柑桔白粉虱的发生规律与防治对策

柑桔白粉虱已成为危害柑桔生产的主要害虫。文章简述柑桔白粉虱的为害表现,发生规律及生活习性,分析柑桔白粉虱发生原因,并提出防治措施。     

基于灰色关联的机械总体设计方案模糊优选

针对机械系统设计方案各评价技术指标间模糊且相互关联的特点,研究了机械系统方案设计的决策问题,该文在综合考虑从优隶属度和灰色关联的基础上,提出了改进灰色关联模糊决策方法,从整体角度寻求复杂系统的最优设计方案。运用模糊数学隶属函数理论,对原始数据进行无量纲化和归一化处理,为防止技术指标信息在评价过程中丢失,建立了技术指标权重集及灰色关联系数矩阵,通过综合评价模型,实现了机械产品总体设计方案的模糊优选。最后,以YF27-315型薄板冲压液压机设计为例,验证该模型可以有效减少评价过程中的主观因素干扰,能全面、客观地对机械产品设计方案作出决策。     

冬闲田深水灌溉放养群鸭控制二化螟越冬基数及其为害研究

通过大田调查和试验表明,冬闲田春季深水灌溉放养群鸭,20d后对二化螟越冬基数的校正减退率达82.8%,对其1代为害的保苗效果达74.4%,对其2代为害的保穗效果达74.6%。表明该项措施可有效降低螟虫越冬基数和后期螟虫的发生为害。     

Disease severity and pathotype dynamics of Puccinia striiformis f.sp. tritici in Denmark

Disease severity of wheat yellow rust, Puccinia striiformis f.sp. tritici , was analysed in Denmark from 1985 to 1999 in relation to the effects of weather on winter survival, distribution of host cultivars and pathotype dynamics. Below-average temperatures in January and February (midwinter) reduced yellow rust on the susceptible cv. Anja, and in three of four growth seasons following cold winters no yellow rust was observed on any cultivar under natural conditions. The agronomic consequences of dispersal of yellow rust urediniospores from external sources to Denmark, in a period during which large areas were planted with relatively few wheat cultivars, were demonstrated in several cases, most evidently when the Yr9 and Yr17 resistance genes became ineffective. Yr9 was overcome by the pathogen in a period with severe yellow rust epidemics on commercial cultivars, while virulence for Yr17 was first observed in a year with almost no yellow rust. In contrast, the resistance in cv. Kraka ( Yr1, CV ) was increasingly effective in controlling yellow rust, because pathotypes with the matching combination of virulence declined in the pathogen population. Pathotype frequency dynamics were thus influenced by selection forces within the country, and by selection forces in areas where spores were spread to Denmark from outside. The importance of a sufficient level of partial resistance in the wheat germplasm to prevent too much damage by yellow rust epidemics, in the event that the resistance genes are overcome by the pathogen population, is emphasized.     

Spatial and Temporal Variation in Photon Flux Density on Rice (Oryza sativa L.) Leaf Surface

Abstract

Spatial and temporal variations of photosynthetic photon flux density (PFD) measured using small photodiodes (Hamamatsu, model G1118) attached on the leaf surface of rice (Oryza sativa L.) differed with the orientation and inclination even at the same height of the canopy. Under sunny conditions, the fluctuation pattern of PFD was mainly determined by the orientation and inclination of the leaf surface, and not by the daily change of PFD in the open, e. g., high peaks of PFD were observed in the morning on east-oriented leaves, but only low peaks on north-oriented leaves. Under overcast conditions, however, the PFD on the leaf surface depended highly on the PFD in the open irrespective of the leaf orientation and inclination. The present study suggests that the orientation and inclination should be considered as the major factors influencing the PFD regime (spatial variation and daily total PFD) within the rice canopy. To determine the effects of spatial and temporal variations of PFD on crop productivity, the daily net assimilation of each leaf was estimated from the obtained data and the light-photosynthesis curve.     

灰色关联度组合模型在涝灾预测中的应用

传统灰色预测模型在涝灾预测中有较多应用,但其预测精度较低。为提高模型的预测精度,在传统灰色预测模型基础上加入灰色关联度分析,从灰色关联度的角度发现数据之间的依赖关系,运用灰色预测模型预测数据的发展走向。以沈阳市1960-2010年涝灾年份数据为依据,建立灰色关联度组合模型,应用结果表明,该模型比传统灰色预测模型效果好,为涝灾预测增添了新手段。     

“一品红”花卉上烟粉虱的消长和防治研究

[目的]研究烟粉虱在"一品红"上的消长,为烟粉虱的防治提供参考。[方法]调查"一品红"不同生育生长期内烟粉虱的数量,研究其消长;比较不同处理在不同时期对烟粉虱的防治效果,研究优化综合防治措施。[结果]"一品红"全生育期有2个危害高峰;通过综合防治措施的落实,"一品红"的白茎病从2005年的30%下降到2006年的1.5%,2007年无发病植株。[结论]综合防治措施对烟粉虱的抑制效果较好。     

安徽凤阳玉米茎基腐病主要病原菌鉴定 及玉米新种质（自交系）的抗性分析

从凤阳县不同的玉米种植区采集玉米茎基腐病病株进行分离、纯化培养,并用分子生物学方法对病原菌进行鉴定。结果表明,凤阳的玉米茎基腐病的病原菌主要为禾谷镰孢菌(Fusarium.graminearum)、串珠镰孢菌(Fusarium.verticillioides)、尖孢镰孢菌(Fusarium.axysporum)、层出镰孢菌(Fusarium.proliferatum)和木贼镰孢菌(Fusarium.equiseti),其中,禾谷镰孢菌的分离频率最高,达47.05%,串珠镰孢菌次之,达26.47%。通过菌丝生长速度和致病性测定得出禾谷镰孢菌菌株QF12的致病性较强;品种抗性试验结果表明,玉米新种质(自交系)HZC15083、HZC15109、HZC15115、HZC15117和HZC15126达到中抗水平,13个新种质(自交系)为高感品种,1个为感病品种。     

Incidence of Viruses Infecting Allium Spp. in Greece

A survey identified viruses infecting garlic, leek and onion crops and wild Allium species in Greece. Virus identification was based on ELISA, immunoelectron microscopy, and occasionally on RT-PCR. Samples of cultivated Allium species were collected from five districts, whereas samples of twenty-seven wild Allium species were also collected from all over Greece. Onion yellow dwarf virus (OYDV) and Leek yellow stripe virus (LYSV) were identified in 98.5% and 83.7% of all samples, respectively, and were found in all regions. Allexiviruses were also detected in all regions and their incidence ranged from 62.5% to 70.5% (depending on region and type of allexivirus). Garlic common latent virus (GCLV) was detected in samples from Arcadia (97.6%) and Evia (18.0%) and in one field in Larissa (23.0%). Shallot latent virus (SLV) was found only in two areas (Evros and Theva) and in fields planted with imported propagative material, from Iran and China. The incidence of virus-like symptoms in leek crops ranged from 10.0% to 90.0% in different regions and fields and all symptomatic plants were found to be infected by LYSV. Onion yellow dwarf virus was only found in seven symptomatic onion samples from southern Greece. Allium ampeloprasum spp. ampeloprasum and Allium flavum, were the only wild Allium species found to be infected with LYSV. Finally Turnip mosaic virus (TuMV) was found in A. sphaerocephalon, A. guttatum, A. subhirsutum, and A. neapolitanum.     

室内空气品质的灰色评价

利用灰色系统理论的灰色关联分析方法 ,根据灰色关联矩阵提供的丰富信息对室内空气品质进行综合评价。通过比较分析 ,灰色评价方法计算过程简单方便 ,充分利用了获得的信息 ,结果直观可靠 ,是多因子综合评价较好的方法