除草剂对盾壳霉菌丝生长的影响研究

[目的]在实验室条件下,研究三峡库区常用油菜除草剂对盾壳霉菌丝生长影响,筛选出对盾壳霉菌丝生长没有拮抗作用的除草剂。[方法]采用9种除草剂,每种除草剂设置6个浓度梯度,3个重复,对盾壳霉菌丝进行室内毒力测定。[结果]室内毒力测定结果表明:在正常使用浓度(1MRAR)下,9种除草剂对盾壳霉均有强烈的抑制作用,但没有杀灭作用,大多数除草剂稀释至正常使用浓度的1/8时,对盾壳霉菌丝影响较小,同类的除草剂(不同厂家)对盾壳霉菌丝生长抑制情况相接近。在所有除草剂中,乙草胺对盾壳霉菌丝生长抑制率和毒力最弱。[结论]乙草胺对盾壳霉菌丝生长影响最小,推荐乙草胺与盾壳霉混合施用。     

广西不同地区小菜蛾对杀虫剂的敏感性研究

采用浸叶法在室内测定了广西5个菜区的小菜蛾种群对13种杀虫剂的敏感性.结果表明,这5个小菜蛾种群对印楝素和氟虫腈的敏感性最高,LC50值在0.08～0.26 mg/L之间;对苏云金杆菌、多杀菌素、溴虫腈、阿维菌素和定虫隆也具有较高的敏感性,LC50值在0.30～16.39 mg/L之间;而对辛硫磷、杀虫双、毒死蜱和敌敌畏的敏感性较低,LC50值在319.74～8 133.98 mg/L之间;对灭多威和杀螟丹的敏感性极低,已无法建立这两种杀虫剂对南宁安吉和石埠种群的毒力回归方程.不同地区小菜蛾种群对苏云金杆菌和毒死蜱的敏感性差异最大,超过6倍;其次为灭多威、杀虫双和定虫隆,种群敏感性差异达4～6倍;而不同种群对辛硫磷和溴虫腈的敏感性几乎没有差异.     

丁草胺和苄嘧磺隆对钝顶螺旋藻的毒性效应研究

采用实验室摇瓶实验法研究了除草剂丁草胺和苄嘧磺隆对钝顶螺旋藻的毒性效应。结果表明,丁草胺浓度与藻生长（以OD560计）存在明显的剂量-效应关系,64mg·L^-1丁草胺严重抑制藻生长,比生长速率为0.111d-1,仅为对照的24%。在7d实验时间内EC50值随染毒时间延长呈指数下降,96h的EC50值为45.4mg·L^-1,到第7d降为15.2mg·L^-1。与丁草胺相似,在实验浓度范围内随浓度增加,苄嘧磺隆对钝顶螺旋藻的生长抑制作用逐渐增强,最高浓度44.8mg·L^-1处理的比生长速率为0.458d-1,约为对照的82%。在8d实验时间内EC50值随染毒时间延长呈指数增长,96h的EC50值为51.3mg·L^-1,到第8d达到215mg·L^-1。两种除草剂在较高浓度条件下均使钝顶螺旋藻藻丝变短,部分藻丝由螺旋型变为直线型,随浓度增加直线型藻丝逐渐增加,到最高浓度几乎全部变为直线型,且藻细胞颜色变浅。依据96h-EC50值判断丁草胺对钝顶螺旋藻的毒性大于苄嘧磺隆,二者毒性强度均为中等,但随着染毒时间延长丁草胺的毒性作用增强而苄嘧磺隆的毒性逐渐降低。同时,高浓度的两种除草剂使部分藻丝断裂变短,且诱导藻丝形态由螺旋型向直线型转变。     

11种杀菌剂对梨树黑斑病菌的室内毒力测定

为筛选出防治梨黑斑病的高效低毒杀菌剂,采用菌丝生长速率法测定了 11种杀菌剂对梨树黑斑病菌的毒力。结果表明:40%氟硅唑乳油对梨树黑斑病菌丝的毒力最强,EC50 值最低,为0.401 6 μg/mL;其次是10%苯醚甲环唑乳油、20%丙环唑乳油、25%戊唑醇乳油,EC50 值分别为1.478 0、2.018 5、4.101 0 μg/mL;1.5%噻霉酮乳油和75%百菌清可湿性粉对菌丝的抑制效果相对较差,EC50较高,分别为886.52、759.468 μg/mL。11种杀菌剂对梨树黑斑病菌菌丝生长均有抑制作用。     

三种植物生长调节剂对大豆生长发育及产量的影响

为提高单作大豆产量,本研究以大豆品种南豆12为材料,分别探究了不同浓度的3种植物生长调节剂拌种对大豆田间出苗的影响,及叶面喷施对大豆生长发育、产量及品质的影响。结果表明,不同浓度的褐藻胶寡糖、壳寡糖、冠菌素拌种均能提高大豆的田间出苗率,而叶面喷施均能提高大豆的株高与茎粗,褐藻胶寡糖和冠菌素拌种可增加大豆分枝数,壳寡糖拌种则减少了大豆分枝数。3种植物生长调节剂均能在一定程度上提高单株粒数与百粒重,进而提高大豆产量,同时还可提高大豆粗蛋白含量,降低粗脂肪酸含量以及满粒期大豆籽粒中可溶性糖与还原性糖的含量。此外,叶面喷施植物生长调节剂并不会影响收获子代大豆的萌发。褐藻胶寡糖、壳寡糖、冠菌素拌种推荐每公斤大豆使用100 mL植物生长水溶液拌种,浓度分别为25、100、0.05 mg·L^-1;叶面喷施的推荐使用量分别为50、50、0.01 g·hm^-2。 本研究结果为大豆丰产栽培提供了理论依据。     

蛇床子素对6种植物病原真菌的毒力测定

采用生长速率法,在离体条件下测定了蛇床子素对6种植物病原真菌的室内抑制效果。结果表明,蛇床子素对供试6种植物病原真菌均有不同程度的抑制作用,其中对向日葵菌核病病菌的毒力最强,其EC50值为3.628 μg/mL,相关系数为0.942 9;对西瓜蔓枯病病菌的毒力次之,其EC50值是3.940 μg/mL,相关系数为0.992 5;对葡萄灰霉病病菌的的毒力居第3位,其EC50值为4.153 μg/mL,相关系数为0.988 8;对葡萄炭疽病、棉花枯萎病病菌的毒力也较强,其EC50值分别为5.569、4.996 μg/mL,相关系数分别为0.937 7、0.962 1;对玉米茎基腐病病菌的毒力最弱,EC50值为11.371 μg/mL。     

杀虫剂对甘蓝蚜与七星瓢虫的毒力及选择性研究

试验研究杀虫剂对甘蓝蚜及其天敌七星瓢虫幼虫的毒力及选择性结果表明,15种供试杀虫剂中以吡虫啉对七星瓢虫幼虫和甘蓝蚜的选择性最高,其选择性毒力比值(瓢虫LD50/甘蓝蚜LD50)为174.29。5种有机磷类杀虫剂中以马拉硫磷的选择性最高,其次为敌敌畏,其选择性毒力比值分别为35.73和25.32;7种菊酯类杀虫剂中以氟氯氰菊酯和氯氰菊酯的选择性最高,其选择性毒力比值分别为55.16和30.00。故吡虫啉、氟氯氰菊酯和马拉硫磷等选择性较高的杀虫剂对甘蓝蚜相对毒力高,而对其天敌瓢虫相对安全,为防治菜田甘蓝蚜的理想品种。     

哈茨木霉对几种常见蔬菜病害防治效果探究

哈茨木霉是一种重要的蔬菜病害生防真菌,其对蔬菜病害致病菌具有拮抗作用,可以抑制病原菌的生长。基于此,通过离体抑菌实验探究哈茨木霉对黑斑病、灰霉病、细菌性软腐病3种常见蔬菜病害的生防效果。通过生长抑制率及有效中浓度(EC50)的测定发现:哈茨木霉制剂对灰霉病、黑斑病致病菌抑制效果显著,在高浓度下生长抑制率分别为95.38%和88.62%,对灰霉病的EC50为3.28 g·L-1,对黑斑病的EC50为10.03 g·L-1,但其对细菌性软腐病抑制效果不明显,最高生长抑制率仅为45.39%,EC50为596.07 g·L-1。     

四种杀虫剂对十字花科蔬菜蚜虫的田间药效试验

为了筛选出对十字花科蔬菜蚜虫防治效果好的杀虫剂,通过田间药效试验研究了4种杀虫剂的药效。结果表明:3%啶虫脒EC、7.5%鱼藤酮EC、70%吡虫啉WG和5%苦豆子生物碱SL对十字花科蔬菜蚜虫有好的防治效果,且持效性好。     

天水地区苹果腐烂病病菌对3种杀菌剂的敏感性测定

采用菌丝生长速率法测定了采自天水地区的8个苹果腐烂病菌株对杀菌剂戊唑醇、噻霉酮及吡唑醚菌酯的敏感性。结果表明:戊唑醇对供试8株苹果腐烂病病菌菌丝生长的抑制效果最为明显, EC50值均小于1.0 μg/mL,平均为0.03 917 μg/mL;其次为吡唑醚菌酯,EC50值为0.362 9～1.0262 6 μg/mL,平均为0.609 4 μg/mL;噻霉酮的抑制率较低, EC50值平均为20.226 39 μg/mL。     

杀虫剂对苹果黄蚜与七星瓢虫的毒力及选择性研究

采用FAO推荐的点滴法,测定了15种常用杀虫剂对苹果黄蚜及其天敌七星瓢虫幼虫的毒力,比较了药剂在二者之间的毒力选择性。结果表明,供试杀虫剂中以吡虫啉对七星瓢虫幼虫和苹果黄蚜的选择性最高,其选择性比值(七里瓢虫LD50/苹果黄蚜LD50)为135．56,其次为氟氯氰菊酯、氯氰菊酯和马拉硫磷,其选择性比值分别为114．00、62．86和45．43。吡虫啉、氟氯氰菊酯、氯氰菊酯和马拉硫磷等选择性高的杀虫剂对苹果黄蚜相对毒力高,而对其天敌七星瓢虫相对安全,在协调苹果黄蚜的化学防治与生物防治策略中应选用对害虫毒力高,而对天敌相对安全的杀虫剂。     

Fast extraction and dilution flow injection mass spectrometry method for quantitative chemical residue screening in food

A prototype multiresidue method based on fast extraction and dilution of samples followed by flow injection mass spectrometric analysis is proposed here for high-throughput chemical screening in complex matrices. The method was tested for sulfonylurea herbicides (triflusulfuron methyl, azimsulfuron, chlorimuron ethyl, sulfometuron methyl, chlorsulfuron, and flupyrsulfuron methyl), carbamate insecticides (oxamyl and methomyl), pyrimidine carboxylic acid herbicides (aminocyclopyrachlor and aminocyclopyrachlor methyl), and anthranilic diamide insecticides (chlorantraniliprole and cyantraniliprole). Lemon and pecan were used as representative high-water and low-water content matrices, respectively, and a sample extraction procedure was designed for each commodity type. Matrix-matched external standards were used for calibration, yielding linear responses with correlation coefficients (r) consistently >0.99. The limits of detection (LOD) were estimated to be between 0.01 and 0.03 mg/kg for all analytes, allowing execution of recovery tests with samples fortified at ≥0.05 mg/kg. Average analyte recoveries obtained during method validation for lemon and pecan ranged from 75 to 118% with standard deviations between 3 and 21%. Representative food processed fractions were also tested, that is, soybean oil and corn meal, yielding individual analyte average recoveries ranging from 62 to 114% with standard deviations between 4 and 18%. An intralaboratory blind test was also performed; the method excelled with 0 false positives and 0 false negatives in 240 residue measurements (20 samples × 12 analytes). The daily throughput of the fast extraction and dilution (FED) procedure is estimated at 72 samples/chemist, whereas the flow injection mass spectrometry (FI-MS) throughput could be as high as 4.3 sample injections/min, making very efficient use of mass spectrometers with negligible instrumental analysis time compared to the sample homogenization, preparation, and data processing steps.     

Rhizobia in tropical legumes—XI. survival in the seed environment

Factors affecting rhizobia in the seed environment of the legumes Cajanus cajan, Centrosema pubescens, Glycine max, and Psophocarpus tetragonolobus were investigated. These included the effects of fungicides, insecticides, and herbicides on the survival and growth of rhizobia on agar and in liquid cultures. The pesticides used varied in their toxicity towards rhizobia but many fungicides and insecticides could be used in the vicinity of inoculated seeds. Certain fungicides and insecticides were shown to have little or no effect on the Rhizobium-legume symbiosis of C. cajan, C. pubescens, G. max, and P. tetragonolobus when added directly to inoculated seed. Various protective pelleting procedures were investigated including preparation of coating materials containing rock phosphates from different localities, talc, and bonemeal. These were applied to the seed in mixtures suspended in aqueous solutions of substituted celluloses, or gum arabic. Talc and Christmas Island rock phosphate both proved satisfactory, while “Cellofas” is recommended as the adhesive in this formulation. Soaking seeds before pelleting in an effort to remove anti-rhizobial substances from G. max seeds was beneficial in the case of soyabean cultivar KS437, but harmful when applied to Palmetto seeds.     

Assessment of pesticide effects on non-target soil microorganisms

Agricultural pesticides should be free of side effects that may cause a lasting disruption of microbial processes that are essential for continued soil fertility. A test program is described here for the assessment of the potential effects of newly-developed pesticides on non-target soil micro-organisms. The pesticides to be tested are applied at the equivalent of their recommended field application concentration and, for a margin of safety, also at the tenfold thereof. The measurement of pesticide effects on the microbial cycling of C, N and S constitute the core of the test program. These measurements are, in some cases, complemented by evaluation of pesticide effects on total and viable microbial numbers, on the abundance of specific components of the soil microbial community, and on the growth rates of selected soil microorganisms. The above test program was applied to evaluate the safety of the herbicides N-(1-ethylpropyl)-3,4-dimethyl-2,6-clinitrobenzeneamine(pendimethalin) l,2-dimethyl-3,5-diphenyl-1H pyrazolium (difenzoquat), S-(4-chlorophenyl)-N,N-diethyldithiocarbamate (thiobencarb), and the fungicides N-[(trichloromethyl) thio]-phthalimide (folpet) and cis-N-[(l,l,2,2-tetrachloroethyl) thio]-4-cyclohexene-1,2-dicarboximide (captafol). No detectable adverse effects were caused by any of the tested herbicides. The fungicides inhibited some of the C cycling activities, but the inhibition was temporary and was associated with their effect on soil fungi.     

Lethal and sublethal effects of imidacloprid on two earthworm species (Aporrectodea nocturna and Allolobophora icterica)

The chemical imidacloprid is the major component of many widely used insecticides and is relatively persistent in soils. A set of experiments was carried out to estimate the lethal (mortality) and sublethal (weight loss) effects of one of these insecticides, Confidor, on two earthworm species commonly found in agricultural soils. A preliminary experiment in the absence of earthworms showed that imidacloprid was not rapidly degraded, with a decrease of less than 10% after 2 weeks, and that it was distributed in a reasonably homogeneous manner throughout the soil (less than 10% of variation between samples). The LC₅₀ of imidacloprid for the anecic species Aporrectodea nocturna and the endogeic species Allolobophora icterica was between 2 and 4 mg kg^–1 dry soil. This result is consistent with previous findings obtained with other earthworm species and natural soils. When sublethal effects were examined, significant decreases in weight were observed at concentrations of 0.5 and 1 mg kg^–1 dry soil for the two earthworm species whereas no effect was observed at a concentration of 0.1 mg kg^–1 dry soil (NOEC value). These concentrations are close to 0.33 mg kg^–1 which is the Predictive Environmental Concentration. Weight loss appears to be a valuable endpoint that can be used with worms freshly collected in the field as long as variability in the response of a control is taken into account.     

Enantioselective separation and phytotoxicity on rice seedlings of paclobutrazol

The environmental significance of enantioselectivity in chiral insecticides and herbicides has been widely studied. However, little information is currently available on the enantioselective behavior of chiral plant growth regulators. In this study, paclobutrazol enantiomers were resolved and prepared by chiral high-performance liquid chromatography with a Sino-chiral OJ column. The relationship among absolute configuration, optical activity and circular dichroism of paclobutrazol enantiomers was established. The enantioselective behavior of paclobutrazol, including enantioselective effect of paclobutrazol on the growth of rice seedlings and cyanobacteria and enantioselective loss of paclobutrazol in rice seedling growth media, in rice culture system was studied. The (2S,3S)-(-)-enantiomer was almost 3.1 times more active than the (2R,3R)-(+)-enantiomer toward shoot growth as measured by 7 day EC50 values. Enantioselectivity could not be determined with respect to root growth of rice seedlings because a typical dosage response was not observed in the range of the concentrations studied. The dissipation of paclobutrazol in rice growth medium is not enantioselective. Enantiomers and diastereoisomer of paclobutrazol all facilitated the growth of cyanobacteria, which increase the effectiveness of rice biofertilizers. The (2S,3S)-(-)-enantiomer showed stronger stimulatory activity on Microcystis aeruginosa cyanobacteria than the (2R,3R)-(+)-enantiomer, whereas the latter was a more potent stimulator of Anabaena sp. growth. These observations indicate that application of the (2S,3S)-(-)-enantiomer of paclobutrazol and Microcystis aeruginosa in rice cultivation is a good strategy for improving rice seedling performance.     

Low Concentrations of Glyphosate-Based Herbicide Affects the Development of <Emphasis Type="Italic">Chironomus xanthus</Emphasis>

Glyphosate is an herbicide commonly used worldwide for weed control and generally applied as part of a formulated product, such as Roundup. Contamination of surface water by glyphosate-based herbicides can cause deleterious effects in organisms, mainly in aquatic systems near to intensive agricultural areas (e.g., transgenic soybean crops). Given the lack of toxicological information concerning effects of glyphosate-based herbicides on tropical aquatic ecosystems, we aimed to evaluate the lethal and sub-lethal effects of Roundup Original® on the dipteran Chironomus xanthus. The endpoints evaluated included survival, growth, and emergence. The results showed that the 48 h LC₅₀ for glyphosate to C. xanthus was 251.5 mg a.e./L. Larval growth of C. xanthus was reduced under glyphosate exposure (LOEC for body length = 12.06 mg/L; LOEC for head capsule width = 0.49 mg/L). No effects were observed in terms of cumulative percentage of imagoes emergence. However, low concentrations of glyphosate caused delayed emergence of females (at 1.53 mg/L) and induced fast emergence of males (at 0.49 mg/L), compared to control treatment. The deleterious effects of environmental relevant concentrations of glyphosate (0.7 mg/L) observed in terms of C. xanthus growth and development suggest that glyphosate-based herbicides can have negative consequences for aquatic non-target invertebrates such as Chironomus. Multigerational assays are needed to assess the long term effects of glyphosate on C. xanthus populations. Finally, our study adds ecotoxicological data on the effects of glyphosate-based herbicides on tropical freshwater invertebrates.     

陇西县玉米病虫害种类及农药使用情况调查

为掌握玉米病虫害发生种类和农药使用情况,制定玉米病虫害防治规范。采用定点调查方法,对陇西县玉米病虫害及农药使用情况进行了调查。调查发现,该县玉米主要病害有茎基腐病、锈病、大斑病和小斑病,虫害有玉米螟、蚜虫、红蜘蛛、蓟马、黏虫和地下害虫等。将农药使用情况录入全国农药信息管理系统进行分析,表明在玉米整个生育期,按其类型,除草剂用量最大,其次为杀虫剂和杀菌剂,生长调节剂用量最小;按毒性,低毒农药用量最大,其次为中毒农药,微毒农药用量最小;按种类,以化学农药为主、生物农药为辅;按农药成分,辛硫磷、莠去津用量较大。