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.