复合菌剂PS21对氧乐果胁迫下小麦幼苗生长及抗氧化酶的影响

采用溶液培养法研究了不同浓度的复合菌剂PS21与氧乐果协同处理对小麦幼苗生长及抗氧化酶的影响, 初步探讨复合菌剂PS21缓解氧乐果对小麦生长和抗氧化酶的抑制效应。研究结果表明, 106～108 cfu/mL浓度的复合菌剂PS21对氧乐果的毒害具有缓解作用, 缓解作用与复合菌剂PS21浓度呈正相关性, 菌液浓度为108 cfu/mL时, 缓解作用明显, 与氧乐果单独处理相比, 小麦株高、茎粗、干重、湿重、叶绿素含量显著增加; 在抗氧化酶系统中随复合菌剂PS21浓度的升高, 幼苗叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性均有不同程度的提高, 丙二醛(MDA)含量下降。同浓度复合菌剂PS21的不同施用方法对氧乐果毒害的缓解作用存在差异, 灌根法对氧乐果毒害小麦具有较强的缓解作用。     

氧乐果和吡虫啉对小麦过氧化物酶、谷胱甘肽还原酶及过氧化氢酶活性的影响

为明确常用杀虫剂对小麦抗氧化性的影响,研究了小麦幼苗期用不同浓度氧乐果和吡虫啉的营养液处理后144 h内对其过氧化物酶(POD)、谷胱甘肽还原酶(GR)及过氧化氢酶(CAT)活性的影响。结果表明:用400、800和1 600 mg/L的氧乐果处理小麦幼苗后24 h,POD活性均显著降低;1 600 mg/L的氧乐果处理后6 h,其CAT活性比对照降低了32.9%;各浓度氧乐果处理后144 h,GR活性均显著降低。而用25、50和100 mg/L的吡虫啉处理小麦幼苗后144 h内,只有50 mg/L处理组在12 h时的POD活性比对照升高了65.0%。杀虫剂对小麦幼苗中3种抗氧化酶活性的影响不仅与药剂种类有关,还具有一定的剂量效应与时间效应。     

土壤水分和氮素对春小麦叶片抗氧化系统的影响

植物的抗逆性与其清除活性氧(ROS)的能力相关,提高抗氧化代谢水平是增强植物胁迫耐性的有效途径.以抗旱性不同的3个品种为材料,研究土壤水分和氮素水平及其耦合效应对春小麦叶片抗氧化系统的影响,以探讨水、氮对春小麦抗氧化系统的影响规律及抗氧化系统与抗旱性间的关系.结果表明:干旱胁迫使春小麦叶片丙二醛(MDA)含量升高,膜质...     

药液浓度、雾滴密度与氧乐果防治麦蚜的关系研究

氧乐果药液浓度、雾滴密度与小麦蚜虫防治效果关系紧密,室内定量喷雾试验表明:雾滴体积中径(VMD)为85μm,氧乐果药液浓度 1.0、1.5、2 .0、3.0 g·L-1条件下 ,蚜虫致死90%时雾滴覆盖密度LN90分别为336.1、237.6、2 0 8.8和115.3cm-2;氧乐果雾滴覆盖密度为26、50、102cm-2条件下,蚜虫致死90%药液浓度LC90分别为29.5、7.2和 4.0g· L-1。田间采用泰山-18BC机动喷雾机水平顺风喷雾,雾滴中径(VMD)为173μm,施药液量75L·hm-2和150L·hm-2条件下,麦穗上平均雾滴沉积密度分别为132cm-2和280cm-2;药液浓度分别为1.2、1.6、2.0和2.4、3.2、4 .0 g·L-1时,对麦蚜的防治效果差异不明显。生产中用泰山-18BC机动喷雾机防治麦蚜时,建议采用75L·hm-2施药液量和2.4g·L-1氧乐果药液。     

麦田草地贪夜蛾农药防治技术研究

草地贪夜蛾可为害苗期至灌浆期的小麦, 但国内目前尚未进行麦田农药防治的研究工作。我们利用农业农村部推荐的草地贪夜蛾防控药剂在云南完成了对拔节期麦田草地贪夜蛾的防治试验, 结果表明, 不同类型农药7 d后的防治效果有显著差别。25%乙基多杀菌素WG、200 g/L氯虫苯甲酰胺SC、5%多杀霉素SC、5%甲维盐ME、10%虫螨腈SC、50 g/L虱螨脲EC、150 g/L茚虫威及10%高效氯氟氰菊酯EC防效为70.4%~97.2%, 拟除虫菊酯类杀虫剂10%高效氯氰菊酯EC和有机磷杀虫剂40%氧乐果EC的防效分别为49.8%和46.8%。生物农药32 000 IU/mg苏云金杆菌WP防效为65.1%, 100亿孢子/mL短稳杆菌SC、300亿孢子/g球孢白僵菌WP和10亿PIB/L斜纹夜蛾核型多角体病毒SC的防效为35.3%~41.9%。因此, 麦田草地贪夜蛾种群高密度下建议使用乙基多杀菌素、氯虫苯甲酰胺等化学农药防治, 低密度下可选择苏云金杆菌、短稳杆菌等生物农药, 研究结果为麦类作物草地贪夜蛾的应急防控提供了依据。     

Synergistic and antagonistic effects of atrazine on the toxicity of organophosphorodithioate and organophosphorothioate insecticides to Chironomus tentans (Diptera: Chironomidae)

The acute toxicities of two organophosphorodithioate (dimethoate and disulfoton) and two organophosphorothioate (omethoate and demeton-S-methyl) insecticides were evaluated individually and in binary combination with the herbicide atrazine using fourth-instar larvae of the aquatic midge, Chironomus tentans. Atrazine alone up to 1000 μg/L did not show significant toxicity to the midges in a 48-h bioassay. However, atrazine concentrations as low as 1 μg/L in combination with dimethoate at EC₂₅ (concentration to affect 25% of tested midges), 100 μg/L in combination with disulfoton (EC₂₅), and 10 μg/L in combination with demeton-S-methyl (EC₂₅) significantly enhanced the toxicity of each organophosphate insecticide. In contrast, atrazine concentrations of 10 μg/L and above in combination with omethoate (EC₂₅) significantly decreased the toxicity of the insecticide. Biochemical analysis indicated that increased toxicity of dimethoate, disulfoton, and demeton-S-methyl in binary combination with atrazine correlated to the increased inhibition of acetylcholinesterase. Furthermore, cytochrome P450-dependent O-deethylation activity in the midges exposed to atrazine at 1000 μg/L was 1.5-fold higher than that in the control midges. Thus, atrazine appeared to induce cytochrome P450 monooxygenases in the midges. Elevated cytochrome P450 monooxygenase activity may increase the toxicities of dimethoate, disulfoton, and demeton-S-methyl by enhancing the oxidative activation of dimethoate into omethoate, and disulfoton and demeton-S-methyl into their sulfoxide analogs with increased anticholinesterase activity. In contrast, atrazine reduced the toxicity of omethoate possibly by enhancing the oxidative metabolic detoxification since omethoate does not require oxidative activation.     

蜡质芽孢杆菌AR156对辣椒的防病促生机理研究

 蜡质芽孢杆菌AR156是南京农业大学与新沂中凯农用化工有限公司合作开发的生物农药。为了解AR156对辣椒的防病促生机制, 本文研究了AR156在温室条件下对青枯劳尔氏菌引起的辣椒青枯病的生防效果, 对辣椒的促生作用, 在辣椒根围的定殖能力, 诱导植物细胞防卫反应, 如活性氧积累和胼胝质沉积, 以及植物防御相关酶的活力。结果表明, 蜡质芽孢杆菌AR156对辣椒青枯病的温室防效高达73.31%。AR156的使用使辣椒植株干重增加 22.30%, 并能稳定的在辣椒根围定殖, 接种60 d后, 其定殖量为5×10⁵ cfu·g^-1FW。AR156预处理后挑战接种病原菌能诱导植株更迅速的产生细胞防卫反应, 并可显著提高超氧化物歧化酶(SOD)和过氧化物酶(POD)的活力。可见AR156菌株诱导的植物细胞防卫反应, 提高植物防御相关酶活和在辣椒根围稳定的定殖能力使其产生对病害的广谱抗性。研究还发现 AR156菌剂可增加辣椒叶片叶绿素的含量, 这可能是该菌剂促进辣椒生长的原因之一。     

三种杀虫剂对麦田蚜虫和捕食性天敌群落的影响

以2种选择性杀虫剂吡虫啉、抗蚜威和一种广谱性杀虫剂氧化乐果为试验材料，研究了选择性杀虫剂对麦田蚜虫和捕食性天敌群落结构特征的影响。结果表明，施用选择性杀虫剂的小区在农药持效期内麦蚜群落的多样性指数和均匀度低于空白对照区，高于氧化乐果处理区，而优势度和优势集中度高于空白对照区，低于氧化乐果处理区；捕食性天敌群落的多样性指数低于空白对照区，高于氧化乐果处理区，优势度和优势集中度高于空白对照区，低于氧化乐果处理区。选择性杀虫剂处理区瓢蚜比小于空白对照区和氧化乐果处理区，且有效期长达15－16d。根据害虫和天敌发生的特点及选择性杀虫剂的特性，提出了麦蚜的有效防治措施，即在麦蚜为害关键时期，每667m^2用吡虫啉1g(ai)或抗蚜威2.5g(ai)喷施1次，再利用自然天敌调控作用，即可有效控制麦蚜。     

茉莉酸诱导对枸杞叶生化物质及酶活性的影响

茉莉酸是植物的重要信号抗逆物质,当植物受到刺激时,起到激素和信号传递作用。本文研究了茉莉酸处理引起枸杞叶黄酮、单宁酸、蛋白质、可溶性糖、PPO和POD含量的变化及其时间效应。结果发现,茉莉酸处理使枸杞黄酮和单宁酸含量显著增加;蛋白质和可溶性糖含量显著降低;PPO和POD活性显著增加。0.1mmol/LJA处理使枸杞黄酮和单宁酸含量增加最显著,均在处理后第5天增幅最大。0.001mmol/LJA处理使枸杞蛋白质含量降低最显著,处理后第7天降幅最大。0.1mmol/LJA处理使枸杞可溶性糖含量降低最显著,处理后第1天降幅最大。0.1mmol/LJA处理使枸杞PPO活性增加最显著,处理后第3天增幅最大。0.01mmol/LJA处理使枸杞POD活性增加最显著,处理后第7天增幅最大。     

Effects of trichlorfon and sodium dodecyl sulphate on antioxidant defense system and acetylcholinesterase of Tilapia nilotica in vitro

The effects of organophosphorus insecticide trichlorfon, surfactant sodium dodecyl sulphate (SDS), and the mixture of trichlorfon and SDS on the antioxidant defense system and acetylcholinesterase (AChE) in Tilapia nilotica were assessed in vitro. Various concentrations of trichlorfon (0, 0.0001, 0.001, 0.01, 0.1 and 1 g/L) and SDS (0, 0.0625, 0.125, 0.25, 0.5, 1 g/L) were incubated with homogenate of liver and muscle, respectively, at 25 °C for 0, 30, 60 and 90 min. Two concentrations of mixture of trichlorfon and SDS (0.0001 g/L trichlorfon + 0.5 g/L SDS, 0.1 g/L trichlorfon + 0.5 g/L SDS) and 0.0001 g/L trichlorfon, 0.1 g/L trichlorfon, 0.5 g/L SDS and control, were incubated simultaneously with homogenate of liver and muscle, respectively, at 25 °C for 60 min. After incubation, the content of reduced-glutathione (GSH) and the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) in homogenate of liver were determined, and the activities of AChE in homogenate of muscle were also measured.Treatment with trichlorfon caused a significant concentration-dependent and time-related inhibition of AChE activity at all treatment concentrations and times since trichlorfon is a cholinesterase inhibitor. For the same trichlorfon treatment, an apparent decrease in GSH content was found in concentration of 0.01, 0.1, 1 g/L, whereas no significant alteration in antioxidant enzyme activity were found at all experiment concentrations and times, which might indicate that antioxidant enzymes have not involved in the metabolism of trichlorfon. The depletion of GSH might indicate that ROS could be involved in the toxic effects of trichlorfon. Exposure of SDS can inhibit activities of AChE, GST and CAT at concentrations of 0.5 and/or 1 g/L, which could be due to the denaturing process of SDS to the enzymes. For the mixture exposure of trichlorfon and SDS, the effect of the mixture of 0.0001 g/L trichlorfon and 0.5 g/L SDS on inhibition of AChE shows synergistic other than simple additive of trichlorfon and SDS. The combined effects of chemicals and detergents deserve to be particularly noted. It should be noted that the toxicity experiments were made in tissue homogenates instead of whole organisms. The responses against the toxic compounds will not be the same in both systems.     

Weed communities of winter wheat as influenced by input level and rotation

The influence of cropping systems constituted by the combination of three input levels (low, intermediate and high) and four 2-year rotations between a spring summer crop and winter wheat ( Triticum aestivum L.) on the density and composition of the winter wheat weed flora was evaluated from 1989 to 1992. Spring summer crops were maize ( Zea mays L.). soyabean ( Glycine max (L.) Merr.). sugar beet ( Beta vulgaris L.) and sunflower ( Helianthus and L.) Total weed density at the end of the wheat tillering stage ranged from 2.5 to 128.7 plants m^-2 and generally decreased with cropping intensity, although to a differing extent, depending upon rotation. Differences among weed communities of the 12 cropping systems were mostly dependent upon input level. The effect of the preceding crop on the weed flora composition of winter wheat was evident only with reduced herbicide use (low-input systems). Weed species could be ascribed to four categories: (a) species sporadically associated with cropping systems (most of the weeds); (b) species associated with a specific input level (e.g. Papaver rhoeas L. to low and intermediate input levels and Veronica persica Poiret to the high input ievel): (c) species associated with a specific rotation (e.g. Anm majus L. to sugar beet winter wheat): and (d) species associated with specitie plots that become important every other year (e.g. Convolvulus arvensis L. and Stellaria media (L.) Vill.).     

Peanut priming induced by biocontrol agents

Selected strains of rhizobacteria induce systemic resistance in plant (ISR), enhancing the capacity to mobilize infection-induced cellular defense responses (priming). Bacillus sp. CHEP5 and Pseudomonas sp BREN6 strains reduced root and stem wilt disease severity caused by Sclerotium rolfsii in Arachis hypogaea L. Strains inoculation increased the activity of phenylalanine ammonia-lyase and peroxidase, after pathogen-challenge, indicating priming. CHEP5 primes plants to produce more ethylene upon stimulation with ACC. A. hypogaea L is an ISR-positive plant and BREN6 and CHEP5 strains enhance the plant’s defense capacity by priming for potentiated activity of defense proteins and ACC-converting capacity.     

精噁唑禾草灵、甲基二磺隆、扑草净处理后日本看麦娘残存植株的生长和结实能力

以采自江苏省扬州市小麦田的3个日本看麦娘种群(AJ191、AJ193、AJ195)为例,研究了供试种群对精噁唑禾草灵、甲基二磺隆、扑草净3种不同作用机理的代表性麦田除草剂的敏感性及药剂处理后残存植株的生长和结实能力.结果 表明,在推荐剂量处理下,精噁唑禾草灵对3个种群的控制效果均不理想,扑草净对3个种群均有高活性,甲基...     

牡丹叶及其不同溶剂提取物对生菜等幼苗生长的抑制效应

为了进一步明确牡丹叶及其不同溶剂提取物的化感活性大小,于室内采用琼脂混粉法测定了牡丹叶粉末在不同浓度下对生菜、小麦、黄瓜、稗、夏至草、播娘蒿和独行菜等7种受体植物幼苗生长的影响.结果表明,虽然在低浓度下牡丹叶粉末对各受体植物幼苗生长的影响差异较大,但在高浓度时均表现出了较高的抑制作用,且对胚根(或种子根)的抑制效果明显高于对胚轴或胚芽鞘的抑制.计算对各受体植物胚根或种子根、胚轴或胚芽鞘的有效中浓度(EC50),生菜为0.93～5.25 g/L、小麦为1.20 ～4.65 g/L)、黄瓜为3.58～＞10.0 g/L、稗为0.64～3.36 g/L、夏至草为1.09～5.27 g/L、播娘蒿为1.02 ～9.65 g/L、独行菜为0.79 ～6.84 g/L,以稗的敏感性最高,黄瓜最低.继而探索了牡丹叶乙醇、甲醇和蒸馏水3种溶剂提取物对生菜幼苗生长的抑制效果,发现乙醇提取物的活性最高,提取浓度以80％ (V/V)为宜.     

冠菌素对玉米苗期植株形态建成的调控效应

以玉米品种金海5号为材料,采用不同浓度植物生长调节剂冠菌素(COR)拌种和三叶期(V3)叶面喷施的方法,研究了COR对玉米苗期植株地上部和根系形态建成的影响,分析了其对叶面积、叶绿素含量和可溶性蛋白的调控效应。结果表明:不同浓度冠菌素对玉米幼苗形态建成的调控呈单峰曲线,即低浓度下促进幼苗生长,高浓度下抑制生长。用0.1 mg/L的COR拌种或叶面喷施处理,可促进玉米苗期植株株高和茎粗生长,增加单株叶面积,提高叶片叶绿素和可溶性蛋白含量,促进植株干物质积累。同时,COR可促进玉米苗期根系生长,增加根长和根表面积,进而可有效增加根系吸收能力。研究结果表明,适宜浓度的COR处理可以提高玉米幼苗光合性能,增强根系吸收能力,促进植株地上部和地下部的生长,有利于培育壮苗。     

非致死浓度农药对智利植绥螨繁殖和定居的影响

用6种农药的非致死浓度(LC_(n-13)),在实验室内处理菜豆叶的结果说明,对智利螨的繁殖有显著的影响。三氯杀螨醇(84ppm)、氧化乐果(1ppm)、速灭杀丁(0.2ppm)、氯氰菊酯(0.1ppm)、溴氰菊酯(0.025ppm)和灭扫利(0.026ppm)使智利螨的产卵量比对照分别减少35.3％,41.2％、20.8％,65.1％、49.4％和74.7％。用上述农药在温室处理菜豆植株的结果说明,当对照植株上的智利螨定居率为96.7％时,上述农药处理植株上的智利螨定居率依次为48.4％、50.0％、25.0％、11.7％,3.3％和6.7％。菊酯类农药对智利螨定居率的影响明显大于氧化乐果和三氯杀螨醇。植株上残留的微量农药不仅能影响智利螨繁殖能力,而且严重影响其定居率,在螨类的综防工作中值得引起重视。     

Defence responses in flag leaves and spikes of common wheat Triticum aestivum cultivars with contrasting levels of basal resistance to blast caused by Pyricularia oryzae

Wheat blast, caused by Pyricularia oryzae, can cause large yield losses in crops. This study aimed to investigate defence responses in flag leaves and spikes of wheat cultivars BR-18 (moderately resistant) and BRS-Guamirim (susceptible), which differ in their levels of basal resistance. In contrast to cultivar BRS-Guamirim, infected plants of cultivar BR-18 showed more pronounced increases in activities of β-1,3-glucanase and chitinase as well as higher concentrations of lignin-thioglycolic acid derivatives in the flag leaves and total soluble phenolics in the spikes. Polyphenoloxidase activity increased in both flag leaves and spikes in response to fungal infection, regardless of cultivar. Phenylalanine ammonia-lyase (PAL) activity increased in infected flag leaves of both cultivars, especially in BR-18. PAL activity was lower in spikes of infected compared to noninfected plants of both cultivars, although to a lesser extent in BR-18. Compared to BRS-Guamirim, the antioxidative system in both flag leaves and spikes of BR-18 was more efficient in removing reactive oxygen species, reducing cellular damage caused by fungal infection. The lower catalase and peroxidase activities, associated with high superoxide dismutase activity, in flag leaves and spikes of infected BR-18 culminated in a high hydrogen peroxide concentration. The increase in ascorbate peroxidase activity was higher in both flag leaves and spikes of infected plants of BR-18 than in infected BRS-Guamirim. It was concluded that wheat resistance to blast depended on the basal level of resistance of the cultivar, which was mainly associated with the activities of defence enzymes and a more effective antioxidative system.     

1-(1-苯基-1,2,4-三氮唑-3-氧代乙酰氧基)烃基膦酸酯的合成与植物生长调节活性

合成了一系列新的1-(1-苯基-1, 2, 4-三氮唑-3-氧代乙酰氧基) 烃基膦酸酯, 并测定了它们对小麦和黄瓜的植物生长调节活性。结果表明, 在100 Lg/g 时, 所有化合物对小麦芽鞘的生长具有抑制作用, 而在10 Lg/g时化合物6a、6g 对黄瓜显示了较高的促生长活性。     

Phytotoxicity of Roundup Ultra 360 SL in aquatic ecosystems: Biochemical evaluation with duckweed (Lemna minor L.) as a model plant

Glyphosate-based herbicides (e.g. Roundup Ultra 360 SL) are extensively used in aquatic environment. Although glyphosate is more environmental favorable than many other herbicides, it may be exceptionally dangerous for aquatic ecosystems through high water solubility. Thus, the aim of the work was quantification of influence of Roundup Ultra 360 SL (containing isopropylamine salt of glyphosate as an active ingredient) on biomass and chlorophyll content within duckweed (Lemna minor L.). Moreover, changes in polyamine content and activity of such antioxidative enzymes as catalase (CAT) and ascorbate peroxidase (APX) were assayed in order to determine the biochemical mechanisms of L. minor response to the herbicide treatment. Obtained results showed that phytotoxicity of the herbicide was connected with decrease in chlorophyll-a, b and a+b content, and reduction of biomass growth. Roundup, similarly to some abiotic and biotic stressors, caused over-accumulation of putrescine, spermidine and total polyamines (PAs) within duckweed tissues. In addition an increase in CAT and APX activities suggested that stress generated by the herbicide treatment was at least partially connected with oxidative burst. Intensity of the duckweed responses to the herbicide was dependent on the applied herbicide level and/or duration of treatment.     

The allelopathic effect of three Amaranthus spp. (pigweeds) on wheat (Triticum durum)

The allelopathic effect of Amaranthus retroflexus L., Amaranthus blitoides S. Wats, and Amaranthus gracilis Desf. on wheat Triticum durum L. was investigated under laboratory, glasshouse and field conditions. Laboratory experiments showed that fresh shoot or root extract of the three weed species reduced germination, coleoptile length, root length and root dry weight of wheat seedlings. The inhibitory effects were rate dependent, with low concentrations of shoot extract promoting shoot growth of wheat. Fresh plant extracts were more phytotoxic than dried plant extracts and shoot extracts had higher detrimental effects than root extracts. In pot experiments, dried shoot extract of A. gracilis increased shoot and root dry weights of wheat seedlings. For A retroflexus and A. blitoides the extracts of these and dried shoots (8 g kg^?1), which had been added to soil mixtures significantly reduced ger-mination and growth of wheat seedlings. Addition of up to 16 g kg^?1 of A. gracilis residues promoted shoot growth of wheat and had no significant harmful effect on root growth. Roots appeared more sensitive to allelopathic effect than shoots. Under field conditions, incorporation of A. retroflexus or A. blitoides residues in the soil reduced height, grain and straw yield of wheat, whereas A. gracilis residues stimulated plant height and increased yield.