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.

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.

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.

Flavonol synthase gene MsFLS13 regulates saline-alkali stress tolerance in alfalfa

Alfalfa(Medicago sativa L.) is one of the most extensively grown leguminous forage worldwide.Environmental saline-alkali stress significantly influences the growth,development,and yield of alfalfa,posing a threat to its agricultural production.However,little is known about the potential mechanisms by which alfalfa responds to saline-alkali stress.Here,we investigated these mechanisms by cloning a saline-alkali-induced flavonol synthase gene(Ms FLS13) from alfalfa,which was previously reported to be significantly upregulated under saline-alkali stress,and examining its function in the saline-alkali response.Overexpression of Ms FLS13 in alfalfa promoted plant tolerance to saline-alkali stress by enhancing flavonol accumulation,antioxidant capacity,osmotic balance,and photosynthetic efficiency.Conversely,Ms FLS13 inhibition using RNA interference reduced flavonol synthase activity and inhibited hairy root growth under saline-alkali stress.Yeast one-hybrid and dual-luciferase reporter assays indicated that the R2R3-MYB Ms MYB12 transcription factor activates Ms FLS13 expression by binding to the MBS motif in the Ms FLS13 promoter.Further analysis revealed that abscisic acid mediates the salinealkali stress response partially by inducing Ms MYB12 and Ms FLS13 expression,which consequently increases flavonol levels and maintains antioxidant homeostasis in alfalfa.Collectively,our findings highlight the crucial role of Ms FLS13 in alfalfa in response to saline-alkali stress and provide a novel genetic resource for creating saline-alkali-resistant alfalfa through genetic engineering.

Overexpression of ZxABCG11 from Zygophyllum xanthoxylum enhances tolerance to drought and heat in alfalfa by increasing cuticular wax deposition

Drought and heat stresses cause yield losses in alfalfa,a forage crop cultivated worldwide.Improving its drought and heat tolerance is desirable for maintaining alfalfa productivity in hot,arid regions.Cuticular wax forms a protective barrier on aerial surfaces of land plants against environmental stresses.ABCG11encodes an ATP binding cassette(ABC) transporter that functions in the cuticular wax transport pathway.In this study,Zx ABCG11 from the xerophyte Zygophyllum xanthoxylum was introduced into alfalfa by Agrobacterium tumefaciens-mediated transformation.Compared to the wild type(WT),transgenic alfalfa displayed faster growth,higher wax crystal density,and thicker cuticle on leaves under normal condition.Under either drought or heat treatment in greenhouse conditions,the plant height and shoot biomass of transgenic lines were significantly higher than those of the WT.Transgenic alfalfa showed excellent growth and 50% greater hay yield than WT under field conditions in a hot,arid region.Overexpression of Zx ABCG11 up-regulated wax-related genes and resulted in more cuticular wax deposition,which contributed to reduction of cuticle permeability and thus increased water retention and photosynthesis capacity of transgenic alfalfa.Thus,overexpression of Zx ABCG11 can simultaneously improve biomass yield,drought and heat tolerance in alfalfa by increasing cuticular wax deposition.Our study provides a promising avenue for developing novel forage cultivars suitable for planting in hot,arid,marginal lands.

Effects of Different Herbicides on Weed Control in Alfalfa Field

[Objectives]The paper was to systematically study the technology of weed control in alfalfa field.[Methods]Reviving alfalfa field and newly sown alfalfa field after emergence were selected,and the effects of different herbicides on weed control and alfalfa yield were discussed.[Results]The optimal herbicides after alfalfa reviving were 5%imazethapyr and 10%imazethapyr,and the optimal dosages were 1.5 and 1.05 L/hm 2,respectively.The optimal herbicides after emergence of newly born alfalfa were 5%imazethapyr and 10%imazethapyr,and the optimal dosages were 1.5 and 0.75 L/hm 2,respectively.[Conclusions]This study will provide a technical support for high quality production of alfalfa.

不同苜蓿品种叶片特征、光合生理特性与产量性状的比较

以国内外引进的8个紫花苜蓿(Medicago sativa L.)品种为试验材料,对比研究不同品种的叶片特征、产量性状和光合生理特性,采用相关性分析和通径分析法,探讨其与产量的关联性,以期为高产紫花苜蓿种质的筛选提供依据。结果表明:供试紫花苜蓿品种单株干重的变幅为0.88~1.21 g;各性状与单株干重的相关性按大小排序依次为:单株叶干重>比叶重>蒸腾速率>单株叶片数>叶形指数,单株叶干重是最突出的叶片特征指标。对单株干重的影响程度从大到小依次为:比叶重>气孔导度>可溶性蛋白>株高>蔗糖>可溶性糖>叶绿素总量,其中,比叶重是单株干重的主要决定因子。综上,高产紫花苜蓿种质筛选的重要指标包括:单株叶干重和比叶重,8个紫花苜蓿品种中‘甘农9号’、‘WL319HQ’和‘SG501’的单株干重、单株叶干重和比叶重均较大,可作为高产种质在育种工作中加以研究利用。

LED3A强化紫花苜蓿修复Cd污染土壤的效果研究

研究可生物降解螯合剂N-十二酰基乙二胺三乙酸盐(LED3A)诱导强化紫花苜蓿修复Cd污染土壤的效果,采用盆栽方法,考察LED3A对紫花苜蓿生理指标、Cd亚细胞分布和化学形态以及增效提取土壤中Cd的影响.结果表明,Cd胁迫显著抑制紫花苜蓿的生长及光合作用,增加丙二醛(MDA)的积累.而在土培体系中施用LED3A,可以提高植株生物量、光合色素含量、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性,缓解细胞膜脂过氧化损伤和Cd诱导产生的氧化应激.LED3A的螯合强化作用能够增大紫花苜蓿细胞质中Cd的分布比例,促使植株中的Cd由高活性形态向低活性形态转化,通过细胞壁固持和液泡区隔化提高耐Cd性能,进而减轻毒害.与不添加LED3A组相比,最佳LED3A添加量(321.3 mg·kg^(-1))组紫花苜蓿植株中的总Cd含量和积累量分别提高了29.4%和69.1%,地下/地上富集系数及转运系数分别增加了28.6%,36.4%和10.5%.说明添加适量LED3A可有效提高紫花苜蓿对Cd的耐受性与修复Cd污染土壤的效果.

紫花苜蓿资源萌发期耐碱性评价

为了筛选适合东北盐碱地区种植的优质紫花苜蓿品种,研究选取130份国内外紫花苜蓿品种及新选育资源,分别用30 mmol/L的Na2CO3溶液和50 mmol/L的NaHCO3溶液对其萌发期种子进行碱胁迫处理,通过检测萌发指标及隶属函数分析对供试紫花苜蓿品种进行耐碱性综合评价。结果显示:130份紫花苜蓿在Na2CO3与NaHCO3胁迫下的平均相对萌发率分别为68.54%、79.17%,相对萌发势分别为57.30%、65.78%,相对根长分别为23.70%、17.61%,相对芽长分别为53.21%、46.37%。隶属函数分析发现,LJ112、LJ66、LJ33、5010、DARA、农菁1号、巨能耐盐等7个品种的种子在两种碱胁迫下萌发态势较好。通过分析130份紫花苜蓿在两种碱胁迫下的综合隶属函数值,农菁1号和LJ33在两种碱胁迫下保持较高的萌发率及生长势。研究表明,该试验有利于指导盐碱地苜蓿种植,并为耐盐碱紫花苜蓿品种选育提供种质资源保障。

聚乙烯吡咯酮对‘甘农三号’紫花苜蓿愈伤组织褐化及抗氧化物质活性的影响

本研究旨在探讨不同浓度的聚乙烯吡咯酮(PVP)对紫花苜蓿(Medicago sativa L.)愈伤组织在增殖过程中褐化的抑制效果。选取‘甘农三号’紫花苜蓿下胚轴作为外植体,通过外源添加不同浓度PVP,观察其对愈伤组织增殖过程中褐化进程的抑制作用。结果显示,与对照组相比,所有处理组的褐化率均有所降低。但不同浓度的PVP对愈伤组织褐化产生影响的程度不同,当PVP浓度为300 mg/L时,紫花苜蓿愈伤组织的褐化程度显著减少(P<0.05),此时测得的丙二醛(MDA)含量和多酚氧化酶(PPO)活性均达到最低值,分别为0.1μmol/g FW和32.8 U/g。过氧化物酶(POD)活性相对较低,为232.0 U/g,而超氧化物歧化酶(SOD)活性相对较高,为168.1 U/g。因此,得出结论,300 mg/L PVP对抑制‘甘农三号’紫花苜蓿愈伤组织的褐化具有最佳效果。

氮肥与复硝酚钠复配施用对紫花苜蓿生理特性及种子产量的影响

本试验以‘新牧4号’紫花苜蓿(Medicago sativa L.‘Xinmu No.4’)为试验材料,研究在盛花期喷施氮肥(N)、复硝酚钠(CSN)、氮肥和复硝酚钠复配(N+CSN)对紫花苜蓿生理特性、种子产量及产量构成因子的影响,发现喷施N,CSN,N+CSN能够提高紫花苜蓿叶片可溶性糖、淀粉、可溶性蛋白含量、SOD、POD和CAT活性。喷施N+CSN优于单施N和CSN,其中,N+CSN显著提高紫花苜蓿二级分枝数/生殖枝、荚果数/花序、种子数/荚果和千粒重,从而提高种子产量;与对照相比,单施N和CSN后种子产量提高了6.84%~38.49%,N+CSN施用后种子产量提高了44.39%~57.76%。根据相关性分析,不同处理下种子产量与可溶性糖、淀粉和可溶性蛋白含量,以及SOD、POD和CAT活性、千粒重、种子数/荚果、荚果/花序、小花数/花序、结荚率、二级分枝数/生殖枝都呈显著正相关关系。综上所述,隶属函数综合分析得出N+T2(0.5%N+6 mg·L^(-1)CSN)是提高种子产量和优化种子产量构成因子最优组合。

紫花苜蓿幼苗氧化应激防御系统对自毒作用的响应

【目的】通过研究自毒作用对紫花苜蓿品种种子萌发、幼苗生长及叶片细胞膜氧化防御系统的影响,明确紫花苜蓿幼苗响应自毒作用的活性氧代谢机理,为进一步阐明自毒物质对紫花苜蓿的抑制机理和自毒效应防控提供理论基础。【方法】选用紫花苜蓿品种德宝和WL298HQ为试验材料,取开花期叶片制备成T1(0.0025 g/mL)、T2(0.0125 g/mL)、T3(0.0225 g/mL)浸提液模拟自毒作用,研究自毒作用对种子生物活性和化感指数的影响,以及对幼苗生长、活性氧(H_(2)O_(2)、OH.和O_(2)^(.-))、氧化防御系统中的抗氧化酶和抗氧化剂、渗透调节物质的影响。【结果】不同浓度的叶浸提液抑制德宝和WL298HQ苜蓿种子萌发,T3抑制幼苗生长。与WL298HQ相比,德宝响应自毒作用具有明显的生理差异:(1)自毒物质作用于细胞膜上,诱发了氧化应激,加速活性氧ROS代谢,导致了MDA、H_(2)O_(2)和OH·过量积累;(2)德宝在T1下可通过提高叶片保护酶(SOD、POD、CAT、APX、GR)活性和抗氧化剂(AsA、DHA)含量来响应自毒作用。但在T3下,可溶性糖、可溶性蛋白和游离脯氨酸升高,自毒作用影响氧化防御系统的稳定性,导致叶片出现严重的氧化损伤。【结论】WL298HQ通过激活保护机制增加抗氧化剂的活性,以及渗透物质的积累,进而保持细胞膜的相对完整性和氧化清除能力。德宝苜蓿在自毒作用下,ROS的产生大于抗氧化防御系统的能力,导致氧化损伤。

10种紫花苜蓿在低温胁迫下的生理特性及耐寒性评价

为了明确紫花苜蓿在低温胁迫下的生理特性并筛选出具有高耐寒能力的品种,选取了来自不同地区的10个紫花苜蓿品种作为试验材料,通过测定其幼苗在4℃低温胁迫下的12项生理指标,结合相关性分析、主成分分析和隶属函数评价方法,对其耐寒能力进行了评价;同时,采用半致死温度(LT_(50))对评估出的耐寒能力进行验证。结果表明:1)在4℃低温胁迫下,10个紫花苜蓿品种的叶片蒸腾速率(Tr)较对照组均有不同程度的下降,而相对电导率(REC)、脯氨酸(Pro)、可溶性糖(SS)、可溶性蛋白(SP)含量以及超氧化物歧化酶(SOD)和过氧化物酶(POD)活性均呈现出不同程度的增加趋势;2)隶属函数评价结果显示耐寒能力为龙牧801>肇东>Bara 520 YQ>公农1号>佰苜401>敖汉>挑战者>东农1号>骑士>新牧4号。各品种叶片的半致死温度(LT_(50))揭示,龙牧801和新牧4号分别是LT_(50)值最低和最高的品种,与隶属函数的评价结果吻合;3)紫花苜蓿苗期耐寒性综合评价值(D)=0.138+0.178×SP+0.203×POD+0.170×Pro,表明SP、POD和Pro是评估紫花苜蓿幼苗耐寒性的关键生理指标。上述研究结果为深入了解紫花苜蓿幼苗的低温适应机制及耐寒紫花苜蓿品种的筛选奠定了基础。

苜蓿草田间作功能植物对苜蓿蓟马及天敌小花蝽种群的影响

本研究将苜蓿Medicago sativa与百脉根Lotus corniculatus、红豆草Onobrychis viciifolia、白三叶Trifolium repens、小冠花Coronilla varia及除虫菊Tanacetum cinerariifolium等不同功能植物以不同比例进行间作,在田间系统监测基础上,研究基于有害生物推拉策略和生物多样性保护的苜蓿蓟马生态调控技术。结果表明,苜蓿刈割前,苜蓿草田内蓟马及天敌小花蝽Orius similis的数量均显著高于对应间作的功能植物区;刈割1周后,与百脉根、红豆草、白三叶和除虫菊间作的苜蓿草田内小花蝽种群密度显著下降,对应的功能植物区内小花蝽数量显著上升,其中,百脉根、红豆草及白三叶3种功能植物区内小花蝽种群密度分别由刈割前的3.67头/10复网、3.00头/10复网、3.67头/10复网增加到了刈割1周后的11.50头/10复网、29.17头/10复网、15.00头/10复网,分别是刈割前的3.13倍、9.73倍和4.09倍,苜蓿草田内蓟马种群密度显著下降,对应不同功能植物区内蓟马种群密度不同,在红豆草和白三叶功能植物区内显著升高,而在其它区内刈割前无显著差异;刈割2周后,苜蓿再生期蓟马种群密度显著上升,各功能植物区内的小花蝽密度显著下降,与其间作的苜蓿草田内小花蝽种群数量显著增加;刈割3~4周后,随着苜蓿草田内蓟马种群密度的下降,其天敌小花蝽种群数量显著下降,不同功能植物区间小花蝽及蓟马种群密度变化不显著。苜蓿与五种功能植物以4:1比例间作对蓟马的调控效果由高到低依次为白三叶,除虫菊,红豆草,百脉根,小冠花。本研究为保护苜蓿草田生态系统天敌发挥生态效能提供可借鉴的策略与方法。

天山北坡平原荒漠灌区9个紫花苜蓿品种生产性能综合评价

【目的】筛选出适宜在天山北坡平原荒漠区推广种植的紫花苜蓿品种。【方法】采用单因素随机区组设计,测定9个紫花苜蓿品种的株高、草产量、品质等指标,并利用灰色关联法对9个品种进行综合评价。【结果】随种植年限增加,供试材料的鲜草和干草产量均呈下降趋势,其中第1年的干草产量占比较高,平均为37.77%;佰苜341的株高积累量最大,为939.8 cm,显著高于其他品种;骑士T干草总产量、粗蛋白含量和相对饲喂价值最高,分别为61602.03 kg/hm^(2)、16.83%和119.16%;灰色关联度综合评价结果由高到低的顺序为:骑士T>佰苜202>大银河>阿迪娜>佰苜341>佰苜371>挑战者>佰苜401>康赛。【结论】骑士T的综合表现较好,建议在天山北坡平原荒漠灌区引种种植。

根癌农杆菌介导的紫花苜蓿遗传转化体系的优化

为进一步提高根癌农杆菌介导的紫花苜蓿遗传转化效率,本试验以紫花苜蓿(Medicago sativa L.)品种‘中苜1号’为试验材料,通过筛选高效再生的植株,以筛选出的植株叶片为外植体,并通过调节培养基激素配比,在农杆菌侵染过程中添加谷氨酰胺、进行冷处理等措施优化苜蓿由农杆菌介导的遗传转化体系。试验结果表明:转化过程中以嫩叶作为外植体,菌液和重悬液中添加150μmol·L^(-1)乙酰丁香酮,侵染过程中使用300μmol·L^(-1)的谷氨酰胺将瞬时转化效率从32%提高至92%,转化效率提高到31%。研究紫花苜蓿的遗传转化体系可为紫花苜蓿高效遗传改良及基因功能研究提供了技术支持。

紫花苜蓿地下滴灌灌水均匀性与适宜灌溉定额研究

研究主要探究不同灌溉方式紫花苜蓿地下滴灌灌水均匀性差距,并提出适宜的灌水定额。采用田间试验,设3个地下滴灌灌水定额(20、25、30 mm),2个埋设深度(10、20 cm)和2个滴头流量(1.38、2.0 L/h),研究了滴灌带流量、埋深在不同紫花苜蓿生育期内的灌水均匀度差异,同时进一步探究了不同灌水处理对紫花苜蓿株高、产量等参数的影响。滴灌带滴头流量对滴灌灌水均匀性的影响相对较大。在相同的滴灌带滴头流量下,滴灌带埋设深度10 cm与20 cm对滴灌灌水均匀系数影响不显著。当耗水量为456.69 mm时,紫花苜蓿干草产量最大,为12847.78 kg/hm-2。基于节水效果、产量和高效等多生产因素的综合考虑,建议鄂尔多斯鄂托克前旗地区紫花苜蓿地下滴灌灌水定额为25 mm,灌水12~14次。

苜蓿抗寒突变体生理生化及性状指标分析

为选育在黑龙江省可越冬的理想紫花苜蓿品种。以‘龙牧806’零磁空间诱变处理后二代群体中获得的lm1609、lm1625、lm1704三个抗寒突变体为实验材料,通过测定发芽指标、越冬率、产量特性指标及根系生理生化指标,进行抗寒性能鉴定。3个突变体发芽指数与对照差异不显著;发芽势、简化活力指数lm1609显著高于lm1625、lm1704,分别为82.05%、469.82(P<0.05);3个突变体的越冬率都显著低于对照组;突变体和对照6月6日起始株高差异不显著,随着植株生长,7月6日和8月6日lm1609、lm1704显著高于lm1625和对照;突变体lm1609、lm1625、lm1704三者鲜草产量差异不显著,但显著高于对照(P<0.05);三个苜蓿突变体植株根系过氧化物酶、超氧化物歧化酶均显著高于对照,并且突变体lm1609 POD、SOD最高,分别达到304.85 OD470/(min·g)、208.41 U/g(P<0.05)。lm1609突变体具有较高的抗寒特性及产量特性,是为理想的抗寒突变体材料。

低温下紫花苜蓿叶片的光破坏防御作用

低温是影响植物正常生长发育的重要环境因素。本研究以‘新牧4号’紫花苜蓿(Medicago sativa L.‘Xinmu No.4’)和‘甘农5号’紫花苜蓿(Medicago sativa L.‘Gannong No.5’)为试验材料,探究低温下紫花苜蓿叶片光破坏防御作用的变化。结果表明,低温下紫花苜蓿叶片的光合速率、最大光化学效率(Fv/Fm)及核心蛋白下降;低温下非光化学淬灭系数(NPQ)降低,环式电子传递(CEF)上调,使用NPQ抑制剂后Fv/Fm显著下降;低温下交替氧化酶(AOX)呼吸速率以及蛋白含量降低,但AOX呼吸的占比升高,AOX抑制剂和光呼吸抑制剂的施用均加重Fv/Fm的下降;低温下超氧阴离子、过氧化氢和丙二醛含量上升,抗坏血酸酶(APX)活性上升。低温下NPQ被抑制,CEF的上调弥补了NPQ作用的下降从而保护叶片减少光破坏;AOX增加电子分流从而维持光呼吸正常运作;低温下活性氧的清除主要依靠APX,但仍有大量活性氧产生使光系统受到损伤,引起光抑制。

食用菌渣堆肥还田对苜蓿产量和品质的影响研究

食用菌渣是有机废弃物,也是可回收利用的优质农业资源,食用菌渣的高效资源化利用对于发展可持续农业有重要意义。以苜蓿为试验材料,设计不同堆肥施用方案(3 000 kg/hm^(2)、4 500 kg/hm^(2)和6 000 kg/hm^(2)),辅以两种补充灌溉量,观测食用菌渣堆肥还田对苜蓿产量和品质的影响。结果表明,4 500 kg/hm^(2)菌渣肥料协同240 mm补充灌溉量有利于苜蓿增产提质,该组合下熵权系数评价值达到0.81,可作为食用菌渣资源高效利用方案。