Leveraging the achievements of the smart meteorological system nationwide,a meteorological monitoring and early warning system for alfalfa pests and diseases can be formed through the establishment of four systems,nam...Leveraging the achievements of the smart meteorological system nationwide,a meteorological monitoring and early warning system for alfalfa pests and diseases can be formed through the establishment of four systems,namely,"real-time monitoring system,forecasting and prediction system,monitoring and early warning system,and smart service system".It will enable intelligent,dynamic meteorological monitoring,early warning,and forecasting services for the occurrence and development of alfalfa pests and diseases,providing technical support for scientifically controlling their harm and improving yield and quality.展开更多
In order to reduce alfalfa losses, the effect of bale density and alfalfa moisture content on the losses of baled alfalfa during the baling and transportation process was determined in this study. Three ranges of mois...In order to reduce alfalfa losses, the effect of bale density and alfalfa moisture content on the losses of baled alfalfa during the baling and transportation process was determined in this study. Three ranges of moisture content including 14%-17%, 17% -20%, and 20%-23% （wb） were considered in this study. Bale densities considered in this research were 110-120, 120-130, 130-140, and 140-150 kg/m3. The study was conducted in the form of a split-plot experimental design with three replications and a small rectangular baler was used to bale the second cut alfalfa. Alfalfa losses were measured in the pickup system and compression chamber of baler and losses were separated to stems and leaves. Alfalfa losses were also determined during the bale transportation process. Results showed that alfalfa moisture content had significant effect on the leaf and stem losses of the baler pickup system and alfalfa losses during the transportation process while; leaf and stem losses of baler compression chamber were not affected by alfalfa moisture content. Results also revealed that the bale density had no significant effect on the leaf and stem losses of the baler pickup system and alfalfa losses during the transportation process but leaf and stem losses of baler compression chamber were significantly affected by the bale density.展开更多
[Objective] The aim of this study was to investigate the effect of space flight factors on plant biomass in the generation of alfalfa carried by the satellite.[Method]Seeds from three lines of alfalfa were carried by ...[Objective] The aim of this study was to investigate the effect of space flight factors on plant biomass in the generation of alfalfa carried by the satellite.[Method]Seeds from three lines of alfalfa were carried by the seed-breeding satellite Shijian-8.After the satellite returned to the ground,stem diameter,primary branch number and current-year individual biomass of alfalfa were studied.[Result]After space flight,primary branch number and current-year individual biomass of alfalfa increased significantly,while the stem diameter had no significant change.Using the value over(the mean value of control + three standard deviation)as a criterion to screen,the variants with enlarged stem diameter,increased primary branch number and individual biomass was two,five and twelve respectively.[Conclusion]The obtained variants can be used in the variety improvement of alfalfa and its new variety breeding,but whether its favorable variation can inherit stably to the progenies needs further study.展开更多
[Objective]The aim was to solve the weeds existed in seedling period of alfalfa in Chongqing.[Method]The naked oat and common oat were selected.Through the analysis of determiners such as plant number,plant height,yie...[Objective]The aim was to solve the weeds existed in seedling period of alfalfa in Chongqing.[Method]The naked oat and common oat were selected.Through the analysis of determiners such as plant number,plant height,yield and weeds ratio,the oat type and sowing method were screened through all the accompany sowing crops to better control weeds in the seedling period of alfalfa.[Result]Compared with common oat,the tested naked oat as the companion crop of alfalfa seeding can prevent weeds more effectively;the proper companion-seeding disposal of alfalfa sowed in spring in Chongqing area was 15 kg/hm2 of alfalfa and 120 kg/hm2 of naked oat,sowing in strip in 40 cm row spacing;the proper mowing period of oat was during the time from May 11th to May 21st;the proper mowing period of alfalfa was ten days later.[Conclusion]Spring sowing oats with alfalfa can control seedling weeds effectively.展开更多
The agronomic and qualitative traits of 17 alfalfa varieties were analyzed in field and lab from 2006 to 2008, and these traits were evaluated by principal component analysis and cluster analysis. A total of 10 main t...The agronomic and qualitative traits of 17 alfalfa varieties were analyzed in field and lab from 2006 to 2008, and these traits were evaluated by principal component analysis and cluster analysis. A total of 10 main traits were classified as five factors： growth factor, quality factor, stem and leaf factors, plant factor and yield factor. These five factors and their correlation were selected for breeding. These 17 varieties can be divided into five clusters. The domestic varieties have better agronomic traits, while the introduced ones have better qualitative traits.展开更多
Nitrogen addition is rather important to the growth of alfalfa. In this study, the effects of different nitrogen application levels on various growth characteristics of alfalfa were investigated. The results showed th...Nitrogen addition is rather important to the growth of alfalfa. In this study, the effects of different nitrogen application levels on various growth characteristics of alfalfa were investigated. The results showed that nitrogen application exhibited no significant effects on plant height and stem diameter but posed significant effects on branch number of alfalfa. Branch number of alfalfa in each cutting raised with the increasing application level of nitrogen, with significant differences among different treatments （P〈0.05）; individual aboveground biomass increased with the increasing application level of nitrogen, but the increasing trend gradually tended to be steady from the first to the fourth cutting. Nitrogen application affected significantly （P〈0.05） individual aboveground biomass of alfalfa in the first, second and fourth cutting, but exhibited no significant effects on individual aboveground biomass of alfalfa in the third cutting. With the increase of nitrogen application level, total surface area, total volume, collar diameter and crossing number of alfalfa roots increased gradually, but total length, average diameter and furcating number of alfalfa roots increased first and then declined. Total length, average diameter and furcating number of alfalfa roots reached the maximum in N60 treatment.展开更多
[Objective] This study was to reveal the correlation between leaf area and drought resistance in different varieties of alfalfa.[Method] Using various alfalfa varieties as experimental materials,the drought resistance...[Objective] This study was to reveal the correlation between leaf area and drought resistance in different varieties of alfalfa.[Method] Using various alfalfa varieties as experimental materials,the drought resistance of leaves of drought-stressed alfalfa plants was assessed by measuring the content of free proline for analyzing its correlation with leaf area.[Result] Under drought condition,the drought resistance of alfalfa is directly related to leaf area in a positive correlation.[Conclusion] Leaf area could be used as an institutional assistant index to reflect the resistance of different alfalfa varieties.展开更多
[Objective] The aim of this study was to reveal and analyze the spatial distribution pattern of thrip（Odentot hrips lati） on alfalfa（Medicago sativa）.[Method] Within alfalfa plantation areas,experimental plots wit...[Objective] The aim of this study was to reveal and analyze the spatial distribution pattern of thrip（Odentot hrips lati） on alfalfa（Medicago sativa）.[Method] Within alfalfa plantation areas,experimental plots with the sizes of 10×10,10×20,10×30,20×30,20×40,20×80,30×30,30×40,30×50,40×40,40×50,40×80 and 50×50 m2 respectively were set up in the randomly selected sampling sites of 1 m ×2 m in size.During bud-emerging period and florescence period of alfalfa in the experimental plots,the number of thrips was counted and their distribution pattern was measured using XU Ru-mei＇s method.[Result] During bud-emerging period of alfalfa,the spatial distribution of thrips assumed an elliptic shape sized of 40×30-40×40 cm2 at horizontal level and that presented an ascending-falling trend of tress density down from the top at vertical level.During the florescence period of alfalfa,it showed a homogeneous distribution or randomly distributed pattern at horizontal level and a falling trend of tress density from the top to the apex to the root at vertical level.[Conclusion] Our results provide theoretical basis for field selection of insect-resistant alfalfa varieties.展开更多
This study examines the development and trends of China’s alfalfa market and imports, identifies key factors for the rapid increase in China’s alfalfa imports, and discusses potential impacts of the U.S.-China trade...This study examines the development and trends of China’s alfalfa market and imports, identifies key factors for the rapid increase in China’s alfalfa imports, and discusses potential impacts of the U.S.-China trade dispute and retaliations on the alfalfa markets and trade in both nations. China’s rapid transition toward larger-scale commercial dairy production, with enhanced feed and cost management as well as quality and safety control, and its limited resources for high-quality alfalfa production are key factors for the dramatic increase in its alfalfa imports, from 19 601 metric tons in 2008 to 1.38 million metric tons(mmt) in 2018. While the United States dominated China’s alfalfa imports with an average share of 97.01% from 2007 to 2017, the share dropped to 83.76% in 2018 and 63.28% in January 2019 due to the trade dispute and retaliations started in 2018. China will likely remain a large importer of alfalfa because of both its growing demand and the comparative advantages of imported alfalfa in quality and price, but the imports from the United States will be highly affected by the ongoing trade dispute and negotiations. China is also expected to make more efforts to reduce its dependence on U.S. alfalfa through increased investment in domestic alfalfa production and identification of alternative sources of alfalfa and other hay imports.展开更多
[Objective] This study aimed to perform the bioinformatics analysis of Zinc transporter （ZnT） from Baoding Alfalfa. [Method] Based on the amino acid sequence, the physical and chemical properties, hydrophilicity/hyd...[Objective] This study aimed to perform the bioinformatics analysis of Zinc transporter （ZnT） from Baoding Alfalfa. [Method] Based on the amino acid sequence, the physical and chemical properties, hydrophilicity/hydrophobicity, secondary structure of ZnT from Baoding alfalfa were predicted by a series of bioinformatics software. And the transmembrane domains were predicted by using different online tools. [Result] ZnT is a hydrophobic protein containing 408 amino acids with the theoretical pl of 5.94, and it has 7 potential transmembrane hydrophobic regions. In the sec- ondary structure, co-helix （Hh） accounted for 48.04%, extended strand （Ee） for 9.56%, random coil （Cc） for 42.40%, which was accored with the characteristic of transmembrane protein. [Conclusion] mZnT is a member of CDF family, responsible for transporting Zn^2＋ out of the cell membrane to reduce the concentration and toxicity of Zn^2＋.展开更多
[ Objective] The paper presents the diumal changes of photosynthesis and transpiration of different alfalfa varieties and their relationship with the associated physiological and ecological factors during branching st...[ Objective] The paper presents the diumal changes of photosynthesis and transpiration of different alfalfa varieties and their relationship with the associated physiological and ecological factors during branching stage, so as to provide a basis for the development, utilization, and breed- ing of alfalfa. [ Method] Under natural conditions, the diurnal changes of net photosynthetic rate （Pn）, transpiration rate （Tr）, the relevant physio- logical factors including leaf temperature （TI）, stomatal conductance （Gs） and intemal COn concentration （Ci）, as well as the relevant physiologi- cal factors including photosynthetic available radiation （PAR）, CO2 concentration in field （Ca） and air temperature （Ta） were measured in four al- falfa varieties （Algonguin, WL323 HQ, WL414, and Millionaire）. The water use efficiency （WUE） and light use efficiency （LUE） were calculated, and the correlation among them was also analyzed. [Result] The Pn, Tr, PAR and Ta of the four varieties appeared to vary in a single-peak curve; the sequence of WUE was WL323 HQ ~ Algonguin ~ WL414 ~ Millionaire; there was no significant difference in LUE of the four alfalfa varieties; coef- ficient analysis showed that Pn was mainly affected by PAR, Gs, and Ci, while Tr by PAR and Ta. [ Conclusion] WL323 HQ is the variety with high Pn, high WUE and low Tr, and it has strong adaptability to drought. In four alfalfa varieties, PAR, Ta, Gs, and TI are the primary determining fac- tors while Ca and Ci the limiting factors of Tr; Gs is the primary determining factor while Ci the limiting factor of Pn.展开更多
[Objective] Actinomycetes with high antagonistic effects on alfalfa root rot pathogen was isolated from 10 soil samples in Chifeng Inner Mongolia. [Method] 91 actinomyces were separated from 10 soil samples in Chifeng...[Objective] Actinomycetes with high antagonistic effects on alfalfa root rot pathogen was isolated from 10 soil samples in Chifeng Inner Mongolia. [Method] 91 actinomyces were separated from 10 soil samples in Chifeng Inner Mongolia by gradient dilution separation method. In duel culture tests, all isolates were tested for their antagonism by using 3 strains including Fusarium solani, F. oxysoporum, F. avenaceum of alfalfa root rot pathogenic bacteria as indicator strains. [Result] 5 strains with strong antagonistic effect on tested alfalfa root rot pathogen were obtained from No.1, No.4, No.6 and No.7 soil samples which were numbered 1-3-6, 4-4-2, 6-2-27 and 7-2-13 respectively, accounted for 5.50% in separated strains. [Conclusion] This study laid certain foundation for biological control of alfalfa root rot disease.展开更多
Alfalfa （Medicago sativa L） is one of the most important leguminous forage in China, and distributed most widely in the world. Because of Its high nutritional value, large biomass and strong reproducibility and impr...Alfalfa （Medicago sativa L） is one of the most important leguminous forage in China, and distributed most widely in the world. Because of Its high nutritional value, large biomass and strong reproducibility and improved soil green ma- nure plants, it is a kind of green manure plant capable of improving soil and known as ＂the king of forage＂. Alfalfa has strong adaptability under drought stress, and could adapt drought conditions through its physiological metabolism, structure devel- opment and morphology construction. Drought resistance in alfalfa is always a hot research subject of forage, and the research has been gradually developed from the morphological level to more-deeply physiological, biochemical and molecular biology fields, and has made many valuable research achievements.展开更多
Background: Pork produced by outdoor-reared pigs raised mostly on alfalfa pastures attracts increasing population of consumer from most of the world. In China, pigs were raised with alfalfa-containing diets to seek fo...Background: Pork produced by outdoor-reared pigs raised mostly on alfalfa pastures attracts increasing population of consumer from most of the world. In China, pigs were raised with alfalfa-containing diets to seek for good quality pork.However, the influence of dietary alfalfa involving high level of insoluble dietary fiber(IDF) on pig intestinal luminal microbiota composition remains unclear. The objective of this study was to investigate the effects of alfalfa on luminal microbiota and short chain fatty acids(SCFA) production, and gene expressions involved in SCFA sensing, transporting and absorbing in pig caecal mucosa.Results: Twenty-four growing pigs were randomly allotted to four diets containing 0%, 5%, 10% and 15% alfalfa meal for a 28-d experiment. Ingestion of alfalfa meal-contained diets significantly increased the ratio of body weight gain to feed consumption. Illumina MiS eq sequencing of the V3 region of the 16 S r RNA genes showed that alfalfa-containing diet significantly decreased the relative abundance of genera Turicibacter, Acidiphilium, Paracoccus, Propionibacterium,Corynebacterium, Pseudomonas, Acinetobacter, and Staphylococcus, and increased the relative abundance of genera Lachnospira, Marvinbryantia, and Desulfovibrio in the caecal digesta. Butyrate concentration was significantly increased in the hindgut by the supplementation of alfalfa meal in diets. The m RNA gene expressions of FFAR3, SMCT1, MCT1,PYY, and GCG were significantly increased in the caecal mucosa of pigs fed alfalfa meal.Conclusions: Our results suggested that alfalfa-containing diet has exerted significant impacts on caecal microbiota composition, butyrate concentration and significantly upregulated m RNA expression of host caecal mucosal genes involved in SCFA sensing and absorption as well as regulation of satiety.展开更多
This study assessed the effects of lactic acid bacteria(LAB), cellulase, cellulase-producing Bacillus pumilus and their combinations on the fermentation characteristics, chemical composition, bacterial community and i...This study assessed the effects of lactic acid bacteria(LAB), cellulase, cellulase-producing Bacillus pumilus and their combinations on the fermentation characteristics, chemical composition, bacterial community and in vitro digestibility of alfalfa silage. A completely randomized design involving a 8(silage additives)×3 or 2(silage days) factorial arrangement of treatments was adopted in the present study. The 8 silage additive treatments were: untreated alfalfa(control); two commercial additives(GFJ and Chikuso-1); an originally selected LAB(Lactobacillus plantarum a214) isolated from alfalfa silage; a cellulase-producing Bacillus(CB) isolated from fresh alfalfa; cellulase(C); and the combined additives(a214+C and a214+CB). Silage fermentation characteristics, chemical composition and microorganism populations were analysed after 30, 60 and 65 days(60 days followed by exposure to air for five additional days). In vitro digestibility was analysed for 30 and 60 days. Compared with the other treatments, selected LAB a214, a214 combined with either C or CB, and Chikuso-1 had the decreased(P<0.001) pH and increased(P<0.001) lactic acid concentrations during the ensiling process, and there were no differences(P>0.05) among them. Fiber degradation was not significant(P≥0.054) in any C or CB treatments. The a214 treatment showed the highest(P=0.009) in vitro digestibility of dry matter(595.0 g kg–1DM) after ensiling and the highest abundance of Lactobacillus(69.42 and 79.81%, respectively) on days 60 and 65, compared to all of other treatments. Overall, the silage quality of alfalfa was improved with the addition of a214, which indicates its potential as an alfalfa silage inoculant.展开更多
The fiber level and composition have an important effect on nutrient digestibility of swine diets. Little information is known about the effects of fiber level and composition from alfalfa meal on nutrient digestibili...The fiber level and composition have an important effect on nutrient digestibility of swine diets. Little information is known about the effects of fiber level and composition from alfalfa meal on nutrient digestibility of fattening pigs fed a corn-soybean meal-based diet. The objective of this experiment was to determine the effects of alfalfa fiber on the growth performance, intestinal nutrient flow and apparent total tract digestibility（ATTD） of nutrients in fattening pigs. 24 barrows（Duroc×（Large White×Landrace）, body weight=（60.6±0.7） kg） were randomly allotted to 4 treatments with 6 replicates of 1 pig per replicate. The pigs were provided a control diet or a diet containing 5, 10 or 20% of alfalfa meal during a 14-d experiment period. Average daily gain（ADG） and the ATTD of dry matter（DM）, organic matter（OM）, crude protein（CP）, neutral detergent fiber（NDF）, acid detergent fiber（ADF） and gross energy（GE） reduced linearly as the level of alfalfa meal in the diet increased（P〈0.01）. The total tract flow of DM, OM, CP, NDF, ADF, and GE increased with the increase in dietary alfalfa（linear, P〈0.05）. Growth performance and nutrient digestion were not affected by inclusion of 5% alfalfa meal in the diet（P〉0.05）. A multiple linear regression analysis, taking into account both soluble and insoluble fiber intake, explained approximately 70% of the variation in the ATTD of DM, OM, NDF, and GE（P〈0.01）. In conclusion, alfalfa meal should be limited to less than 5% of the diet in fattening pigs to maximize growth performance and nutrient digestion. Soluble and insoluble fiber from alfalfa meal has the differential roles in nutrient digestion, which may help explain the main variation observed in nutrient digestibility. These findings suggest that knowledge of specific fiber components is necessary to accurately predict the effects of dietary fiber on nutrient digestibility.展开更多
[Objective] The study aimed to isolate and screen efficient phosphorus-sol- ubilizing strains from the root soil of alfalfa in Guizhou, and investigate its growth promoting mechanism. [Method] Phosphorus solubilizing ...[Objective] The study aimed to isolate and screen efficient phosphorus-sol- ubilizing strains from the root soil of alfalfa in Guizhou, and investigate its growth promoting mechanism. [Method] Phosphorus solubilizing bacteria were isolated from rhizosphere of alfalfa with inorganic and organic phosphorous medium and the strains with higher capacity of dissolving phosphorus were screened through dissolv- ing phosphate zone and further researched. Meanwhile the phosphorus solubilizing capability of strains cultured in liquid medium was investigated by molybdenum blue colorimetric method. [Result] The capacity of dissolving calcium phosphate of 11 se- lected strains differed significantly and tended to be volatile from 150.40 to 268.20 μg/ml; phosphate solubilization capacity, IAA secretion and the pH of culture media did not show any significant correlation; all strains could produce IAA, and the se- cretion was from 12.09 to 22.16 μg/ml; the selected strains all could produce alka- line matter, and most of colonies were pale or milky white, irregular, opaque, jagged, flat and non-pigmented; utilization of carbon sources by different strains varied signifi- cantly. [Conclusion] The study laid the foundation for relieving phosphorus in unpro- ductive land, saving phosphate resources, reducing environmental pollution and pro- viding fertilizer in alfalfa production.展开更多
The effects of neutral salt and alkali on the ion distribution were investigated in two alfalfa （Medicago sativa L.） cultivars, including Zhongmu 1, a high salt-tolerant cultivar, and Algonquin, a low salt-tolerant ...The effects of neutral salt and alkali on the ion distribution were investigated in two alfalfa （Medicago sativa L.） cultivars, including Zhongmu 1, a high salt-tolerant cultivar, and Algonquin, a low salt-tolerant cultivar. The alkali stress expressed more serious growth inhibition than the neutral salt stress at the same Na＋ concentration. Compared with Algonquin, Zhongmu 1 did not exhibit a higher alkali tolerance under the Na2CO3-NaHCO3 treatment with the low Na＋ concentration （50 mmol L-l）. The alkali increased the accumulation of Na＋, Ca2＋, and Mg2＋ in the root and changed the Ca2＋ and Mg2＋ balance in the entire alfalfa plant. The salt and alkali stresses decreased the K＋ and Fe3＋ contents of the roots and leaves, the root Mn2＋ content, and the shoot Zn2＋ content, but they increased the Fe3＋ accumulation of the shoots, the shoot and leaf Cu2＋ contents, and the leaf Zn2＋ content in both alfalfa cultivars. Based on the results obtained under the conditions of this experiment, we found that the salt and alkali stresses reduced the plant growth in both alfalfa cultivars, while the alkali caused a stronger stress than the neutral salt in alfalfa. Thus, we conclude that under hydroponic conditions, the deleterious effects of the alkali on plants are due to the distribution change of some trophic ion balance in the roots, shoots, and leaves of the plants by causing of Na＋, CO3^2-, and/or HCO3- stresses.展开更多
Alfalfa(M. sativa L.) is a highly valuable forage crop, providing >58 Mt of hay, silage, and pasture each year in the United States. As alfalfa is an outcrossing autotetraploid crop,however, breeding for enhanced a...Alfalfa(M. sativa L.) is a highly valuable forage crop, providing >58 Mt of hay, silage, and pasture each year in the United States. As alfalfa is an outcrossing autotetraploid crop,however, breeding for enhanced agronomic traits is challenging and progress has historically not been rapid. Methods that make use of genotypic information and statistical models to generate a genomic estimated breeding value(GEBV) for each plant at a young age hold a great deal of promise to accelerate breeding gains. An emerging genomic breeding pipeline employs SNP chips or genotyping-by-sequencing(GBS) to identify SNP markers in a training population, followed by the use of a statistical model to find associations between the discovered SNPs and traits of interest, followed by genomic selection(GS), a breeding program utilizing the trained model to predict breeding values and making selections based on the estimated breeding value(EBV). Much work has been done in recent years in all of these areas, to generate marker sets and discover SNPs associated with desirable traits, and the application of these technologies in alfalfa breeding programs is under way. However, GBS/GWAS/GS is still a new breeding paradigm,and work is ongoing to evaluate different models, software, and methods for use in such programs. In this review, we look at the progress of alfalfa genomics over the past halfdecade, and review work comparing models and methods relevant to this new type of breeding strategy.展开更多
Planting grass and legume mixtures on improved grasslands has the potential advantage of realizing both higher yields and lower environmental pollution by optimizing the balance between applied N fertilizer and the na...Planting grass and legume mixtures on improved grasslands has the potential advantage of realizing both higher yields and lower environmental pollution by optimizing the balance between applied N fertilizer and the natural process of legume biological nitrogen fixation. However, the optimal level of N fertilization for grass-legume mixtures, to obtain the highest yield, quality, and contribution of N2 fixation, varies with species. A greenhouse pot experiment was conducted to study the temporal dynamics of N2 fixation of alfalfa （Medicago sativa L.） grown alone and in mixture with smooth bromegrass （Bromus inermis Leyss.） in response to the addition of fertilizer N. Three levels of N （0, 75, and 150 kg ha-1） were examined using 15N-labeled urea to evaluate N2 fixation via the 15N isotope dilution method. Treatments were designated NO （0.001 g per pot）, N75 （1.07 g per pot） and N150 （2.14 g per pot）. Alfalfa grown alone did not benefit from the addition of fertilizer N; dry matter was not significantly increased. In contrast, dry weight and N content of smooth bromegrass grown alone was increased significantly by N application. When grown as a mixture, smooth bromegrass biomass was increased significantly by N application, resulted in a decrease in alfalfa biomass. In addition, individual alfalfa plant dry weight （shoots＋roots） was significantly lower in the mixture than when grown alone at all N levels. Smooth bromegrass shoot and root dry weight were significantly higher when grown with alfalfa than when grown alone, regardless of N application level. When grown alone, alfalfa＇s N2 fixation was reduced with N fertilization （R2=0.9376,P=0.0057）. When grown in a mixture with smooth bromegrass, with 75 kg ha-1 of N fertilizer, the percentage of atmospheric N2 fixation contribution to total N in alfalfa （%Ndfa） had a maximum of 84.07 and 83.05% in the 2nd and 3rd harvests, respectively. Total 3-harvest %Ndfa was higher when alfalfa was grown in a mixture than when grown alone （shoots： ｜t｜=3.39, P=0.0096; root： ｜t｜=3.57, P=0.0073）. We believe this was due to smooth bromegrass being better able to absorb available soil N （due to its fibrous root system）, resulting inlower soil N availability and allowing alfalfa to develop an effective N2 fixing symbiosis prior to the 1st harvest. Once soil N levels were depleted, alfalfa was able to fix N2, resulting in the majority of its tissue N being derived from biological nitrogen fixation （BNF） in the 2nd and 3rd harvests. When grown in a mixture, with added N, alfalfa established an effective symbiosis earlier than when grown alone; in monoculture BNF did not contribute a significant portion of plant N in the N75 and N150 treatments, whereas in the mixture, BNF contributed 17.90 and 16.28% for these treatments respectively. Alfalfa has a higher BNF efficiency when grown in a mixture, initiating BNF earlier, and having higher N2 fixation due to less inhibition by soil-available N. For the greatest N-use-efficiency and sustainable production, grass-legume mixtures are recommended for imDrovino orasslands, usino a moderate amount of N fertilizer （75 kq N ha-l） to provide optimum benefits.展开更多
文摘Leveraging the achievements of the smart meteorological system nationwide,a meteorological monitoring and early warning system for alfalfa pests and diseases can be formed through the establishment of four systems,namely,"real-time monitoring system,forecasting and prediction system,monitoring and early warning system,and smart service system".It will enable intelligent,dynamic meteorological monitoring,early warning,and forecasting services for the occurrence and development of alfalfa pests and diseases,providing technical support for scientifically controlling their harm and improving yield and quality.
文摘In order to reduce alfalfa losses, the effect of bale density and alfalfa moisture content on the losses of baled alfalfa during the baling and transportation process was determined in this study. Three ranges of moisture content including 14%-17%, 17% -20%, and 20%-23% （wb） were considered in this study. Bale densities considered in this research were 110-120, 120-130, 130-140, and 140-150 kg/m3. The study was conducted in the form of a split-plot experimental design with three replications and a small rectangular baler was used to bale the second cut alfalfa. Alfalfa losses were measured in the pickup system and compression chamber of baler and losses were separated to stems and leaves. Alfalfa losses were also determined during the bale transportation process. Results showed that alfalfa moisture content had significant effect on the leaf and stem losses of the baler pickup system and alfalfa losses during the transportation process while; leaf and stem losses of baler compression chamber were not affected by alfalfa moisture content. Results also revealed that the bale density had no significant effect on the leaf and stem losses of the baler pickup system and alfalfa losses during the transportation process but leaf and stem losses of baler compression chamber were significantly affected by the bale density.
基金Supported by the Special Fund of Basic Scientific Research-Related Subsidy of State-Level Scientific Research Institute for Public InterestKey Project of National Science and Technology Planning during"the Eleventh Five-year Plan"(2008BADB3B04)~~
文摘[Objective] The aim of this study was to investigate the effect of space flight factors on plant biomass in the generation of alfalfa carried by the satellite.[Method]Seeds from three lines of alfalfa were carried by the seed-breeding satellite Shijian-8.After the satellite returned to the ground,stem diameter,primary branch number and current-year individual biomass of alfalfa were studied.[Result]After space flight,primary branch number and current-year individual biomass of alfalfa increased significantly,while the stem diameter had no significant change.Using the value over(the mean value of control + three standard deviation)as a criterion to screen,the variants with enlarged stem diameter,increased primary branch number and individual biomass was two,five and twelve respectively.[Conclusion]The obtained variants can be used in the variety improvement of alfalfa and its new variety breeding,but whether its favorable variation can inherit stably to the progenies needs further study.
文摘[Objective]The aim was to solve the weeds existed in seedling period of alfalfa in Chongqing.[Method]The naked oat and common oat were selected.Through the analysis of determiners such as plant number,plant height,yield and weeds ratio,the oat type and sowing method were screened through all the accompany sowing crops to better control weeds in the seedling period of alfalfa.[Result]Compared with common oat,the tested naked oat as the companion crop of alfalfa seeding can prevent weeds more effectively;the proper companion-seeding disposal of alfalfa sowed in spring in Chongqing area was 15 kg/hm2 of alfalfa and 120 kg/hm2 of naked oat,sowing in strip in 40 cm row spacing;the proper mowing period of oat was during the time from May 11th to May 21st;the proper mowing period of alfalfa was ten days later.[Conclusion]Spring sowing oats with alfalfa can control seedling weeds effectively.
基金Supported by National Basic Research Program of China ( 973 Program) ( 2007CB108906)~~
文摘The agronomic and qualitative traits of 17 alfalfa varieties were analyzed in field and lab from 2006 to 2008, and these traits were evaluated by principal component analysis and cluster analysis. A total of 10 main traits were classified as five factors： growth factor, quality factor, stem and leaf factors, plant factor and yield factor. These five factors and their correlation were selected for breeding. These 17 varieties can be divided into five clusters. The domestic varieties have better agronomic traits, while the introduced ones have better qualitative traits.
基金Supported by National Natural Science Foundation of China(Grant No.31372370)~~
文摘Nitrogen addition is rather important to the growth of alfalfa. In this study, the effects of different nitrogen application levels on various growth characteristics of alfalfa were investigated. The results showed that nitrogen application exhibited no significant effects on plant height and stem diameter but posed significant effects on branch number of alfalfa. Branch number of alfalfa in each cutting raised with the increasing application level of nitrogen, with significant differences among different treatments （P〈0.05）; individual aboveground biomass increased with the increasing application level of nitrogen, but the increasing trend gradually tended to be steady from the first to the fourth cutting. Nitrogen application affected significantly （P〈0.05） individual aboveground biomass of alfalfa in the first, second and fourth cutting, but exhibited no significant effects on individual aboveground biomass of alfalfa in the third cutting. With the increase of nitrogen application level, total surface area, total volume, collar diameter and crossing number of alfalfa roots increased gradually, but total length, average diameter and furcating number of alfalfa roots increased first and then declined. Total length, average diameter and furcating number of alfalfa roots reached the maximum in N60 treatment.
基金Supported by National Nonprofit Institute Research Grant(BRF090202)~~
文摘[Objective] This study was to reveal the correlation between leaf area and drought resistance in different varieties of alfalfa.[Method] Using various alfalfa varieties as experimental materials,the drought resistance of leaves of drought-stressed alfalfa plants was assessed by measuring the content of free proline for analyzing its correlation with leaf area.[Result] Under drought condition,the drought resistance of alfalfa is directly related to leaf area in a positive correlation.[Conclusion] Leaf area could be used as an institutional assistant index to reflect the resistance of different alfalfa varieties.
基金Supported by Natural Science Foundation of Guizhou Province(J[2010]2248)~~
文摘[Objective] The aim of this study was to reveal and analyze the spatial distribution pattern of thrip（Odentot hrips lati） on alfalfa（Medicago sativa）.[Method] Within alfalfa plantation areas,experimental plots with the sizes of 10×10,10×20,10×30,20×30,20×40,20×80,30×30,30×40,30×50,40×40,40×50,40×80 and 50×50 m2 respectively were set up in the randomly selected sampling sites of 1 m ×2 m in size.During bud-emerging period and florescence period of alfalfa in the experimental plots,the number of thrips was counted and their distribution pattern was measured using XU Ru-mei＇s method.[Result] During bud-emerging period of alfalfa,the spatial distribution of thrips assumed an elliptic shape sized of 40×30-40×40 cm2 at horizontal level and that presented an ascending-falling trend of tress density down from the top at vertical level.During the florescence period of alfalfa,it showed a homogeneous distribution or randomly distributed pattern at horizontal level and a falling trend of tress density from the top to the apex to the root at vertical level.[Conclusion] Our results provide theoretical basis for field selection of insect-resistant alfalfa varieties.
基金the Vermont Agricultural Experiment Station at the University Vermont,USA,and the National Social Science Fund of China(17ZDA067)for financial support of this project。
文摘This study examines the development and trends of China’s alfalfa market and imports, identifies key factors for the rapid increase in China’s alfalfa imports, and discusses potential impacts of the U.S.-China trade dispute and retaliations on the alfalfa markets and trade in both nations. China’s rapid transition toward larger-scale commercial dairy production, with enhanced feed and cost management as well as quality and safety control, and its limited resources for high-quality alfalfa production are key factors for the dramatic increase in its alfalfa imports, from 19 601 metric tons in 2008 to 1.38 million metric tons(mmt) in 2018. While the United States dominated China’s alfalfa imports with an average share of 97.01% from 2007 to 2017, the share dropped to 83.76% in 2018 and 63.28% in January 2019 due to the trade dispute and retaliations started in 2018. China will likely remain a large importer of alfalfa because of both its growing demand and the comparative advantages of imported alfalfa in quality and price, but the imports from the United States will be highly affected by the ongoing trade dispute and negotiations. China is also expected to make more efforts to reduce its dependence on U.S. alfalfa through increased investment in domestic alfalfa production and identification of alternative sources of alfalfa and other hay imports.
基金Supported by the General Project of Qujing Normal University(2010MS007)~~
文摘[Objective] This study aimed to perform the bioinformatics analysis of Zinc transporter （ZnT） from Baoding Alfalfa. [Method] Based on the amino acid sequence, the physical and chemical properties, hydrophilicity/hydrophobicity, secondary structure of ZnT from Baoding alfalfa were predicted by a series of bioinformatics software. And the transmembrane domains were predicted by using different online tools. [Result] ZnT is a hydrophobic protein containing 408 amino acids with the theoretical pl of 5.94, and it has 7 potential transmembrane hydrophobic regions. In the sec- ondary structure, co-helix （Hh） accounted for 48.04%, extended strand （Ee） for 9.56%, random coil （Cc） for 42.40%, which was accored with the characteristic of transmembrane protein. [Conclusion] mZnT is a member of CDF family, responsible for transporting Zn^2＋ out of the cell membrane to reduce the concentration and toxicity of Zn^2＋.
文摘[ Objective] The paper presents the diumal changes of photosynthesis and transpiration of different alfalfa varieties and their relationship with the associated physiological and ecological factors during branching stage, so as to provide a basis for the development, utilization, and breed- ing of alfalfa. [ Method] Under natural conditions, the diurnal changes of net photosynthetic rate （Pn）, transpiration rate （Tr）, the relevant physio- logical factors including leaf temperature （TI）, stomatal conductance （Gs） and intemal COn concentration （Ci）, as well as the relevant physiologi- cal factors including photosynthetic available radiation （PAR）, CO2 concentration in field （Ca） and air temperature （Ta） were measured in four al- falfa varieties （Algonguin, WL323 HQ, WL414, and Millionaire）. The water use efficiency （WUE） and light use efficiency （LUE） were calculated, and the correlation among them was also analyzed. [Result] The Pn, Tr, PAR and Ta of the four varieties appeared to vary in a single-peak curve; the sequence of WUE was WL323 HQ ~ Algonguin ~ WL414 ~ Millionaire; there was no significant difference in LUE of the four alfalfa varieties; coef- ficient analysis showed that Pn was mainly affected by PAR, Gs, and Ci, while Tr by PAR and Ta. [ Conclusion] WL323 HQ is the variety with high Pn, high WUE and low Tr, and it has strong adaptability to drought. In four alfalfa varieties, PAR, Ta, Gs, and TI are the primary determining fac- tors while Ca and Ci the limiting factors of Tr; Gs is the primary determining factor while Ci the limiting factor of Pn.
基金Supported by Central Nonprofit Research Institutions Basic Scientific Research Operating Expenses(Grassland Research Institute,Chinese Academy of Agricultural Sciences2006-01-05)~~
文摘[Objective] Actinomycetes with high antagonistic effects on alfalfa root rot pathogen was isolated from 10 soil samples in Chifeng Inner Mongolia. [Method] 91 actinomyces were separated from 10 soil samples in Chifeng Inner Mongolia by gradient dilution separation method. In duel culture tests, all isolates were tested for their antagonism by using 3 strains including Fusarium solani, F. oxysoporum, F. avenaceum of alfalfa root rot pathogenic bacteria as indicator strains. [Result] 5 strains with strong antagonistic effect on tested alfalfa root rot pathogen were obtained from No.1, No.4, No.6 and No.7 soil samples which were numbered 1-3-6, 4-4-2, 6-2-27 and 7-2-13 respectively, accounted for 5.50% in separated strains. [Conclusion] This study laid certain foundation for biological control of alfalfa root rot disease.
文摘Alfalfa （Medicago sativa L） is one of the most important leguminous forage in China, and distributed most widely in the world. Because of Its high nutritional value, large biomass and strong reproducibility and improved soil green ma- nure plants, it is a kind of green manure plant capable of improving soil and known as ＂the king of forage＂. Alfalfa has strong adaptability under drought stress, and could adapt drought conditions through its physiological metabolism, structure devel- opment and morphology construction. Drought resistance in alfalfa is always a hot research subject of forage, and the research has been gradually developed from the morphological level to more-deeply physiological, biochemical and molecular biology fields, and has made many valuable research achievements.
基金financially supported by the National Key Basic Research Program of China(2012CB124702,2013CB127302)National Natural Science Foundation of China(31272452)the National Key Technology R&D Program of China(2011BAD26B01)
文摘Background: Pork produced by outdoor-reared pigs raised mostly on alfalfa pastures attracts increasing population of consumer from most of the world. In China, pigs were raised with alfalfa-containing diets to seek for good quality pork.However, the influence of dietary alfalfa involving high level of insoluble dietary fiber(IDF) on pig intestinal luminal microbiota composition remains unclear. The objective of this study was to investigate the effects of alfalfa on luminal microbiota and short chain fatty acids(SCFA) production, and gene expressions involved in SCFA sensing, transporting and absorbing in pig caecal mucosa.Results: Twenty-four growing pigs were randomly allotted to four diets containing 0%, 5%, 10% and 15% alfalfa meal for a 28-d experiment. Ingestion of alfalfa meal-contained diets significantly increased the ratio of body weight gain to feed consumption. Illumina MiS eq sequencing of the V3 region of the 16 S r RNA genes showed that alfalfa-containing diet significantly decreased the relative abundance of genera Turicibacter, Acidiphilium, Paracoccus, Propionibacterium,Corynebacterium, Pseudomonas, Acinetobacter, and Staphylococcus, and increased the relative abundance of genera Lachnospira, Marvinbryantia, and Desulfovibrio in the caecal digesta. Butyrate concentration was significantly increased in the hindgut by the supplementation of alfalfa meal in diets. The m RNA gene expressions of FFAR3, SMCT1, MCT1,PYY, and GCG were significantly increased in the caecal mucosa of pigs fed alfalfa meal.Conclusions: Our results suggested that alfalfa-containing diet has exerted significant impacts on caecal microbiota composition, butyrate concentration and significantly upregulated m RNA expression of host caecal mucosal genes involved in SCFA sensing and absorption as well as regulation of satiety.
基金supported by the National Key R&D Program of China (2017YFD0502102)the National Technology Leader “Ten Thousand People Plan” of China (201502510410040)the National Key Technology R&D Program of China during the 12th Five-year Plan period of China (2011BAD17B02)
文摘This study assessed the effects of lactic acid bacteria(LAB), cellulase, cellulase-producing Bacillus pumilus and their combinations on the fermentation characteristics, chemical composition, bacterial community and in vitro digestibility of alfalfa silage. A completely randomized design involving a 8(silage additives)×3 or 2(silage days) factorial arrangement of treatments was adopted in the present study. The 8 silage additive treatments were: untreated alfalfa(control); two commercial additives(GFJ and Chikuso-1); an originally selected LAB(Lactobacillus plantarum a214) isolated from alfalfa silage; a cellulase-producing Bacillus(CB) isolated from fresh alfalfa; cellulase(C); and the combined additives(a214+C and a214+CB). Silage fermentation characteristics, chemical composition and microorganism populations were analysed after 30, 60 and 65 days(60 days followed by exposure to air for five additional days). In vitro digestibility was analysed for 30 and 60 days. Compared with the other treatments, selected LAB a214, a214 combined with either C or CB, and Chikuso-1 had the decreased(P<0.001) pH and increased(P<0.001) lactic acid concentrations during the ensiling process, and there were no differences(P>0.05) among them. Fiber degradation was not significant(P≥0.054) in any C or CB treatments. The a214 treatment showed the highest(P=0.009) in vitro digestibility of dry matter(595.0 g kg–1DM) after ensiling and the highest abundance of Lactobacillus(69.42 and 79.81%, respectively) on days 60 and 65, compared to all of other treatments. Overall, the silage quality of alfalfa was improved with the addition of a214, which indicates its potential as an alfalfa silage inoculant.
基金the Project of State Key Laboratory of Animal Nutrition, Ministry of Science and Technology, China (2004DA125184G1104)the Special Fund for Agro-scientific Research in the Public Interest, Ministry of Agriculture, China (200903006)the National Key Technology R&D Program of China (2012BAD39B01)
文摘The fiber level and composition have an important effect on nutrient digestibility of swine diets. Little information is known about the effects of fiber level and composition from alfalfa meal on nutrient digestibility of fattening pigs fed a corn-soybean meal-based diet. The objective of this experiment was to determine the effects of alfalfa fiber on the growth performance, intestinal nutrient flow and apparent total tract digestibility（ATTD） of nutrients in fattening pigs. 24 barrows（Duroc×（Large White×Landrace）, body weight=（60.6±0.7） kg） were randomly allotted to 4 treatments with 6 replicates of 1 pig per replicate. The pigs were provided a control diet or a diet containing 5, 10 or 20% of alfalfa meal during a 14-d experiment period. Average daily gain（ADG） and the ATTD of dry matter（DM）, organic matter（OM）, crude protein（CP）, neutral detergent fiber（NDF）, acid detergent fiber（ADF） and gross energy（GE） reduced linearly as the level of alfalfa meal in the diet increased（P〈0.01）. The total tract flow of DM, OM, CP, NDF, ADF, and GE increased with the increase in dietary alfalfa（linear, P〈0.05）. Growth performance and nutrient digestion were not affected by inclusion of 5% alfalfa meal in the diet（P〉0.05）. A multiple linear regression analysis, taking into account both soluble and insoluble fiber intake, explained approximately 70% of the variation in the ATTD of DM, OM, NDF, and GE（P〈0.01）. In conclusion, alfalfa meal should be limited to less than 5% of the diet in fattening pigs to maximize growth performance and nutrient digestion. Soluble and insoluble fiber from alfalfa meal has the differential roles in nutrient digestion, which may help explain the main variation observed in nutrient digestibility. These findings suggest that knowledge of specific fiber components is necessary to accurately predict the effects of dietary fiber on nutrient digestibility.
基金Supported by Key Agricultural Program of Guizhou Province([2009]3067)Science and Technology Foundation of Guizhou Province([2012]2199)~~
文摘[Objective] The study aimed to isolate and screen efficient phosphorus-sol- ubilizing strains from the root soil of alfalfa in Guizhou, and investigate its growth promoting mechanism. [Method] Phosphorus solubilizing bacteria were isolated from rhizosphere of alfalfa with inorganic and organic phosphorous medium and the strains with higher capacity of dissolving phosphorus were screened through dissolv- ing phosphate zone and further researched. Meanwhile the phosphorus solubilizing capability of strains cultured in liquid medium was investigated by molybdenum blue colorimetric method. [Result] The capacity of dissolving calcium phosphate of 11 se- lected strains differed significantly and tended to be volatile from 150.40 to 268.20 μg/ml; phosphate solubilization capacity, IAA secretion and the pH of culture media did not show any significant correlation; all strains could produce IAA, and the se- cretion was from 12.09 to 22.16 μg/ml; the selected strains all could produce alka- line matter, and most of colonies were pale or milky white, irregular, opaque, jagged, flat and non-pigmented; utilization of carbon sources by different strains varied signifi- cantly. [Conclusion] The study laid the foundation for relieving phosphorus in unpro- ductive land, saving phosphate resources, reducing environmental pollution and pro- viding fertilizer in alfalfa production.
基金supported financially by the Open Project of the National Key Laboratory for Grassland Agro-ecosytems hosted at Lanzhou University,Chinathe construction project of Key Discipline of Jiangsu Province for grass science,China
文摘The effects of neutral salt and alkali on the ion distribution were investigated in two alfalfa （Medicago sativa L.） cultivars, including Zhongmu 1, a high salt-tolerant cultivar, and Algonquin, a low salt-tolerant cultivar. The alkali stress expressed more serious growth inhibition than the neutral salt stress at the same Na＋ concentration. Compared with Algonquin, Zhongmu 1 did not exhibit a higher alkali tolerance under the Na2CO3-NaHCO3 treatment with the low Na＋ concentration （50 mmol L-l）. The alkali increased the accumulation of Na＋, Ca2＋, and Mg2＋ in the root and changed the Ca2＋ and Mg2＋ balance in the entire alfalfa plant. The salt and alkali stresses decreased the K＋ and Fe3＋ contents of the roots and leaves, the root Mn2＋ content, and the shoot Zn2＋ content, but they increased the Fe3＋ accumulation of the shoots, the shoot and leaf Cu2＋ contents, and the leaf Zn2＋ content in both alfalfa cultivars. Based on the results obtained under the conditions of this experiment, we found that the salt and alkali stresses reduced the plant growth in both alfalfa cultivars, while the alkali caused a stronger stress than the neutral salt in alfalfa. Thus, we conclude that under hydroponic conditions, the deleterious effects of the alkali on plants are due to the distribution change of some trophic ion balance in the roots, shoots, and leaves of the plants by causing of Na＋, CO3^2-, and/or HCO3- stresses.
基金supported by the United States Department of Agriculture NIFA_AFRP(2015-70005-24071)the Agricultural Research Service base fund
文摘Alfalfa(M. sativa L.) is a highly valuable forage crop, providing >58 Mt of hay, silage, and pasture each year in the United States. As alfalfa is an outcrossing autotetraploid crop,however, breeding for enhanced agronomic traits is challenging and progress has historically not been rapid. Methods that make use of genotypic information and statistical models to generate a genomic estimated breeding value(GEBV) for each plant at a young age hold a great deal of promise to accelerate breeding gains. An emerging genomic breeding pipeline employs SNP chips or genotyping-by-sequencing(GBS) to identify SNP markers in a training population, followed by the use of a statistical model to find associations between the discovered SNPs and traits of interest, followed by genomic selection(GS), a breeding program utilizing the trained model to predict breeding values and making selections based on the estimated breeding value(EBV). Much work has been done in recent years in all of these areas, to generate marker sets and discover SNPs associated with desirable traits, and the application of these technologies in alfalfa breeding programs is under way. However, GBS/GWAS/GS is still a new breeding paradigm,and work is ongoing to evaluate different models, software, and methods for use in such programs. In this review, we look at the progress of alfalfa genomics over the past halfdecade, and review work comparing models and methods relevant to this new type of breeding strategy.
基金supported by the China Forage and Grass Research System (CARS-35)the National Key Technology R&D Program of China (2011BAD17B01)
文摘Planting grass and legume mixtures on improved grasslands has the potential advantage of realizing both higher yields and lower environmental pollution by optimizing the balance between applied N fertilizer and the natural process of legume biological nitrogen fixation. However, the optimal level of N fertilization for grass-legume mixtures, to obtain the highest yield, quality, and contribution of N2 fixation, varies with species. A greenhouse pot experiment was conducted to study the temporal dynamics of N2 fixation of alfalfa （Medicago sativa L.） grown alone and in mixture with smooth bromegrass （Bromus inermis Leyss.） in response to the addition of fertilizer N. Three levels of N （0, 75, and 150 kg ha-1） were examined using 15N-labeled urea to evaluate N2 fixation via the 15N isotope dilution method. Treatments were designated NO （0.001 g per pot）, N75 （1.07 g per pot） and N150 （2.14 g per pot）. Alfalfa grown alone did not benefit from the addition of fertilizer N; dry matter was not significantly increased. In contrast, dry weight and N content of smooth bromegrass grown alone was increased significantly by N application. When grown as a mixture, smooth bromegrass biomass was increased significantly by N application, resulted in a decrease in alfalfa biomass. In addition, individual alfalfa plant dry weight （shoots＋roots） was significantly lower in the mixture than when grown alone at all N levels. Smooth bromegrass shoot and root dry weight were significantly higher when grown with alfalfa than when grown alone, regardless of N application level. When grown alone, alfalfa＇s N2 fixation was reduced with N fertilization （R2=0.9376,P=0.0057）. When grown in a mixture with smooth bromegrass, with 75 kg ha-1 of N fertilizer, the percentage of atmospheric N2 fixation contribution to total N in alfalfa （%Ndfa） had a maximum of 84.07 and 83.05% in the 2nd and 3rd harvests, respectively. Total 3-harvest %Ndfa was higher when alfalfa was grown in a mixture than when grown alone （shoots： ｜t｜=3.39, P=0.0096; root： ｜t｜=3.57, P=0.0073）. We believe this was due to smooth bromegrass being better able to absorb available soil N （due to its fibrous root system）, resulting inlower soil N availability and allowing alfalfa to develop an effective N2 fixing symbiosis prior to the 1st harvest. Once soil N levels were depleted, alfalfa was able to fix N2, resulting in the majority of its tissue N being derived from biological nitrogen fixation （BNF） in the 2nd and 3rd harvests. When grown in a mixture, with added N, alfalfa established an effective symbiosis earlier than when grown alone; in monoculture BNF did not contribute a significant portion of plant N in the N75 and N150 treatments, whereas in the mixture, BNF contributed 17.90 and 16.28% for these treatments respectively. Alfalfa has a higher BNF efficiency when grown in a mixture, initiating BNF earlier, and having higher N2 fixation due to less inhibition by soil-available N. For the greatest N-use-efficiency and sustainable production, grass-legume mixtures are recommended for imDrovino orasslands, usino a moderate amount of N fertilizer （75 kq N ha-l） to provide optimum benefits.
