烟草花叶病普遍率与严重度的关系及感病品种与转基因抗病品系间的比较

 利用田间调查取得的数据,分析了烟草花叶病在转基因抗病品系上和感病对照品种上的普遍率与严重度的关系(I-S)。结果表明感病品种的I-S关系以指数函数拟合较好;在普遍率小于35%左右时可以用直线方程(b₁)拟合。在转基因抗病品系上I-S关系呈现为直线方程(b₂)。b₁、b₂两直线方程的斜率不同,感病品种的斜率显著大于转基因抗病品系的。根据两品种(系)间的I-S关系的显著差异,从流行学角度探讨了转基因抗病品系对压低流行强度的作用、并分别用抗感品种(系)建模以外的另一种数据对利用普遍率估测严重度的可行性进行验证,抗感品种(系)预测的平均准确度分别为85.9%和83.3%。     

稻瘟病普遍率与严重度关系初步探讨

作者对田间自然发病情况的观察和盔栽接种试验,获得92组叶稻瘟和80组穗颈稻瘟普遍率和严重度间对应关系的数据,在计算机上分别分析了叶瘟和穗颈瘟普遍率与严重度之间的关系(I-S)。结果表明:叶瘟I-S关系和穗颈瘟I-S关系均可用直线方程描述,其直线回归方程为:叶瘟:SL=-1.104+0.455IL(SL,IL——叶瘟严重度和普遍率)穗颈瘟:SE=-3.717+0.737IE(SE,IE——穗颈瘟严重度和普遍率)协方差分析结果表明:水稻品种的抗病性对稻瘟病 I-S 关系有一定影响。     

大豆品种感染灰斑病前后氨基酸含量的比较

在植物抗病机制的研究中,经常提到氨基酸的作用,作者对大豆灰斑病的抗病品种和感病品种在接种前后氨基酸的含量进行了比较,结果如下。 1 材料与方法 1.1 供试材料:抗病品种:东农9674、合丰29、东农8090;感病品种:东农1330、黑农39、合丰27。     

小麦叶锈病、白粉病和条锈病普遍率与严重度间的关系

 在田间接种条件下,详细地观察了小麦叶锈病、白粉病和条锈病普遍率与严重度之间的关系(I-S关系)。结果表明供试三种病害的I-S关系均可用指数函数描述;在普遍率小于70%左右时,用直线方程拟合效果更好;普遍率大于90%时,对严重度的预测效果较差。分别建立了各病的I-S关系式。小麦生育阶段(拔节期、抽穗开花期、灌浆期)对叶锈病和白粉病I-S关系没有明显的影响,而条锈病的I-S关系在不同生育阶段有一定的差异。文章最后对I-S关系的使用进行了讨论。     

大豆灰斑病病叶、病荚、病粒间的关系及其对产量的影响

１９９２～１９９５年进行了大豆灰斑病田疃小区接种试验,获得了病叶率、病荚率、病粒率及大豆产量的系统资料。回归分析结果表明,大豆灰斑病病叶率与病英率、病粒率之间及病英率与病粒率之间均呈直线相关 叶率、病英率、病粒率与产昨损失率之间亦呈直线相关,相关系数均达极显著水平,拟合率在８０％以上。协方差分析结果表明,大豆品种的抗生对这一相关关系有一定的影响。     

感染灰斑病大豆叶组织的自由基代谢

作者以电子自旋共振技术(ESR)为手段对大豆感染灰斑病后叶内自由基代谢的变化进行了研究。结果表明,不同品种病叶内的自由基浓度均远远高于正常叶片,感病品种显著高于抗病品种。病斑周围绿色组织的自由基浓度基本上与正常组织相同,但近病斑组织自由基浓度却明显高于正常组织。病致黄化组织与自然黄化组织相比,前者自由基浓度更高。因此,自由基浓度的高低与组织的病理状态和品种的抗病性有密切关系。     

水稻不育系粒黑粉病普遍率与严重度间的关系

 稻粒黑粉病(病原菌Neovossia horrida (TaK.)Padw. et A. Kahn)是杂交稻繁殖制种田不育系上的主要病害,流行频率高,危害损失大。普遍率和严重度的关系(I-S关系)是植病流行学观测技术上的一个重要问题。     

枇杷灰斑病在不同枇杷品种上感染程度的灰色综合评价

本文选取平均病叶率,平均病斑数和病斑平均宽度3个指标,应用灰色聚类法,对枇杷灰斑病在15个枇杷品种上的感染程度进行了灰色综合评价,将15个枇杷品种分为感染重、感染中等,感染轻三类、为生产中推广抗病品种提供了依据。     

枇杷灰斑病在不同枇杷品种上感染程度的灰色综合评价

本文选取平均病叶率,平均病斑数和病斑平均宽度3个指标,应用灰色聚类法,对枇杷灰斑病在15个枇杷品种上的感染程度进行了灰色综合评价,将15个枇杷品种分为感染重、感染中等,感染轻三类、为生产中推广抗病品种提供了依据。     

水稻对恶苗病的抗性与病原菌致病性的研究

 室内鉴定了411个水稻品种对恶苗病的抗性,没有免疫品种,高抗品种1个(Te₇₀),抗病品种12(TR₉等),其余为感病品种。籼稻比粳稻感病,杂交稻比常规稻感病。初选10个鉴别品种对湖南收集分离的50个菌株的致病性分化进行测定,表明恶苗病菌致病性存在分化,50个菌株分属4个群11个小种。小种I₁为湖南的优势小种。抗病品种的锌、酚类物质含量比感病品种高,而可溶性糖/淀粉比值则感病品种比抗病品种高。     

大豆灰斑病潜育期的预测模型

 通过人工接种试验证明,在品种和小种组合一定时,大豆灰斑病的潜育期主要是由温度决定的,用有效积温可以预测潜育期的动态变化。本文供试3个品种的日显证率与有效积温的关系可以用Gompertz模型,并获得了3个品种的显症率预测式。     

The effect of timing of fungicide applications on control of frogeye leaf spot and grain yield of soybeans

Soybean cultivar Samsoy 1, and the breeding lines TGx 849-313D and TGx 996-26E, grown in a field with a heavy epidemic of frogeye leaf spot caused byCercospora sojina, were treated with double foliar applications of the fungicide benomyl. The treatments were made using four application schedules at six different growth stages, starting from V₃ (fully developed leaves, beginning with trifoliate nodes) to R₅ (beginning seed_, to determine the effect of the fungucide timing on frogeye leaf spot severity, soybean grain yield and grain quality. Generally, applications at R₁ (beginning bloom) and R₃ (beginning pod) significantly (P<-0.05) reduced disease severity in the 2 susceptible genotypes, Samsoy 1 and TGx 849-313D. Plot yields of these genotypes were also significantly greater than the untreated controls when the fungicide applications were made at R₁ and R₃. There was no significant difference in diseave severity or grain yield, between the untreated control and the different times of application, on the resistant genotype TGx 996-26E. Improved seed germination and lower levels of seed infection byC. sojina occurred for all fungicide timings in the susceptible genotypes. The results suggest that fungicide spraying initiated at R₁ and followed up at R₃ is most effective in frogeye leaf spot control and can also result in higher grain yields, than applications made earlier or later in the season. Control of frogeye leaf spot, however, is best achieved by growing resistant cultivars.     

枸杞褐斑病菌Stigmella lycii生物学特性研究

枸杞小黑梨孢褐斑病自2010年在甘肃省枸杞种植区发现以来已扩展至甘肃省各枸杞种植区,关于其病原枸杞小黑梨孢Stigmella lycii的生物学特性研究国内外尚属空白。本研究通过植物病理学常规方法测定了该菌的生物学特性,结果表明,该菌菌丝生长的温度范围为10~35℃,最适25℃;产孢的温度范围为20~25℃,最适25℃;子囊孢子和分生孢子萌发的温度范围及最适温度分别为5~30℃(最适20℃)和0~35℃(最适25℃)。连续光照有利于菌落生长、产孢和分生孢子萌发,光暗交替有利于子囊孢子萌发;pH 4.0~10.0范围内菌丝均可生长,最适为pH 6.5,产孢的pH范围为6.0~7.0,最适6.5,pH 4.5~9.2条件下孢子均可萌发,最适pH为7.0;子囊孢子和分生孢子分别在相对湿度95%和75%以上可萌发,水中萌发最好;枸杞叶片浸渍液、葡萄糖液等营养条件对孢子萌发有一定促进作用。本研究结果为枸杞小黑梨孢褐斑病后续研究提供一定的理论依据,同时为制定枸杞褐斑病的综合防控措施提供了一定的技术支撑。     

大豆灰斑病菌(Cercospora sojina Hara)及其对寄主作用的研究

 大豆灰斑病是一种世界性大豆病害,曾给我国的大豆生产造成重大的损失。本文主要从应用的角度论述了大豆灰斑病菌(Cercospora sojina Hara)的生物学特性、侵染循环、潜育期以及病害的预测,同时从病原物与寄主相互作用的角度,对大豆灰斑病生理小种的分化、抗性的遗传及代谢毒素等方面进行了综述,以期为该病害的防治及抗病育种研究提供资料与指导。     

A temperature and leaf wetness duration-based model for prediction of gray leaf spot of perennial ryegrass turf

ABSTRACT Gray leaf spot is a serious disease of perennial ryegrass (Lolium perenne), causing severe epidemics in golf course fairways. The effects of temperature and leaf wetness duration on the development of gray leaf spot of perennial ryegrass turf were evaluated in controlled environment chambers. Six-week-old Legacy II ryegrass plants were inoculated with an aqueous conidial suspension of Pyricularia grisea (approximately 8 x 10(4) conidia per ml of water) and subjected to four different temperatures (20, 24, 28, and 32 degrees C) and 12 leaf wetness durations (3 to 36 h at 3-h intervals). Three days after inoculation, gray leaf spot developed on plants at all temperatures and leaf wetness durations. Disease incidence (percent leaf blades symptomatic) and severity (index 0 to 10; 0 = leaf blades asymptomatic, 10 = >90% leaf area necrotic) were assessed 7 days after inoculation. There were significant effects ( alpha = 0.0001) of temperature and leaf wetness duration on disease incidence and severity, and there were significant interactions ( alpha = 0.0001) between them. Among the four temperatures tested, 28 degrees C was most favorable to gray leaf spot development. Disease incidence and severity increased with increased leaf wetness duration at all temperatures. A shorter leaf wetness duration was required for disease development under warmer temperatures. Analysis of variance with orthogonal polynomial contrasts and regression analyses were used to determine the functional relationships among temperature and leaf wetness duration and gray leaf spot incidence and severity. Significant effects were included in a regression model that described the relationship. The polynomial model included linear, quadratic, and cubic terms for temperature and leaf wetness duration effects. The adjusted coefficients of determination for the fitted model for disease incidence and severity were 0.84 and 0.87, respectively. The predictive model may be used as part of an integrated gray leaf spot forecasting system for perennial ryegrass turf.     

内蒙古燕麦叶斑病的发生及其影响因素

为探究内蒙古田间影响燕麦叶斑病的因素，采用正交试验设计对燕麦品种、播期、种植密度、施氮量、施磷量和灌水量6个因素及其组合于2009—2011年进行连续3年的重复试验，运用逐步回归法对3年试验数据进行分析，探讨不同因素及其组合对燕麦叶斑病的影响。正交方差和分析表明，播期和品种是影响燕麦叶斑病的主要因素，方差贡献率分别为78.69%和12.20%；而施氮量、施磷量和灌水量对燕麦叶斑病发生程度均无显著影响。拟合分析获得燕麦叶斑病发生程度与播期(x₂)、品种(x₁)和种植密度(x₃)之间的非线性回归方程为y=51.99-6.45x2-0.39x₁x₃，表明适当推迟播期、选择抗性较高的燕麦品种且相对密植可减轻燕麦叶斑病的发生程度。     

Effect of target spot on soybean yield and factors affecting this relationship

The lack of robust estimates of soybean yield losses due to target spot led to this study. The objective was to determine whether soybean yield at stage R8 (W, expressed as kg ha⁻¹) was related to target spot severity at soybean stage R5–R6 (S, expressed as %) and to identify variables that could affect this relationship. Plot-level estimates of mean disease severity and yield from 41 selected Uniform Fungicide Trials carried out in Brazil during 2012–2016 growing seasons were used to estimate linear regression coefficients for the relationship between yield and target spot severity through random-coefficient mixed effects model analysis. The overall estimated mean regression intercept and slope were  = 3564 kg ha⁻¹ (disease-free yield) and  = −17.1 kg ha⁻¹ %⁻¹ (W decrease per percent increase in S), respectively. The model was then refitted with different covariates to determine their effects on model parameters. β₀ was influenced by baseline yield (less than or greater than 3300 kg ha⁻¹) and β₁ was affected by yield response to fungicide treatments. Estimated yield loss at 50% target spot severity ranged from 8% to 42%. Cultivar also had a significant effect on the magnitude of yield reduction due to target spot, which ranged from 11% to 42%, depending on the cultivar.     

不同植物秸秆对番茄及南方根结线虫的影响

为有效防治南方根结线虫,本试验研究了添加不同剂量的玉米秸秆(8.32、4.16、2.08g/kg)、辣椒秸秆(4.16、2.08、1.04g/kg)和茵陈蒿秸秆(4.16、2.08、1.04g/kg)对温室大棚番茄及根结线虫的影响。结果显示,在根结线虫侵染的土壤中添加植物秸秆后30d,玉米秸秆(4.16、2.08g/kg)对番茄株高有显著影响,辣椒(4.16、1.04g/kg)和茵陈蒿(4.16、2.08g/kg)秸秆对番茄茎粗影响显著;60d时经茵陈蒿处理的番茄植株比对照生长发育良好,对形态指标的影响程度依次为茎粗开花分枝;120d时番茄的茎粗、分枝和果实重量均显著高于对照。末次接种后20d调查,每种作物秸秆处理以高剂量对根结线虫的防治效果最好,防治效果依次为:茵陈蒿秸秆辣椒秸秆玉米秸秆,分别为79.60%、71.32%、68.89%,表明茵陈蒿秸秆处理既可降低根结线虫危害程度,又可提高番茄产量。本研究为温室大棚有效防治根结线虫提供了依据。