不同小麦品种小麦白粉病发病程度及其田间发生动态分析

【目的】研究新冬60号、新冬57号、新冬40号和新冬20号小麦白粉病危害程度和田间发生动态,为科学防控小麦白粉病提供理论依据。【方法】采用定期定点调查的方法,系统调查不同品种小麦白粉病发生情况。【结果】新冬60号、新冬57号、新冬40号小麦白粉病田间发生动态基本一致。新冬60号、新冬57号、新冬40号和新冬20号小麦白粉病病情指数最高分别为8.22、7.11、37.63和25.48。新冬60号和新冬57号小麦白粉病田间发生程度极显著轻于新冬40号和新冬20号,新冬40号小麦白粉病田间危害程度极显著重于新冬20号。【结论】新冬60号和新冬57号小麦白粉病田间危害程度极显著轻于新冬20号,可根据田间发病情况,合理减施农药。新冬40号小麦白粉病田间发生程度极显著重于新冬20号,应加强对小麦白粉病的预防。     

青海高原禾草内生真菌资源的调查和分离

青海高原的高寒特性决定其生境内禾草植物的多样性和特异性,然而有关青海高原地区禾草内生真菌的研究报道较少,本研究对青海高原地区48个样点内禾草植物内生真菌带菌率和内生真菌分离进行了研究.结果表明,14种禾本科植物内生真菌平均感染率低于50％,而12种植物内生真菌平均感染率大于50％.其中,缘毛鹅观草(Roegneria pendulina)、紫花针茅(Stipa purpurea)、醉马草(Achnatherum inebrians)、中华羊茅(Festuca sinensis)、硬质早熟禾(Poa sphondylodes)、微药羊茅(F.nitidula)、毛稃羊茅(F.kiritowii)和紫羊茅(F.rubra) 的平均带菌率均超过80％.同时,同属禾草植物内生真菌带菌率存在差异.禾草内生真菌分离率较低,其中紫花针茅、麦宾草(El ymus tangutorum)、光稃早熟禾(P.psiolepis)和异针茅(S.aliena)内生真菌在菌落和分生孢子形态上存在差异.可见,青海高原禾草内生真菌带菌率较高,同时不同禾草内生真菌可能存在多样性.     

毛竹枯梢病普遍率与严重度关系初步探讨

通过对毛竹林自然发病情况连续3年的调查，获得了218组毛竹枯梢病普遍率和严重度问对应关系（I-S关系）的数据，在计算机上分析了其I-S间的关系。结果表明：毛竹枯梢病的I-S关系可用指数函数描述，病害逐年流行动态对I-S关系没有明显的影响，但寄主毛竹的抗病性和环境因子对病害的I-S关系有一定的影响。     

基于多指标区间数关联分析的相对隶属度方法

针对具有区间数的多指标决策问题,借鉴一种逼近于理想点(TOPS IS)分析方法的思想,采用区间数灰色关联度的计算方法,对正、负关联度,利用相对隶属度方法对多方案进行排序,给出了解决区间数多指标决策问题的计算步骤.本文将整个评价方案看作一个整体来寻求正、负理想方案,该方法避免了区间数难以排序的问题,具有可理解性和可操作性.最后给出实例以验证该方法的有效性和实用性.     

Rhynchosporium leaf scald disease incidence: seed source and spatial pattern

A programme of field trials for the study of the winter barley–Rhynchosporium commune pathosystem is reported. The associated seedborne disease rhynchosporium leaf scald is regarded as having an important impact on barley yields. The analysis in this study relates to the impact of the seed source (commercial or farm-saved seed) on disease incidence and to the spatial pattern of rhynchosporium leaf scald disease incidence. Disease incidence data were calculated from field data recorded as disease severity. Mean disease incidence was higher in the crops grown from farm-saved seed than in those grown from commercial seed, although great agronomic significance cannot be attached to this result. The spatial pattern of rhynchosporium leaf scald disease incidence was characterized in terms of the binary power law (BPL) and was indicative of an aggregated pattern. Programme-wide BPL results were described using a novel phytopathological application of a random coefficients model. These results have application in field sampling for rhynchosporium leaf scald disease.     

一类具有饱和发生率的虫媒传染病模型研究

考虑虫媒传染病具有潜伏期的特征,研究了一类具有饱和发生率的时滞传染病模型的动力学行为,确定了疾病是否流行的阈值R_0.当R_01时,无病平衡点全局渐近稳定,疾病将最终灭绝;当R_01时,唯一地方病平衡点条件稳定,系统会产生Hopf分支.     

The Evaluating Model of the BSC in the Audit of the Capacity of Sustainable Operation

With the increasingly economic competition in the World, the audit industry, numerous investors and the enterprises pay more and more attention on the audit of company's sustainable operation. In view of existing situation that the audit on the capacity of sustainable operation attach main importance to the finance of the audited company, in the result, it is difficult to recognize it completely. The model of the balanced scorecard is used, an indicator system that combine company's finance condition and non-finance condition is built in the sustainable operation audit. Basing on the way to process non-dimensional quantities of indicators, the audit use the analytic hierarchy process to determine the weights of the evaluating indicators and take the degree of gray incidence as the evaluation criteria.     

Mature plant and tissue resistance in the groundnut-peanut bud necrosis virus system

Summary Leaves and plants of different ages of a susceptible and two resistant groundnut genotypes were mechanically inoculated with peanut bud necrosis virus, and the percentage of plants with systemic symptoms (incidence) and the incubation period were determined. The incidence decreased sharply in all three genotypes with the age of the inoculated leaves and plants. The incubation period increased with the age of leaves and plants. Apparently, only young tissue of young plants is susceptible, while mature tissue and plants are highly resistant. This mature tissue and plant resistance occurs irrespective of the susceptibility level of the genotype to peanut bud necrosis virus, however, it develops earlier in the resistant than in the susceptible genotypes.Abbreviations IP₅₀ incubation period - PBNV peanut bud necrosis virus - TSWV tomato spotted wilt virus     

改制毛竹林害虫虫情变动的探讨

改制前的毛竹林，每两年有一年无笋或少有笋、有几个月林内立竹上无叶，竹子上的害虫种类简单，危害不重，有些害虫少发生或不能发生；能发生或危害重的竹子害虫，在生活过程中，习性多少都发生一些变化，如竹织叶野螟有迁飞习性，毛笋泉蝇、毛竹黑叶蜂部分蛹有滞育习性，赭翅双叉端环野螟有同时以小幼虫和老熟幼虫越冬习性，以适应无笋、少叶的营养环境。改制后的毛竹林地被物挖锄，天敌资源锐减，竹林中年年有笋，立竹上终年披叶，使竹子害虫食物条件改善，竹子害虫种类逐年增加，害虫迁飞、滞育习性的比例逐年减少，危害逐年加重。