Simulating evolution of glyphosate resistance in Lolium rigidum II: past, present and future glyphosate use in Australian cropping   总被引：1，自引：0，他引：1  

P Neve  A J Diggle†  F P Smith‡  & S B Powles 《Weed Research》2003,43(6):418-427

Glyphosate is a key component of weed control strategies in Australia and worldwide. Despite widespread and frequent use, evolved resistance to glyphosate is rare. A herbicide resistance model, parameterized for Lolium rigidum has been used to perform a number of simulations to compare predicted rates of evolution of glyphosate resistance under past, present and projected future use strategies. In a 30‐year wheat, lupin, wheat, oilseed rape crop rotation with minimum tillage (100% shallow depth soil disturbance at sowing) and annual use of glyphosate pre‐sowing, L. rigidum control was sustainable with no predicted glyphosate resistance. When the crop establishment system was changed to annual no‐tillage (15% soil disturbance at sowing), glyphosate resistance was predicted in 90% of populations, with resistance becoming apparent after between 10 and 18 years when sowing was delayed. Resistance was predicted in 20% of populations after 25–30 years with early sowing. Risks of glyphosate resistance could be reduced by rotating between no‐tillage and minimum‐tillage establishment systems, or by rotating between glyphosate and paraquat for pre‐sowing weed control. The double knockdown strategy (sequential full rate applications of glyphosate and paraquat) reduced risks of glyphosate and paraquat resistance to <2%. Introduction of glyphosate‐resistant oilseed rape significantly increased predicted risks of glyphosate resistance in no‐tillage systems even when the double knockdown was practised. These increased risks could be offset by high crop sowing rates and weed seed collection at harvest. When no selective herbicides were available in wheat crops, the introduction of glyphosate‐resistant oilseed rape necessitated a return to a minimum‐tillage crop establishment system.  相似文献   

Analysis of the association among three viruses infecting hop in Australia     

S. J. Pethybridge †  W. W. Turechek 《Plant pathology》2003,52(2):158-167

Associations among Hop latent virus (HpLV), Hop mosaic virus (HpMV), and Apple mosaic virus (ApMV) were assessed in five hop cultivars at four commercial hop-growing regions in Victoria and Tasmania, Australia. The presence or absence of each virus was confirmed by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Spatial patterns of virus-infected plants were characterized using the Spatial Analysis by Distance IndicEs ( sadie ) system of pattern analysis. The association among viruses (occurrence and covariation) was assessed using the Jaccard similarity index, Spearman's rank correlation coefficient, and sadie . The spatial pattern of plants infected by HpLV and HpMV ranged from random to highly aggregated depending upon the cultivar infected and the mean disease incidence. The spatial pattern of plants infected by ApMV was aggregated in six of the seven plots where ApMV was present. A strong positive association between HpLV and HpMV was found in all cultivars at all locations. This association may be the result of the viruses sharing a common aphid vector species, the presence of one virus enhancing the ability of the aphid vector to acquire the other virus either through transencapsidation or influences on virus titre, or mixed infections within source plants. Significant associations, positive or negative, were found less frequently between HpLV and ApMV, and HpMV and ApMV.  相似文献   

Predicting effective doses for the joint action of two fungicide applications   总被引：1，自引：0，他引：1  

N. D. Paveley †  J. M. Thomas  T. B. Vaughan  N. D. Havis  D. R. Jones 《Plant pathology》2003,52(5):638-647

A function was derived to predict fungicide efficacy when more than one application of a single active ingredient is made to a crop, given parameters describing the dose–response curves of the component single-spray applications. In the function, a second application is considered to act on that proportion of the total pathogen population which was uncontrollable at the time of the first application (represented by the lower asymptote of the dose–response curve for the first treatment), plus any additional part of the population which survived the first application as a result of a finite dose being applied. Data to estimate the single-spray dose–response curve parameters and validate predictions of two-spray programme efficacy were obtained from separate subsets of treatments in four field experiments. A systemic fungicide spray was applied to wheat at a range of doses, at one or both of two times (t₁ and t₂), in all dose combinations. Observed values of the area under the disease progress curve (AUDPC) for septoria leaf blotch (Mycosphaerella graminicola) were used to construct response surfaces of dose at t₁ by dose at t₂ for each culm leaf layer. Parameters were estimated from single-spray and zero-dose treatment data only. The model predicted a high proportion (R² = 71–95%) of the variation in efficacy of the two-spray programmes. AUDPC isobols showed that the dose required at t₂ was inversely related to the dose at t₁, but the slope of the relationship varied with the relative timings of t₁ and t₂ in relation to culm leaf emergence. Isobols were curved, so the effective dose – the total dose required to achieve a given level of disease suppression – was lower when administered as two applications.  相似文献   

Modelling Plant Disease Epidemics     

A. van Maanen  X.-M. Xu 《European journal of plant pathology / European Foundation for Plant Pathology》2003,109(7):669-682

An epidemic is the progress of disease in time and space. Each epidemic has a structure whose temporal dynamics and spatial patterns are jointly determined by the pathosystem characteristics and environmental conditions. One of the important objectives in epidemiology is to understand such spatio-temporal dynamics via mathematical and statistical modelling. In this paper, we outline common methodologies that are used to quantify and model spatio-temporal dynamics of plant diseases, with emphasis on developing temporal forecast models and on quantifying spatial patterns. Several examples of epidemiological models in cereal crops are described, including one for Fusarium head blight.  相似文献   

桃品种需冷量评价模式的探讨   总被引：34，自引：2，他引：34  

王力荣  朱更瑞  方伟超  左覃元 《园艺学报》2003,30(4):379-383

 通过1986～2001年对450余份桃品种需冷量的7．2℃模式、0～7．2℃模式(不包括0℃)和犹它模式比较分析，归纳出桃品种需冷量的评价模式为：以秋季日平均温度稳定低于7．2~C的日期为需冷量测定的起点，以0～7．2℃累积低温值作为需冷量的评价标准比较适宜；犹它模式在中需冷量和长需冷量范围内能有效预测休眠的结束，而不适宜低需冷量品种的测定；7．2℃模式不适宜作为需冷量的评价模式。品种的需冷量与叶芽开放和始花期的相关系数分别为0．52和0．58，均达到极显著水平。提出了桃品种需冷量评价的系列标准参照品种。  相似文献   

新疆冬小麦农田蒸散估算模型的研究   总被引：1，自引：0，他引：1  

刘绍民  傅伟东 《干旱区资源与环境》1997,11(4):68-72

本文在田间试验资料的基础上，综合考虑了影响冬小麦农田蒸散的气象、生物学特性和土壤水分等因素，选用蒸发力、冬小麦的叶面积指数和相对有效土壤湿度建立了新疆冬小麦农田蒸散估算模型，并且检验了该模型的计算效果。  相似文献   

纤维粗度对浆张性能的影响   总被引：3，自引：0，他引：3  

洪传真 《林产工业》1997,(6)

利用纤维质量分析仪研究针、阔叶木浆打浆后的纤维形态，观察打浆后的纤维粗度及测定手抄片的性能。结果表明，打浆能改变纤维的粗度，从而影响手抄片的物理性能和不透明度。  相似文献   

山羊传染性胸膜肺炎支原体和绵羊肺炎支原体对抗菌药物敏感性的研究   总被引：4，自引：0，他引：4  

林密  柴静  孙继国  王爱华 《中国兽药杂志》2004,38(5):29-32

测定了环丙沙星、氧氟沙星、单诺沙星、红霉素、罗红霉素、泰乐菌素、泰妙菌素、四环素等8种药物对羊肺炎支原体两个标准株Y-98和Y-goat的体外抑菌浓度以及红霉素与氧氟沙星、泰乐菌素对Y-goat和四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏作用.结果表明,这8种抗菌药物对Y-goat和Y-98的MIC(μg/mL)分别为:环丙沙星0.223、0.002 23,氧氟沙星0.281、0.014 0,单诺沙星0.136、0.014 0,红霉素0.021 8、无效,罗红霉素0.032 7、无效,泰乐菌素0.042 2、0.039 0,泰妙菌素0.021 7、0.052 0,四环素0.195、0.052 0.红霉素与氧氟沙星的联合药敏指数为1,是相加作用;红霉素与泰乐菌素对Y-goat的联合药敏指数为1.5,是无关作用;四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏试验指数均为0.375,是协同作用.  相似文献   

景观生态学原理与方法在荒漠化研究中应用的理论分析     

王力  郭广  胡爱军  马明亮 《青海草业》2004,13(3):20-23,35

荒漠化发生发展的过程实际上是指在自然和人为因素的作用下，生态系统结构遭受破坏、功能过程受阻和演变发生异化的过程，其防治的根本措施是恢复和重建健康的生态系统。所以，景观生态学理念在荒漠化的研究和防治中有着重要的意义。本文从荒漠化与生态系统结构、功能变化、荒漠化与生物多样性、荒漠化生态系统的物质循环和能量流动以及荒漠化生态系统的稳定性等方面论述了景观生态学理念在荒漠化研究中应用的可行性，并重点分析了景观生态学关于景观格局变化的评价指标与荒漠化土地动态变化之间的关系。  相似文献   

稻瘟菌激发子CSB I专化性及相关性质研究   总被引：5，自引：1，他引：5  

李云锋  王振中  贾显禄 《植物病理学报》2004,34(3):237-243

 以一套水稻抗稻瘟病近等基因系为材料,接种稻瘟菌(Magnaporthe grisea)细胞壁来源的糖蛋白激发子CSB I,其诱导植保素的积累在高度非亲和性互作水稻远高于亲和性互作水稻;研究同时表明,CSB I可专化性诱导完全非亲和性互作和高度非亲和性互作水稻的过敏性坏死反应;表明该激发子具有小种-品种专化性。经热、胰蛋白酶和过碘酸钠处理后的生物活性检测结果表明,CSB I的活性位点为糖基部分。经pH稳定性检测,CSB I在酸性及相对弱碱性条件下较稳定;而在强碱性条件下,激发子活性下降较多,甚至完全丧失。对CSB I诱导活性的有效浓度测定表明,激发子诱导水稻叶片酶活性升高的最低有效浓度为0.07~0.70 nmol/L。  相似文献