Yield and Nutritive Values of Semi- and Non-Fall Dormant Alfalfa Cultivars under Late-Cutting Schedule in California’s Central Valley

California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield and nutritive value under late-cutting schedule strategy may help identify cultivars that growers can use to maximize yield while maintaining area for sustainable alfalfa production, but there is little information on this strategy. A field study was conducted to determine cumulative dry matter (DM) and nutritive values of 20 semi- and non-fall dormant (FD) ratings (FD 7 and FD 8 - 10, respectively) cultivars under 35-day cut in California’s Central Valley in 2020-2022. Seasonal cumulative DM yields ranged from 6.8 in 2020 to 37.0 Mg·ha−1 in 2021. Four FD 8 - 9 cultivars were the highest yielding with 3-yrs avg. DM greater than the lowest yielding lines by 46%. FD 7 cultivar “715RR” produced the highest crude protein (CP: 240 g·Kg−1) while FD 8 cultivar “HVX840RR” resulted in the highest neutral detergent fiber digestibility (NDFD: 484 g·Kg−1, 7% greater than the top yielding cultivars) but with DM yield intermediate. Yields and NDFD correlated positively but weakly indicating some semi- and non-FD cultivars performing similarly. These results suggest that selecting high yielding cultivars under 35-day cutting schedule strategy can be used as a tool to help growers to maximize yield while achieving good quality forages for sustainable alfalfa production in California’s Central Valley.

Effect of Space Flight Factors on Plant Biomass Developed from Alfalfa Seeds Carried by the Satellite

[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.

苜蓿小区育种气吸式排种器设计与试验

为提高苜蓿小区育种播种机械化水平,设计了一种苜蓿小区育种气吸式排种器。首先,阐述了排种器的结构和工作原理;接着,对排种器的主要结构参数进行理论计算,并分析排种器充种过程力学特性,找出影响排种效果的关键因素。为得到排种器的最佳性能参数,进行二次回归正交试验设计,以排种盘转速、工作压强、吸种孔数量为试验因素,以合格率、重播率、漏播率为性能指标,采用Design-Expert软件对试验数据进行回归方程分析和响应曲面分析,获得影响试验指标的各试验因素主次关系。研究结果表明:在排种器的最佳参数,排种盘转速24.2 r/min、吸种孔数量36个、工作压强3.7 kPa时,合格率92.81%,重播率3.35%,漏播率3.42%。验证试验表明:该排种器可以实现有效排种,可为后续研究提供理论基础,具有参考价值。

Traits Analysis and Evaluation on Several Alfalfa Varieties

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.

Photosynthesis and Transpiration Characters of Alfalfa (Medicago sativa) and Their Relationship with Relevant Factors during Branching Stage

[ 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.

Separation and Screening of Biocontrol Actinomyces against Alfalfa Root Rot

[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.

Streptomyces alfalfae XY25^(T)对植物幼苗抗逆性和根系生长的影响

采用干旱胁迫和种子催芽实验,研究Streptomyces alfalfae XY25^(T)对幼苗抗逆性及根系生长的影响,为该菌株在农业上的应用提供依据。辣椒播种时,处理组施用S.alfalfae XY25^(T)菌液,对照组用无菌水,待幼苗径长7 cm,干旱处理7 d,测定抗逆生理指标;通过根系的生长指标测定和石蜡切片观察,研究辣椒、紫云英种子经S.alfalfae XY25^(T)菌液处理对根系生长的影响。处理组幼苗叶片相对含水量和根系活力显著提高,其中根系活力差异尤为明显,提高48.23%;叶片相对电导率和丙二醛含量显著下降,降幅分别为67.31%和34.51%。种子经S.alfalfae XY25^(T)菌液催芽处理,进行根系扫描表明,与对照组相比,处理组辣椒根系总长、直径、总体积和单位体积土壤根长,分别显著提高8.96%,15.22%,46.85%和26.77%;紫云英根系直径增大44.76%;石蜡切片观察表明,S.alfalfae XY25^(T)促进紫云英根尖细胞生长。S.alfalfae XY25^(T)提高辣椒幼苗对干旱胁迫的耐受能力,促进辣椒幼苗根系、紫云英幼苗根尖细胞及根系生长。

Effect of Graded Levels of Fiber from Alfalfa Meal on Nutrient Digestibility and Flow of Fattening Pigs

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.

Alfalfa-containing diets alter luminal microbiota structure and short chain fatty acid sensing in the caecal mucosa of pigs

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.

Influence of lactic acid bacteria, cellulase, cellulase-producing Bacillus pumilus and their combinations on alfalfa silage quality

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.

Recent progress in alfalfa(Medicago sativa L.)genomics and genomic selection

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.

Effects of neutral salt and alkali on ion distributions in the roots,shoots,and leaves of two alfalfa cultivars with differing degrees of salt tolerance

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.

Proteome analysis of alfalfa roots in response to water deficit stress

To evaluate the response of alfalfa to water deficit （WD） stress, WD-induced candidates were investigated through a proteomic approach. Alfalfa seedlings were exposed to WD stress for 12 and 15 days respectively, followed by 3 days re-watering. Water deficit increased H202 content, lipid peroxidation, DPPH （1,1-diphenyl-2-picrylhydrazyl）-radical scavenging activity, and the free proline level in alfalfa roots. Root proteins were extracted and separated by two-dimentional polyacrylamide gel electrophoresis （2-DE）. A total of 49 WD-responsive proteins were identified in alfalfa roots; 25 proteins were reproducibly found to be up-regulated and 24 were down-regulated. Two proteins, namely cytosolic ascorbate peroxidase （APx2） and putative F-box protein were newly detected on 2-DE maps of WD-treated plants. We identified several proteins including agamous-like 65, albumin b-32, inward rectifying potassium channel, and auxin-independent growth promoter. The identified proteins are involved in a variety of cellular functions including calcium signaling, abacisic acid （ABA） biosynthesis, reactive oxygen species （ROS） regulation, transcription/translation, antioxidant/detoxification/stress defense, energy metabolism, signal transduction, and storage. These results indicate the potential candidates were responsible for adaptive response in alfalfa roots.

Changes in aggregate-associated organic carbon and nitrogen after 27 years of fertilization in a dryland alfalfa grassland on the Loess Plateau of China

Changes in the distribution of soil aggregate sizes and concentrations of aggregate-associated organic carbon （OC） and nitrogen （N） in response to the fertilization of grasslands are not well understood. Understanding these changes is essential to the sustainable development of artificial grasslands. For understanding these changes, we collected soil samples at 0-20 and 20-40 cm depths from a semi-arid artificial alfalfa grassland after 27 years of applications of phosphorus （P） and nitrogen＋phosphorus＋manure （NPM） fertilizers on the Loess Pla- teau of China. The distribution of aggregate sizes and the concentrations and stocks of OC and N in total soils were determined. The results showed that NPM treatment significantly increased the proportions of 〉2.0 mm and 2.0-0.25 mm size fractions, the mean geometric diameter （MGD） and the mean weight diameter （MWD） in the 0-20 cm layer. Phosphorous fertilizer significantly increased the proportion of 〉2.0 mm size fractions, the MGD and the MWD in the 0-20 cm layer. Long-term application of fertilization （P and NPM） resulted in the accumulation of OC and N in soil aggregates. The largest changes in aggregate-associated OC and N in the 0-20 cm layer were found at the NPM treatment, whereas the largest changes in the 20-40 cm layer were found at the P treatment. The results suggest that long-term fertilization in the grassland leads to the accumulation of OC and N in the coarse size fractions and the redistribution of OC and N from fine size fractions to coarse size fractions.

Characteristics of Endogenous Hormone Variations in the Roots of Alfalfa (Medicago sativa L.) Cultivars of Different Fall Dormancies During Spring Regrowth Stage

Regrowth traits of alfalfa （Medicago sativa L.） in spring are closely related to its fall dormancy before winter. In order to determine the relationship between fall dormancy （FD） grade and hormone variation pattern and provide academic references for the variety improvement and production of alfalfa, the variations of gibberellins （GA3）, indole-3-acetic acid （IAA）, and abscisic acid （ABA） in alfalfa roots during regrowth period in spring were examined by high performance liquid chromatography （HPLC）. The study involved seven alfalfa cultivars that belonged to four fall dormant grades, i.e., 2, 4, 6, and 8. The results showed that the differences in spring regrowth among the alfalfa cultivars were partially associated with their root hormone levels. The alfalfa cultivars that belonged to the same dormancy grades presented similar variation trends in endogenous hormone content in their roots during the spring regrowth stage. At the early regrowth stage, cultivars with a higher dormant grade had a higher GA3 concent and a lower ABA content in their roots than the cultivars with a lower dormant grade; and IAA content in roots of non- and semi-fall dormancy cultivars was higher than that of fall dormancy cultivars. During the whole period of spring regrowth, the root ABA content of fall dormancy alfalfa cultivar is significantly higher than those of semi- and non-fall dormancy cultivars. GA3 contents in the roots of all cultivars under study showed a double-peak dynamic curve; root IAA contents of the studied cultivars presented a downward trend. But the trend did not significantly differed among the different fall dormant cultivars. The higher GA3 content and lower ABA content in root of non-fall dormancy alfalfa lead to its earlier regrowth. Regrowth time and rate of alfalfa can be regulated by exogenous GA3 or ABA at the early regrowth stage to meet producing requirement.

Effect of nitrogen fertilization on yield, N content, and nitrogen fixation of alfalfa and smooth bromegrass grown alone or in mixture in greenhouse pots

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.

Development of Alfalfa (Medicago sativa L.) Regeneration System and Agrobacterium-Mediated Genetic Transformation

The regeneration ability of four alfalfa （Medicago sativa L.） cultivars, Xinjiang Daye, Longdong, Gannong 1 and Gannong 3, was studied, and the effects of various cultivars, explant sources and medium recipes on regeneration were compared. The better callus forming frequency obtained from hypocotyls of Xinjiang Daye is 88.5% and regeneration frequency is 9.8% in our initial experiments. To further optimize regeneration system for genetic transformation, we therefore changed concentrations of plant growth regulators and supplemented with glutamine into callus-induction and shoot-regeneration media. Callus forming frequency and shoot differentiation frequency were increased to 100%. The time taken to generate transgenic plants （16 weeks） was shorter than that for previouse procedure （25 weeks） and regeneration frequency was promoted to 15.1%. The results show that addition of glutamine is particularly important for shortening period of regeneration and promoting regeneration frequency. For study of genetic transformation of alfalfa, Agrobacterium tumefaciens-mediated transformation of Xinjiang Daye was developed based on this optimized regeneration system. The plant expression vector carrying two glutamine synthetases （GS 1 and GS2） and △1-pyrroline-5-carboxylate synthetase （P5CS） gene was used for alfalfa in vitro transformation. Six transgenic alfalfa plantlets with resistance to PPT were obtained. The introduction of foreign genes into plants was assessed in the transformants by PCR analysis and Southern hybridizations.

Effects of cold plasma treatment on alfalfa seed growth under simulated drought stress

The effect of different cold plasma treatments on the germination and seedling growth of alfalfa（Medicago sativa L.） seeds under simulated drought stress conditions was investigated.Polyethyleneglycol-6000（PEG 6000）with the mass fraction of 0%（purified water）, 5%, 10%,and 15% were applied to simulate the drought environment. The alfalfa seeds were treated with15 different power levels ranged between 0–280 W for 15 s. The germination potential,germination rate, germination index, seedling root length, seedling height, and vigor index were investigated. Results indicated significant differences between treated with proper power and untreated alfalfa seeds. With the increase of treatment power, these indexes mentioned above almost presented bimodal curves. Under the different mass fractions of PEG 6000, results showed that the lower power led to increased germination, and the seedlings presented good adaptability to different drought conditions. Meanwhile, higher power levels resulted in a decreased germination rate. Seeds treated with 40 W resulted in higher germination potential,germination rate, seedling height, root length, and vigor index. Vigor indexes of the treated seeds under different PEG 6000 stresses increased by 38.68%, 43.91%, 74.34%, and 39.20%respectively compared to CK_（0-0）, CK_（5-0）, CK_（10-0）, and CK_（15-0）（the control sample under 0%, 5%,10%, and 15% PEG 6000）. Therefore, 40 W was regarded as the best treatment in this research.Although the trend indexes of alfalfa seeds treated with the same power were statistically the same under different PEG 6000 stresses, the cold plasma treatment had a significant effect on the adaptability of alfalfa seeds in different drought environments. Thus, this kind of treatment is worth implementing to promote seed growth under drought situations.

Effect of lactic acid bacteria inoculants on alfalfa(Medicago sativa L.) silage quality:assessment of degradation(in situ) and gas production(in vitro)

Alfalfa （Medicago sativa） is difficult to ensile successfully because of the low content of moisture and water-soluble carbohydrates （WSC） in fresh alfalfa and the high buffering capacity in fresh alfalfa. Here, we conducted a study to evaluate the effects of three lactic acid bacteria （LAB） inoculants （Lactobacillus case/, lactobacillus plantarum, and Pediococcus pentosaceus） on silage quality, in sitE/ruminal degradability, and in vitro fermentation of alfalfa silage. The first cut of alfalfa was wilted, chopped, and randomly divided into four groups： the control （CON） and control mixed with three separate LAB inoculants （106 cfu g-1）. Simmental steers with a body weight of （452±18） kg and with installed rumen fistulas were prepared for in situ degradation and for in vitro gas production. LAB inoculants had a lower （P〈0.05） content of butyric acid than the CON group. Among them, the L. casei inoculated silage had a higher （P〈0.05） content of water-soluble carbohydrate （WSC） and a lower （P〈0.05） NH3-H content. The effective degradation （ED） of crude protein in LAB inoculation decreased （P〈0.05）, while the ED of acid detergent fiber increased （P〈0.05） in situ fermentation. The alfalfa silage with LAB inoculants produced more carbon dioxide （P〈0.05）. The NH3-H content of mixed incubation fluid in L. casei inoculated silage was lower （P〈0.05） compared with other groups. Therefore, this study showed that LAB inoculants could improve both ensiling quality and degradation. In particular, the L. casei inoculations exhibited better performance by limiting proteolysis during ensiling.

Overexpression of a Cytosolic Ascorbate Peroxidase Gene, OsAPX2, Increases Salt Tolerance in Transgenic Alfalfa

Alfalfa （Medicago sativa L.） is an important forage crop in the world and it is of great signiifcance for the improvement of its salt tolerance. To improve salt tolerance in alfalfa, a rice ascorbate peroxidase gene （OsAPX2） was introduced into alfalfa using Agrobacterium tumefaciens-mediated transformation with marker gene bar. The different T-DNA insertions in T1 transgenic alfalfa were identiifed by Southern hybridization. Three independent T2 transgenic lines were selected for stress analysis and the results showed that all of them were salt tolerant compared with wild-type plants. The transgenic plants had low levels of H2O2, malondialdehyde and relative electrical conductivity under salt and drought stresses. Moreover, the contents of chlorophyll and proline, and APX activity were high in transgenic plants under salt and drought stresses. Taken together, the overexpression of OsAPX2 enhances salt tolerance in alfalfa through scavenging reactive oxygen species.