To explore the relationship between root characteristics and productivity of alfalfa in early growth stage,in this study,a field experiment was conducted with alfalfa ‘Gannong NO. 7’,‘Gannong NO. 3’,‘LW6010’ and ‘Longdong’ as experiment materials,and two treatments of no nitrogen application and nitrogen application (103.5 kg·hm ^-2) were set to study the performance and root characteristics of the 1 ^st cut alfalfa cut in the planting year and their correlation. The results showed as follows:regardless of nitrogen application,plant height,yield,taproot length,root volume,root surface area,root nodule number per plant,nodule weight per plant,crude protein content and relative feeding value of ‘LW6010’ were the highest,and the plant height,yield,taproot length,root surface area,crude protein content and relative feeding value of ‘LW6010’ were significantly higher than those of ‘Longdong’ alfalfa (P<0.05). The agronomic traits and quality of all varieties were better than that without nitrogen application. According to the correlation analysis,the root characteristics of alfalfa were positively correlated with yield,The root length,root volume,root surface area and nodule weight were positively correlated,and the number of nodule was positively correlated. Therefore,improving the taproot length,root surface area,root volume and nodule characteristics in the early growth stage of alfalfa will improve its yield.

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.

Seed dormancy and germination are complex adaptive traits of plants influenced by a great number of genes and environmental factors.Although the utilization of quantity genetics methods(such as QTL analysis) and mutant approaches have made great development for dormancy and germination,the detailed mechanisms of dormancy and germination are not yet fully reported.Hormone,a factor to initiate seed germination,plays a key role in the regulation of seed dormancy and germination.Therefore,the relation between hormones and both germination and dormancy continues to be a research focus of seed physiology and biochemistry.With advancing understanding of the molecular biology and the discovery of a large number of mutants,regulatory mechanisms for a single hormone and interactions among hormones during seed dormancy and germination processes are better known.However,little knowledge about key points of networks for different hormones is known.This paper will focus on the functions of abscisic acid(ABA),gibberellin(GA),ethylene(ETH),brassinosteroids(BR) and other hormones during seed dormancy and germination progress,and further discusses the signaling relationship among these four hormones.

To explore the effect of Chinese herbal medicine on ram semen quality,19 kinds of Chinese herbal medicines as feed additives (adding 1% daily feed quantity per ram) were fed to rams for 3 weeks.The sexual reaction and semen quality of rams were studied after feeding Chinese herbal medicine additives.Results showed that sexual reaction time was shortened significantly compared with contro.Ejaculate volume and sperm density were increased significantly in test groups compared with that in the control group.Effective sperm number was up to 61.64 × 10 ⁹ every time,which was significantly higher than that in control group by about 2.36 times ( P<0.01).Sperm head deformity was about 8% lower than that of control.Semen quality had significantly improved after feeding with Chinese herbal medicine feed additives for one week.The rate of sperm quality decline was delayed until one week after three weeks feeding.After freezing,both sperm motility rate and recovery rate were significantly higher than that of control ( P<0.05).Sperm motility rate of tested group increased 38.7% and sperm recovery rate was increased 28.9% over the control after freezing ( P<0.05).Therefore,Chinese herbal medicine as feed additives can be used to improve the quality of ram’s semen,and to improve the storage quality of semen in artificial insemination process.

Glutathione (GSH), an important antioxidant in plants, can scavenge the redundant active oxygen free radicals produced during cell metabolism processes and relieve the damage caused by membrane lipid peroxidation. GSH contributes to the role of adversity stress resistance in plants. This review summarizes GSH activities including the types of GSH in plants, the application of GSH and the physiological mechanism of GSH protecting plant cells including scavenging intracellular active oxygen free radicals, forming non-toxic compound by combining with toxic heavy metal material, absorbing and transporting amino acid, resisting to adversity stress (temperature stress, drought stress, heavy metal stress and salt stress). GSH metabolism plays a positive role for understanding the physiological function of plant antioxidants, knowing the mechanism of scavenging active oxygen free radicals, and studying plant resistance.

In order to provide evidence for grassland ecosystem scientific management of Kanas Scenic Area, a more clear definition with associated evaluation of ecosystem resilience is suggested. Plant diversities of damaged mountain meadow ecosystem by human disturbance (tourism, grazing and other human activities) were investigated using the indices of ecosystem (community) structure, function maintenance, recovery capability, and resistance ability. Results showed that the maintenance of ecosystem (community) structure and function as well as recovery capability all had a decreasing trend with human disturbance increasing. There were significant differences between buffer zone and intense activity zone, background zone and activity zone, as well as background zone and intense activity zone ( P<0.05). The resistance ability of species diversity decreased while human disturbance increased. Perennial plants were the main contributors of the resistance ability of species diversity. However, trend and change amplitudes of resistance ability were slowed in functional diversity and community diversity due to the functional redundancy of functional groups and community. The stability of community productivity and ecological processes could resist human disturbance. Therefore, the evaluation system of grassland ecosystem resilience is more rational and avoids the deficiency of evaluating deviation of single index.

The root-growth rhythm of four leguminous forage species in immature loess subsoil was studied by root-tube soil column culture methods.Results indicated that the root growth index of four legume species followed an "S"-shaped growth model(classified as slow-increased period,rapid-increased period and peak period).Root biomass had no sharp decrease with root aging death during a one-year growth period.Vertical distribution of roots had significant difference for all tested legume species.The dry biomass of root showed "T"-shaped distribution model for vertical depth and root biomass followed an index mode of decreasing successive reduction( Y= A· e^-bx).The root and shoot growth model of four leguminous forage species typified the following four categories: synchronous growth type of root and seeding(crown vetch),permanent growth type of seeding strength(sweet clove),persistent growth type of root strength(alfalfa),growth type of weak seed and root(red clover).The root-growth climax of legumes appeared in a subsequent growth period and later than canopy.This study supplied a theoretical basis for developing a sound technical system of high yield and promoting coordinated growth of seedling and root system of leguminous forage in immature loess subsoil.

Different methods(temperatures,KNO ₃ solutions and pre-cooling treatments)were investigated to break the dormancy and promote seed germination of: Digitaria sanguinalis(L.)Scop, Digitaria ischaemum(Schreib.) Schreib, Cleistogenes gracilis Keng and Cleistogenes squarrosa(Trin.) Keng.Results indicated that Digitaria sanguinalis seeds had no dormancy and both pre-cooling and KNO ₃ solution did not significantly promote germination. Digitaria ischaemum seeds had both dormancy and low-viability;pre-cooling treatment could break the dormancy effectively and KNO ₃ solution could effectively improve viability.The low seed germination percentage of Cleistogenes gracilis and Cleistogenes squarrosa was enhanced with a KNO ₃ solution improving both seed viability and seed germination percentage.Optimum seed germination conditions were: Digitaria sanguinalis seed germinated at 30℃ with or without KNO ₃(0.2%)solution treatment; Digilaria lschaemum, Cleistogenes gracilis and Cleistogenes spuarrosa seeds germinated at 20~30℃ with KNO ₃(0.2%)solution and pre-cooling treatment(7 d).

This article discussed the reasons, distribution, areas, the interpretative keys of thealpine grassland and its degenerated gusland in Dari county, Qinzhang Plateau Bayankela Mountains,Qinghai province.It divided the grasland into five types, two subtypes and three degenerate grassland.Special emphasis was paid to find out reason for degeneraion and interpretative marks of landsat image.The results show, the local region of alpine meadow pastureland in Qingzhang plateau, carrying capacity ofpastureland were close relations with physicochemical charateristics of soil parent maerial.To make sci-entific and proper carrying capacity must be considered on the parent maerials of natural pastureland soil.

The effects of additives on cultivated grass silage ( Elymus sibiricns L. and Phalaris arundinacea L.) from alpine meadow in northwest Sichuan grassland were studied and the numbers of adhesive microbe were analyzed. Cellulase, sucrose, urea and acetic acid were tested additives. Results showed that the numbers of lactic acid bacteria were less than that of molds, yeast and butyric acid bacteria in silage. Sucrose and urea improved the fermentation quality of both forages. Lactic acid and ammonia nitrogen/total nitrogen (AN/TN) were significantly lower than that of control ( P<0.05). Acetic acid improved the fermentation quality of both forages in which pH and AN/TN were significantly lower and acetic acid (AA) was higher than control group ( P<0.05). Cellulase did not improve fermentation quality and chemical composition of Phalaris arundinacea L. significantly.

Salt tolerance indicators of Italian ryegrass( Lolium multif lourum Lam.) at seedling stage were integrated evaluated in order to identify and utilize the suitable germplasm for alkaline soil.Under salt stress at 0% and 0.2% NaCl,the botanical,physiological,and biochemical indicators of Italian ryegrass were determined and analyzed for salt tolerance comparison.The results show that the average plant height,root length,and underground biomass of 16 varieties at 0.2% NaCl were significantly lesser than those at 0% NaCl( P<0.05),the average aboveground biomass was lower than that at 0% NaCl,and the average tiller no.per plant was slightly more than that at 0% NaCl without significant difference.Soluble sugar contents of 7 varieties at 0.2% NaCl were significantly lower than those at 0% NaCl and relative electrical conductivity rate of 11 varieties were significantly higher than those at 0% NaCl( P<0.05).According to the clustering analysis based on the botanical,physiological,and biochemical indicators,the tested 16 varieties were divided into three groups as 8 varieties were relatively salt tolerant,4 varieties moderately salt tolerant,and 4 varieties relatively susceptive to salt stress.

Psathyrostachys perennis Keng adapted in semi-arid regions is a good grass resources for its high yield, fine quality and tolerant to harsh stress.In this paper, we have studied the effects of differen hormone combinations and concentrations on callus induchon and plant regeneration of Psathyrostachys perennis Keng.The experimental results showed that the higher rate of callus induction and differentiation were obtained from young inflorescences on MS medium containing 2,4-D(3mg/L)and 6-BA(0.2 mg/L).The rate of plant regeneration can reach to over 80%.

According to random design,alfalfa hay is stacked at 60 cm × 60 cm with 10 cm or 20 cm thick,respectively.Raining effects on different humidity mow of alfalfa hay are studied.First group had simulated 90,450,900,and 1800 mL of rain while the second group was treated similarly after moisture content was air-cured at 50%.Results show that the DM(dry matter) and CP(crude protein) contents decrease significantly in air-cured mows with 10 cm thickness compared with first group for 10 cm thickness,whereas the NDF(neutral detergent fiber) and ADF(acid detergent fiber) contents increase significantly( P<0.01).These effects are enhanced with rain amounts increasing for 10 cm thickness mows.Comparing 20 cm mows with 10 cm ones,both CP and WSC(water soluble carbohydrate) contents increase significantly,whereas both NDF and ADF contents decrease significantly( P<0.01).Alfalfa hay quality declines with rain.

In order to solve the problem of legume variety shortage in sub-tropical red soil region, Chamaecrista rotundif olia Greene.(CPI 86134) was firstly introduced from ATFGRC,Australia in 1996,and was registered and named C.rotundifolia cv.Minyin by China Forage Cultivar Registration Board in 2005.Variety comparison trial,regional trial and productive trial was carried out during 1997 to 1999,1998 to 2001,and 1999 to 2002,respectively.Results show that Minyin was an important annual or perennial tropical legume with hay yield of 9400 to 11000 kg·hm ^-2 and seed yield of 140 to 280 kg·hm ^-2 which were 130% and 77% higher than those of cultivar Wynn.Crude protein content was 17% when harvested at full blooming stage.In summary,Minyin should be recommended for extensive planting,due to its good performance,on hilly red soils in tropical and sub-tropical region in China.

This study reports the salt tolerance of Artemisia anethifolia regarding the change of the rate of salt injury,activity of superoxide dismutase(SOD) and peroxidase(POD),malondidehyde(MDA) content,free proline(Pro) content,H ₂O ₂ contents and superoxide radical(O ₂ ^-) production rate in seedling of Artemisia anethifolia under different alkali concentration NaCl(0,25,50,100,200,400 mmol·L ^-1) under greenhouse conditions.Results show that,with the increase of salt concentration,the seedling pre-integrated relative salt injury rates and H ₂O ₂ contents increased;SOD,POD,free proline,superoxide radical production rate and MDA contents of Artemisia anethifolia had low-high-low trend.We concluded that Artemisia anethifolia had a strong salt tolerance while SOD activity,POD activity,MDA content and free proline content could be used as important physiological indexes for salt tolerance in Artemisia anethifolia.

Based on field investigations of growth and early bolting rate of biennial angelica cultivated in 31 ecoregions of 4 counties of Gansu Province,the effects of altitude,longitude and latitude on angelica growth and early bolting at medicine formation period were investigated to provide theoretic evidence for determining Angelica planting ecoregion properly.Results showed significant geographical effects on both early bolting and growth of Angelica.Heteromorphosis was classified into following rank order: bolting rate>plant height>leaf numbers.Plant height,leaf numbers and bolting rate had significantly negative correlations with altitude and longitude.However,all were significantly positive for latitude correlations.Multiple regression analysis showed that plant height,leaves and bolting rate had significant linear regression relationships with altitude.Results showed altitude as the main ecological factor influencing angelica growth and early bolting.Both height and bolting rate of angelica plants decreased significantly in high altitude areas.

Haibei Alpine Meadow Ecosystem Research Station with the Chinese Academy of Sciences conducted an investigation of the plant community and soil environment factors of a Potentilla fruticosa shrub meadow,a Kobresia humilis meadow and a swamp meadow.Results show that the annual aboveground biomass of the K.humilis meadow reached 339.594 g/m ²,that of the swamp meadow,339.358 g/m ²,and of the P.fruticosa shrub meadow,278.299 g/m ².The rate of solar energy utilization of the K.humilis meadow was 0.099%,of the swamp meadow,0.091%,and of the P.fruticosa shrub meadow,0.075%.There were 54 species in the plant community of the K.humilis meadow,47 species in the community of the P.fruticosa shrub meadow,and 24 species in the swamp meadow.The soil temperature within 0～20 cm depth of the K.humilis meadow was higher than that of the P.fruticosa shrub meadow at the same depth,but the soil humidity density of the two was the reverse.To sum up,the soil of K.humilis meadow boasted higher temperature and lower humidity than those of the P.fruticosa shrub meadow,while the soil of the swamp meadow had the highest humidity of saturation but the lowest temperature.

High temperature is harmful to alfalfa and induces slow growth and incidence of disease.In this paper,leaf cell membrane permeability,chlorophyll content,anti-oxidative system,and the chlorophyll fluorescence characteristics of Medicago sativa L.cv.Zhaodong were analyzed under high temperature stress(40℃).The results show that with the increasing exposure time to high temperature,leaf cell membrane permeability and MDA content were increased,while leaf chlorophyll content,activities of POD,SOD and CAT,chlorophyll fluorescence Fv/Fm and Fv/Fo had a decreasing tendency.This study offers the theoretical guidance for alfalfa planting and management in high temperature region and the breeding and selection of high temperature resistant variety.

The cell wall component and ultra-structure of plant were compared between brittleness mutation(BM) rice obtained by seed gamma-ray(γ) treatment and its wild type from japonica variety Zhonghua-11 in this study.The cellulose content in leaf,stem,and root of BM-rice significantly decreased( P<0.01) by 18.99%,37.29% and 23.34% compared with those of wild type,respectively,while the hemi-cellulose content in leaf,stem and root for BM-rice significantly increased( P<0.01) by 46.07%,85.26% and 61.96%,respectively.The leaf parenchyma of BM-rice was much larger than that of wild type rice by the observation of SEM.For the BM-rice,the sclerenchyma of leaves was shrunken,vascular bundle of leaves was reduced,the strumae of outer epidermis of stem was sparse and the link of phloem of root was loosed and dispersed.The hiberarchy of sclerenchyma cell wall of BM-rice leaf was not obvious by the observation of TEM.Besides,the arrangement of parenchyma cells of BM-rice stem was disordered and the exterior of parenchyma cell wall of BM-rice root was knaggy.In conclusion,BM-rice has potential advantages in utilization as a fodder-rice.

Nutrient removal is essential for swine wastewater treatment to protect receiving waters from eutrophication and for potential reuse of the treated water.The study was conducted to examine the growth status of knotgrass( Paspalum distichum L.) and the wastewater purification effects under various swine wastewater concentration(25%,50%,75%,and 100%) in order to choose the proper swine wastewater concentration for enhanced purification efficiency and productivity.The results show that knotgrass biomass increased significantly and root length decreased significantly with swine wastwater concentration increasing( P<0.05).But there was no significant difference in plant height of knotgrass.Knotgrass had excellent nitrogen and phosphorus removal efficiencies with removal percentage of 98.75 to 99.31% for TN and 96.54 to 99.79% for TP.The highest nitrogen and phosphorus removal amounts were achieved for 100% concentration of swine wastewater at the rate of 507 mg·L ^-1 for TN and 32 mg·L ^-1 for TP,respectively.Knotgrass had no significant removal effects on COD and NH ⁺ ₄-N.

It is important to use superior cultivars for the breeding and extension of alfalfa to cultivate grassland for hay and for modifying environment. The RAPD reaction system for verifying alfalfa cultivars was applied to optimize by gradient quantity of the annealing temperature, template DNA, Taq polymerase, Mg ²⁺,dNTP, and the primer in the Zhongmu No.1 alfalfa. The results show that when the annealing temperature reached 37℃ and the volume of the RAPD reaction system was 25 μl, the optimal amount of template DNA would be 80 ng; of Taq polymerase, 1.5 U; of Mg ²⁺, 6.25×10 ^-5mmol; of dNTP, 0.3×10 ^-5mmol; of primer, 0.4×10 ^-5mmol; and of buffer KCl, 1.25×10 ^-3mmol. The electrophoretic patterns of amplifying in the optimized reaction system were similar in the 3 different types of PCR amplifiers.

Herbage layer in forest is one of main parts of the whole forest ecosystem and plays vital roles in adjusting carbon balance,decreasing concentration of carbon dioxide and delaying climate change in the global scale.Carbon density of the natural secondary Pinus tabulaeforims Carr.forest ecosystem was estimated using stratified sampling method applied to definite quantities of herbage plots under a given accuracy in Huoditang forest zone,Qinling Mountains.Biomasses of herbage layers were investigated and the carbon content rate(CCR) of organs in various herbage species was measured by TOC-VTH-2000A analyzer.Differences of CCR in same organs among various herbage species and in various organs of the same herbage species were analyzed respectively.Carbon density of herbage layer in the study area was estimated by combining CCR of organs in various herbage species with their biomass and densities.The findings indicate as follows: significant or extremely significant differences occurred in CCR of roots or stems among various herbage species and the maximum CCR difference for stems or roots was 14.46% and 26.06%,respectively;significant or extremely significant differences also existed in CCR of leaves and stems,stems and roots,leaves and roots in same herbage species and the maximum CCR difference between leaves and stems,stems and roots,leaves and roots was 11.31%,16.83%,and 19.86%,respectively;average carbon density in herbage layer was estimated at 1.829 MgC穐m ^-2 by the accuracy of 95% and error scale?0.0198 MgC穐m ^-2 and was 3.660% of the carbon density in aboveground parts of the forest.

With the development of molecular biology, the research of plant salt-tolerance has been extended into many domains, including gene cloning, analysis of gene structure and function and feature of gene expression, etc. Alfalfa is comparatively a more salt-tolerant plant. By cloning the salt-stress-induced genes of the plant, and analyzing the functions of its products, we could not only further our understanding of the molecular mechanism of plant salt-tolerance, but also have an applicable prospect in plant genetic engineering open to us. The present paper summarizes a research on the advancement of salt tress nduced genes.

The economic-social benefits and influencing factors of grazing withdrawal project were studied in Alashan Left Banner,a typical project application area,in Inner Mongolia Autonomous Region based on the demonstration and theoretical analysis.The results show that the project maintained the steady increase of local farmers′ income and local economy on the one hand;on the other hand,grazing prohibition promoted the industrial structure change obviously and offered a new way for local economic development,however also caused the labor force surplus in project application area as well as further over-grazing in non-project areas.The animal husbandry profit of a herder household was not only affected by the grazing withdrawal project,but also by the household features themselves.Of which,the grassland resource possessed by the herder household and the labor attending rate had notably effects on the animal husbandry profit.This study provides the scientific basis for the improvement of compensation mechanism,consolidation of the grazing withdrawal achievements,realization of anticipative goals,and sustainable development of local grass industry.

In order to provide the evidences for further research of alfalfa ( Medicago sativa L.), the substantial studies of alfalfa root biomass in China, the United States and Canada were summarized. The vertical distribution pattern of alfalfa root biomass and its dominant factors in different natural regions were discussed. Factors included the depth of soil layer, underground water level, soil properties, fertilization, irrigation, cutting, mixture sowing, cultivar, and growth period. The distribution of alfalfa root biomass in topsoil was increased as the depth of soil layer lessened and the level of underground water increased, or soil conditions became worse. Fertilization, especially phosphate fertilizer increased the distribution in submerged soil. Different irrigation amount, frequency and pattern had the complex effect on vertical distribution of alfalfa root biomass. Less single irrigation amounts and higher irrigation frequency increased the distribution of alfalfa root biomass in topsoil. Higher cutting frequency decreased the distribution in submerged soil. Mixture sowing with graminous plants increased the distribution of alfalfa root biomass in topsoil. Alfalfa cultivars have different vertical distribution patterns of root biomass. The soil layer of vertical distribution became deeper as the plants grew. Alfalfa root biomass decreased exponentially with soil depth increasing. Under normal conditions, the distribution ratios of alfalfa root biomass in the 0~30 cm depth were about 60% to 90%, and in the 0~60 cm depth were about 65% to 95%.

In order to probe into the effect of grassland degeneration on the arbuscular mycorrhizal symbiosis of Leymus chinensis(Trin.) Tzvel.in typical steppe,the arbuscular mycorrhizal colonization rate and the rhizosphere soil spore density were compared of the L.chinensis typical steppe with different degenerated gradients in Xilinhote city and the surrounding areas.The results show that the moderate degeneration and heavy degeneration site had significantly lower L.chinensis arbuscular mycorrhizal colonization rate and rhizosphere soil spore density than non-degeneration and the light degeneration sites.In summary,the moderate to heavy grassland degeneration prominently reduced the arbuscular mycorrhizal symbiosis of L.chinensis in typical steppe.

The physiological responses of six warm-season turfgrass species, Zoysia tenuifolia Willd.ex Trin., Axonopus compressus(Swartz) Beauv., Paspalum vaginatum Sw., Eremochloa ophiuroides(Munro) Hack.cv.No.5, Zoysia japonica Steud.cv.Lanyin No.3,and Stenotaphrum secundatum(Walt.) Kuntze,to chilling injury were comparatively studied in field during the cold weather by the end of December,2004. E.ophiuroides showed no injury during chilling stress,whereas A.compressus and Z.japonica showed seriously injury.The photosynthetic rate was decreased greatly in Z.tenuifolia, Z.japonica,and S.secundatum,but almost unaltered in E.ophiuroides and P.vaginatum.The content of leaf water soluble sugar was little changed in A.compressus and Z.japonica,whereas increased in other grasses.In contrast,the content of root water soluble sugar was decreased in all grasses.The results indicate that the chilling tolerant species,e.g. E.ophiuroides,was characteristic of stable photosynthetic rate and higher level of leaf water soluble sugar during chilling stress in comparison to the chilling sensitive turfgrass species.

To explore the planting methods of high yield and quality with efficient use of nitrogen fertilizer in tall fescue ( Festuca arundinacea L.) in the Longdong area,two years field trials were conducted by using three nitrogen application rates of 0 kg·hm ^-2(N1),80 kg·hm ^-2(N2)and 160 kg·hm ^-2(N3). In addition,three mowing frequencies including mowing every 25 days (M1),every 50 days (M2),and every 75 days (M3) were set under each nitrogen rate. The results showed that the annual hay yield,crude protein yield,and nitrogen uptake was significantly higher for N2 and N3 treatments than that of N1 in both years. Compared to N1,the average hay yield of N2 and N3 treatments was increased by 13.5% and 15.5%,and the average crude protein yield increased by 21.34% and 25.25%. The N2 treatment significantly improved nitrogen use efficiency compared to N3 treatment. Moreover,the hay yield and crude protein yield of M2 treatment were higher than that of M3 treatment,but the difference between the two treatments was not significant. Compared to M2 and M3 treatments,M1 significantly decreased the content of acid detergent fiber and neutral detergent fiber,which obviously increased the relative feed value. Compared to M3 treatment,M2 significantly improved the nitrogen uptake and nitrogen use efficiency. Among all the treatments,N3M2 treatment has the best comprehensive evaluation of nutritional quality and can be considered as a best management measure for improved forage quality in tall fescue,while N2M2 treatment obtained higher hay yield and nitrogen use efficiency,and can be adopted as a suitable management strategy for efficient use of nitrogen fertilizers.