Effects of winter wheat cultivars and seed rate on the biological characteristics of naturally occurring weed flora   总被引：3，自引：0，他引：3  

N E Korres  & R J Froud-Williams 《Weed Research》2002,42(6):417-428

Summary Differential competitive ability of six winter wheat cultivars and traits that confer such attributes were investigated for a range of seed rates in the presence or absence of weeds for a naturally occurring weed flora in two successive years in split-plot field experiments. Crop height and tillering capacity were considered suitable attributes for weed suppression, although competitiveness is a relative rather than an absolute characteristic. Maris Huntsman and Maris Widgeon were the most competitive cultivars whereas Fresco was the least competitive. Manipulation of seed rate was a more reliable factor than cultivar selection for enhancement of weed suppression, although competitiveness of cultivars Buster, Riband and Maris Widgeon was not enhanced by increased seed rate. Crop densities ranging between 125 and 270 plants m⁻² were found to offer adequate weed suppression. Linear relationships were observed between individual and total weed species dry weight and reproductive structures per unit area.  相似文献   

Studies on the Epidemiology of Tropical Theileriosis (Theileria annulata Infection) in Cattle in Central Anatolia,Turkey     

Sayin F  Dinçer S  Karaer Z  Cakmak A  Inci A  Yukari BA  Eren H  Vatansever Z  Nalbantoglu S 《Tropical animal health and production》2003,35(6):521-539

An epidemiological survey for Theileria annulata infection was conducted in 12 selected villages around Ankara in Central Anatolia, Turkey, during the period April 1990 to January 1993. During the survey, 198 cattle of 30 local breeds, 84 Holstein-Friesian×local breeds and 84 Holstein-Friesian breed were examined for antibodies to T. annulata and the presence of the vector ticks. Four species of Hyalomma ticks were identified: Hyalomma anatolicum anatolicum, Hyalomma anatolicum excavtum, Hyalomma detritum and Hyalomma marginatum marginatum. Salivary gland staining indicated that infected adult ticks of all four species were present and, therefore, were implicated in the transmission of tropical theileriosis in the field. Generally, the Hyalomma infestation rate was low, with the heaviest infestations occurring on the older animals. Young adults and calves had very low infestation rates. Most ticks seen on cattle were adults, very few nymphs were found. The blood smear and serological examination of the 198 cattle conducted in March, before the start of the first disease season, showed that the prevalence of piroplasmosis was 11.1% (22 out of 198) and the seroprevalence of T. annulata was 10.6% (21 out of 198). Forty-three animals were then excluded from the study because they were seropositive and/or harboured piroplasms. Ninety-two seronegative animals showed piroplasmosis (92 out of 155) and 34 seronegative animals became seropositive for T. annulata (34 out of 155) during the three disease seasons. One animal became clinically ill with tropical theileriosis and required treatment. The incidence of cattle showing piroplasmosis and disease in the total study sample was 50.7% and 0.5% per disease season, respectively. The seroconversion rate of new infection with T. annulata in the total study was 14.3% per animal season. The number of cattle showing piroplasmosis was much greater than the number of seropositive cattle, which may indicate the presence of another species of Theileria. The two different management systems encountered in the study were considered to have influenced the tick infestation levels.  相似文献   

Plant yield response to artificial infestation of the false chinch bug,Nysius raphanus, confined on spring canola     

N. Demirel  W. Cranshaw 《Phytoparasitica》2006,34(5):477-485

A 2-year study was conducted to evaluate the relationship of plant yield responses to artificial infestations of the false chinch bug (FCB)Nysius raphanus (Howard) on spring canola in Colorado, USA. Yield losses were greater when infestation occurred at the early flowering stage (EFS) than at the early pod stage (EPS), in both 2001 and 2002. In the first trial in 2001, with infestations of 10, 20 and 40 FCB/head, the respective average yield losses over all cultivars were 43%, 68% and 69%, respectively, compared with the non-infested control at the EFS, but 11%, 26% and 23% at the EPS. In the second trial in 2001, with infestations of 10, 20 and 40 FCB/head, the respective average yield losses over all cultivars were 26%, 58% and 55% at the early EFS, but 35%, 20% and 35% at the EPS. Yield reductions from FCB infestation were lower in 2002 than in 2001. In the first trial in 2002, with infestations of 10, 20 and 40 FCB/head, the respective average yield losses of all cultivars combined were 31%, 51% and 68% at the EFS, and 13%, 32% and 18% at the EPS. However, in the second trial in 2002, with the same numbers of FCB per head, no yield reductions were observed at either EFS or EPS. The number of FCB causing 10% yield loss in the four trials ranged from 6.1 to 39.4 FCB/head (avg. 14.8) following infestation at the EFS and 15.4–109.8 (avg. 41.8) following infestation at the EPS. Cultivar responses to FCB may also influence FCB yield reductions. However, in these studies all eight tested cultivars sustained yield loss in at least one trial at some FCB infestation level. Variation between trials was substantial but a significant level of resistance to FCB injury did not occur among the tested cultivars. http://www.phytoparasitica.org posting Sept. 18, 2006.  相似文献   

大豆锈病研究现状与进展   总被引：4，自引：0，他引：4  

许艳丽;李春杰;赵丹  ;刘喜梅  ;潘凤娟  ;王宏 《植物保护》2006,32(4):9-13

大豆锈病近年在东南亚、南美洲发展迅速,对大豆生产威胁越来越大,尤其2004年11月登陆美国大陆,更引起大豆研究者、大豆生产国和进口国的极大关注。本文介绍了近年国际上大豆锈病的研究进展,主要包括大豆锈病的发现、地理分布、病原、症状、寄主范围、病原菌生理分化和防治技术研究等。  相似文献   

香菇烂筒病及其病因研究初报   总被引：1，自引：1，他引：0  

姜华芳  林进心 《食用菌学报》1998,5(1):61-64

本文报道了香菇烂筒病的发生情况、症状及病原体的鉴定。笔者在福建省不同地方调查了早、中、晚期发病且症状明显的菇筒,分离、培养、鉴定了病原,并作回接发病试验,证实土壤中的木霉(Trichoderma spp.)是引起烂筒病的重要病原。  相似文献   

Fruit infestation of Acacia tortilis (Forsk) hyne by Bruchidius andrewesi Pic. (Coleoptera: Bruchidae) in the Thar desert     

Satya Vir  S.K. Jindal 《Forest Ecology and Management》1994,70(1-3):349-352

Bruchidius andrewesi Pic. has been recorded as a serious pest of pods and seeds of Acacia tortilis in the Thar desert of India. Pest infestation on developing pods and its relationship with morphological traits is reported. Pod infestation varied from 5 to 19% with 5–29% infestation of seeds. Infestation of pods is directly related to infestation of seed (r = 0.72^**), and both pod and seed infestation are also directly correlated with loss in seed biomass (r = 0.79^** and R = 0.88^**). The infestation of pods starts in November and increases steady until harvest. Seeds kept in the laboratory for further studies were found to be 100% infested with B. andrewesi, as the insect multiplied faster under these conditions. The heavy infestation is damaging not only to A. tortilis but also to other leguminous trees of the desert. Bruchidius andrewesi has also been found on pods and seeds of Prosopis cineraria, an important indigenous tree of the region.  相似文献   

Q型烟粉虱为害对不同辣椒品种叶绿素及营养物质的影响   总被引：1，自引：0，他引：1  

吕敏  吴琳  苏建坤  祝树德 《江苏农业学报》2014,(6)

为明确辣椒品种对烟粉虱的抗性机制,以不同抗性程度的辣椒为试验材料,研究了其受Q型烟粉虱危害后体内生理指标的变化。结果显示,Q型烟粉虱危害后,辣椒叶绿素和可溶性糖含量均较对照(未接虫)增加,其中抗性品种(苏椒5号、新研988椒王)叶绿素含量增加显著(P0.05);可溶性糖含量以抗性品种增幅最大(P0.05),中抗品种(萧新九号、湘辛三号)次之(P0.05),感虫品种(港上红尖椒、大禹牛角王)的增幅最小。烟粉虱危害后所有参试品种除中抗品种湘辛三号外,其余品种的可溶性蛋白含量均较对照降低;所有参试品种的游离脯氨酸含量均显著降低(P0.05),感虫品种港上红尖椒、大禹牛角王的游离脯氨酸含量均显著高于高抗及中抗品种(P0.05)。因此,辣椒品种对Q型烟粉虱的抗性强弱与叶片叶绿素含量、可溶性糖含量、游离脯氨酸含量有关,而与可溶性蛋白含量无明显相关。  相似文献   

The use of ethylene diffusers is comparable to treatments with sprayed ethylene to reduce the damage caused by the olive moth (<Emphasis Type="Italic">Prays oleae</Emphasis> Bern.)     

I. Sabouni  R. Rosales  D. Garrido  J. M. Ramos 《Journal of pest science》2008,81(4):193-197

In 2002 and 2003, six field experiments were conducted at three olive groves of southern Spain in order to compare the effects of two types of ethylene treatments (sprayed and diffusers) on the olive losses caused by the olive moth (Prays oleae Bern.) as well as on the activity and effectiveness of oofagous predators. Both treatments showed to be effective to control the pest; in the two years studied the mean reduction in final infestation due to ethylene was of 35% with respect to the controls trees, and none affected negatively the action of natural predators of P. oleae. In addition, the use of diffusers set on the trees at the end of flowering period will help the farmers to overcome the problems of determination of optimum time for sprayed treatments of ethylene.  相似文献   

Resistance to bird cherry-oat aphid (Rhopalosiphum padi L.) in winter wheat varieties     

Mária Papp  Ákos Mesterházy 《Euphytica》1993,67(1-2):49-57

Summary In Hungary the bird cherry-oat aphid (Rhopalosiphum padi L.) is the most frequent aphid species in winter wheat (Triticum aestivum L.). Estimations of infestation by R. padi as well as measurements of grain yield and thousand-kernel mass were carried out in 26 winter wheat genotypes in conditions of naturally infested and not infested (protected) control plots. The experiment was performed in isolated conditions in two field cages covered by nets. The aphids overwintered on wheat and got into cage, extremely quickly multiplied, therefore there was no need to apply any artificial aphid infestation. Highly significant differences were demonstrated among genotypes in infestation severity of R. padi as well as in losses of grain yield and thousand-kernel mass. The most resistant variety GK Zombor had 25% infestation, and the most susceptible one GK Lili had 79.2%. The reduction of grain yield of the most tolerant genotypes (GK Korány, Downy, Mv 4, Jubilejnaja 50, Mv 8, GK Kincsö and GK Zombor) was 26–33%, and that of thousand-kernel mass was 23–30%. The most sensitive genotypes (GK Lili, GK Örzse, GK Koppány and Mv 13) suffered 58–63% losses in yield, and 40–50% in thousand-kernel mass. A close correlation was found between infestation of R. padi in different wheat genotypes and losses of grain yield (r=0.7572, P<0.001). Also there were tolerance differences among genotypes even within the same level of infestation. The reductions of thousand-kernel mass correlated very closely with the reductions of grain yield (r=0.9212, P<0.001), that makes screening possible by reductions of thousand-kernel mass. These results have found application in breeding. The leaf pubescence of the varieties studied did not generally influence the infestation by R. padi.  相似文献   

Sources of resistance to Verticillium wilt in Capsicum     

M. M. González-Salán  P. W. Bosland 《Euphytica》1991,59(1):49-53

Summary A total of 125 novel accessions of Capsicum annuum L. and Capsicum baccatum L. were screened for sources of resistance to Verticillium wilt (Verticillium dahliae Kleb). A soil infestation method with 2000 microsclerotia of V. dahliae per gram of planting medium, and a soil temperature of 25±3°C, identified 27 Capsicum accessions with resistance to Verticillium wilt. P.I. 215699 (a mixture of Capsicum baccatum var. microcarpum and Capsicum annuum), P.I. 535616 (Capsicum annuum), and P.I. 555614 (Capsicum annuum), had the lowest disease severity and the highest percentage of resistant plants.  相似文献