To elucidate the mechanism by which grazing intensity affects ecosystem multifunctionality （EMF） in alpine grasslands. In this study， the alpine grassland of Qinghai Lake was selected as the study area. Four treatments were set up， including grazing prohibition， light grazing， moderate grazing and heavy grazing. The effects of grazing intensity on plant functional traits， soil factors and ecosystem multifunctionality （EMF） were analyzed. The results showed that grazing intensity significantly changed plant community traits （P<0.05）. As grazing intensity increased， community-weighted height and leaf area decreased， while leaf nitrogen and phosphorus contents increased. Aboveground and belowground biomass significantly declined under heavy grazing （P<0.05）. The soil exhibited a decoupling character of nitrogen and phosphorus， with nitrate-nitrogen and ammonium-nitrogen decreasing while total phosphorus and available phosphorus accumulated. Moderate grazing had the most pronounced effects on soil moisture and pH （P<0.05）. The functional dispersion index increased with grazing intensity， and EMF peaked under moderate grazing. The structural equation model showed that grazing indirectly affected ecosystem multifunctionality （EMF） by regulating plant traits， functional dispersion index， and soil quality index （SQI）， with soil quality being the key driving factor. This study elucidated the intrinsic mechanism by which grazing intensities influences EMF through the coordination of plant functional strategies and soil nutrient patterns， providing a theoretical basis for the scientific management of alpine grasslands around Qinghai Lake.

To overcome the limitations of an imperfect mutagenesis breeding system for Leymus chinensis and the shortage of germplasm with high seed setting rates， this study established an efficient mutagenesis technology using a combination of spatial and atmospheric pressure room-temperature plasma （SP+ARTP）. A high-throughput， accurate phenotypic analysis of large-scale mutant populations was achieved by utilizing an automatic seed setting rate identification model based on the YOLO algorithm. The results indicated that cultivar ‘Xiwuzhumuqin’ was the most suitable material for mutagenesis； a 60-minute treatment with 20% NaOH was the optimal pretreatment method. Single-space mutagenesis significantly promoted seed germination and seedling growth. The mutagenesis efficiency of the M₁ generation using the SP+ARTP combination reached 1.20%， and 23 new germplasm lines with high seed setting rate were successfully selected. These lines exhibited a seed setting rate of 30% higher than that of the control group. The combined mutagenesis and high-throughput phenotyping system developed in this study provides key technical support and germplasm resources for the targeted breeding of high-seed-setting L. chinensis varieties and their industrial application.

To develop a rapid quality detection model for oat （Avena sativa） hay applicable across environments， 849 samples were collected at three sites （Baoding and Zhangjiakou in Hebei， Guyuan in Ningxia） for two years. Crude protein （CP）， neutral detergent fiber （NDF）， acid detergent fiber （ADF）， soluble sugars （SS）， and total potassium （K） were measured. Prediction models were established using near-infrared spectroscopy （NIRS） combined with partial least squares regression （PLSR）. All five traits showed broad， near-normal distributions， indicating good sample representativeness. The CP， SS， and K models performed well， with cross-validation coefficients （R²） ≥ 0.89， ratio of performance to deviation （RPD） ≥ 3.0， and validation set correlations （r） of 0.84， 0.86， and 0.83， respectively， demonstrating strong external predictive ability. The NDF and ADF models achieved R² ≥ 0.85 and RPD ≥ 2.5， with r values of 0.78 and 0.79， meeting requirements for routine screening. Based on model predictions and forage quality standards， 56 high-quality forage oat accessions were identified. This study provides an efficient technical platform for high-throughput phenotyping and quality-based breeding in oat germplasm.

To investigate the role of exogenous selenium in regulating plant tolerance to saline-alkali stress， alfalfa （Medicago sativa L.） ‘WL298HQ’ was used as experimental material. Different concentrations of exogenous selenium were applied during seed germination and seedling stages to explore the effects on seed germination and physiological characteristics under mixed saline-alkali stress. The results showed that applying exogenous selenium at concentrations of 0.5， 1， and 2 mmol·L^-1 significantly promoted the germination of WL298HQ seeds under stress. The most pronounced promoting effect on seed germination was observed at 0.5 mmol·L^-1. Comprehensive analysis of various physiological indicators at the seedling stage revealed that 2 mmol·L^-1 exogenous selenium effectively alleviated the physiological damage caused by mixed saline-alkali stress to alfalfa seedlings. Mixed saline-alkali stress significantly inhibited the antioxidant capacity and increased cell membrane permeability of alfalfa. However， exogenous selenium application under mixed saline-alkali stress promoted plant growth， reduced the degree of membrane lipid peroxidation， and simultaneously enhanced the activities of various antioxidant enzymes in the leaves.

As an important turfgrass and forage grass， perennial ryegrass （Lolium perenne L.） is frequently constrained by high temperature stress during its growth. To explore the effects of PvPCF5 gene functional repression on heat tolerance of perennial ryegrass and its correlation with photosynthesis， wild-type （WT）， PvPCF5 functional repression （PvPCF5-SRDX）， and overexpression （PvPCF5-OX） plants were used as experimental materials and divided into 2 groups with or without heat acclimation， followed by heat stress treatment at 42℃ for different durations. The results showed that under high temperature stress， PvPCF5-SRDX plants exhibited superior physiological performance compared with WT ones， with significantly higher relative water content， and significantly lower electrolyte leakage and malondialdehyde content （P<0.05）. Meanwhile， the photosynthetic pigment contents of PvPCF5-SRDX plants were significantly higher than those of PvPCF5-OX ones （P<0.05）， accompanied by the highest net photosynthetic rate， stomatal conductance and transpiration rate， as well as the lowest intercellular CO₂ concentration. In conclusion， repression of PvPCF5 gene function can effectively improve the photosynthesis of perennial ryegrass and thereby significantly enhance its high temperature tolerance. This study provides a theoretical basis for breeding new heat-tolerant perennial ryegrass varieties.

The genus Elymus is an important native grass species for ecological restoration. Screening low nitrogen-tolerant germination germplasm and improving nitrogen use efficiency are one of the effective approaches for near-natural restoration of degraded grasslands. In this study， twelve indicators during germination and seedling growth stages of 60 Elymus germplasms were measured under low nitrogen （0.01 mmol·L^-1） and control （1.00 mmol·L^-1）conditions using the petri dish germination method. Their responses to low nitrogen were explored， and comprehensive evaluation of low nitrogen tolerance was conducted by combining membership function and systematic clustering analysis. The results showed that under low nitrogen stress， all the indicators of the germplasms were decreased. The average germination rate， germination vigor， germination index， seedling length， root length， seedling fresh weight， root fresh weight， total fresh weight， seedling dry weight， root dry weight， total dry weight， and root-shoot ratio decreased by 5.95%， 12.07%， 8.21%， 6.40%， 14.80%， 29.04%， 36.28%， 25.54%， 30.00%， 40.74%， 28.77% and 8.08%， respectively. There were significant differences in low nitrogen tolerance among the different germplasms. Seven germplasms， including E22， E58and E47， had a comprehensive low nitrogen tolerance coefficient exceeding 0.850， while E32 and E49 were below 0.66. Based on the low nitrogen tolerance coefficient， cluster analysis divided the tested germplasms into six categories： super-strong， medium-strong， low-strong， low-weak， medium-weak， and super-weak. Among them， 10 materials， including E47 and E22， were classified as super-strong low nitrogen-tolerant germplasms， and 3 materials， including E49 and E32， were classified as super-weak low nitrogen-tolerant germplasms. This study provides excellent parental materials for the mining and functional research of candidate genes related to Elymus low nitrogen tolerance， genetic improvement， and breeding of new varieties.

In this study， the forage oat （Avena sativa L.） cultivar ‘Zhongtian No. 4’ was used as the experimental material to establish an optimized ethyl methanesulfonate （EMS） mutagenesis system. A series of pretreatments steps were employed， including husk removal and a 30-hour seed moisture conditioning period， followed by EMS mutagenesis treatments at different concentrations and durations， and a post-treatment involving exogenous gibberellin application. An M₂ mutant population was constructed. Agronomic traits were investigated at the milk stage to evaluate the mutagenic effects and to screen the high-yielding germplasm. The results indicated that soaking seeds in 98% concentrated sulfuric acid for 6 minutes effectively removed the husk barrier of forage oat seeds. Adjusting seed moisture content to 50% via a 4-hour soaking facilitated efficient penetration of EMS into the seed. The optimal EMS mutagenesis conditions for forage oat were determined to be 1.0% EMS treatment for 16 hours. Treatment of mutagenized seeds with 50 mg·L^-1 exogenous gibberellin significantly improved seedling growth. Compared with the control without added gibberellin， the germination rate increased by 8.5%， and the seedling length also recovered to the level of the non-mutagenized seedlings. This EMS mutagenesis technique systematically addressed key limiting factors in forage oat， including seed permeability barriers， inconsistent physiological states， and mutagen-induced damage. In the M₂ generation， the mutagenic efficiency for obtaining high-yield potential germplasm reached 1.92%， and 13 elite high-yield potential germplasms were successfully identified.

Field phenotyping is fundamental to crop variety evaluation. However， traditional data acquisition methods are often destructive， costly， and subjective， and conventional 3D reconstruction techniques struggle to capture fine plant structures. To address these challenges， this study proposed a high-throughput phenotyping method for individual oat plants based on smartphone video acquisition and 3D Gaussian Splatting （3DGS） technology. The experiment utilized 187 oat plants at the milky stage as tested materials. Multi-view video data captured by smartphones were used to generate 3DGS point cloud models， from which canopy structural parameters—including projected area， maximum canopy width， and average canopy width-were extracted. Canopy volume was calculated using both Convex Hull and Voxelization （voxel size 0.01 m and 0.005 m） methods. Furthermore， biomass （fresh and dry weight） prediction models based on canopy volume were constructed using Random Forest （RF） and Support Vector Machine （SVM） algorithms. The results showed that： （1） 3DGS technology achieved high-fidelity reconstruction of the complex morphology of oats， effectively resolving issues related to slender leaves， thin stems， and severe self-occlusion， thereby demonstrating significant advantages over traditional reconstruction methods in restoring intricate structural forms； （2） Biomass estimation models based on 3DGS point cloud volume were reliable， with dry weight prediction accuracy （Accuracy≈0.88） generally superior to that of fresh weight； notably， high-resolution voxelization （voxel size 0.005 m） demonstrated a slight advantage in accurately describing the physical canopy structure. The workflow established in this study-“Smartphone Video Acquisition-3DGS Modeling-Phenotypic Parameter Extraction”-offered a low-cost， high-precision， and non-destructive solution， providing effective technical support for high-throughput phenotypic analysis of fields.

To screen novel germplasm of Pennisetum purpureum with high-yield potential， 800 F₁ hybrid individuals were generated by crossing ‘Guimu 1’ hybrid P. purpureum （female parent） with F-AI P. purpureum （male parent）. SSR molecular markers were employed to authenticate true hybrids， followed by analyses of diversity， correlation， clustering， and principal components for 10 yield-related traits in the true hybrid population. The results revealed that 300 true hybrids were identified using two primer pairs （SSR24 and WSSR31）. The true hybrid population exhibited abundant phenotypic variation， with coefficients of variation ranging from 13.91% to 45.58% and diversity indices from 1.37 to 2.84. Correlation analysis demonstrated that all traits were highly significantly positively correlated with single-plant yield （P<0.01）， among which plant height showed the strongest correlations with fresh weight and dry weight， with correlation coefficients of 0.55 and 0.66， respectively. Heterosis analysis indicated that most yield-related traits of the F₁ generation displayed positive dominance， and the relative heritability of the female parent was stronger than that of the male parent. Principal component analysis extracted two principal components， accounting for a cumulative variance contribution rate of 64.819%， with plant height， single-plant dry weight， tiller number， and internode length identified as core influencing factors.

To investigate the variation patterns of fresh weight and cold tolerance traits in new breeding materials of Pennisetum purpureum， identify the main trait factors affecting fresh weight， and select superior materials with high fresh weight and strong cold tolerance， this study used 86 materials of P. purpureum as experimental subjects and analyzed twelve traits for diversity， correlation， regression， path， cluster and principal component analysis. The results showed that the coefficient of variation for each trait of the tested materials ranged from 6.45% （leaf length） to 18.17% （tiller number after regreening）， and the genetic diversity index ranged from 1.8992 （plant height） to 2.0958 （fresh weight）. Regression and path analysis indicated that regreening speed， leaf length， internode length， and stem diameter had significant direct positive effects on fresh weight. Cluster analysis classified the materials into four clusters， with cluster I exhibiting better comprehensive traits and cluster IV the worst. Principal component analysis extracted three principal components， with a cumulative contribution rate of 68.12%. Based on principal component scores， the comprehensive evaluation D value was calculated using the fuzzy membership function method combined with the contribution rates. According to the D value ranking， 17 P. purpureum breeding materials with relatively superior comprehensive traits， including GM1×F-Y189， GM1×F-Y557， and GM1×F-A591， were selected. These results can provide a phenotypic evaluation basis for breeding new high-fresh-weight and cold-tolerant P. purpureum varieties.