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1.
通过田间试验研究了底墒差异对西瓜生长和产量以及水分利用效率的影响。结果表明:播前适宜的底墒(0~100 cm土层储水量在223~238 mm)可以促进西瓜主蔓长的生长、叶片的发生以及提高西瓜叶面积;播前底墒较丰时(0~100 cm土层储水量在283 mm),不利于西瓜前期的生长。与播前不灌水相比,播前灌水造墒处理不同程度地提高了地上部生物量和西瓜产量;其中播前灌水量达到70m3/667m2时,西瓜产量和瓜蔓重最大,分别为1 645 kg/667m2和25.4 kg/667m2,相比播前不灌水处理分别提高了30%和49%。西瓜水分利用效率随播前土壤储水量增加而降低。 相似文献
2.
通过田间试验研究了播前灌水营造底墒差异对压砂地土壤水分动态变化、西瓜耗水规律、西瓜产量和水分利用效率的影响。结果表明：播前灌水造墒处理不同程度提高了1 m土层土壤水分含量,但灌水定额过大（70 m3·667m-2和55 m3·667m-2）会引起水分深层渗漏;西瓜生育前期耗水量随着播前灌水量降低而降低;西瓜需水高峰期,当1 m土层底墒在222～270 mm范围内,耗水量随1 m土层底墒增加而降低;底墒差异还会影响收获期1 m土层土壤水分含量;综合西瓜产量和水分利用效率,在试验区域内,当西瓜生育期降雨量在85 mm左右,1 m土层土壤储水量在250 mm就可保证西瓜正常生长。另外,压砂地夏季休闲措施提高了土壤水分含量,1 m土层土壤储水量增加了2.7 mm,为下一季作物提供了良好的土壤水分条件。 相似文献
3.
旱地不同生态型冬小麦水分利用效率对播前底墒的响应 总被引：13，自引：1，他引：12
针对甘肃陇东旱作区冬小麦产量低而不稳、水分利用效率低下,冬小麦夏季休闲期正值该区的降雨高峰期,降雨和无效蒸发同步且土壤保持水分不足的问题开展试验研究。通过夏季休闲期的地膜覆盖、集雨抑蒸,提高播前底墒,并对模拟底墒试验的产量、水分利用效率(WUE)进行分析,得出:冬小麦产量与播前底墒具有显著的相关性,基于一定底墒条件下的底墒和生育期降水互作分析表明,产量与播前底墒的拟合度高于与生育期降水拟合;播前底墒对不同生态类型冬小麦产量和WUE有显著的影响,高底墒条件下的产量、WUE分别较中底墒和低底墒高28.40、70.43和22.94、75.06个百分点;在夏休闲期采用集流入渗抑蒸技术,使土壤蓄水效率由传统耕作的33%~38%提高到60%~70%,蓄保夏休闲期的降雨于土壤中,对于稳定提高适宜生态型冬小麦产量有显著的作用。 相似文献
4.
土壤底墒与苗期灌溉量对玉米出苗和苗期生长发育的影响 总被引：4，自引：3，他引：4
采用二次回归正交设计方法,进行了土壤底墒和苗期灌溉量对玉米出苗和苗期生长发育影响的盆栽试验研究,分别建立了苗期株高、总干重与土壤底墒、灌溉量关系回归模型。研究结果表明,土壤底墒显著影响玉米出苗率,玉米出苗率最高时的壤土和沙土底墒分别为20.6%和13.6%;土壤底墒和苗期灌溉量的交互作用对株高和单株干物质重量具有相互协同效应和替代效应;玉米苗期株高和总干重最大时的壤土底墒均为15.1%,最佳灌溉量分别为86.7 mm和91.7 mm;玉米苗期株高和总干重最大时的沙土底墒分别为12%和13%,最佳灌溉量均为76 mm。 相似文献
5.
于2015—2016年选用优质小麦品种新麦26进行大田试验,在拔节期和开花期分别设置目标相对含水量为田间持水量的70%、75%、80%进行补灌。通过3个测墒补灌处理W70、W75、W80和一个传统灌溉Wck,用全生育期补灌水(W0)为对照,研究不同生育时期和不同目标含水量的测墒补灌对冬小麦产量、耗水特性、品质等的影响。结果得出:冬小麦在拔节期和开花期补充灌水量为WckW80W75W70;四个灌水处理下冬小麦对土壤水的消耗量主要分布在0～80 cm土层且测墒补灌处理增加了对土壤水的消耗比例。三个测墒补灌处理下的冬小麦湿面筋含量显著高于Wck。水分利用效率为W75W70W80WckW0,W70、W75、W8处理之间差异不显著。W75处理下籽粒产量显著高于W70。综合考虑不同处理的灌水量、籽粒产量和水分利用效率等指标,可得在本试验条件下在冬小麦的需水关键期(拔节期、开花期)将土壤墒情保持在田间持水量的75%为较佳灌水处理,冬小麦高产节水成效显著。 相似文献
6.
陇中半干旱区集雨限灌对马铃薯干物质积累和产量的影响 总被引：6，自引：0，他引：6
研究了大田条件下集雨有限补偿灌溉对旱区马铃薯干物质积累分配和产量的影响。结果表明:进行有限补充灌溉对旱作马铃薯有显著的增产效果,其经济系数也得到相应提高,与对照(不灌水)相比,补灌处理产量增幅在3.91%~21.21%之间,苗期补灌45 mm与90 mm对马铃薯产量的补偿效应显著;补灌马铃薯干物质积累量与对照相比无显著差异,但花后干物质的分配运转,苗期补灌处理比对照移动量大,转换率高,有利于花后薯块营养物质的积累;薯块膨大期补灌45 mm和90 mm,在干物质积累和花后干物质转化方面均低于对照,增产效果也并不显著。 相似文献
7.
为探明沟垄集雨结合不同时期补灌措施的集雨保墒效果,2013-2015年在宁南半干旱区设置不同补灌模式(全生育期不灌溉、前期(拔节期)补灌、后期(抽穗期)补灌、前后期均补灌)结合补灌方式(集雨补灌和传统畦灌),研究集雨补灌措施对土壤水分、冬小麦产量及水分利用效率的影响。结果表明:沟垄集雨补灌模式可有效改善0~200 cm土层土壤贮水量,尤其对0~40 cm土层提高较为明显。在2013-2014年(枯水年)灌水量减半的情况下,前期补灌和全生育期不灌溉处理的小麦产量均高于相对应的畦灌处理,分别提高了2.6%和6.2%,其余处理和对应的畦灌处理相比无增产效应;在4种补灌模式下,集雨补灌处理的水分利用效率、灌溉水利用效率均显著高于对应的畦灌处理,其中前期补灌最为显著,分别提高8.5%和105.1%。2014-2015年(丰水年),除集雨前后期均补灌处理外,前期补灌、后期补灌和全程不灌溉处理的产量均高于对应的畦灌处理,分别提高4.5%、7.4%(p0.05)和4.9%;在四种补灌模式下,除集雨前后期均补灌和不灌溉处理的水分利用效率与对应的畦灌处理相差不大外,其余各补灌处理的水分利用效率和灌溉水利用效率均显著高于相对应的畦灌处理,最大增幅分别为3.8%和114.7%。可见,沟垄集雨结合适量补灌措施可显著提高冬小麦产量和水分利用效率。 相似文献
8.
侯琼 《干旱地区农业研究》2005,23(2):36-42,53
利用内蒙古农牧交错区13个站点20a的土壤水分观测资料和常规气象资料,分析了前期不同时段降水量(R)和参考作物蒸散量(Eo)与春季实测底墒的关系,分别建立了不同生态气候经济类型地区0～50cm和0～20cm土层的底墒估算模型,并利用2001～2002年土壤湿度和相应的气象资料对模型进行了检验,预测准确率平均为91.1%。 相似文献
9.
水氮互作对小麦旗叶光合特性、籽粒产量及氮素和水分利用率的影响 总被引：3，自引：0，他引：3
在高产条件下,研究了水氮互作对小麦旗叶光合特性、籽粒产量及水分和氮素利用率的影响.结果表明:(1)同一灌水处理下,旗叶光合速率、蔗糖磷酸合成酶活性、蔗糖含量和籽粒产量均随施氮水平的增加而提高,千粒重、氮素收获指数和氮素表观利用率随施氮水平的提高而降低.(2)同一施氮水平下,W1(底墒水+拔节水+开花水)、W2(底墒水+冬水+拔节水+开花水)和W3(底墒水+冬水+拔节水+开花水+灌浆水)处理的旗叶光合速率、蔗糖磷酸合成酶活性和蔗糖含量在开花后0～14 d无显著差异;开花21 d后,W3处理显著高于W1和W2处理.(3)在N0(不施氮)和N1(180 kg/hm2)水平下,W1和W2处理的籽粒产量显著低于W3处理,在N2(240 kg/hm2)水平下则反之;氮素表观利用率和氮素生产效率为W0相似文献
10.
民勤沙漠绿洲膜下滴灌洋葱灌溉试验研究初探 总被引：2，自引：0，他引：2
在民勤沙漠绿洲进行了洋葱膜下滴灌灌溉试验研究,结果表明:膜下滴灌适当减少灌水可以促使洋葱更多的利用土壤底墒,灌水相对较少的处理T2底墒利用率最高,分别比T1、T3、对照CK高10.73%、9.85%和9.92%。膜下滴灌不同灌水处理以灌水最多的T3洋葱产量最高,水分利用效率也最高;灌水最多的常规灌溉CK水分利用效率最低,分别比T1、T2、T3低35.28%、55.21%、58.79%。膜下滴灌条件下适当增加灌水量在一定程度上可增加洋葱产量,当灌水量在一定范围内,洋葱产量和水分利用效率均会显著提高。 相似文献
11.
为探究黄瓜花叶病毒(Cucumber mosaic virus,CMV)、马铃薯Y病毒(Potato virus Y,PVY)混合侵染烟株对烟蚜取食行为的影响,利用刺探电位图谱(electrical penetration graph,EPG)技术记录了烟蚜在健康烟株与CMV、PVY混合侵染后不同发病级别烟株上的取食波形。结果显示:烟蚜在健康烟株上的刺探次数最少,在感病烟株上的C波总持续时间均显著长于健康烟株;第1次到达韧皮部前的刺探次数,健康植株上仅为4.00次,3级感病烟株上的为健康烟株上的2倍;在健康烟株上E2波总持续时间为120.65 min,极显著大于2级和3级感病烟株;刺探过程中,感病烟株上的pd波出现次数均高于健康烟株,且pd波II-1和II-3亚波的持续时间也显著高于健康烟株。研究表明,CMV、PVY混合侵染烟株可降低寄主对烟蚜的适合度,且能促进烟蚜对病毒的传播。 相似文献
12.
Dr. W. Gams Dr. A. Van Zaayen 《European journal of plant pathology / European Foundation for Plant Pathology》1982,88(2):57-78
The genusVerticillium is divided into four sections (two new) and a residual group. The new sectionNigrescentia comprises the well-known plant-pathogenic and some other saprophytic species with dark resting structures. The new sectionAlbo-erecta is characterized by white (or yellowish) colonies and erect conidiophores and contains mainly fungicolous species. Seven (two new) species and two new varieties are described and keyed out. Three other species have known teleomorphs ofNectriopsis (one new and two new combinations). This genus had been merged withNectria by Samuels, but its retention is justified, as the original and the here described fungicolous (and myxomyceticolous) species are more suitably accomodated inNectriopsis than inHypomyces.The common causal agent of dry bubble inAgaricus bisporus, Verticillium fungicola var.fungicola, is redescribed and defined more narrowly than by Gams (1971) by its maximum growth temperature below 27°C. A similar fungus with a maximum growth temperature near 33°C, causing brown spots inA. bitorquis, is described asV. fungicola var.aleophilum. Isolates from wild agarics with a strongly reduced growth at 24°C and a maximum below 27°C, a yellowish mycelium and inconspicuous sclerotia, are described asV. fungicola var.flavidum. V. biguttatum W. Gams,sp. nov., with cylindrical biguttulate conidia, is a common soil fungus and hyperparasite ofRhizoctonia solani. Gliocladium microspermum (Sacc.) W. Gams,comb. nov., the anamorph ofNectriopsis broomeana (Tul.) W. Gams,comb. nov., which is intermediate betweenGliocladium andVerticillium, is included because of its fungicolous habit.Samenvatting Het geslachtVerticillium wordt onderverdeeld in vier secties (waaronder twee nieuwe) en een restgroep. De nieuwe sectieNigrescentia bevat onder meer de bekende ziekteverwekkende soorten met donkere ruststructuren. De nieuwe sectieAlbo-erecta wordt gekarakteriseerd door witte (of geelachtige) kolonies en rechtopstaande conidioforen en bevat hoofdzakelijk op andere fungi groeiende soorten. Zeven soorten (waaronder twee nieuwe) en twee nieuwe variëteiten worden beschreven en in een sleutel verwerkt. Drie andere soorten bezitten perfecte vormen vanNectriopsis (waaronder één nieuwe en twee nieuwe combinaties). Dit geslacht werd door Samuels metNectria samengevoegd, maar kan gehandhaafd worden en lijkt beter geschikt om de hier beschreven ascomyceten onder te brengen danHypomyces.
Verticillium fungicola var.fungicola, de algemene veroorzaker van droge mollen bij de champignon (Agaricus bisporus), wordt beschreven en met zijn temperatuur-maximum beneden 27°C nauwkeuriger gedefiniëerd dan in een vroegere studie (Gams, 1971). Een vergelijkbare schimmel met een temperatuurmaximum van ongeveer 33°C, die bijA. bitorquis bruine vlekken veroorzaakt, wordt beschreven alsV. fungicola var.aleophilum. Isolaten van wilde paddestoelen met een optimum duidelijk beneden 24°C en een maximum beneden 27°C, geelachtig mycelium en onopvallende sclerotiën, worden beschreven alsV. fungicola var.flavidum. V. biguttatum W. Gams, sp. nov., met cilindrische, biguttate conidiën, is een algemene grondschimmel en hyperparasiet vanRhizoctonia solani. Gliocladium microspermum (Sacc.) W. Gams, comb. nov., de imperfecte vorm vanNectriopsis broomeana (Tul.) W. Gams, comb. nov., een tussenvorm tussenGliocladium enVerticillium, wordt opgenomen wegens zijn voorkomen op vruchtlichamen van de dennemoorder. 相似文献
13.
为探明烟蚜茧蜂Aphidius gifuensis Ashmead对烟蚜Myzus persicae(Sulzer)取食感染马铃薯Y病毒(Potato virus Y,PVY)烟株的适应性,利用刺探电位图谱(EPG)技术记录了烟蚜在感病烟株与健康烟株上的取食行为,并测定了烟蚜茧蜂对取食2种烟株烟蚜的寄生率以及烟蚜茧蜂的羽化率、发育时间及性比等指标。结果表明,与健康烟株相比,烟蚜在感染PVY烟株上的第1次刺探取食持续时间显著延长,且口针遇到阻力的次数(F波)和总持续时间均显著减少。烟蚜在感病烟株木质部的吸食时间(G波)显著长于健康烟株。感病烟株上烟蚜在韧皮部阶段的分泌唾液时间(E1波)较在健康烟株上显著缩短,而被动吸食汁液时间(E2波)显著延长。烟蚜茧蜂寄生取食感染PVY烟株的烟蚜,虽然能成功完成其生活史,但适应性与寄生取食健康烟株烟蚜的蚜茧蜂存在差异。在感染PVY烟株上,烟蚜茧蜂对烟蚜的寄生率为33.67%,显著低于对照的64.67%;且僵蚜体重明显下降,羽化的成蜂个体较小;成蜂存活时间1.48 d也极显著短于对照组的2.25 d。表明烟蚜茧蜂对取食感染PVY烟株烟蚜的适应性较低,PVY可通过烟蚜为介体间接降低烟蚜茧蜂的适应力。 相似文献
14.
M. Platero Sanz 《European journal of plant pathology / European Foundation for Plant Pathology》1981,87(4):119-129
Bean hypocotyls, pea pods and tomato fruits were tested for phaseollin, pisatin and rishitin production when challenged with the phytopathogenic bacteriaErwinia carotovora, Pseudomonas phaseolicola, P. pisi andP. solanacearum, and their isolated extracellular polysaccharides. All bacteria induced phytoalexin accumulation, whereas only phaseollin and pisatin, but not rishitin, were elicited by EPS. The inhibitory effect of these three phytoalexins on bacterial growth was studied in liquid medium; whereas phaseollin and pisatin strongly inhibited growth, only a slight inhibitory effect resulted from the presence of rishitin in the medium.Samenvatting Bonehypocotylen, erwtepeulen en tomatevruchten werden onderzocht op hun vermogen tot vorming van respectievelijk faseolline, pisatine en rishitine, na inoculatie met de fytopathogene bacteriënErwinia carotovora, Pseudomonas phaseolicola, P. pisi enP. solanacearum en na behandeling met oplossingen van hun extracellulaire polysacchariden (EPS). Alle bacteriesoorten induceerden fytoalexinevorming, terwijl hun EPS wel faseolline- en pisatine-, maar geen rishitinevorming induceerden. Faseolline en pisatine remden de groei van de bacteriën in vloeibaar medium sterk; rishitine daarentegen had slechts een geringe groeiremming tengevolge. 相似文献
15.
Stefania Loreti Angela Gallelli 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(3):237-244
Specific oligonucleotides, based on hrpW (hypersensitive response and pathogenicity) gene sequences encoding harpin protein in phytopathogenic bacteria, were designed to detect and identify virulent strains of Pseudomonas avellanae by polymerase chain reaction (PCR). A population of virulent P. avellanae strains, isolated in central Italy (Viterbo region), was assessed with hrpW-derived primers, producing a specific band of about 350 base pairs in length. This target was successfully amplified from purified genomic DNA, from bacterial culture and from hazelnut bark tissue. No amplification was obtained when the PCR assay was performed on other plant-pathogenic species from the following genera Agrobacterium, Erwinia, Brenneria, Pseudomonas, Ralstonia, Xanthomonas or from hazelnut-associated bacteria, indicating the specificity of these primers. Moreover DNA from strain ISPaVe-MCB-596, isolated from north Italy (Piedmont region) and belonging to the less aggressive population of P. avellanae, did not amplify in PCR. The PCR assay with the primers described here provides a rapid, specific and sensitive diagnostic method for virulent P. avellanae strains and a useful tool to evaluate the progress of sanitation of the area. 相似文献
16.
为研究沉水植物在不同水深和生长时期对不同种类入侵植物的响应,选取2种湿地入侵植物凤眼莲Eichhornia crassipes、水盾草Cabomba caroliniana和2种常见本地沉水植物黑藻Hydrillaverticillata、菹草Potamogeton crispus为研究对象,通过模拟试验探究在不同水深（0.2、0.4 m）和生长时期（生长初期和生长旺期）的本地沉水植物对2种入侵植物的响应。结果显示,当水深为0.4 m时更有利于黑藻的生长,并可削弱入侵植物对黑藻生长的消极作用,而水深对菹草的生长无显著影响;入侵植物种类对本地沉水植物的生长无显著影响,但影响方式却存在差异,其中水盾草倾向于直接抑制本地沉水植物的生长,而凤眼莲可以通过降低水体透明度以及总磷含量进而间接抑制本地沉水植物的生长。此外,外来植物在本地沉水植物生长初期入侵对本地沉水植物产生的消极影响较生长旺期入侵时更显著。表明凤眼莲及水盾草入侵对本地沉水植物生长的影响机制存在差异,本地沉水植物在适宜水深和生长旺期对2种入侵植物具有更强的抵抗能力。 相似文献
17.
18.
Tachinid parasitoidsExorista xanthaspis (Wiedemann),Nemorilla maculosa (Meigen),Palesisa maculosa (Villeneuve) andDrino imberbis (Wiedemann) were obtained fromSpodoptera exigua (Hübner) (Noctuidae) larvae collected from cotton fields in Turkey.S. exigua is a new host record forN. maculosa, andP. maculosa is recorded from Turkey for the first time.
http://www.phytoparasitica.org posting July 14, 2004. 相似文献
19.
H. A. Van Hoof H. Huttinga A. Knaap H. P. Maas Geesteranus W. H. M. Mosch D. G. J. De Raay-Wieringa 《European journal of plant pathology / European Foundation for Plant Pathology》1979,85(3):87-98
In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten. 相似文献
20.
Potato seed tubers are imported to Israel from northern Europe and planted in spring; tubers harvested early from the spring
crop are used as seed for the autumn crop. Although only seed lots registered as certified are imported, a previous survey
(1984–1994) indicated that most imported lots were affected by latent or active infections caused byErwinia carotovora,Streptomyces scabies, Rhizoctonia solani, Fusarium spp. andSpongospora subterranae. The survey was extended until 1998, and included additional pathogens:Ralstonia solanacearum,Helminthosporium solani, Colletotrichum coccodes andVerticillium dahliae. Most of these pathogens were also monitored in domestic seed tubers, and are reported for the first time. Brown rot was not
observed in any of the imported lots. Blackleg and soft rot caused byErwinia spp. were detected in most of the imported lots; however, less than 7% of the lots were contaminated at high levels, while
approximately 65% were contaminated at moderate levels. Common scab was detected in most of the imported lots; 51% of the
imported lots were contaminated at moderate or high levels, whereas only 6.5% of the domestic seed lots were contaminated
at these levels. Black scurf was detected in most of the imported lots; on average, 47.3%, 44.2% and 1.4% of the lots were
contaminated at low, moderate and high levels, respectively, and only 7.1% were disease-free. In contrast, most of the domestic
lots were either disease-free (45.4%) or had a low disease incidence (37.3%). Only 16.7% of the lots were moderately infected
and 0.2% were highly contaminated. Silver scurf was observed in most of the imported lots during all years of the survey,
with no differences among the producing countries; on average, 22.7%, 66.1% and 7.5% of the lots were contaminated at low,
moderate and high levels, respectively, and only 3.7% were disease-free. Most of the domestic lots (76%) were disease-free
and only 6.6% were infected at moderate or high levels. Black dot was observed in a considerable portion of the shipments
from Holland during all years of the survey, particularly in 1998, when 34% of the lots were infected. The shipments from
France and Germany were infected at low levels, except in 1998, when 19% and 11% of the lots, respectively, arrived infected.
In shipments from Scotland and Ireland low incidences of the disease were observed in 1994 and 1995. In the domestic lots,
black dot incidence was low (<2.4%) except in 1996, when 11% of the lots were infected.V. dahliae was monitored only in domestic seed tubers. The incidence of disease-free lots was 56–64%, whereas in 20–30% of the lots
the level of infection was <5%, and in 6–16% of the lots the level was >5%. The survey findings demonstrate transmission of
seedborne pathogens; most of these pathogens can become established in the soil and eventually cause severe outbreaks of disease
in potatoes grown in Israel.
http://www.phytoparasitica.org posting May 16, 1999. 相似文献