The role of fungal endophyte infection in the evolution of Lolium multiflorum resistance to diclofop-methyl     

M M Vila Aiub  & C M Ghersa 《Weed Research》2001,41(3):265-274

Diclofop-methyl resistance was evaluated in populations of Italian ryegrass ( Lolium multiflorum Lam.) infected and uninfected with fungal endophyte ( Neotyphodium ). Survival was tested in susceptible populations using herbicide screening. The results served as inputs to a model for investigating the role of endophyte infection in the evolution of L. multiflorum resistance to herbicide. The tolerance of infected plants varied depending on the origin of the population and the herbicide dose. Only in some populations and at some diclofop-methyl doses did plants infected with these endophytes have higher survivorship than endophyte-free plants. The model demonstrated that endophytes might indeed play an important role in the evolution of herbicide-resistant weeds, delaying the appearance of herbicide resistance.  相似文献   

Cutting weeds with a CO₂ laser     

T Heisel  J Schou  S Christensen  & C Andreasen† 《Weed Research》2001,41(1):19-29

Stems of Chenopodium album . and Sinapis arvensis . and leaves of Lolium perenne . were cut with a CO₂ laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO₂ laser than C. album . When stems were cut below the meristems, 0.9 and 2.3 J mm⁻¹ of CO₂ laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2-true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne .  相似文献   

N-(pyrid-3-yl)thioureas and derivatives as acaricides. II. Quantitative structure-activity relationships and chemodynamic behaviour     

Alfons Pascual  Alfred Rindlisbacher  Heinz Schmidli  Erich Stamm 《Pest management science》1995,44(4):369-379

The biological activity of a series of N-(pyrid-3-yl)thioureas and -carbodiimides, analogues of the insecticide/acaricide diafenthiuron, towards the carmine spider mite (Tetranychus cinnabarinus Boisd.) and the two-spotted spider mite (T. urticae Koch) was analysed using QSAR methodology. A canonical correlation analysis allowed for the establishment of a prediction model and the identification of outliers within that model. The chemodynamic behaviour of certain compounds in the two series, including these outliers, determined by using photochemical experiments in the laboratory as well as in the glasshouse, was shown to be responsible for anomalous results obtained in the biological tests. It was found from the above study that the biological activity towards both spider mite species is extremely sensitive to the kinetics of formation of the carbodiimides from the corresponding thioureas and to the photostability of the former. The results obtained with a thiourea which underwent no appreciable photochemical transformation into the corresponding carbodiimide supported the hypothesis that the thioureas are also in-vivo propesticides of the acaricidal carbodiimides.  相似文献   

一年生黑麦草品种在贵州南部的引种试验   总被引：4，自引：0，他引：4  

左相兵尚以顺  陈培燕 《四川草原》2006,(1):6-9

对国内14个一年生黑麦草品种在贵州南部独山地区进行引种试验比较。结果表明:各参试品种均能良好生长,安全越冬。一年可刈割4～5次,鲜草产量58429.2～84842.4kg/hm2,多数品种2、3、4月鲜草产量较高,2月份产量在20000kg/hm2以上的就有5个。综合性状表现较好的依次为:抗锈王,邦德,凯牧,沃土,特高,杰威和海湾等,可以在贵州大部分地区栽培利用。  相似文献   

Effect of temperature and leaf wetness duration on infection of sweet oranges by Asiatic citrus canker   总被引：2，自引：0，他引：2  

M. Dalla Pria  R. C. S. Christiano  E. L. Furtado  L. Amorim  A. Bergamin Filho 《Plant pathology》2006,55(5):657-663

Asiatic citrus canker, caused by Xanthomonas smithii ssp. citri , formerly X. axonopodis pv. citri , is one of the most serious phytosanitary problems in Brazilian citrus crops. Experiments were conducted under controlled conditions to assess the influence of temperature and leaf wetness duration on infection and subsequent symptom development of citrus canker in sweet orange cvs Hamlin, Natal, Pera and Valencia. The quantified variables were incubation period, disease incidence, disease severity, mean lesion density and mean lesion size at temperatures of 12, 15, 20, 25, 30, 35, 40 and 42°C, and leaf wetness durations of 0, 4, 8, 12, 16, 20 and 24 h. Symptoms did not develop at 42°C. A generalized beta function showed a good fit to the temperature data, severity being highest in the range 30–35°C. The relationship between citrus canker severity and leaf wetness duration was explained by a monomolecular model, with the greatest severity occurring at 24 h of leaf wetness, with 4 h of wetness being the minimum duration sufficient to cause 100% incidence at optimal temperatures of 25–35°C. Mean lesion density behaved similarly to disease severity in relation to temperature variation and leaf wetness duration. A combined monomolecular-beta generalized model fitted disease severity, mean lesion density or lesion size as a function of both temperature and duration of leaf wetness. The estimated minimum and maximum temperatures for the occurrence of disease were 12°C and 40°C, respectively.  相似文献   

Major gene resistance in Brassica napus (oilseed rape) is overcome by changes in virulence of populations of Leptosphaeria maculans in France and Australia     

Susan J. Sprague  Marie-Hélène Balesdent  Hortense Brun  Helen L. Hayden  Stephen J. Marcroft  Xavier Pinochet  Thierry Rouxel  Barbara J. Howlett 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(1):33-40

Resistance of Brassica napus (oilseed rape, canola) conferred by three different major resistance genes has been overcome by changes in virulence of Leptosphaeria maculans populations in France and Australia. In South Australia where B. napus cultivars with major gene resistance derived from Brassica rapa ssp. sylvestris were grown extensively, resistance was rendered ineffective within 3 years of commercial release of the cultivar. Disease severity was higher on cultivars with sylvestris-derived resistance than cultivars with polygenic resistance. This Australian situation is compared to that in France, where resistance conferred by the Rlm1 gene was overcome nation-wide in 5 years under commercial cropping practices, and also where a source of resistance introgressed into B. napus from B. juncea was rendered inefficient in 3 years in experimental field plots near Rennes.  相似文献   

Spatial and temporal patterns of Lolium rigidum–Avena sterilis mixed populations in a cereal field     

J M BLANCO-MORENO  L CHAMORRO  & F X SANS 《Weed Research》2006,46(3):207-218

Through a detailed case study of a two‐species (Lolium rigidum and Avena sterilis) weed community at contrasting scales, this paper examined factors that affect weed distribution across space and time in a commercial wheat field in north‐east Spain. A. sterilis showed relatively stable spatial distribution and spatial structure of its population over time at large scale, with well‐defined patches, although weed density rose quickly. L. rigidum showed poorly defined patches that were not stable across time. Interaction between species could explain to some degree the spatial distribution at large scale: a negative relationship was detected between the spatial structures of both weed populations. At fine scale, both species showed a clear interaction effect from primary dispersal (more important in A. sterilis) and secondary dispersal from combine harvesting (more important in L. rigidum).  相似文献   

A target-site mutation is present in a glyphosate-resistant Lolium rigidum population   总被引：2，自引：1，他引：2  

AM WAKELIN  & C PRESTON† 《Weed Research》2006,46(5):432-440

Annual ryegrass (Lolium rigidum) is the only weed species to have evolved resistance to the broad‐spectrum herbicide glyphosate in Australia. A population that had failed to be controlled by glyphosate was collected from a vineyard in the Adelaide Hills region of South Australia. Dose–response experiments on this population (SLR 77) showed that it was glyphosate resistant, with an LD₅₀ that was 1.9–3.4 times higher than that of a susceptible population (VLR 1). The movement of radiolabelled glyphosate within SLR 77 plants showed that this population did not have the differential glyphosate translocation mechanism of resistance common to several other Australian glyphosate‐resistant populations. Subsequent analysis of shikimic acid accumulation within the plant after glyphosate treatment showed that this population accumulated significantly less shikimic acid than a susceptible population, but more than a glyphosate‐resistant population with the translocation mechanism, indicating the possible involvement of another mechanism of resistance. Sequencing of a portion of the SLR 77 5‐enolpyruvylshikimate‐3‐phosphate synthase gene was carried out and a mutation causing an amino acid change at position 106 from proline to threonine was identified. This mutation is likely to be responsible for glyphosate resistance in this population, as mutations in this position have been found to be responsible for glyphosate resistance in goosegrass (Eleusine indica) from Malaysia. This paper represents the first report of target‐site glyphosate resistance in L. rigidum and provides evidence that this species has at least two mechanisms of glyphosate resistance present in Australia.  相似文献   

盐胁迫下百合两个品种的叶绿体和线粒体超微结构比较   总被引：15，自引：0，他引：15  

左志锐  高俊平  穆鼎  刘春 《园艺学报》2006,33(2):429-432

 对两个百合品种盐胁迫下超微结构的变化进行了研究分析。结果表明: ‘Prato’对照和低盐浓度处理下, 叶肉细胞内细胞器丰富, 叶绿体片层排列整齐, 高盐处理导致细胞器减少, 叶绿体解体; 而‘Sorbonne’在低盐处理水平表现异常, 其细胞器降解, 叶绿体空化, 片层排列松散, 且两品种的线粒体较叶绿体早表现出异常, 故推测可能是线粒体结构的损伤进而功能丧失, 最终导致叶绿体结构和功能的破坏,叶片提前衰老。  相似文献   

白菜病程相关蛋白1基因cDNA全长的克隆与分析   总被引：1，自引：0，他引：1  

王彦华  侯喜林  申书兴 《园艺学报》2006,33(5):985-988

 以水杨酸处理后的‘苏州青’白菜为材料, 通过RT2PCR和RACE技术, 获得了白菜病程相关蛋白PR-1基因的cDNA全长序列。该基因与甘蓝型油菜PR-1基因氨基酸序列的同源性为91% , 与拟南芥的同源性为78% , 与其它植物的同源性为57%～60%。Southern杂交表明该基因在白菜基因组中的拷贝数至少为2个。半定量RT2PCR分析表明, 2 mmol/L的水杨酸处理后12 h, 该基因的表达量达到高峰。  相似文献