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1.
The herbicide safener N-dichloroacetyl-1-oxa-4-aza-spiro-4,5-decane (AD-67) is of similar efficiency as the extensively used N.N-diallyl-2,2-dichloroacetamide (R-25788) and the structurally related 3-(dichloroacetyl)-2,2-dimethyl-1,3-oxa-zolidine (AD-2) in reducing EPTC [S-ethyl-N,N-dipropyl (thiocarhamate)] injury to maize (Zea mays L. cv. KSC 360). EPTC treatment produces growth retardation and deformities and inhibits CO2 fixation. It does not reduce epicuticular lipids appreciably but affects wax arrangement on the leaf surface. When EPTC is applied together with one of these safeners, these injuries are not observed. All three safeners act similarly. Each prevents the herbicide-induced aggregation of epicuticular wax of maize, thereby protecting the plants against the formation of areas where the underlying cuticle layers are exposed and increase in transpiration.  相似文献   

2.
The effects of abamectin (AVMB1) on intracellular potassium ion activity (aKi) and resting membrane potential (Em) of the skeletal muscle cells of final instar larvae of Phormia terraenovae (Diptera) were investigated using K+-selective micro-electrodes. Bathing the preparation in 10? M AVMB1(+ 1 ml litre?1 dimethylsulfoxide) for 60 min caused a significant (31%) decrease in aKi, whilst Em depolarized on average by 19 mV (nearly 50% of the original control value). The difference EK-Em increased by 9 mV, although EK (potassium equilibrium potential) remained more negative than Em. These results could be due to a cationic effect of AVMB1 possibly involving an increase in K+ and Na+ conductances of the muscle plasma membrane.  相似文献   

3.
The ascomycete fungus Microdochium nivale is a major pathogen of many species of the gramineae. Control measures rely heavily on chemical fungicides, making alternative means of disease reduction desirable. Phosphite (PO33?), has proven efficacy in reducing susceptibility of different species of gramineae to oomycetes, and has adverse effects on the in vitro growth of numerous other pathogens. The effect of phosphorous acid (H3PO3), phosphoric acid (H3PO4), dihydrogen potassium phosphite (KH2PO3), dihydrogen potassium phosphate (KH2PO4) and potassium hydroxide (KOH) on the in vitro mycelial growth and development of M. nivale was determined. Radial growth on amended potato dextrose agar (PDA) was used to calculate mean daily growth and percentage inhibition. PO33? had a significant inhibitory effect on mycelial growth, with EC50 values ranging between 35.9 and 40.99 μg mL?1, whilst PO43? and KOH had no significant inhibitory effect. Microscopic examination of mycelia showed morphological deformities in hyphae growing on PO33? amended PDA, whilst hyphal growth was normal on PO43? and KOH amended PDA. Conidial germination of M. nivale was significantly reduced following immersion in solutions of 50, 100 and 250 μg mL?1 of PO33?, while PO43? and KOH at the same concentrations induced no inhibitory affect. These results show that PO33? is a significant inhibitor of the growth of M. nivale and may have the potential to be used as a chemical control agent in the field.  相似文献   

4.
Butter  N. S.  Singh  Gurmeet  Dhawan  A. K. 《Phytoparasitica》2003,31(2):200-203
An insect growth regulator (IGR), lufenuron (Match 5EC), was tested for its toxicity toHelicoverpa armigera on cotton. Potency of the IGR against the larval stage of the pest was demonstrated with respect to larval instars; the LC90 values of 1st, 2nd, 3rd, 4th and 5th instar larvae were 5.63, 7.89, 8.03, 11.39 and 14.76 mg a.i.l −1, respectively. However, different larval instars did not differ significantly with respect to LC50 and LC10. IGR-treated larvae had swollen heads and were significantly smaller (1.5–2.3 mm) than the untreated control (2.9 mm). Larval weight was significantly reduced from 190 mg in the control to 50–70 mg in the lufenuron treatment. IGR treatment in the larval stage significantly affected both pupal length and pupal weight. Pupal duration of the test insect was significantly extended by IGR treatment. Pupal deformities, including an inability to shed the last larval skin and formation of larval-pupal intermediates, occurred following treatment. A significant reduction in adult emergence was recorded. In addition, abnormalities in the form of development of cavities in the forewings of adult were evident. A significant decline in fecundity was noted in the studies. http://www.phytoparasitica.org posting Feb. 3, 2003.  相似文献   

5.
为阐明杀虫剂哌虫啶在SD大鼠体内的代谢动力学过程,以期为进一步的毒理学研究提供依据,采用所建立的高效液相色谱-串联质谱(HPLC-MS/MS)分析方法,测定了单次灌胃给药后大鼠血浆、组织(心、肝、脾、肺、肾、脑、骨骼肌、脂肪)、粪便和尿液样品中哌虫啶的含量,对该药在大鼠体内的吸收、分布和排泄进行了研究。结果表明:哌虫啶750 mg/kg单次经口灌胃给药,雌性大鼠血药浓度-时间曲线下面积(AUC)高于雄性大鼠,且达到峰值时间(T_(max))明显长于雄性大鼠,具有统计学差异,提示在此剂量下,哌虫啶在代谢及毒性效应上可能存在性别差异;在100~750 mg/kg受试剂量范围内,哌虫啶的平均半衰期为4~8 h,表观分布容积为10~30 L/kg,给药剂量与血药浓度-时间曲线下总面积(AUC_(0-inf))呈线性相关性(雄:r=0.996 4,雌:r=0.991 3)。组织分布试验表明,哌虫啶经口给药后,能迅速、广泛地分布到各组织中,并可有效地透过血脑屏障,其中肝、肾中哌虫啶的含量最高,提示其可能主要经肝、肾代谢。排泄试验显示,经尿液及粪便排出的原形哌虫啶含量极低,提示哌虫啶在大鼠体内可能发生广泛的代谢后再排出体外。  相似文献   

6.
The toxicity of ryanodine ( 1 ) and 9,21-didehydroryanodine ( 2 ) (the principal active ingredients of the botanical insecticide ryania) to adult female house flies (Musca domestica L.) is attributable to binding to the ryanodine receptor (ryr) and thereby disrupting the Ca2+-release channel. These ryanoids, assayed in house flies with piperonyl butoxide (PBO) to suppress cytochrome P450-dependent detoxification, give injected KD50 values of 0·07–0·11 μg g-1, injected LD50 values of 0·39–0·45 μg g-1 and topical LD50 values of 12– 50 μg g-1. They inhibit the [3H]ryanodine binding site of house fly and rabbit muscle with IC50 values of 3–10 nM . This study examines the effect of structure on potency, with 15 variants of the cyclohexane substituents, two 4,6-cyclic boron and two methylated derivatives, and four modifications of the isopropyl and ester substituents. The most effective compound examined was 10-deoxy- 2 ( 3 ) which was more potent than 2 by 2–4-fold on injection and 29-fold applied topically following PBO (LD50 0·41 μg g-1). Additional high-potency compounds were 10-oxo- 1 and the cyclohexane variants with lactam, 21-nor-9-oxo and 21-nor-10-deoxy substituents. Other modifications usually reduced toxicity. The injected knockdown potency of the ester ryanoids was generally related to their effectiveness in competing with [3H]ryanodine at the ryr of rabbit skeletal muscle. Two non-ester ryanoids, ryanodol and 9,21-didehydroryanodol, were found to be more toxic than predicted from their potency at the ryr and may therefore act in a different manner such as at a K+ channel, as suggested by Usherwood and Vais. Clearly ryanoids are challenging prototypes for a potential new generation of insecticides. © 1997 SCI.  相似文献   

7.
Feeding the last instar larvae of Nephantis serinopa, the coconut black-headed caterpillar, on coconut leaves that had been dipped in diflubenzuron suspensions (0.2-4.0 g litre?1) and dried, inhibited the moulting process and caused morphogenetic deformities of their pupae. The inhibition of moulting ranged from 27.5 to 75% The maximum effect was produced by suspensions of 4.0 g litre?1 when only 5% of the larvae survived to become adults against 97.5% of untreated larvae.  相似文献   

8.
In order to find the biorational pesticides, eight novel 4β-substituted phenoxyaniline derivatives of podophyllotoxin have been synthesized with significant stereoselectivity and improved yields by employing the BF3·Et2O/NaI reagent system and evaluated for their antifeedant effect against 5th instar larvae of Pieris rapae and effect on the development of 5th instar larvae of P. rapae as well as for insecticidal activity against P. rapae. The antifeedant activities showed that these compounds exhibited less potent than podophyllotoxin. Though these derivatives showed less potent antifeedant activities than podophyllotoxin, they acted as growth development inhibitor to 5th instar larvae of P. rapae, which were found that the animals treated with podophyllotoxin and its derivatives showed moulting disturbances and/or deformities. Also, the insecticidal activity results show that all of these derivatives of PPT showed delayed insecticidal activity, which differs from traditional neurotoxic insecticides. Among them, compounds possessing a 4β-phenoxyaniline moiety substituted (CO2C2H5, Cl and OH) at para position exhibited greater insecticidal activity against P. rapae than podophyllotoxin.  相似文献   

9.
A second gene conferring resistance to the chickpea wilt pathogen, Fusarium oxysporum f. sp ciceris race 0, has been mapped to linkage group 2 (LG2) of the chickpea genetic map. Resistance to race 0 is controlled by two genes which segregate independently; one present in accession JG62 (Foc0 1 /foc0 1 ) and mapping to LG5 and the second present in accession CA2139 (Foc0 2 /foc0 2 ) but remaining unmapped. Both genes separately confer complete resistance to race 0 of the wilt pathogen. Using a Recombinant Inbred Line (RIL) population that segregated for both genes (CA2139 × JG62) and the genotypic information provided by two markers flanking Foc0 1 /foc0 1 ten resistant lines containing the resistant allele Foc0 2 /foc0 2 were selected. Genotypic analysis using these ten resistant lines paired with ten susceptible RILs, selected in the same population, revealed that sequence tagged microsatellite sites (STMS) markers sited on LG2 were strongly associated with Foc0 2 /foc0 2 . Linkage analysis, using data from two mapping populations (CA2139/JG62 and CA2156/JG62), located Foc0 2 /foc0 2 in a region where genes for resistance to wilt races 1, 2, 3, 4 and 5 have previously been reported and which is highly saturated with tightly-linked STMS markers that could be used in marker-assisted selection (MAS).  相似文献   

10.
太阳辐射是利用FAO推荐的Penman-Monteith(PM)公式计算参考作物需水量(ET_0)的必要参数。为了探究PM公式在辐射数据缺失的条件下,利用FAO推荐的公式及参数获得太阳辐射值(R_(s_c))替代观测值(R_(s_o))在中国大陆地区的适用性,本研究选用了中国大陆112个站点至少15 a的多年月平均观测数据,通过逐点计算分析了R_(s_c)和R_(s_o)的时空差异及二者分别输入PM公式获得的参考作物需水量ET_(0_c)和ET_(0_o)的时空差异。结果表明,R_(s_c)与R_(s_o)存在显著的时空差异性,二者相对差值范围为-2.86～4.41 MJ·m~(-2)·d~(-1),且在4—8月份差异较大;大致以"胡焕庸线"为界,线西北区域R_(s_c)与R_(s_o)的时空差异相对较小,且稳定,线东南区域的时空差异较大,且不稳定。但是,基于二者计算的ET_(0_c)和ET_(0_o)时空差异却不显著,平均只有0.06～0.26 mm·d~(-1)的误差;"胡焕庸线"西北地区的ET_(0_c)和ET_(0_o)绝对差值常年稳定在0.00～0.25 mm·d~(-1),"胡焕庸线"线东南地区则随季节而变化,夏季差异相对较大。在实际的应用中,西北地区全年和北方地区春、秋、冬三季以及长江、珠江流域所覆盖的南方地区在1、2、10、11、12月使用R_(s_c)替代R_(s_o)获得ET_0具有较好的适用性,北方地区的夏季、南方地区的3—9月份使用R_(s_c)计算ET_0则必须研究相应的方法对结果进行矫正,否则会有误差,且偏大。  相似文献   

11.
Trichoderma spp. are widely used in agriculture as biofungicides. In this study, effects of elevated CO2 on the growth and enzyme activities of Nilaparvata lugens infected by T. asperellum were studied. The results showed that fecundity of N. lugens adversely decreased under elevated CO2 relative to ambient CO2 irrespective of infection with T. asperellum. The contents of protein and alkaline phosphatase significantly decreased in N. lugens nymphs with T. asperellum infection under elevated CO2 relative to ambient CO2. Significantly higher activities of carboxylesterase and acetylcholinesterase were observed in N. lugens infested with T. asperellum under elevated CO2 compared with ambient CO2. While significantly lower catalase and glutathione S-transferase were observed in N. lugens nymphs infested by T. asperellum under elevated CO2 relative to ambient CO2. Measuring the antioxidases and detoxification enzymes in N. lugens infected with T. asperellum can partly explain the response of fitness parameters of N. lugens under elevated CO2.  相似文献   

12.
The effect of organotin compounds on the growth of Ceratocystis ulmi, the causative agent of Dutch elm disease, was studied in shake culture. Triphenyltin, (C6H5)3SnX, tricyclohexyltin, (C6H11)3SnX, and tributyltin, (C4H9)3SnX, compounds were all effective in the inhibition of C. ulmi in vitro. The anionic group, X, did not play a major role in the inhibitory activities of these compounds, suggesting that the species involved in the inhibition is R3Sn+ or the hydrated cation.  相似文献   

13.
不同基因型燕麦苗期耐盐碱性分析 及其鉴定指标的筛选   总被引：1，自引：0，他引：1  
为探讨不同基因型燕麦苗期的耐盐碱性,筛选适宜松嫩平原种植的燕麦品种,本研究采用Hoagland营养液水培法,以250 mmol·L-1高浓度NaHCO3胁迫模拟松嫩平原盐碱环境,对49份来自国内外不同地区的主栽燕麦品种进行研究。试验测定了250 mmol·L-1 NaHCO3胁迫下燕麦的株高（X1）、根长（X2）、地上部鲜重（X3）、地下部鲜重（X4）、地上部干重（X5）、地下部干重（X6）、地上部含水量（X7）、地下部含水量（X8）、根冠比（X9）9个指标,以各单项指标的耐盐碱系数(SATC) 作为衡量耐盐碱性的依据,利用多元分析方法对不同燕麦品种耐盐碱能力进行了综合评价。结果表明：通过对各指标的耐盐碱系数进行主成分分析,得到X4、X7、X8 3个综合指标,涵盖了全部数据86.155%的信息量;通过隶属函数分析和聚类分析将49份燕麦品种分为3类,其中草莜1号、张燕7、T7等3个品种为耐盐碱品种,HLJ 1、白燕2号等41个品种为中度耐盐碱品种,三分三、坝莜13号等5个品种为盐碱敏感品种。  相似文献   

14.
Penultimate and last instar larvae of the common citrus swallowtail butterfly, Papilio demoleus L. (Papilionidae: Lepidoptera), were treated with different doses of a novel juvenoid, diofenolan. Several deformities were observed as a result of topical administration of diofenolan which include delay in larval–larval and larval–pupal ecdysis, ecdysial failure, mortality, severe reduction in pupation, deformed pupae and complete inhibition of adult emergence. The juvenoid diofenolan severely hampers the normal growth, development and metamorphosis of P. demoleus and can be incorporated into integrated pest management programs for successful control of this important pest of citrus all over the world.  相似文献   

15.
There are several fungicide chemistries used for disease control on pecan (Carya illinoinensis), but there is little or no knowledge of subtle short‐ or long‐term side effects of these chemistries on host physiological processes, including net photosynthesis (Pn). This study quantifies the impact of several fungicides used to control scab on Pn and other gas exchange characteristics of pecan foliage and provides much‐needed insight to ensure proper usage in commercial pecan operations. Multiple field experiments found that certain fungicide chemistries have the potential to reduce Pn, stomatal conductance (Cs), transpiration rate (Tr) and water use efficiency (Ew; Pn/Tr), whereas others are benign. For example, neither triphenyltin hydroxide nor the triazoles tested had a negative impact on gas exchange characteristics, regardless of when measurements were taken or the number of spray applications. However, dodine, phosphorous acid, ziram and certain strobilurins were capable of suppressing gas exchange, especially Pn, up to several weeks after a single treatment. Suppression of Pn by some fungicides was relatively short term, but was long term or permanent for other fungicides. In certain cases, leaf Pn was suppressed by as much as 50–80% for at least several weeks after a single exposure. These studies suggest that use of fungicides in commercial pecan orchards might result in negative side effects that need to be taken into consideration when determining how best to use these fungicides in pecan disease management.  相似文献   

16.
为探究油菜菌核病田间发生流行的影响因子并建立病情预测模型,采用田间调查法测定油菜田菌核密度、子囊盘密度、花朵带菌率,并分析了2008—2014年各气候因子与病叶率、成熟期茎秆病株率、病情指数之间的关系。结果显示,田间菌核密度、子囊盘密度、花朵带菌率与病叶率及成熟期茎秆病株率均呈极显著正相关;2月下旬至5月上旬日均气温及2月下旬至4月上旬日均相对湿度、降雨量及降雨天数与各年度成熟期病株率及病情指数均呈显著正相关,而日照时数与各年度成熟期病株率及病情指数均呈极显著负相关。以油菜盛花期花朵带菌率作为指标,可预测其田间成熟期病株率;以降雨量(x_2)、降雨天数(x_3)及日照时数(x_4)与各年度成熟期病株率(y_1)及病情指数(y_2)分别建立了预测模型y_1=15.47+0.07x_2+0.42x_3-0.03x_4和y_2=10.36+0.07x_2+0.38x_3-0.03x_4,其拟合度均最高,分别为99.07%和98.43%,可作为油菜成熟期茎秆发病株率及病情指数的预测模型。表明油菜菌核病菌源量和气候因子是影响病害发生流行的关键因子。  相似文献   

17.
河北省禾谷孢囊线虫种群密度和冬小麦产量损失的关系   总被引：3，自引：2，他引：1  
为明确禾谷孢囊线虫Heterodera avenae对小麦的危害,于2011年10月—2012年6月在自然环境条件下采用定量接种方法测定了其在不同接种密度下对冬小麦产量和线虫繁殖的影响。结果表明,随着禾谷孢囊线虫接种密度的增加,小麦的株高、穗长、小穗数、分蘖数和籽粒重均呈下降趋势。小麦产量随着接种密度的增加损失率增加,在接种密度大于29个卵和2龄幼虫/g土时,小麦产量损失率均达50%以上,接种密度为465个卵和2龄幼虫/g土时损失率最大,达到77.7%;当接种密度小于116个卵和2龄幼虫/g土时,禾谷孢囊线虫的最终密度随着接种密度的增加而增加,但接种密度大于该值时,最终线虫密度则随着接种密度的增加而减少;且其繁殖系数随着接种密度的增加而降低。以小麦单株籽粒重为参数,利用Seinhorst模型拟合孢囊线虫密度与产量的关系,可知小麦对禾谷孢囊线虫的最低忍耐值为5个卵和2龄幼虫/g土,相对最低产量为0.23。  相似文献   

18.
Timely detection of herbicide resistance at an early stage of crop cultivation is essential to help farmers find alternative solutions to manage herbicide resistance in their fields. In this study, maximum quantum yield of PS II [Fv/Fm = (Fm – Fo)/Fm] was measured at the 4–5 leaf stage to discriminate between herbicide‐resistant and susceptible biotypes of Echinochloa species. The differences in Fv/Fm between herbicide‐resistant and susceptible Echinochloa spp. were consistent with the whole‐plant assay based on I50 (herbicide doses causing a 50% inhibition of Fv/Fm) and GR50 (herbicide doses causing a 50% reduction in plant fresh weight) values and R/S ratios (herbicide resistance index), regardless of the mode of action of the tested herbicides. A PS II inhibitor caused the fastest inhibition of Fv/Fm, compared with ACCase and ALS inhibitors, after herbicide treatment. The required time for discrimination between herbicide‐resistant and susceptible Echinochloa spp. was 64 h after PS II inhibitor treatment, much shorter than those of ACCase and ALS inhibitor‐treated plants, which required 168 and 192 h respectively. The leaf chlorophyll fluorescence assay provided reliable diagnostics of herbicide resistance in Echinochloa spp. with significant time savings and convenient measurement in field conditions compared with the conventional whole‐plant assay.  相似文献   

19.
在开顶式小型温室内模拟大气CO2浓度增高,并在N0,N100,N200计3个氮素水平〔施N量分别为纯N0、0.1、0.2 g/kg(土)〕下盆栽小麦,研究小麦光合作用和水分利用效率(WUE)对大气CO2升高的响应及其氮素调控机制。结果表明,760μmol/molCO2浓度×N素小麦叶片的净光合速率、叶片胞间CO2浓度、气孔限制值及叶片水分利用效率较对照呈明显上升趋势,叶片气孔导度显著降低,蒸腾速率则呈先降后升的趋势;在400μmol/molCO2浓度下,N0和N100处理的小麦光合速率明显下降,但N200处理较当前CO2浓度处理明显升高;气孔导度,胞间CO2浓度以及蒸腾速率呈现下降的趋势,小麦的气孔限制值Ls和WUE在N200条件下表现最高,较各个处理均达到极显著水平。两种大气CO2浓度下的小麦叶片光合速率和气孔导度均随氮素水平的升高而明显升高,胞间CO2浓度和蒸腾速率表现均不一致。因此,长期高CO2浓度使得小麦叶片WUE和Ls值显著升高,在低中氮处理下产生明显的光合下调现象,但在高氮处理下却不发生。  相似文献   

20.
自流式注射法中苹果树体吸收量回归方程的建立   总被引：1，自引：0，他引：1  
为确定苹果树体的有效吸收期并建立初始流速v0与有效吸收期内树体吸收量的回归方程,以纯水为注射液,研究了输液流速与树体吸收量的关系,通过统计软件分析相邻观测时间与对应流速间的函数关系,建立了初始流速v0与树体有效吸收期内吸收量的回归方程。结果表明:树体的有效吸收期为注射开始后0~48 h;相邻观测时间与对应的流速间存在极显著的一元线性关系和幂函数曲线关系,同时注射期间温度对流速具有一定影响,温度上升时流速上升,温度下降则流速亦下降;v0与48 h内树体的吸收量呈显著回归关系。建立回归方程时,若不区分9:00 am开始注射时的初始流速v0与注射开始后3 h (12:00 am)时流速v3的比值(流速比,v0/v3)关系,且v0在0~1 mL/min时,采用一元回归方程时的差异率显著高于幂函数方程,而当v0在2~4 mL/min时,采用幂函数方程的差异率显著高于一元回归方程;若区分流速比,且流速比为0.6~1,v0为1~4 mL/min时,采用一元函数方程估测的差异率显著低于幂函数方程,流速比为1~1.6,v0为0~4 mL/min时,一元函数与幂函数方程估测的差异率无显著性差异。在不区分流速比的情况下,两类方程的差异率均在20%~30%之间。因此,当v 0在0~1 mL/min之间时,建议采用幂函数方程;当v0为1~2 mL/min时,采用一元函数或幂函数方程均可;当v0在2~4 mL/min之间时,建议采用一元函数方程。区分流速比时,两类方程的差异率均小于15%。因此,当流速比为0.6~1,v0在0~1 mL/min之间时,采用一元函数或幂函数方程均可,当v0为1~4 mL/min时,建议采用一元函数方程;当流速比为1~1.6, v0在0~4 mL/min之间时,采用一元函数或幂函数方程均可。  相似文献   

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