野生大豆资源对灰斑病抗性鉴定与评价

开展野生大豆资源对灰斑病抗性鉴定,旨在为拓宽大豆灰斑病抗病的新基因资源和鉴定新的抗病种质,用于抗灰斑病育种工作。在大豆生育阶段R3-R4时期对104份野生大豆材料进行人工接种灰斑病菌。结果表明：抗病材料有29份,占供试材料的27.9%;中抗材料有45份,占供试材料的43.3%;感病材料有30份,占供试材料的28.8%。用灰斑病菌多菌株接种于104份野生大豆材料进行抗病性指数测定,结果表明：有86份材料抗性指数较高,对不同来源的菌株均表现了一定的抗病性,这些材料可用于水平抗性育种工作。野生大豆资源中有丰富的抗灰斑病基因资源,即有单一抗性资源还有广谱抗性资源。     

A time series analysis of brown eye spot progress in conventional and organic coffee production systems

Brown eye spot (BES), caused by Cercospora coffeicola, is an important coffee disease in Brazil. Losses related to this disease have increased over the last few years. Because the factors associated with the disease dynamics are not fully understood, it is important to gather information about this in different cropping systems. BES epidemics were compared from three production systems: organic (OS), organic under shade (OSS) and conventional under full sun (CS). This study was conducted in Ervália‐MG, Brazil, from November 2004 to October 2008. Disease progress was modelled with all 4 years of data in a time series analysis. Disease intensity (severity (SEV) and incidence (INC)), leaf setting (LS) and leaf fall (LF) were assessed on a monthly basis. The highest values for SEV, INC, LF, LS, as well as a larger area under the disease progress curve and maximum disease occurred in CS and in the upper branches, whereas the lowest values for all variables occurred in OSS and in the lower branches. The highest values occurred for SEV and INC from May to July, for LF from July to September, and for LS from October to January. The disease progress was successfully modelled via a time series analysis. The seasonal behaviour of disease progress for all years and production systems was modelled with a nonlinear sinusoidal model with autoregressive moving average (ARMA) errors. Estimated parameters were generated which could be useful for comparative epidemiology, and it was shown that shade could be used in the field for BES management.     

黄帚橐吾提取物对棉铃虫的生物活性

为掌握贵州甘蔗真菌病害种类及发生情况,采用随机踏查、定点调查、症状诊断与病原菌形态特征观察等方法对贵州甘蔗产区7个县进行真菌病害调查;采用菌丝生长速率法,对甘蔗褐斑病进行了5种杀菌剂室内毒力测定和田间防效试验。结果表明,贵州甘蔗主要真菌病害有褐斑病、褐锈病、赤腐病、黄斑病、轮斑病、褐条病、煤烟病、黑穗病,其中褐斑病、轮斑病、褐条病发生较重,煤烟病发生严重;5种杀菌剂中,325 g/L苯甲· 嘧菌酯悬浮剂对甘蔗褐斑病毒力最高和防效最好,EC50为0.0025 mg/L,第3次药后10 d防效达86.46%。其他4种杀菌剂对褐斑病均有较好的防治效果,可应用于甘蔗生产防治褐斑病。     

花生褐斑病和网斑病田间混发流行过程及其产量损失研究

 通过田间小区人工接种试验,分析比较了花生褐斑病和网斑病单独及混合发生的流行过程及对花生产量损失的影响。结果表明,在病害混发初期,病害间无明显的相关性,随着病情加重,病害间的负相关性逐渐增大并达到显著水平,说明病害间有明显的抑制作用。在不同生育期接种发病情况有所差异,在开花初期和盛花期接种,褐斑病和网斑病的病情较重,而在开花末期接种的病情较轻,但都能表现病害间的抑制作用。病害混发时造成的产量损失小于各病害单独造成损失之和,对白沙1016和四粒红接种2种病菌,病害混合发生所造成产量损失约为各病害单独引起损失之和的77.2% ~ 85.7%和76.1% ~ 79.6%。在不同生育期接种2种病菌,2个品种产量的损失均随着侵染时期的推迟而逐渐降低。     

玉米灰斑病菌毒素对离体玉米叶片电导率的影响

为了研究玉米灰斑病菌的产毒条件和致病机理,采用电导率法测定了静止培养下,以Fries培养液为基质,不同培养时间和培养温度下获得的玉米灰斑病菌毒素对离体玉米叶片电导率的影响。结果表明,相同培养温度和培养时间获得的玉米灰斑病菌毒素（浓度25%）处理不同时间对离体玉米叶片电导率的影响,主要随毒素处理时间的延长,电导率提高率表现为下降趋势;不同培养时间、不同培养温度获得的玉米灰斑病菌毒素对离体玉米叶片电导率均有明显的影响,(20±1)℃培养15天获得的玉米灰斑病菌毒素对离体叶片电导率的影响效果最理想。     

2006～2010年黑龙江省大豆灰斑病菌生理小种监测及部分主栽品种抗性鉴定

通过对2006～2010年黑龙江省大豆灰斑病生理小种的监测,明确了大豆灰斑病生理小种出现频率和分布情况.结果表明:1号生理小种在各大豆产区出现频率最高,为50.5%,平均为40.1%;其次是7号,出现频率为35.9%,平均为26.2%.出现频率较高的还有6、10和11号生理小种,平均出现频率分别为18.8%、12.0%...     

Early detection and classification of plant diseases with Support Vector Machines based on hyperspectral reflectance

Automatic methods for an early detection of plant diseases are vital for precision crop protection. The main contribution of this paper is a procedure for the early detection and differentiation of sugar beet diseases based on Support Vector Machines and spectral vegetation indices. The aim was (I) to discriminate diseased from non-diseased sugar beet leaves, (II) to differentiate between the diseases Cercospora leaf spot, leaf rust and powdery mildew, and (III) to identify diseases even before specific symptoms became visible. Hyperspectral data were recorded from healthy leaves and leaves inoculated with the pathogens Cercospora beticola, Uromyces betae or Erysiphe betae causing Cercospora leaf spot, sugar beet rust and powdery mildew, respectively for a period of 21 days after inoculation. Nine spectral vegetation indices, related to physiological parameters were used as features for an automatic classification. Early differentiation between healthy and inoculated plants as well as among specific diseases can be achieved by a Support Vector Machine with a radial basis function as kernel.The discrimination between healthy sugar beet leaves and diseased leaves resulted in classification accuracies up to 97%. The multiple classification between healthy leaves and leaves with symptoms of the three diseases still achieved an accuracy higher than 86%. Furthermore the potential of presymptomatic detection of the plant diseases was demonstrated. Depending on the type and stage of disease the classification accuracy was between 65% and 90%.     

玉米灰斑病脉冲Logistic模型研究

[目的]采用脉冲Logistic模型模拟玉米灰斑病流行过程。[方法]在不同品种玉米上接种玉米灰斑病菌并观察记录发病情况,采用脉冲Logistic模型对该病发展过程进行模拟,并与实际发病情况进行比较。[结果]人工接种验证结果表明,脉冲Logistic模型能够反映玉米灰斑病病害时间动态。推导得到,玉米灰斑病指数增长期从玉米出苗开始到每年7月上旬,逻辑斯蒂期从7月上旬到8月下旬,衰退期从9月上旬到玉米生育期结束。[结论]由模型推导的结果符合玉米灰斑病发展的生物学规律。     

黑龙江省大豆灰斑病菌生理小种鉴定

２００６～２００７年在黑龙江省各主要大豆产区采集并分离大豆灰斑病菌菌株２１０个,采用一套鉴别寄主对 采集的大豆灰斑病菌进行鉴定,结果表明：黑龙江省大豆灰斑病菌共有１６个生理小种,除以往报道的１～４号、６～ １１号生理小种外,又增加了５号、１２～１６号等６个新的生理小种。从主要生理小种在黑龙江省内各地的出现频率 来看,以１号小种出现频率最高,为４１．４３％,其次是７号小种,为１３．３３％,１０号小种出现频率为６．６７％,占第三 位。黑龙江省内大豆种植区主要以１号小种占优势,各地小种的组成和比例均有所不同。     

<Emphasis Type="Italic">Cercospora zeina</Emphasis> is the causal agent of grey leaf spot disease of maize in southern Africa

The aim of our study was to identify the causal agent of grey leaf spot disease of maize in southern Africa. Single-conidial cultures were recovered from maize leaves with typical disease symptoms sampled from several fields in South Africa, Zambia and Zimbabwe. Morphology, cultural characteristics, and a PCR-based test using Cercospora zeae-maydis and C. zeina-specific primer sets identified all single-conidial cultures as C. zeina. In addition, sequence alignment of DNA fragments of the internal transcribed spacer region (ITS1, ITS2, and the 5.8S gene) and elongation factor 1-α grouped all cultures in the same clade as the C. zeina ex-type culture CBS 118820. To by-pass cultivation of the slow-growing fungus, a rapid method to isolate DNA directly from lesions was successfully applied for PCR identification of C. zeina with species-specific ITS and histone primers. Koch’s postulates were fulfilled for C. zeina by artificially inoculating maize plants in a greenhouse, re-isolating conidia emerging from lesions and verifying pathogen identity with molecular techniques. These results provide evidence that confirms the presence of C. zeina and absence of C. zeae-maydis in commercial maize plantations in southern Africa.