing scientific support for regional grassland carbon management and enhancing soil carbon sequestration potential.

In order to screen out the germplasm resources of Medicago falcata L. with strong drought tolerance， 20 resources of M. falcata were selected in this study， and their drought tolerance was comprehensively evaluated by analyzing the changes in the content of morphological and physiological indexes of the seedlings， and by adopting the affiliation function method and cluster analysis.The results showed that under different drought stress treatments， all the 20 M. falcata germplasm resources showed different drought responses， as indicated by a downward trend in plant height， leaf area， survival rate， above ground biomass and chlorophyll fluorescence parameters. The drought resistance of the 20 M. falcata seedlings was classified into 7 categories by cluster analysis， among which， the material A2Z311 had extremely drought-resistant， and the material A2Z525 had the weakest drought-resistant. Based on the D value of the affiliation function， the drought resistance was ranked from strong to weak as A2Z311>A2Z588>A2Z355>A2Z600>A2Z317>A2Z480>A2Z423>A2Z534>A2Z528>A2Z316>A2Z350>A2Z436>A2Z302>A2Z491>A2Z351>A2Z594>A2Z599>A2Z622>A2Z353>A2Z525. The present study indicates that the material A2Z311 could better adapt to the treatment of drought stress， and the survival rate， leaf area and chlorophyll fluorescence parameters all being 1， showing stronger drought resistance， which provides a theoretical basis for the selection and breeding of alfalfa varieties in arid areas.

Seeds diffusion involving ants is a key link in the renewal of plant populations in desert ecosystems. Analyzing the interaction mechanisms between ants and plants is of great value for the conservation of endangered species. This study focused on Ephedra rhytidosperma， a plant species endemic to the Helan Mountains. Through field behavior observations （continuous tracking and recording for 3 days）， controlled experiments （removal treatment of aril， density gradients of 10， 20 and 30 individuals·m^-2） and combined with laboratory analysis， this study revealed the mechanism of action of Cataglyphis aenescens in the seeds dispersal of this species. The results showed that the peak of seeds transportation by Cataglyphis aenescens occurs from 10：00 to 11：00 in the morning， with an average transportation distance of 4.0 meters. The aril， due to its high nutritional content， has become a key factor affecting the transportation of Ephedra rhytidosperma seeds. The transportation quantity of Cataglyphis aenescens for the three different types of targets is as follows： intact seeds > aril > seeds with aril removed， and the transportation efficiency also decreases after aril removal. Cataglyphis aenescens shows bidirectional regulation in the transportation of seeds of different densities. High-density seeds are more likely to attract ants， but the removal rate is lower. This study revealed the nutritional reciprocity mechanism of Ephedra rhytidosperma seeds diffusion mediated by Cataglyphis aenescens， providing an important scientific basis for the recovery of endangered plant populations in desert ecosystems.

Soil nematodes are pivotal for material cycling and energy flow in grassland ecosystems. Clipping is a widespread grassland management practice in northern China. However， the mechanisms by which clipping affects the composition and structure of soil nematode communities remain unclear. nematode functional footprints across plant communities remain poorly understood. This experiment examined how clipping influenced soil nematode composition， structure， and functional footprint across six plant communities in the typical steppe of Inner Mongolia， providing a theoretical basis for grassland ecosystem management. Clipping significantly increased the total abundance of soil nematodes， the relative abundance of bacterivores， the maturity index， and the Wasilewska index. At the same time， it reduced the relative abundance of plant parasitic nematodes， the nutritional diversity index， the Shannon-Wiener index， the evenness index， and the enrichment index. Fauna analysis revealed that clipping increased the functional footprint of soil nematodes and food web complexity， while it reduced the enrichment index. Soil nematode community composition was significantly affected by soil nitrate nitrogen content， total carbon content， and litter mass. Our results demonstrated that clipping restructured nematode community composition， reducing plant parasitic nematodes’ abundance， thereby improving soil nutrient functions and promoting plant growth. This study concludes that clipping effectively maintains soil nematode community structure in typical steppe， offering a science-based framework for sustainable grassland management in northern China.

To screen cold-tolerant Medicago falcata germplasms and to clarify their physiological response mechanisms to low-temperature stress， this study systematically evaluated the physiological and chlorophyll fluorescence characteristics of 20 accessions under gradient low-temperature stresses （25℃， 10℃， 5℃， 0℃）. By measuring seven key indicators， it was found that the contents of malondialdehyde （MDA）， soluble sugar （SS）， and proline （Pro）， as well as the level of initial fluorescence （F_o）， exhibited upward trends with decreasing temperature， all significantly increasing at 0℃ （P<0.05）； while the relative chlorophyll content （Soil and plant analyzer development， SPAD）， maximum fluorescence （F_m）， and maximum photochemical efficiency of PSⅡ （Maximal photochemical efficiency of photosystem II， F_v/F_m） showed downward trends. A comprehensive evaluation using the membership function method combined with the standard deviation coefficient weighting method identified M₄， M₁， and M₁₀ as accessions with stronger cold tolerance. Stepwise regression analysis further established a cold tolerance prediction model （R²=0.932）， confirming F_v/F_m and SS content as critical evaluation indices. These results provide excellent germplasm resources and a theoretical basis for cold-tolerance breeding of alfalfa， and it is recommended that future research integrate omics technologies to further elucidate the underlying molecular regulatory networks.

To clarify the distribution characteristics of soil organic carbon （SOC） and its influencing factors under different grazing intensities in a typical Inner Mongolian grassland， this study measured and analyzed SOC， total carbon （STC）， total nitrogen （STN）， total phosphorus （STP）， soil water content （SWC）， soil pH， soil bulk density （SBD）， and aboveground biomass （AGB） across the 0-50 cm soil layers under no grazing （CK）， moderate grazing （MG）， and heavy grazing （HG） in Zhengxiangbai Banner， Xilingol League， Inner Mongolia. Key results included： SOC content decreased with soil depth under all grazing intensities， with the highest SOC content observed in the 0-10 cm layer. From 0 to 50 cm deep layers， SOC declined by 7% （CK）， 17% （MG）， and 8% （HG）. Moderate grazing significantly increased SOC content in the 0-30 cm layer， with the greatest increase （11%） in the 0-10 cm layer （from 35.33 to 39.45 g·kg^-1）. Grazing effects on SOC diminished with soil depth， showing weaker impacts on deeper layers.Grazing intensity altered SOC-environment relationships： SOC was primarily driven by AGB and SWC under CK， shifted to interactions with soil nutrients （STN） and physical properties （SBD， pH） under MG， and strongly correlated with STC， STN， STP， and SBD under HG. The study concludes that moderate grazing enhances SOC accumulation and transformation in the short term， while heavy grazing poses a risk of carbon loss despite no significant SOC reduction. Protecting surface carbon pools through controlled grazing intensity is critical for sustainable grassland management.

To investigate the effects of exogenous Melatonin （MT） on the growth and physiological characteristics of alfalfa （Medicago sativa） under low phosphorus stress， germplasms ‘7890’ and ‘15578’ were used as materials. The normal phosphorus （NP， 1.0 mmol·L^-1 KH₂PO₄） and low phosphorus （LP， 0.01 mmol·L^-1 KH₂PO₄） stresses were imposed by nutrient solution sand culture method. Five different concentrations of MT were applied to the roots of alfalfa seedlings under LP stress to determine their morphology and physiological indicators. The results show that： 90 μmol·L^-1 MT has the best effect in alleviating low phosphorus stress in alfalfa. The plant height， leaf area， aboveground and underground biomass， relative water content， root vitality， transpiration rate， stomatal conductance， net photosynthetic rate， contents of chlorophyll a， chlorophyll b， carotenoids， chlorophyll， proline， soluble sugar and soluble protein， as well as the activities of superoxide dismutase， peroxidase and catalase were all significantly increased. The concentrations of malondialdehyde and intercellular CO₂ were significantly reduced. Principal component analysis indicated that chlorophyll content， soluble sugar content， and leaf stomatal conductance could be used as key indicators for the growth and development of alfalfa under low phosphorus stress by MT. In conclusion， exogenous MT can enhance the activity of antioxidant enzymes and the content of osmotic regulatory substances in alfalfa seedlings under LP stress， and improve their tolerance to low phosphorus.

This study investigated the effects of different addition levels （0， 2.5， 5.0， 7.5 g） of Seriphidium transiliense leaf litter on the enzyme activities and stoichiometric ratios of β-1，4-glucosidase （βG）， N-acetyl-β-glucosaminidase （NAG）， leucine aminopeptidase （LAP）， and alkaline phosphatase （AP） in 100.0 g of soil from Sagebrush desert grassland during 320 d （T₁）， 410 d （T₂）， and 500 d （T₃） of decomposition using an outdoor Mason jar incubation method. The results showed that enzyme activities generally decreased over the decomposition period. Specifically， the βG activity in the 5.0 g treatment at T₂ was significantly higher than that at T₁ and T₃ by 12.16% and 20.53%， respectively （P<0.05）. The NAG activity in the 7.5 g treatment at T₁ was significantly higher than that at T₂ and T₃ by 19.19% and 19.10%， respectively （P<0.05）. Enzyme activities initially decreased and then increased with increasing litter addition. At T₃， the 7.5 g treatment significantly enhanced NAG activity while reducing LAP activity （P<0.05）. The average soil enzyme stoichiometric ratios of C∶N， C∶P， and N∶P were 0.65， 0.91， and 1.41， respectively， with a C∶N∶P stoichiometric ratio of 1∶1.26∶1.05， with the vector angles less than 45°. In conclusion， soil enzyme activities and their stoichiometric ratios were co-regulated by both litter addition amount and decomposition stage， and were constrained by soil nitrogen limitation.

Grassland degradation is one of the major global ecological challenges， especially in the arid and semi-arid areas of northwest China， where degraded grassland seriously affects the ecosystem functions and the development of animal husbandry. In this study， a four-year field experiment was conducted in Yuyang District， Shaanxi Province， and systematically evaluated the effects of reseeding and modern intensive grazing techniques on degraded grassland productivity， vegetation community structure， soil physicochemical properties， and meat quality of sheep. The results showed that reseeding significantly enhanced grassland productivity， particularly by increasing the biomass proportion of legumes， which increased soil nitrogen content and improved vegetation nutritional quality. In addition， principal component analysis （PCA） revealed that reseeding restructured plant communities to include more plants with high nutrtional value. Grazing on reseeded grassland increased amino acid content in sheep meat and enhanced its flavor. In general， reseeding technology plays a pivotal role in restoring degraded grassland and advancing sustainable development of animal husbandry， offering a scientific foundation for grassland management in arid and semi-arid areas.

Nitrogen （N） and phosphorus （P） additions are vital management methods to alleviate plant nutrient limitation and improve grassland productivity. Soil nutrient enrichment may potentially alter the symbiotic relationships between plants and arbuscular mycorrhizal fungi （AMF）. This study conducted a three-factor experiment to study the independent and interactive effects of N and P additions and AMF on the biomass and C∶N∶P of Agropyron mongolicum and Astragalus melilotoides in the desert steppe in Ningxia. We used a kind of fungicide（benomyl）to regulate native AMF activities. Our results showed that N and P additions significantly increased the aboveground biomass of A. mongolicum and A. melilotoides， but AMF did not alter them. AMF significantly reduced the aboveground biomass of A. mongolicum under P alone addition and both N and P addition treatments. AMF increased the C∶N of A. mongolicum plants and the C∶P of A. melilotoides. P addition significantly reduced the C∶P and N∶P of two plants， and alleviated the P limitation of A. mongolicum. In summary， compared with AMF， N and P addition was more beneficial to dominant plants biomass in the desert steppe in Ningxia， and could alleviate the nutrient limitation of A. mongolicum and A. melilotoides.

The soil carbon cycle constitutes the core of the global carbon cycle， governing the carbon sink function of terrestrial ecosystems. As key driving factors， nitrogen and phosphorus additions regulate the balance between soil carbon sequestration and release by altering the transformation processes of soil carbon fractions and microbial community activities. Based on CiteSpace bibliometric analysis， this study systematically reviewed global research progress over the past decades. Results indicated that the number of studies were growing exponentially， with research hotspots focusing on： the dynamics of labile and stable carbon fractions in soils， metabolic responses of microbial functional communities， and the nonlinear equilibrium of carbon input-output fluxes. While domestic research had made significant contributions to regional differential response mechanisms and micro-scale analysis of microbial-carbon coupling processes， shortcomings persisted in experimental designs for multi-factor interactions and the integration of long-term observational data. Future research should prioritize breakthroughs in long-term in-situ controlled experiments to elucidate the coupling mechanisms between nitrogen-phosphorus stoichiometry and carbon component transformation， and achieve precision prediction of carbon turnover through model-data fusion. This study provides a theoretical framework for quantitatively evaluating the carbon sequestration potential of grassland ecosystems under anthropogenic nitrogen and phosphorus input， and has guiding significance for the adaptive management of ecosystems under the goal of “Double Carbon”.

To investigate the effects of different additives on the silage quality and microbial population of Elymus dahuricus，Elymus dahuricus was used as the raw material and herein and set up five treatment groups： P₁ （no additive， add the same amount of distilled water）， P₂ （adding Lactobacillus plantarum，the addition amount was 1×10⁶ CFU·g^-1 FW）， P₃ （adding molasses， the addition amount was 20 g·kg^-1 FW）， P₄ （adding Lactobacillus buchneri，the addition amount was 1×10⁶ CFU·g^-1 FW）， and P₅ （adding cellulase，the addition amount was 50 U·g^-1 FW）. After 60 days of ensiling， the nutritional quality， fermentation characteristics， and microbial counts were determined. The results showed that different silage additives significantly affected the contents of water soluble carbohydrates （WSC）， neutral detergent fiber （NDF）， acid detergent fiber （ADF）， and crude ash in Elymus dahuricus silage（P<0.05）. The additives significantly decreased the pH value of the silage and significantly increased the lactic acid content （P<0.05）， while significantly reducing the propionic acid content （P<0.05）. Comprehensive membership function analysis indicated that quality of Elymus dahuricus silage was the best when the addition amount was 20g·kg^-1 FW molasses.

In　this study， 15 oat varieties were used to investigated the effects of different seed moisture content [12% （T1）， 14% （T2）， and 16% （T3）] and storage methods （conventional and hermetic storage） on the germination characteristics. The results revealed that there were significant genotypic differences （P<0.05） in response to moisture stress among the varieties， which were further influenced by storage duration and method. For example， ‘Baiyan 7’ exhibited the best performance during the initial germination stage at 16% moisture treatment （T3）， whereas varieties such as ‘Qinghai Sweet Oat’ showed higher germination rates under low moisture conditions （T1）. In addition， storage methods significantly altered moisture sensitivity of varieties： conventional storage increased the suitable moisture threshold to T3 for certain varieties， while hermetic storage reduced the moisture requirement of most varieties. Embryo development analysis revealed that distinct patterns in radicle and plumule biomass responses to moisture levels among varieties. Hermetic storage induced a shift from linear to peak-curve responses in these traits. Differential sensitivity to moisture between radicles and plumules was also observed， indicating genotype-specific resource allocation strategies. Hermetic storage had a highly significant effect （P<0.01） on oat seed germination characteristics. Based on TOPSIS comprehensive evaluation， ‘Qingyan 1’ was identified as the best stablity. Furthermore， strong correlations were observed between embryo indicators and germination parameters， suggesting that they could be used as a reliable predictor of seed vigor.

To determine the production performance and suitable planting area of triticale （× Triticosecale Wittmack） variety ‘Zangsi No.3’ in Xizang pastoral area， the plant height， tiller number， fresh yield and hay yield of ‘Zangsi No.3’ in Namling， Dagzê and Lazi experimental sites were studied in 2022 and 2023， with triticale varieties ‘Zangsi No.1’ and ‘Gannong No.2’ as controls. The results showed that the average hay yield of three triticale varieties in 2023 was significantly higher than that in 2022 （P<0.05）， but there were no significant difference in average plant height， tiller number and fresh yield. From the experimental sites of view， the average plant height， fresh yield and hay yield of the three triticale varieties in Namling experimental site were significantly higher than those in Dagzê and Lazi experimental sites （P<0.05）， and the average tiller number in Lazi experimental site was the highest （P<0.05）. From the difference of years×experimental sites×varieties， the fresh yield （52.80 t·hm^-2） of ‘Zangsi No.3’ in Namling experimental site in 2022 was significantly higher than other varieties （P<0.05）， and the hay yield of this variety was the highest in 2023， 19.08 t·hm^-2， significantly higher than the control varieties （P<0.05）. From the comprehensive evaluation， the comprehensive evaluation value of ‘Zangsi No.3’ in Namling experimental site was the highest in 2022 and 2023， and its production performance was the best. In summary， the production performance of ‘Zangsi No.3’ was better than ‘Zangsi No.1’ and ‘Gannong No.2’， which was suitable for planting in Namling experimental site and other similar climate area.

To investigate the effects of Chinese herbal residues on the quality and safety of whole-plant corn silage， this study compared the effects of Eucommia ulmoides， Mentha spicata， and Codonopsis pilosula residues mixed with whole-plant corn （Zea mays） at fresh weight ratios of 5%， 7%， and 10%， respectively， with that of whole-plant corn silage alone. The impacts of these treatments on the quality of corn silage and aflatoxin B1 content were assessed. The results showed that at 60 days of ensiling， except for the 10% Eucommia ulmoides and 5% Mentha spicata treatments， the water soluble carbohydrate（WSC） content of other treatments was significantly higher than that of the control （P<0.05）. The 10% Codonopsis pilosula residue treatment had the highest WSC content. The acidic detergent fiber content in both the Mentha spicata residue treated groups and 10% Eucommia ulmoides residue treatment was significantly lower than that in the control （P<0.05）. Additionally， the lactic acid content in both the 5% Mentha spicata residue and 5% Eucommia ulmoides residue treatments was higher than 100 g·kg^-1 DM and significantly higher than that of other treatments （P<0.05）. Except for the 10% Codonopsis pilosula residue treatment， the aflatoxin B1 （AFB1） content of all treatments was lower than that of the control， and that of the 10% Eucommia ulmoides residue and 5% Mentha spicata residue treatments was significantly lower than other groups （P<0.05）. After 9 days of aerobic exposure， the crude protein （CP） content in all treatments decreased， but the CP loss rate of the Chinese herbal residue treatment groups was significantly lower than that of the control （P<0.05）； the AFB1 content of the 5% Mentha spicata residue treatment was the lowest， and significantly lower than that of other treatments （P<0.05）. Considering the nutritional quality and safety of the whole-plant corn silage， mixing the whole-plant corn with either 5% Mentha spicata residue or 10% Eucommia ulmoides residue for ensiling is recommended.

This study aims to screen the suitable grass species with low sowing rate and high coverage. Four ecological grass species， Poa pretensis ‘Qinghai’， Deschampsia cespitosa， Koeleria macrantha and Elymus tangutorum， were selected as experimental materials to carry out the screening experiment of suitable sowing rate. The characteristics of plant phenotypic traits， biomass and soil nutrients under three sowing rates were analyzed. The results showed that when the sowing rate was 9 g·m^-2， the aboveground biomass of Poa pretensis ‘Qinghai’， Deschampsia cespitosa and Koeleria macrantha were the highest， which were 296.45 g·m^-2，224.32 g·m^-2 and 236.35 g·m^-2 respectively. The aboveground biomass of Elymus tangutorum was 356.24 g·m^-2 when the seeding rate was 18 g·m^-2， which was significantly higher than other treatments （P<0.05）. When the sowing amount of Poa pretensis ‘Qinghai’， Deschampsia cespitosa and Koeleria macrantha reached 9 g·m^-2， the soil nutrient indexes such as organic matter， total nitrogen and total phosphorus performed well. The seeding rate of Elymus tangutorum was 18 g·m^-2， which showed a good soil nutrient status. Principal component analysis of 13 indexes of plants and soil showed that the cumulative contribution rate of the first five principal components reached 89.615%. The comprehensive evaluation of membership function showed that the comprehensive evaluation values of Poa pretensis‘Qinghai’， Deschampsia cespitosa and Koeleria macrantha were the highest when the sowing amount was 9 g·m^-2， which were 0.420， 0.486 and 0.698 respectively. When the seeding rate of Elymus tangutorum was 18 g·m^-2， the comprehensive evaluation value was the highest， which was 0.634. To sum up， 9 g·m^-2 is the most suitabel sowing amount for planting Poa pretensis‘Qinghai’， Deschampsia cespitosa and Koeleria macrantha in Muli mining area， and 18 g·m^-2 is Elymus tangutorum in Muli mining area.

This experiment was conducted to study the effects of combined application of organic fertilizer and chemical fertilizer on the production performance， nutritional quality and economic benefits of different triticale （×Triticosecale） varieties， and to provide theoretical basis for high yield cultivation techniques of triticale in dry farming areas of central Gansu. The experiment used a split-plot design， and the main plot factor was nitrogen application rate， which was set at four levels： 120 （A1）， 240 （A2）， 360 （A3）， and 480 kg·hm^-2 N （A4）. For these nitrogen application treatments， nitrogen was applied as a combination of organic fertilizer and urea， with 2/3 of the nitrogen from organic fertilizer used as base fertilizer and 1/3 from urea as topdressing. Two control treatments were also included： no fertilization （CK1） and single application of chemical fertilizer （CK2）. The subplot was two triticale varieties （C1： ‘Gannong No.2’； C2： ‘Gannong No.4’）. The results showed that among the fertilization treatments， when the combined application rate of organic fertilizer and chemical fertilizer was 360 kg·hm^-2 N， the average hay yield （8.36 t·hm^-2）， crude protein content （10.73%）， and comprehensive evaluation value （0.95%） of the two triticale varieties were relatively higher. From the perspective of triticale varieties， the comprehensive evaluation value of ‘Gannong 2’ triticale （0.60） was higher than that of ‘Gannong 4’ triticale （0.40）. Their interaction showed that when the combined application of organic fertilizer and chemical fertilizer was 360 kg·hm^-2 N， the comprehensive evaluation value of Gannong No.2 was the highest （0.84）， which was higher than that of the two triticale varieties under single application of chemical fertilizer （0.52， 0.72）. In conclusion， under dry climate conditions， to balance high-quality and high-yield forage as well as economic benefits， the recommended nitrogen application strategy is as follows： for ‘Gannong 2’ triticale， a combined application of organic fertilizer and chemical fertilizer at a rate of 240 kg·hm^-2 N is suitable； for 'Gannong 4' triticale， a single application of chemical fertilizer at 360 kg·hm^-2 N is appropriate.