杀稗王防除稻田杂草研究

杀稗王防除稻田杂草研究俞水炎，张志高，王通岭（浙江省植物保护总站杭州３１０００４）（江苏省新沂农药厂）杀稗王又名快杀稗，其主要成份为二氯喹啉酸，是一种稻田专用除稗剂。本文探讨了杀稗王的除草效果和对水稻秧苗的安全性，并提出应用技术规范，现报道如下。１材...     

尖角突脐孢菌在温室环境下侵染稗草的致病体系研究

稗属（Echinochloa）杂草是全世界水稻等作物生产中的一类恶性杂草。人工除稗安全但费时费力，化学除稗高效但伴随农产品安全和环境相融友好方面的潜在风险。因此，寻求安全高效的除稗活性成分和施药技术成为国际上除稗剂发展的重要方向之一。在研究和开发生物除稗剂的技术体系中，满足高通量筛选安全、高效的除稗生防因子的温室检测体系是极为重要的支持平台，同样，生物除稗剂的田间科学施药技术亦应依据生防因子在稗草上致病和致害所需的最佳条件来制定。基于此，亟需探明生防因子侵染稗草致病的相关条件并建立快速有效的生防因子除稗效果温室检测体系和田间施药技术。本文系统研究了影响尖角突脐孢菌侵染稗草的相关因子，建立了稳定的温室环境下尖角突脐孢菌侵染稗草的致病体系。     

Facet稻田除草效果的研究

本试验在中国水稻研究所试验农场进行.Facet(3,7—二氯—8—喹咛羧酸)是一种新型除稗剂,稻田试验结果表明 Facet 除稗效果达95%、除草效果为70%;对水稻生长发育无明显影响,增产效果显著.Facet 明显降低稗草叶片光合强度,提高呼吸强度,降低稗草干物重;Facet 稍降低水稻叶片光合强度,对水稻叶片呼吸强度无影响.     

水稻田除草剂三唑磺草酮的作用特性

为了明确水稻田除草剂三唑磺草酮(QYR301)的最佳施药条件,以稗草Echinochloa crus-galli和水稻Oryza sativa作为测试靶标,采用温室盆栽法研究了其施药适期、耐雨水冲刷性、温度和光照强度对其除草活性的影响。结果显示:三唑磺草酮对不同叶龄水稻具有较高的安全性,在有效成分360 g/hm^2的剂量下,对2叶期以后的水稻干重抑制率为0%;其除草活性与稗草的叶龄显著相关,其中2~3叶期的稗草最为敏感,有效成分30 g/hm^2的三唑磺草酮对其干重抑制率为95%~98%;三唑磺草酮具有一定的耐雨水冲刷能力,药后降雨间隔达到8 h以上,其除草活性与药后降雨间隔时间无显著相关性,在有效成分30~120 g/hm^2的剂量下,对稗草的干重抑制率为75%~93%;在20~35℃区间,三唑磺草酮药效稳定,对稗草的GR50值在44.6~51.4 g/hm^2之间;相较于中度光照(45%)和低光照(4%),高光照(100%)条件下三唑磺草酮对稗草的干重抑制率显著增加。分析表明杂草叶龄、降雨、温度和光照会显著影响三唑磺草酮除草活性,为使其发挥最大药效,应选择在水稻2叶期以后至稗草2~4叶期,天气晴朗,气温高于20℃的情况下施药;如药后8 h以内遇降雨天气,则需进行补喷。     

双唑草腈的除草活性及对不同水稻品种和后茬作物的安全性

双唑草腈(pyraclonil)为原卟啉原氧化酶(PPO)抑制剂,为明确其在水稻田的应用前景,采用室内生物测定法研究了双唑草腈的除草活性及对不同水稻品种的安全性,通过大田试验作了进一步验证,并评价了双唑草腈对水稻及后茬作物的安全性。结果表明,双唑草腈对水稻田禾本科杂草稗草、阔叶杂草鸭舌草均有很好的除草活性。在室内试验中,该药剂对稻田稗草和鸭舌草的ED50分别为11.50g/hm~2和8.22g/hm~2,均高于对照药剂丙草胺对稗草和鸭舌草的活性;双唑草腈在3种水稻和稗草之间的选择性指数分别为4.15、3.44和3.73,高于对照药剂;田间试验结果显示,1.8%双唑草腈颗粒剂162、216、324g/hm~2处理在药后20、40d对稗草、鸭舌草、节节菜及异型莎草的株防效均在98%以上,显著优于对照药剂80%丙炔噁草酮可湿性粉剂和50%丙草胺乳油;双唑草腈对水稻以及三种主要后茬作物小麦、油菜和小白菜安全。研究表明双唑草腈具有很好的应用前景。     

五氟磺草胺与吡氟酰草胺的联合作用及对水稻移栽田杂草的防效

吡氟酰草胺属于类胡萝卜素生物合成抑制剂类除草剂,为明确其与乙酰乳酸合成酶抑制剂类除草剂五氟磺草胺复配的联合作用及复配剂对水稻移栽田杂草的田间防效,采用温室盆栽法,评价了二者复配后的除草活性及联合作用类型,并通过田间小区试验评价了复配制剂对水稻田杂草的防效和对水稻的安全性。温室盆栽试验结果表明:五氟磺草胺与吡氟酰草胺复配后对稗、马唐、异型莎草及鳢肠的活性均表现为相加作用,二者复配的合适配比 (质量比) 范围为 (1~2) : (5~10)。田间小区试验结果表明,于水稻移栽后8 d茎叶喷雾处理,300 g/L五氟磺草胺 ? 吡氟酰草胺 (1 : 5) 悬浮剂对水稻生长安全,且对水稻田稗、异型莎草、耳叶水苋及丁香蓼有良好的防效:在有效成分用量112.5~135.0 g/hm2剂量下,药后35 d,复配悬浮剂对上述杂草的总草株防效和总草鲜重防效分别为93.8%~95.8%和94.1%~96.1%,尤其是显著提高了对较难防除型杂草耳叶水苋及丁香蓼的防效,整体防效显著高于对照两个单剂处理及当地常规用药22%苄嘧磺隆 ? 乙草胺可湿性粉剂处理。五氟磺草胺与吡氟酰草胺复配能够在扩大杀草谱的同时提高防效,且对水稻安全,可用于水稻移栽田防除多种一年生杂草。     

三种ALS抑制剂对四类植物ALS的抑制差异

用乙酰乳酸合成酶(ALS)活性测定方法研究了双草醚、KIH-15127、苄嘧磺隆3种ALS抑制剂对水稻、稗草和油菜ALS活性的抑制差异性。体外测定结果表明，不同植物ALS对双草醚和KIH-15127的敏感性差异较大，粳稻、稗草和油菜ALS的敏感性强于籼稻，而这些植物ALS对苄嘧磺隆的敏感性差异很小。体内结果显示，双草醚和KIH-15127对稗草和油菜ALS的抑制作用较强，对粳稻ALS的抑制作用可以恢复；苄嘧磺隆对油菜ALS的抑制作用也较强，但对稗草、水稻ALS基本无抑制作用；3种ALS抑制剂对籼稻ALS抑制作用均较弱。结果表明，不同植物对ALS抑制剂的敏感性存在差异。     

稻田稗草空间格局及抽样技术研究

稗草是稻田恶性杂草之一，对水稻产量损失极重。根据近几年调查，在不防除的情况下，稗草对水稻产量的损失，一般都在二三成以上，有的甚至更大。对稗草的危害以及防除等方面的研究，已见不少报道，但对其空间分布型以及抽样技术方面的研究则报道甚少。因此，笔者于1994年对其空间格局及抽样技术进行了初步研究。一、调查与方法于1994年早稻末人工除种前，选择连片稻田10块，每块田连续逐丛逐株调查1000丛，将每丛所发生的稗草数依田间实际位置记入座标纸内，然后整理出每丛稗草株数的频次分配表，计算出平均数（M）和方差（S2），见表1。…     

新马歇特乳油和水剂对水稻秧田的除草效果和安全性试验

我区秧田杂草的自然发生量依次为丁香蓼、鳢肠、鸭舌草、节节菜、稗草、异型莎草、矮慈姑。论危害,首推稗草,它除在秧田危害外,还是大田夹棵稗的来源,夹棵稗重发生地区对水稻的产量和质量影响很大。我县秧田化除一直用除草醚,除稗效果差,使稗萆危害日益加重。为此,亟需寻求杀草谱广,除稗效果好的药种替代除草醚。     

新型稻田除草剂去稗安的应用技术

去稗安是由日本安万特作物科学公司生产的稻田除草剂 ,在日本主要是在移栽稻田上应用 ,药效期长 ,除草活性高 ,对千金子、稗草特效 ,对莎草及阔叶杂草高效 ,对水稻及环境有较高安全性 ,扩散性好 ,可直接用瓶甩施 ,除草作业省力。1　去稗安的特点1 1　作用机理去稗安是新型的杂环类除草剂 ,具有内吸传导性。通用名oxaziclomefone ,剂型为 1%悬浮剂 ,主要由杂草的根和茎叶基部吸收 ,除草机理是阻碍植物内生GA3 激素的形成 ,使杂草茎叶失绿 ,生长受抑制 ,直至枯死。杀草保苗的原理主要是药剂在水稻与杂草中的吸收传导以及代谢速度的差异所致。…     

高原人体生理适应学理论在进藏旅游中的应用

青藏铁路的贯通运行,带来了国内外进藏旅游热.然而,青藏高原毕竟是世界屋脊,高海拔带来的低氧及其引发的高原疾病依然威胁着游客的身体健康.健康高原旅行是当前游客进藏旅游的基本前提,通过综合国内外高原医学工作者对高原医学生理学的研究成果,提出阶梯进藏旅游的方法.旨在对越来越多的短期赴西藏高原旅行的人群以正确的健康指导,从而减...     

稻瘟病菌对三环唑抗药性测定方法的建立

研究了稻瘟病菌对三环唑抗药性的测定方法,确定了保绿培养基的成分,建立了抗药性测定的标准化模型。4叶I心期将稻苗在三环唑系列浓度药液中浸根处理36 h,剪取稻苗叶段插于100 μg/mL苯并咪唑+0.5％水琼脂保绿培养基上,用孢子含量为10⁵个/mL的稻瘟病菌孢子悬浮液喷雾接种,保湿培养8 d后调查结果,计算EC₅₀值。该测定方法与小苗测定相比较结果更加稳定且灵敏度高,重复性好。     

白刺花(Sophoraviciifolia)适应土壤干旱的生理学机制

用盆栽的方法人工控制土壤干旱条件,研究白刺花天然实生幼苗适应土壤干旱的生理学机制。结果表明:随土壤含水量的减少,白刺花叶水势在胁迫前期下降缓慢,随胁迫时间的延长,水势大幅度下降。白刺花通过在叶片内积累大量渗透保护性物质可溶性糖和K ,增加细胞的保水力,维持细胞生长所需膨压。白刺花游离脯氨酸含量变化与水分关系不大,可溶性蛋白质含量随土壤含水量减少而下降,可能是水分胁迫下受伤害的表现。随土壤水分含量的减少,白刺花SOD的活性明显升高,POD活性不高但随胁迫时间延长其活性较稳定,CAT活性下降但幅度不大,且CAT活性变化趋势与POD活性相反,说明三个保护酶能够相互配合协同作用,降低膜脂过氧化程度,减少水分胁迫造成的伤害,提高质膜稳定性,维持细胞膜的完整性,表现出很强的抗旱适应性。     

Contribution of Fimbrial and Afimbrial Adhesins of Xylella fastidiosa to Attachment to Surfaces and Virulence to Grape

ABSTRACT The role of fimbrial and afimbrial adhesins of Xylella fastidiosa in biofilm formation was assessed by visualization of cell aggregates of mutant strains after incubation on glass surfaces. FimA- or FimF- fimbrial mutants adhered as solitary cells at a slightly lesser frequency to glass surfaces than the parental strain; however, cell aggregates were not formed, unlike the wild-type strain. Conversely, whereas the XadA- and HxfB- nonfimbrial mutants also exhibited a much lower frequency of adherence to glass surfaces than the wild-type strain, most of the cells retained on the surfaces were in cell aggregates of different sizes, much like that of the parental strain. Neither fimbrial or afimbrial mutants formed a mature biofilm on the sides of flasks of broth cultures, unlike the dense biofilm formed by the wild-type strain. Although FimA- and FimF- mutants did not form cell aggregates on glass surfaces when incubated as individual strains, aggregates of a FimA- or FimF- mutant were observed when co-incubated with either a XadA- mutant or HxfB- mutant, respectively. These results are consistent with a model in which the fimbrial adhesins FimA and FimF are involved preferentially in cell-to-cell aggregate formation whereas the afimbrial adhesions XadA and HxfB preferentially contribute to initial cell binding to surfaces, whereupon further cell aggregation can occur. In each of five separate experiments, FimA, FimF, XadA, and HxfB mutants of X. fastidiosa all were less virulent to grape than the corresponding wild-type strain. Fimbrial and afimbrial mutants might produce a reduced biofilm within vessels of grape and, hence, be deficient in various cell-density-dependent traits required for movement through the plant and, thus, virulence.     

植物抗真菌病害基因工程研究进展

在寄主与病原互作的研究中,通过分子生物学与生物技术成功分离和克隆了大量植物防御相关基因,这些基因的表达产物——蛋白、肽或抗菌素直接对病菌有毒害作用或在侵入位点抑制病菌的生长;直接抑制病菌的毒性产物或增强植物结构抗性基因,直接或间接活化植物整体防御反应;增强过敏性坏死反应中与无毒基因互作的抗性基因。将这些基因引入植物,转基因植物显示出对病原真菌明显的抑制作用,在提高植物抗性方面具有广阔的发展前景。     

寡聚糖诱导黄瓜对白粉病抗病反应的超微结构研究

 中科6号(2%氨基寡糖素)处理黄瓜植株叶片,5 d后接种白粉菌Sphaerotheca fuliginea(Schlecht.) Poll.,可诱导黄瓜Cucumis sativus产生对白粉病的抗病性,寄主细胞对病原菌的侵入产生了防卫反应结构和物质以及过敏性坏死反应。表现为寄主细胞壁加厚,染色加深,寄主细胞壁下产生多层次结构的乳突,在寄主细胞壁与质膜之间有黑色物质沉积;吸器外质膜皱褶,染色加深,吸器外基质中出现染色加深的颗粒状电子沉积物;寄主细胞质紊乱,细胞器解体,整个寄主细胞解体、坏死。     

Characteristics of strains of Septoria nodorum adapted to wheat or to barley

Sixty-four strains of Septoria which had been isolated from a range of hosts at different locations and in different years were characterized for their adaptation to wheat or barley, growth at near-maximum temperature, fluorescence, colony morphology, conidial (pycnidiospore) length and hexokinase and alkaline phosphatase isozymes. For each character except conidial length, the strains could be divided into two or three discrete groups. The variation in these six characters was strongly associated, such that 60 strains could be classified into two groups, designated W-type and B-type. W-type strains are adapted to wheat, produce large colonies at 31 C, fluoresce, produce brown-pigmented colonies, and have fast isozymes. B-type strains are adapted to barley, produce small colonies at 31 C, do not fluoresce, produce pink-pigmented colonies, and have slow isozymes. A few strains differed from these norms in one of the six characters, but only one showed an atypical host adaptation. The four unclassified strains differed from W- or B-type in two or more characters. The many differences between the W- and B-types suggest they are genetically distinct populations within Septoria nodorum.     

Laboratory studies to assess the risk of development of resistance to zoxamide

Laboratory studies were conducted to evaluate the risk of developing field resistance to zoxamide, a new Oomycete fungicide which acts on microtubules. Zoxamide, metalaxyl and dimethomorph were compared with respect to the ease with which fungicide‐resistant mutants could be isolated and their level of resistance. Attempts to generate mutants of Phytophthora capsici and P infestans with resistance to zoxamide by mycelial adaptation on fungicide‐amended medium were unsuccessful. Similarly, changes in sensitivity to zoxamide were small (resistance factors ≤2.2) in mutants of P capsici isolated by chemical mutagenesis of zoospore cysts. In parallel experiments with metalaxyl, highly resistant mutants were obtained using both adaptation (P capsici or P infestans) and chemical mutagenesis (P capsici). For dimethomorph, chemical mutagenesis (P capsici) yielded moderately resistant mutants (maximum resistance factor = 20.9), and adaptation (P capsici or P infestans) did not induce resistance. It is proposed that failure to isolate mutants resistant to zoxamide results from the diploid nature of Oomycete fungi and the likelihood that target‐site mutations would produce a recessive phenotype. Our studies suggest that the risk of a highly resistant pathogen population developing rapidly in the field is much lower for zoxamide than for metalaxyl. However, as with any site‐specific fungicide, appropriate precautions against resistance development should be taken. © 2001 Society of Chemical Industry     

Heritability of Ulmus minor resistance to Dutch elm disease and its relationship to vessel size,but not to xylem vulnerability to drought

Dutch elm disease (DED) is a vascular wilt disease that causes the occlusion and cavitation of xylem vessels. Therefore, it is hypothesized that those elms that are less vulnerable to cavitation by drought might be more resistant to DED. To test this hypothesis, the relationship between xylem vulnerability to cavitation and susceptibility to DED was examined in progenies of crosses between susceptible and resistant individuals of Ulmus minor. Hydraulic conductivity and xylem vulnerability curves were evaluated and anatomical features such as vessel size, length and grouping were measured. Next, elms were inoculated with Ophiostoma novo‐ulmi, the cause of DED, and pre‐dawn and midday water potentials, stomatal conductance and wilting percentages were assessed. Progenies of R × R crosses showed significantly lower mean wilting percentages (30–50%) than the progeny of S × S crosses (75%). Fifty percent conductivity loss was reached at c. ?1 MPa, pointing out a high vulnerability of this species to drought‐induced cavitation. Crown wilting percentage as a result of inoculation and xylem vulnerability to cavitation by water stress did not show any significant correlation. Nevertheless, significant differences in theoretical hydraulic conductivity and vessel size parameters (diameter, length and size distributions) were found among the tested progenies. Susceptible trees had significantly wider and longer vessels. Xylem structure of resistant elms seems to restrict pathogen spread rather than prevent cavitation.     

Binding of azole fungicides related to diclobutrazol to cytochrome P-450

Fungicides containing the imidazole and triazole groups are known to block the 14α-demethylation reaction in ergosterol biosynthesis, which is a cytochrome P-450 enzyme system. Fungicides related to diclobutrazol [(2RS, 3RS)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol] bind to cytochrome P-450 in rat liver microsomes, whole yeast cells, yeast microsomes and to a partially purified cytochrome P-450 from yeast, with Type II spectral changes. The most fungicidally active isomer (2R, 3R) shows greater binding than the less active (2S, 3S)-enantiomer to yeast microsomes; when the cytochrome P-450 was purified, a preparation was obtained to which binding more closely matched the fungicidal activity. Binding to rat liver microsomes does not reflect the fungicidal activity of the compounds.