不同处理下菘蓝苗中IAA和靛玉红含量分析及合成部位研究

自然干旱、20 mmol/L ABA、4℃低温处理培养30 d的菘蓝组培苗,不同时闻内取样,用高效液相色谱法测定其中IAA的含量.结果表明:干旱处理菘蓝组培苗在12 h内能提高其IAA含量242.04%～262.87%;ABA处理与干旱处理有相似结果;低温胁迫处理24 h也能提高IAA含量503.87%.此外用高效液相色谱法测定了生长一个半月的菘蓝实生苗中IAA和靛玉红含量.结果为:花中IAA含量大于根中,叶中没有;靛玉红则在叶中最多,花中次之,根中最少;初步表明菘蓝中IAA和靛玉红虽然具有类似的分子结构,且逆境胁迫处理都可使其含量增加,但在植物体中的产生部位有差异.     

CaM拮抗剂W7对PEG胁迫下番茄幼苗根系生长和ABA、多胺动态变化的影响

以耐旱性不同的两个番茄品种为试材,采用营养液水培,研究了CaM拮抗剂W7〔N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide〕预处理对聚乙二醇(PEG-6000)模拟干旱胁迫下番茄幼苗根系生长及内源ABA、游离态多胺含量的影响。结果表明,用200 mmol/L W7预处理24 h,然后进行干旱胁迫处理,番茄根系内源ABA和多胺含量低于未经W7预处理的PEG胁迫处理下的值,W7处理削弱了番茄对胁迫逆境的抵抗能力,幼苗生长变弱,表明Ca2+-CaM信使系统通过影响多胺的含量参与调节干旱胁迫下多胺的代谢过程,对抵抗干旱逆境胁迫有积极作用。两个品种相比较,‘毛粉802’在PEG胁迫下可以积累更多的亚精胺(Spd)和精胺(Spm),受W7的影响小于‘皇冠’,表现出较强的耐旱性。     

外源水杨酸对盐胁迫下棉花幼苗激素含量及生长特性的影响

以中棉所4l号和中棉所49号为试验材料,通过盆栽试验,研究外源水杨酸(SA)对盐胁迫下棉花幼苗激素水平和生长特性的影响。结果表明:(1)0.6%Na Cl胁迫条件下,棉花幼苗叶片中ABA含量增加,CTK、GA和IAA含量减少,在0.05 mmol·L~(-1)SA浸种+0.2 mmol·L~(-1)叶面喷施复合处理下,中棉所41号和中棉所49号幼苗中ABA含量分别降低了59.14%和76.71%,CTK、GA、IAA含量分别提高了55.39%、21.05%、22.39%和17.08%、12.5%、18.20%,说明SA处理可有效缓解盐胁迫的伤害;(2)ABA/IAA+GA、CTK/IAA和ABA/CTK值在0.6%Na Cl胁迫处理下分别为增高、降低和增高,0.05 mmol·L~(-1)SA浸种+0.2 mmol·L~(-1)叶面喷施复合处理下,中棉所41号和中棉所49号幼苗中ABA/IAA+GA和ABA/CTK值分别降低了63.40%、74.03%和71.66%、79.99%,CTK/IAA值分别增加了28.41%和21.18%,说明SA可使幼苗体内激素恢复动态平衡,促进幼苗的生长发育;(3)0.6%Na Cl胁迫处理下棉花幼苗的株高、根鲜重、茎鲜重和叶鲜重都表现为降低,在不同浓度外源SA浸种和喷施处理下都有所恢复,幼苗根表现最为明显,用0.05 mmol·L~(-1)SA浸种+0.2 mmol·L~(-1)叶面喷施处理0.6%Na Cl胁迫下,两品种棉花幼苗单株鲜重分别增加了24.20%和22.39%。SA能通过调控棉花幼苗激素含量从而提高棉花幼苗的耐盐性,其中以0.05 mmol·L~(-1)SA浸种+0.2 mmol·L~(-1)叶面喷施对缓解棉花幼苗盐胁迫的伤害效果明显。     

Pb和NaCl胁迫对黄瓜幼苗生理生化特性的影响

为了揭示Pb和NaCl单一及复合胁迫对黄瓜幼苗的伤害机理,采用砂培法,以不添加Pb和NaCl为对照,研究了不同浓度Pb(0.5和1.5 mmol/L)、NaCl(50和100 mmol/L)及其复合胁迫对黄瓜幼苗生理生化特性的影响。结果表明,随着Pb、NaCl处理浓度升高,黄瓜叶片的叶绿素a、叶绿素b和叶绿素a+b含量均显著下降;相对于对照,各处理黄瓜叶片的相对电导率、丙二醛含量明显上升,且100 mmol/L NaCl胁迫下黄瓜叶片的相对电导率和丙二醛含量均高于1.5 mmol/L Pb胁迫。不同处理下的可溶性糖含量、脯氨酸含量、SOD和POD活性均高于对照,且复合处理下的含量高于单一因子处理。NaCl对黄瓜叶片细胞膜的破坏作用强于Pb,Pb、NaCl复合胁迫的毒性效应强于单一胁迫,表现为协同作用。     

γ-氨基丁酸对盐胁迫下玉米幼苗根系氧化损伤及内源激素的调控

为研究γ-氨基丁酸(GABA)对盐胁迫下玉米幼苗根系氧化损伤和内源激素的影响,初步明确GABA提高根系抗盐能力的生理途径,以玉米品种郑单958为供试材料,设置清水对照(CK)、0.5 mmol/L GABA(G)、150 mmol/L NaCl胁迫(N)和150 mmol/L NaCl胁迫下0.5 mmol/L GABA处理(NG) 4个处理进行水培试验,测定了玉米幼苗的根系形态指标、干物质质量、根系活力、内源GABA含量、渗透调节物质含量、抗氧化酶活性以及丙二醛(MDA)、超氧阴离子(·O_2~-)和内源激素含量。结果表明:盐胁迫下,外源GABA能显著增加玉米幼苗根长、根表面积、根体积、根尖数及根系干物质质量,根系平均直径下降了9.32%;根系内源GABA含量、根系活力和可溶性蛋白含量显著升高,根系电导率明显下降;外源GABA能显著提高根系内超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,但MDA和的积累减少;根系内源激素会受到外源GABA的影响,表现为生长素(IAA)、赤霉素(GA3)和玉米素核苷(ZR)含量升高,脱落酸(ABA)含量降低,同时促进型激素/抑制型激素比值升高。研究表明:外源GABA在盐胁迫下可诱导内源GABA含量升高,以此提高抗氧化酶活性及改变内源激素平衡,从而降低根系的氧化损伤,维持了细胞膜的完整性,提高了根系活力,进而促进了根系对营养物质的吸收和转运,改善了根系的生长状况。     

NaCl 胁迫对甜高粱幼苗保护酶活性等生理特性的影响

采用不同浓度NaCl溶液(100 mmol/L、200 mmol/L)胁迫处理甜高粱幼苗,测定了叶片中叶绿素含量、脯氨酸含量及三种保护酶活性等生理指标。结果表明:100 mmol/L和200 mmol/L处理的甜高粱幼苗质膜相对透性、脯氨酸和丙二醛含量升高;可溶性蛋白和叶绿素含量降低;保护酶系统中叶片超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性均升高,且在100 mmol/L浓度处理下达到最大,而过氧化物酶(POD)活性呈先升高再降低趋势。NaCl胁迫对甜高粱幼苗的一些生理特性产生一定影响。     

干旱-低温交叉逆境下小麦活性氧清除系统的变化与交叉适应的关系

采用人工气候箱砂培的方法研究了干旱、低温交叉逆境下2个小麦品种活性氧清除系统的变化与交叉适应的关系.结果表明,经单一逆境(干旱或低温)处理后超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和还原型谷胱甘肽(GSH)含量降低,过氧化物酶(POD)活性和抗坏血酸(AsA)含量有所升高,但总体表现出活性氧清除系统功能降低,质膜相对透性增大(膜系统受损).经2种逆境交叉处理后,保护酶活性及抗氧化剂含量均明显增高,质膜相对透性降低至接近正常水平.表明小麦幼苗对干旱和低温逆境存在着明显的交叉适应现象,经一种逆境处理后可提高对另一逆境的抗性.外施脱落酸(ABA)处理同样也能明显提高逆境下小麦活性氧清除系统的功能,增强对干旱和低温逆境的抗性.这些现象表明植物对不同逆境的适应存在着某些共同的生理基础,而这些生理基础与ABA有关.     

外源褪黑素和脱落酸对干旱胁迫下猕猴桃幼苗生理特性的影响

以盆栽‘金实1号’猕猴桃幼苗为材料,在干旱条件下进行根灌100μmol·L~(-1)的褪黑素(MT)溶液和叶面喷施25μmol·L~(-1)的脱落酸(ABA)溶液及MT+ABA处理,探究外源MT与ABA对植物干旱胁迫的缓解作用及机理。结果表明:MT处理可使猕猴桃叶片相对含水量、叶片水势和SOD活性较干旱胁迫处理组分别提高9%、39%和134%,同时使丙二醛(MDA)与H_2O_2含量分别降低66%与7%;ABA处理可使叶绿素含量、净光合速率、干物质积累量和POD活性较干旱胁迫处理组分别提高7%、40%、52%和41%,使H_2O_2含量降低13.5%;MT+ABA处理的效果与ABA处理类似,可使净光合速率、干物质积累量与POD活性较干旱胁迫处理组分别增加29%、110%与35.5%,使MDA与H_2O_2含量分别降低44%、6.5%。表明MT利于提高植株的保水能力与抗氧化能力,ABA处理和MT+ABA处理提高了干旱胁迫下猕猴桃幼苗的光合作用,利于在水分限制下干物质的积累。     

不同逆境对玉米幼苗根系活力及硝酸还原酶活性的影响

用等渗的15％PEG－6000、72mmol/L NaCI和72mmol/L NaHCO3溶液分别模拟干旱、盐和盐碱逆境来处理玉米幼苗。实验结果表明，经干旱、盐碱逆境胁迫处理后，玉米幼苗根系还原活力比对照分别提高8．4％、7．45和5．6％，根系硝酸还原酶活性分别比对照提高3．2％、69．7％和290．4％，叶片硝酸还原酶活性分别比对照下降67．7％、63．3％和59．3％。     

干旱胁迫下NaCl对棉花幼苗抗氧化酶活性及水分特征的影响

测定干旱与0、50、100和200 mmol·L-1NaCl组合条件下棉花叶片抗氧化酶活性和丙二醛(MDA)含量的变化,分析土壤盐分对棉花耐旱性的影响。结果表明,单一干旱处理的棉花幼苗SOD、CAT活性和总抗氧化力在处理后的前21d大幅升高随后又快速下降,POD活性则持续升高,而50～200 mmol·L-1NaCl溶液浇灌的盆栽棉花幼苗在干旱期间SOD、POD、CAT活性和总抗氧化力的变幅明显小于单一干旱;同时,单一干旱棉花幼苗叶片MDA含量明显高于前者,说明NaCl溶液浇灌土壤减弱了干旱胁迫对棉花幼苗的伤害程度。另外,盆土用50～200 mmol·L-1NaCl溶液浇灌后显著提高了土壤的保水能力,增加了植株对Na+的吸收和积累,使叶片渗透势比单一干旱降低了17.5%～40.1%,从而有利于维持较高的细胞膨压,缓解干旱胁迫对棉花的不利影响。     

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。     

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。     

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.     

百合地下害虫主要种类调查及生物（源）农药筛选

调查了甘肃省临洮县为害百合的地下害虫种类, 并以主要发生为害种类为供试对象, 采用拌土法测定了几种生物（源）农药对主要害虫的室内毒力和致死中时。调查发现小云斑鳃金龟Polyphylla gracilicornis、棕色鳃金龟Holotrichia titanis为主要发生及为害种类, 不同时间发生种类存在差异, 9月份以小云斑鳃金龟幼虫发生为害为主, 发生量占地下害虫总数的66.16%, 平均种群密度为10.48头/m2, 10月份, 则以棕色鳃金龟幼虫发生为主, 发生量占地下害虫总数的96.86%, 平均种群密度为7.79头/m2, 主要取食百合根系和鳞茎, 造成根系数量减少, 鳞茎出现不规则褐色缺口或凹陷斑。药剂筛选结果表明, 1.8%阿维菌素乳油、200亿孢子/g球孢白僵菌粉剂对两种蛴螬均具有较高的杀虫活性和速效性, 药后7 d时, 校正死亡率在82.22%以上, 对小云斑鳃金龟幼虫和棕色鳃金龟幼虫的LC50分别为0.161、0.060 mg/g和5.558×107、0.362×107孢子/g, LT50分别为2.237 d（2.2 mg/g）、1.393 d（2.2 mg/g）和6.645 d（40.0×107孢子/g）、4.940 d（2.0×107孢子/g）, 这两种生物（源）农药对两种蛴螬的LC50和LT50值均略大于两种化学农药25%二嗪磷乳油、40%辛硫磷乳油处理的, 且对小云斑鳃金龟幼虫的杀虫活性均低于对棕色鳃金龟幼虫的杀虫活性, 致死中时则长于对棕色鳃金龟幼虫的致死中时。     

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 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.     

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.     

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.     

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。