Effects of antioxidant‑rich Lactiplantibacillus plantarum inoculated alfalfa silage on rumen fermentation, antioxidant and immunity status, and mammary gland gene expression in dairy goats

Background Milk synthesis in lactating animals demands high energy metabolism,which results in an increased production of reactive oxygen metabolites(ROM)causing an imbalance between oxidants and antioxidants thereby inducing oxidative stress(OS)on the animals.To mitigate OS and postpartum disorders in dairy goats and gain insight into the impact of dietary choices on redox status during lactation,a feeding trial was conducted using alfalfa silage inoculated with a high-antioxidant strain of Lactiplantibacillus plantarum.Methods Twenty-four Guanzhong dairy goats(38.1±1.20 kg)were randomly assigned to two dietary treatments:one containing silage inoculated with L.plantarum MTD/1(RSMTD-1),and the other containing silage inoculated with high antioxidant activity L.plantarum 24-7(ES24-7).Results ES24-7-inoculated silage exhibited better fermentation quality and antioxidant activity compared to RSMTD-1.The ES24-7 diet elevated the total antioxidant capacity(T-AOC),superoxide dismutase(SOD),glutathione peroxi-dase(GSH-Px),and catalase(CAT)activities in milk,serum,and feces of lactating goats(with the exception of T-AOC in milk).Additionally,the diet containing ES24-7 inoculated silage enhanced casein yield,milk free fatty acid(FFA)content,and vitamin A level in the goats’milk.Furthermore,an increase of immunoglobulin(Ig)A,IgG,IgM,inter-leukin(IL)-4,and IL-10 concentrations were observed,coupled with a reduction in IL-1β,IL-2,IL-6,interferon(IFN)-γ,and tumor necrosis factor(TNF)-αconcentrations in the serum of lactating goats fed ES24-7.Higher concentrations of total volatile fatty acid(VFA),acetate,and propionate were observed in the rumen fluid of dairy goats fed ES24-7 inoculated silage.Moreover,the diet containing ES24-7 inoculated silage significantly upregulated the expression of nuclear factor erythroid 2 like 2(NFE2L2),beta-carotene oxygenase 1(BCO1),SOD1,SOD2,SOD3,GPX2,CAT,glu-tathione-disulfide reductase(GSR),and heme oxygenase 1(HMOX1)genes in the mammary gland,while decreased the levels of NADPH oxidase 4(NOX4),TNF,and interferon gamma(IFNG).Conclusions These findings indicated that feeding L.plantarum 24-7 inoculated alfalfa silage not only improved rumen fermentation and milk quality in lactating dairy goats but also boosted their immunity and antioxidant status by modulating the expression of several genes related to antioxidant and inflammation in the mammary gland.

Partially substituting alfalfa hay with hemp forage in the diet of goats improved feed efficiency,ruminal fermentation pattern and microbial profiles

The use of hemp as a forage source in livestock diets has been less studied because bioactive residues in animal tissues may pose a risk to consumers.This study investigated the effects of partial substitution of alfalfa hay(AH)with hemp forage(HF)in growing goat diets on growth performance,carcass traits,ruminal fermentation characteristics,rumen microbial communities,blood biochemistry,and antioxidant indices.Forty Xiangdong black goats with body weight(BW)7.82±0.57 kg(mean±SD)were grouped by BW and randomly assigned into one of the four treatment diets(n=10/treatment)in a completely randomized design.The goats were fed ad libitum total mixed rations containing 60%forage and 40%concentrate(DM basis).The diets included control(CON;60%AH and 40%concentrate),55%AH and 5%HF(HF5),50%AH and 10%HF(HF10),and 40%AH and 20%HF(HF20).Increasing the substitution of HF for AH linearly decreased(P=0.004)DM intake and improved feed conversion efficiency.However,final BW,average daily gain,carcass traits,meat quality,and most blood biochemistry indices did not differ among treatments.The ruminal NH3-N concentration(P=0.003)and blood urine nitrogen(P=0.050)linearly increased(P<0.01)with increasing substitution rate of HF,whereas the total volatile fatty acids concentration quadratically changed(P=0.007).Substitution of AH with HF had no effect on the diversity and richness of ruminal microbes,though it linearly decreased(P=0.040)Prevotella_1 and linearly increased(P=0.017)Rike-nellaceae_RC9_gut_group.The cannabinoids and/or their metabolites were detected in both ruminal fil-trates(8)and plasma(4),however,no detectable cannabinoid-related residues were observed in meat.These results indicate that the HF could be used to partially substitute AH in goat diets,whereas the effects vary between substitution rates of HF for AH.Although no cannabinoid-related residues were detected in meat,the presence of cannabinoids residues in blood warrants further study of HF feeding to confirm the cannabinoids residues are not present in the animal products.

Development of a single transcript CRISPR/Cas9 toolkit for efficient genome editing in autotetraploid alfalfa

Alfalfa(Medicago sativa.L.)is a globally significant autotetraploid legume forage crop.However,despite its importance,establishing efficient gene editing systems for cultivated alfalfa remains a formidable challenge.In this study,we pioneered the development of a highly effective ultrasonic-assisted leaf disc transformation system for Gongnong 1 alfalfa,a variety widely cultivated in Northeast China.Subsequently,we created a single transcript CRISPR/Cas9(CRISPR_2.0)toolkit,incorporating multiplex gRNAs,designed for gene editing in Gongnong 1.Both Cas9 and gRNA scaffolds were under the control of the Arabidopsis ubiquitin-10 promoter,a widely employed polymeraseⅡconstitutive promoter known for strong transgene expression in dicots.To assess the toolkit’s efficiency,we targeted PALM1,a gene associated with a recognizable multifoliate phenotype.Utilizing the CRISPR_2.0 toolkit,we directed PALM1 editing at two sites in the wild-type Gongnong 1.Results indicated a 35.1%occurrence of editing events all in target 2 alleles,while no mutations were detected at target 1 in the transgenic-positive lines.To explore more efficient sgRNAs,we developed a rapid,reliable screening system based on Agrobacterium rhizogenes-mediated hairy root transformation,incorporating the visible reporter MtLAP1.This screening system demonstrated that most purple visible hairy roots underwent gene editing.Notably,sgRNA3,with an 83.0%editing efficiency,was selected using the visible hairy root system.As anticipated,tetra-allelic homozygous palm1 mutations exhibited a clear multifoliate phenotype.These palm1 lines demonstrated an average crude protein yield increase of 21.5%compared to trifoliolate alfalfa.Our findings highlight the modified CRISPR_2.0 system as a highly efficient and robust gene editing tool for autotetraploid alfalfa.

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.

Variation Characteristics of Root Traits of Different Alfalfa Cultivars under Saline-Alkaline Stress and their Relationship with Soil Environmental Factors

Soil salinization is the main factor that threatens the growth and development of plants and limits the increase of yield.It is of great significance to study the key soil environmental factors affecting plant root traits to reveal the adaptation strategies of plants to saline-alkaline-stressed soil environments.In this study,the root biomass,root morphological parameters and root mineral nutrient content of two alfalfa cultivars with different sensitivities to alkaline stress were analyzed with black soil as the control group and the mixed saline-alkaline soil with a ratio of 7:3 between black soil and saline-alkaline soil as the saline-alkaline treatment group.At the same time,the correlation analysis of soil salinity indexes,soil nutrient indexes and the activities of key enzymes involved in soil carbon,nitrogen and phosphorus cycles was carried out.The results showed that compared with the control group,the pH,EC,and urease(URE)of the soil surrounding the roots of two alfalfa cultivars were significantly increased,while soil total nitrogen(TN),total phosphorus(TP),organic carbon(SOC),andα-glucosidase activity(AGC)were significantly decreased under saline-alkaline stress.There was no significant difference in root biomass and root morphological parameters of saline-alkaline tolerant cultivar GN under saline-alkaline stress.The number of root tips(RT),root surface area(RS)and root volume(RV)of AG were reduced by 61.16%,44.54%,and 45.31%,respectively,compared with control group.The ratios of K^(+)/Na^(+),Ca^(2+)/Na^(+)and Mg^(2+)/Na^(+)of GN were significantly higher than those of AG(p<0.05).The root fresh weight(RFW)and dry weight(RDW),root length(RL),RV and RT of alfalfa were positively regulated by soil SOC and TN,but negatively regulated by soil pH,EC,and URE(p<0.01).Root Ca^(2+)/Na+ratio was significantly positively correlated with soil TN,TP and SOC(p<0.01).The absorption of Mg and Ca ions in roots is significantly negatively regulated by soilβ-glucosidase activity(BGC)and acid phosphatase activity(APC)(p<0.05).This study improved knowledge of the relationship between root traits and soil environmental factors and offered a theoretical framework for elucidating how plant roots adapt to saline-alkaline stressed soil environments.

紫花苜蓿GLK基因家族鉴定及渗透胁迫下的表达分析

GLK(Golden2-like或G2-like)属于GARP超家族,是植物生长发育过程中的重要转录因子,在调节植物叶绿体发育、叶绿素生物合成和非生物胁迫响应等方面发挥着重要作用。目前,GLK基因家族成员已在多个物种中被系统鉴定,但在四倍体紫花苜蓿全基因组水平上仍然知之甚少。利用生物信息学的方法,在“新疆大叶”紫花苜蓿基因组中鉴定到100个GLK基因(MsGLKs),并对其理化性质、染色体定位、系统进化关系、启动子顺式作用元件以及渗透胁迫和外源脱落酸(ABA)处理下的表达模式进行了分析。结果显示,100个MsGLK基因在32条染色体上不均匀分布,蛋白序列长度为201~860个氨基酸。根据系统发育分析结果,将MsGLK家族成员分为13个组。共线性分析表明,在紫花苜蓿基因组中共发现193个MsGLK基因重复事件,基因非同义替代数/同义替代数(Ka/Ks)分析显示,大部分重复基因对经历了纯化选择。MsGLK基因启动子的顺式作用元件广泛参与了植物生长发育、激素响应和胁迫反应。基因表达数据显示,12个基因的表达具有组织特异性,25个基因在所有组织中表达。RT-qPCR检测发现,MsGLK基因在干旱胁迫、盐胁迫和外源ABA处理下均有一定程度的响应。研究结果将为进一步探索MsGLK基因的功能和紫花苜蓿抗逆性遗传改良提供参考。

调亏灌溉和不同秋眠级品种混播对紫花苜蓿营养品质的影响

为了探究调亏灌溉和不同秋眠级品种混播对紫花苜蓿营养品质的影响,该研究设置2个不同灌溉处理,即调亏灌溉(灌溉量为定额灌溉的75%左右,W1)和定额灌溉(W2),并选择3个不同秋眠级紫花苜蓿品种(WL354HQ、新牧4号和三得利,秋眠级分别为3级、4级和5级)设置7个单播和混播处理,分别为WL354HQ单播(A)、新牧4号单播(B)、三得利单播(C)、WL354HQ和新牧4号混播(AB)、WL354HQ和三得利混播(AC)、新牧4号和三得利混播(BC)以及WL354HQ、新牧4号和三得利混播(ABC)。结果表明:与定额灌溉相比,调亏灌溉可使紫花苜蓿粗蛋白含量提高6.56%,相对饲喂价值降低1.90%;与单播处理中品质较次的WL354HQ相比,4个混播处理均可提高紫花苜蓿粗蛋白含量和相对饲喂价值,其中混播处理AB、AC、ABC粗蛋白含量分别提高3.95%、1.15%和5.85%,相对饲喂价值分别提高4.04%、8.44%和5.89%。

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。

Application of Oats to Control the Weeds in the Seedling Period of Alfalfa Sowed in Spring

[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.

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.

Growth Performance of Alfalfa(Medicago sativa)under Different Nitrogen Application Levels

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.

河西走廊绿洲区灌溉和施氮肥下苜蓿生殖期叶片养分特性及其与种子产量的关联

灌溉和施肥是提高苜蓿种子生产力的重要管理措施,进一步阐明其影响种子产量形成的机制有助于水肥管理措施优化。苜蓿生殖期叶片养分特性与种子产量的关系尚不明确。研究不同灌溉[全生育期充分灌溉(W1)、轻度亏水(W2)和中度亏水(W3),以及现蕾期和结荚期亏灌(W4)、返青期和结荚期亏灌(W5)、返青期和现蕾期亏灌(W6)]和施氮肥(10和40 kg·hm^(-2),分别以N1和N2表示)下,苜蓿生殖生长期叶片养分含量、重吸收效率及其与种子产量的关系。结果表明:1)随灌溉量减少和生育时期推进,生殖期绿叶N、P含量降低;亏缺灌溉下绿叶养分含量不低于W3甚至W2;现蕾期和结荚期N2下绿叶养分含量显著高于N1。生殖期枯叶N、P含量随灌溉量减少和生育时期推进呈升高趋势;亏缺灌溉下现蕾期枯叶N含量低于W1~W3,而结荚期和成熟期高于W1甚至W2;成熟期N2下枯叶N含量高于N1,而结荚期N2下P含量较高。2)随灌溉量减少和生育时期推进,生殖期叶片养分重吸收效率降低;亏缺灌溉下现蕾期养分重吸收效率高于W1~W3,结荚期和成熟期不低于W3;现蕾期N2下N重吸收效率高于N1,其他时期相反,而各时期N2下P重吸收效率较高。3)W3下种子产量低于W1和W2,特定时期亏缺灌溉下种子产量不低于W1甚至W2,W6下最高;N2下种子产量显著高于N1。4)种子产量与结荚期绿叶N、P含量、养分重吸收效率极显著正相关,与枯叶养分含量显著负相关。因此,灌溉和施氮肥对苜蓿生殖期叶片养分含量有显著影响,并表现出生育时期特异性。结荚期养分重吸收能增强种子形成所需养分的供应能力。综合来看,全生育期轻度亏水或返青期和现蕾期亏灌而结荚期充分灌溉下施氮肥40kg·hm^(-2)时可获得较高苜蓿种子产量。

Study on Spatial Distribution Pattern of Thrip (Odentot hrips lati) on Alfalfa (Medicago sativa)

[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.

黄土区深厚土壤严重干化后再植苜蓿地的土壤水分入渗特征

自然降水是半干旱黄土区土壤水分的唯一来源。为了探究黄土丘陵区深厚土壤干化背景下再种植深根系、多年生植物后的土壤水分入渗对降雨的响应特征,本研究在宁夏南部王洼水土保持试验站采用野外实地大规格土柱模拟干燥化土壤的方法种植苜蓿,试验分析2022-2023年每年的3-10月定位观测数据。结果表明:1)能有效产生土壤水分入渗的降雨次数仅占总降雨次数的41.67%,降雨量与入渗量占比为:小雨入渗量占其降雨量的15.89%,中雨入渗量占其降雨量的35.63%,大雨入渗量占其降雨量的52.20%,暴雨入渗量占其降雨量的61.50%,入渗量随着降雨量的增大呈增大的趋势;2)降雨入渗深度小于30 cm的降雨次数占总降雨次数的76.04%,入渗深度在30~80 cm的降雨次数占总降雨次数的18.75%,入渗深度在80 cm以上的降雨次数占总降雨次数的5.21%;3)深层土壤干化背景下种植苜蓿,一龄苜蓿地月尺度土壤剖面水分呈现增加趋势,二龄苜蓿地月尺度土壤剖面水分呈减小趋势,逐月降雨入渗深度(Zm)随月降雨量(Pm)增加呈二次函数增大变化:Z_(m)=-0.0101P_(m)^(2)+3.9426P_(m)(R^(2)=0.9895)。本研究可为黄土高原区深厚土壤严重干化后再植深根系、多年生植物及其可持续发展提供理论与数据支撑。

紫花苜蓿CNGC基因家族全基因组鉴定及干旱胁迫下的调控模式分析

环核苷酸门控通道蛋白(cyclic nucleotide-gated channel proteins,CNGC)在Ca^(2+)信号转导过程中发挥着重要作用。利用生物信息学和分子生物学的研究方法对四倍体紫花苜蓿(Medicago sativa‘Xinjiangdaye’)CNGC基因家族成员进行全基因组鉴定和干旱胁迫下的调控模式分析。结果表明:新疆大叶苜蓿基因组中共包含67个MsCNGC基因,不均匀地分布在30条染色体上,分属5个亚家族,共包含20个Motif,其启动子区域存在多种响应逆境胁迫的作用元件。新疆大叶苜蓿叶片中共表达了28个MsCNGC基因,有26个在干旱胁迫下不均匀上调,其中MsCNGC 59表达量最高且在干旱胁迫下上调倍数最大。MsCNGCs含有29~120个磷酸化位点,能被LRR蛋白激酶磷酸化,MsLRRs与MsCNGCs基因表达之间呈显著的正相关关系。此外,Ca^(2+)信号转导相关基因MsCaM、MsCML和MsCDPK表达量在干旱胁迫下显著上调。综上,四倍体紫花苜蓿MsCNGCs对干旱胁迫的响应包括转录调控和蛋白质的磷酸化调控,在干旱胁迫下能通过参与Ca^(2+)信号转导途径提高紫花苜蓿的抗旱性。

基于熵权-TOPSIS综合评价法的苜蓿最适灌溉方式研究

为探求不同灌溉方式对苜蓿的影响并优选最适宜该地区的灌溉方式,本研究以紫花苜蓿为研究对象,通过小区对比试验,探讨新疆乌昌地区3种主要灌溉方式(W1浅埋式滴灌、W2地表滴灌和W3平移式喷灌)对苜蓿生长、产量和水分利用效率的影响,并采用熵权-TOPSIS综合评价法,优选适宜于该地区苜蓿生产的节水灌溉方式。结果表明,W1处理能够有效提高土壤水分含量,在苜蓿生长期内0~60 cm土壤含水量都显著高于W2和W3处理(P<0.05)。W1处理苜蓿三茬总产量最高,为14379.4 kg·hm^(-2),较W2和W3三茬平均灌溉水利用效率分别提高了11.76%、46.15%。W1处理和W2处理三茬相对饲喂价值没有显著差异(P<0.05),其中W1处理三茬平均相对饲喂价值最高为121.3,其营养品质最好。利用熵权-TOPSIS法加权计算相对贴近度Si,最终得出W1处理贴近度最大,为0.522,是本试验中最优的方案,该处理既能获得较高的产量和品质,又能提高水分生产效能。研究表明,浅埋滴灌可以明显提高苜蓿产量和水分利用效率,在水资源短缺的干旱地区可选用浅埋滴灌作为苜蓿适宜的节水灌溉方式。

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.

Study on the Correlation Between Leaf Area and Drought Resistance in Different Alfalfa Varieties

[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.

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.