混合盐碱胁迫对帚用高粱萌发及苗期生长的影响

将NaHCO3和Na2CO3等摩尔混合,NaHCO3、Na2CO3、NaCl等摩尔混合分别得到250 mmol/L的混合溶液T1和T2,对帚用高粱的种子及幼苗进行混合盐碱胁迫处理。结果表明:混合盐碱胁迫导致帚用高粱种子发芽率降低,幼苗相对生长率减小,叶片电解质外渗率提高,可溶性糖含量增加,叶绿素含量减少;碱性盐混合引起的盐碱胁迫(T1)对帚用高粱种子萌发和幼苗生长的抑制作用明显强于中性盐和碱性盐混合引起的盐碱胁迫(T2);渗透胁迫和离子毒害是引起抑制作用的主要原因。     

柴达木盆地盐爪爪生理特性对盐胁迫的响应研究

通过研究柴达木盆地盐爪爪生理特性对盐胁迫的响应,为合理利用耐盐植物改良盐渍土提供科学依据。以盐爪爪种子及盆栽幼苗为试验材料,以清水为对照,设置10个1.0%~10.0%Na Cl溶液的培养基质浓度梯度,采用单因素随机区组设计,用3a时间对盐爪爪种子萌发、苗木生长及生理特性等耐盐性生化指标进行试验测定。结果表明:不同浓度盐胁迫对盐爪爪生长发育及生理特性都有一定程度的抑制,但不同浓度盐胁迫对盐爪爪生长发育及生理特性影响程度不同;随着盐浓度的增加,盐胁迫对盐爪爪生长发育及生理特性抑制作用越明显,7.0%盐浓度溶液作为对盐爪爪生长发育及生理特性抑制作用的拐点,是其适生耐盐最大阈值;在柴达木盆地荒漠化防治实践中应采取有效措施将水土环境的盐浓度控制在7.0%以下。     

外源NO对NaCl胁迫下玉米幼苗生长和渗透调节能力的影响

采用水培法,研究了50、100、200μmol·L~(-1)外源一氧化氮(NO)供体硝普钠(SNP)对盐胁迫下玉米幼苗生长和渗透调节能力的影响。结果表明,外施NO可明显缓解Na Cl胁迫对玉米幼苗生长的抑制作用,与不施SNP的处理相比,100μmol·L~(-1)SNP处理全株干重的增加幅度达到19%。外施NO降低盐胁迫下玉米幼苗叶片及根系中可溶性糖和可溶性蛋白的含量,其中叶片中可溶性糖和可溶性蛋白分别降低19.9%和7.9%,根系中可溶性糖和可溶性蛋白含量分别降低9.6%和9%。外源一氧化氮(NO)使盐胁迫下玉米幼苗根系、生长叶和成熟叶叶鞘的Na~+含量分别降低38.4%、5.1%和17.2%;同时,增加根系和成熟叶叶鞘中K~+、Ca~(2+)、Mg~(2+)含量,降低玉米幼苗各器官内的Na~+/K~+、Na~+/Ca~(2+)比值,维持盐胁迫下玉米幼苗中的离子平衡,但对成熟叶片中离子含量的影响不大。研究认为,外源NO可维持盐胁迫下玉米幼苗的碳氮代谢平衡,改善玉米幼苗离子的吸收与分配,缓解Na Cl胁迫对玉米幼苗带来的伤害,其中以100μmol·L~(-1)的SNP处理效果最明显。     

NaCl胁迫对蓖麻功能叶光系统Ⅱ荧光特性的影响

以中科院自育蓖麻品种KB-7号为试验材料采用室外盆栽法,研究了不同浓度Na Cl盐胁迫对其功能叶片叶绿素荧光参数的影响及其光响应曲线。结果发现:在高浓度Na Cl(9g·kg-1)胁迫时,蓖麻幼苗叶片光系统II(PSII)最大光化学量子效率(Fv/Fm)显著下降;随着光强的增加,Y(NPQ)、ETR、NPQ上升,Y(II)、qp等荧光参数显著下降,Y(NO)保持稳定。以上结果表明,蓖麻在低浓度Na Cl(0-6g·kg-1)处理下通过自身的调节机制避免盐离子对PSII反应中心造成伤害,高浓度Na Cl(9g·kg-1)盐胁迫处理引发光合电子传递受阻,导致PSII反应中心关闭或不可逆失活,表现出光抑制现象。     

根施外源甜菜碱对胡杨幼苗叶片积累甜菜碱与耐盐特性的影响

在不同盐分处理下(0、100、200、300、500 mmol·L~(-1)Na Cl)对土壤进行盆栽实验,研究根施甜菜碱(GB,5 mmol·L~(-1))对1 a生胡杨(Populus euphratica)幼苗叶片甘氨酸甜菜碱(GB)积累特性与不同时间(第7天、第14天)光合作用的影响。结果表明:(1)盐胁迫单独处理下,相比对照(0 mmol·L~(-1)Na Cl,CK)叶片甜菜碱随盐胁迫强度增大积累量显著增多。盐胁迫和外源GB双重处理下,叶片GB含量总体趋势随盐浓度升高表现为先升高后保持平稳。在低盐胁迫处理时(100~300 mmol·L~(-1)Na Cl)外源GB能诱导叶片产生更多GB,较未经GB处理组叶片GB积累量分别提高44.0%、32.5%和35.9%,而高盐胁迫(500 mmol·L~(-1)Na Cl)则转为抑制,叶片GB含量降低了5.1%。(2)随着盐浓度升高,外源GB虽不能持续促进叶片GB含量,但其对光合维持能力却没有丧失。随着胁迫强度增加,外源GB对叶绿素含量、水分利用效率(WUE)、叶片相对含水量(RWC)及相关光合参数的维持作用越明显。(3)不同时间下盐分和外源GB对胡杨光合作用的影响会改变,外源GB先维持胡杨水分传递过程,后维持CO_2同化能力,最终提高其光合作用。总之,根施GB能够促使胡杨叶片GB积累量发生变化并发挥作用,调节盐胁迫下胡杨光合相关生理过程从而提高其耐盐能力。     

低温胁迫下戊唑醇和苯醚甲环唑种子包衣对玉米种子出苗和幼苗的影响

为研究低温胁迫下种子包衣对玉米种子出苗和幼苗生长的影响,以适宜温度(25℃/20℃,白天/晚上,下同)处理为对照,对不同剂量包衣的玉米种子进行低温胁迫。研究结果表明,戊唑醇和苯醚甲环唑种子包衣在适宜温度下对玉米种子出苗具有促进作用,能提高玉米幼苗植株的叶绿素含量,对玉米幼苗的株高和鲜重没有抑制作用。但在17℃/6℃、15℃/0℃、10℃/0℃低温胁迫下,戊唑醇和苯醚甲环唑均能抑制种子出苗和幼苗生长,加剧低温胁迫导致的膜脂质过氧化作用和对叶绿体的分解。但用苯醚甲环唑处理玉米种子比用戊唑醇更安全,前者能抑制低温胁迫导致的叶片细胞内电解质外渗,后者却会加剧电解质的外渗。比较玉米幼苗根系的呼吸作用也可以发现,苯醚甲环唑比戊唑醇更有利于玉米幼苗补偿和修复低温胁迫所致的伤害。     

不同钠盐胁迫对高冰草种子萌发的影响

通过对高冰草种子在不同钠盐(NaCl、NaHCO3、Na2CO3)溶液中萌发情况的研究,旨在探明高冰草种子在不同盐胁迫下的萌发特性。结果表明:碱性盐(NaHCO3、Na2CO3)胁迫较中性盐(NaCl)胁迫显著降低了高冰草的发芽率。高冰草种子在NaCl浓度150mmol/L、NaHCO3浓度100mmol/L和Na2CO3浓度50mmol/L时萌发受到明显抑制。不同钠盐胁迫下高冰草种子胚根和胚芽的受抑制大小顺序为,中性盐NaCl胁迫:胚根<胚芽;碱性盐NaHCO3和Na2CO3胁迫:胚根>胚芽。     

Response of Main Osmotic Adjustment Substances to NaCI Stress Accumulation in Atriplex canescens

采用盆栽沙培方法,研究四翅滨藜主要渗透调节物质对NaCl浓度和盐胁迫时间的响应。结果表明：①胁迫时间对四翅滨藜叶片中脯氨酸、Na＋、K＋、Cl-含量和K＋/Na＋有极显著影响。随着胁迫时间的延长,叶中脯氨酸、Na＋含量增加,K＋含量、K＋/Na＋下降,Cl-含量变化趋势较复杂;NaCl胁迫〈40 d时,脯氨酸和Na＋含量增加幅度相对较小,〉40 d时均大幅增加。②NaCl浓度对四翅滨藜叶片中脯氨酸、Na＋、K＋、Cl-含量和K＋/Na＋也有极显著影响。随着NaCl浓度的增加,叶中脯氨酸、Na＋含量增加,K＋含量、K＋/Na＋下降;高NaCl浓度处理下,脯氨酸和Na＋含量增加幅度以及K＋含量、K＋/Na＋下降幅度均较大。③四翅滨藜体内离子运输具有选择性。盐胁迫下,根向茎选择运输K＋,将Na＋滞留在根部;茎向叶选择运输Na＋,抑制了K＋向叶片的运输,使从根部运输的K＋贮存在茎中;不同营养器官中K＋/Na＋从高到低依次为：茎〉叶〉根,并且都随着NaCl浓度的增加而降低。随着胁迫时间的延长,NaCl浓度对脯氨酸、K＋、Na＋及K＋/Na＋的影响逐渐放大,并且NaCl浓度与胁迫时间的交互作用也对以上指标（除K＋外）有极显著影响,因此在研究盐分浓度对植物盐胁迫的影响时,应考虑时间因素及盐分浓度与胁迫时间的交互作用。     

NaCl和NA2SO4胁迫对裸果木种子萌发的影响

为了探明裸果木(Gymnocarpos przewalskii)种子在不同盐胁迫条件下的萌发特性,对种子进行了不同浓度(50、100、150、200、250、300、350mmol/L)NaCl和Na_2SO_4溶液的处理,以蒸馏水为对照,研究模拟盐胁迫对种子萌发的影响。结果表明:1)低浓度的NaCl(50、100mmol/L)和Na_2SO_4(50mmol/L)溶液对种子发芽率和相对盐害率的影响不显著;种子的发芽势、发芽指数、活力指数、耐盐指数随着浓度的增大显著降低,相对盐害率明显增大;低浓度(50mmol/L)NaCl处理的胚根和胚轴长度较对照均显著增加,促进了种子胚根和胚轴的生长;Na_2SO_4处理对胚根和胚轴生长的抑制作用随浓度的增加显著加强。2)解除盐胁迫后,种子恢复萌发率随盐胁迫浓度的增加显著升高,盐浓度<300mmol/L时,各处理之间的种子终萌发率与对照无显著差异,表明抑制种子萌发的主要因素是渗透胁迫,高浓度的盐胁迫表现出一定的离子毒害作用。3)裸果木种子的萌发指标对盐胁迫的敏感程度表现为发芽率>发芽势>活力指数>胚根长度>发芽指数>胚轴长度。4)种子萌发对两种盐的耐受性存在差异,Na_2SO_4对种子萌发的抑制程度显著高于NaCl,两种盐胁迫下,种子萌发率的耐盐临界值分别为135. 62mmol/L和198. 57mmol/L。     

DCPTA诱导寒地春玉米种子萌发及幼苗抗旱理化特征的研究

以玉米品种郑单958、先玉335和东农253为试验材料,用15%聚乙二醇(PEG-6000)模拟水分胁迫条件研究了植物生长调节剂DCPTA[2-(3.4-二氧苯氧基)三乙胺]对玉米种子萌发和幼苗生长抗旱性的影响。结果表明,水分胁迫显著抑制了玉米种子萌发和幼苗生长。玉米幼苗叶片内超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性增强,脯氨酸含量增加,幼苗叶片叶绿素含量、初始荧光(F_0)、PSⅡ最大光能化学效率(F_c/F_m)显著下降,且玉米品种之间抗旱性存在差异,表现为先玉335郑单958东农253。DCPTA处理对玉米种子的发芽率、发芽势、萌发抗旱指数伤害减小,对幼苗胚根、胚芽生长和贮藏物质转化的抑制作用减弱,以1.0 mg/L DCPTA处理效果最显著。盆栽试验表明,水分胁迫条件下喷施DCPTA随浓度升高玉米幼苗叶片内抗氧化酶活性和脯氨酸含量均增加,叶绿素含量、F_0、F_v/F_m呈增加趋势,且喷施80 mg/L DCPTA处理效果显著。本研究表明适宜浓度的DCPTA能缓解水分胁迫对玉米种子萌发和幼苗生长的伤害,增强幼苗对水分胁迫的适应能力,并且DCPTA处理效果与品种抗旱性有关。3个供试品种DCPTA作用效果顺序为东农253郑单958先玉335。     

Localization of metabolic sites of action of herbicides

Time- and concentration-course studies were conducted to determine the effect of thirteen herbicides on photosynthesis, respiration, RNA synthesis, protein synthesis, and lipid synthesis using isolated single leaf cells. Each herbicide was from a different chemical class. Appropriate ¹⁴C-substrates and product purification procedures were used for each process prior to liquid scintillation counting. The most sensitive metabolic site of inhibition was photosynthesis for atrazine, bromacil, dichlobenil, monuron, and paraquat; RNA synthesis for dalapon and dinoseb; protein synthesis for chlorpropham; and lipid synthesis for CDAA, chloramben, 2,4-D, EPTC, and trifluralin. However, with several herbicides, one or more process was almost as sensitive as the one mentioned above. All herbicides inhibited more than one process, and the most sensitive site of inhibition may not be the same process that was inhibited the greatest at the maximum concentration and maximum exposure time used. Therefore, a concept of metabolic sites of action, rather than a primary site of action, appears to be more meaningful for herbicides.     

福寿螺配偶个体大小选择性初步观察

通过野外观察与实验研究,掌握了福寿螺的婚配体制及其配偶选择性规律。福寿螺与多数低等动物一样,其婚配属于乱交制,无固定配偶;雌螺对与其交配的雄螺个体大小没有选择性,而雄螺对雌螺的个体大小有选择性,倾向于与较大个的雌螺交配。     

青稞种子带菌检测及杀菌剂消毒处理效果

为了研究青稞种子外部和内部携带真菌情况,比较不同杀菌剂对青稞种子的带菌消毒效果和对幼苗生长的影响,为青稞种子播前包衣处理和种传真菌病害防控提供依据,采用离体平皿法对云南迪庆‘云青1号’、‘云青2号’和‘短白青稞’3个主栽品种进行带菌检测,并对种子进行拌种或浸种处理测定6种杀菌剂对种子消毒效果,分析杀菌剂对种子发芽和幼苗生长的影响。结果表明:供试青稞种子表面携带的优势菌群为青霉(Penicilliumspp.)、镰刀菌(Fusariumspp.);种子内部寄藏的真菌主要为镰刀菌、核腔菌(Pyrenophoraspp.)、附球菌(Epicoccumspp.)、丝核菌(Rhizoctoniaspp.)、链格孢(Alternariaspp.)和木霉(Trichoderma spp.)。青稞不同品种的种子表面及内部携带的真菌种类差异较大。致病性测定表明,镰刀菌对种子萌发和幼苗生长影响最大,后期出现幼苗坏死现象。45%咪鲜胺EW、75%百菌清WP、50%福美双WP对青稞种子携带真菌均有显著抑制作用和消毒效果,50%福美双WP消毒效果最优,达100%;45%咪鲜胺EW、75%百菌清WP、50%福美双WP处理对青稞种子发芽和幼苗生长均无显著影响。     

厚朴病虫害种类的初步调查

采用标准地法和线路调查法,对湖北恩施市新塘乡双河厚朴基地的厚朴病虫害进行了系统调查,记录主要虫害13种,其中叶部害虫9种,枝干害虫2种,根部害虫2种。厚朴主要病害5种。藤壶蚧、厚朴枝角叶蜂和厚朴新丽斑蚜为湖北省首次报道,小绿叶蝉为厚朴新寄主记录种。同时记录了藤壶蚧的天敌6种,其中寄生小蜂2种,瓢虫4种;厚朴新丽斑蚜的天敌昆虫8种。对藤壶蚧、厚朴枝角叶蜂和厚朴苗木根腐病等重要病虫害的发生规律进行了初步调查,同时提出了防治建议。     

Effects of timing and method of application of Penicillium oxalicum on efficacy and duration of control of Fusarium wilt of tomato

The effects of timing and method of application of Penicillium oxalicum on the control of fusarium wilt of tomato were investigated. Application of P. oxalicum to tomato seedlings in seedbeds reduced disease caused by Fusarium oxysporum f.sp. lycopersici in a growth chamber by 45–49% and in glasshouse experiments by 22–69%. Disease suppression was maintained for 60–100 days after inoculation with the pathogen in the glasshouse. No disease reduction was observed in tomato plants where P. oxalicum was applied to seeds. Treatment with P. oxalicum did not affect the population of F. oxysporum f.sp. lycopersici in the rhizosphere.     

Mode of action of etoxazole

The mode of action of the 2,4-diphenyl-1,3-oxazoline acaricide/insecticide etoxazole has been argued to be moulting inhibition, but experimental results supporting this hypothesis are lacking. This study investigated the effect of etoxazole on chitin biosynthesis in the fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). Etoxazole induced moulting defects in fall armyworm larvae similar, if not identical, to those caused by benzoylphenylureas, a well-known class of insecticidal chitin biosynthesis inhibitors. Furthermore, in contrast to untreated larvae, the chitin content in the integuments of larvae several days after treatment did not differ from that in freshly ecdysed individuals, thus suggesting strong chitin biosynthesis inhibition in vivo. A more detailed investigation of the inhibitory potential by incubating cultured integument pieces from larvae of S. frugiperda with [14C]N-acetyl-D-glucosamine, a radiolabelled chitin precursor, revealed I50 values of 2.95 and 0.071 microM for etoxazole and triflumuron respectively. The incorporation of radiolabel into potassium hydroxide-resistant material was inhibited by etoxazole in a dose-dependent manner. Based on these results, it is concluded that the acaricidal and insecticidal mode of action of etoxazole is chitin biosynthesis inhibition.     

Mode of action of meturine

The effect of meturine on the light processes of photosynthesis was studied.Meturine is a herbicide for weed control in potato and cotton crops. It is a N-phenyl—N-hydroxy—N′-methylurea.The experiments were carried out on isolated pea and spinach chloroplasts.When examining photosystem I, reduced DPIP was used as an electron donor, whereas methyl-viologen served as an electron acceptor. When examining photosystem II, DPIP represented the electron acceptor.The obtained experimental results have pointed to the absence of the effect of meturine upon the photoreaction I.Unlike N-phenyl—N′, N′-dimethylureas (CMU, DCMU) meturine has been a very weak inhibitor of photoreaction II.The authors explain the photoreaction II inhibition of chloroplasts from plants treated with herbicidal doses of meturine by conversion of N-phenyl—N-hydroxy—N′-methylurea into Hill reaction inhibitor(s). N-Phenyl—N′-methylurea can be one of such meturine metabolites.Meturine herbicidal action is accounted for by meturine transformation into Hill reaction inhibitor(s) in the plant tissues.     

甲基硫菌灵标样的制备

本文介绍了用进口甲基硫菌灵样品，采用溶剂萃取，高速离心，重结晶，高效液相色谱，红外光谱等分析方法进行系统分离与鉴定，得到其标样的方法。     

Measures of durability of resistance

ABSTRACT Conventional models for the durability of resistant cultivars focus on the dynamics of the frequency of resistance genes. This leads to a definition of the durability of resistance as the time from introduction of the cultivar to the time when the frequency of the virulence gene reaches a preset threshold. It is questionable whether this is the most appropriate way to measure durability. Here we use a simple epidemiological model to link population dynamics and population genetics to compare three measures of durability: (i) the expected time until invasion of the virulent genotype, by mutation or immigration, and subsequent establishment of a population (T(invasion)); (ii) the virulence frequency related measure of the time for the virulent genotype to take-over the pathogen population ( T(take-over)); and (iii) the additional yield, measured by the additional number of uninfected host growth days (T(additional)). Specifically, we show how the measures of durability are affected by deployment and epidemiological parameters. We use a combination of numerical solution and analytical approximation of a model for the population dynamics of avirulent and virulent genotypes of a pathogen growing in dynamically changing populations of resistant and susceptible cultivars. The three measures of durability are compared. Some consequences of the results for durable resistance in multilines and mixtures and the regional deployment of resistant cultivars are discussed.