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1.
为研究和解决阴山北麓农牧交错带地区降水资源不足、雨养农业产量不稳的问题,于2011~2012年在内蒙古武川县进行了不同垄宽和沟宽的集雨措施栽培马铃薯的试验,测定了沟垄集雨处理下土壤水分状况、马铃薯生长、产量和水分利用效率。结果表明:沟垄集雨技术提高了种植区土壤水分,增幅16.1%~26.0%。马铃薯生育期内的叶面积指数和单株干物重均高于对照处理。沟垄集雨处理的商品薯率较平作高5.0~30.5%,商品薯产量高于平作,垄宽1.0m沟宽1.0m集雨处理商品薯产量平作增产52.0%~81.0%。较平作相比,集雨处理提高了马铃薯水分利用效率。沟垄集雨技术对阴山北麓农牧交错带地区雨养农业规避干旱气候风险以实现马铃薯稳产具有重要的应用价值。  相似文献   

2.
在怀安县前所堡旱作示范区以南瓜为试材,采用窄土垄沟、宽土垄沟、窄膜垄沟、宽膜垄沟4种不同沟垄处理方式,常规平作为对照,研究不同的沟垄措施对南瓜地土壤水分含量、水分利用及产量的影响.结果表明:沟垄栽培可使水分聚集于种植沟中较小有效栽培面积中,改善土壤水分分布状况,不同处理间效应大小依次为:宽膜垄沟＞窄膜垄沟＞宽土垄沟＞窄土垄沟＞平作,且覆膜效应大于垄的宽窄效应;沟垄处理对土壤水分在表层影响大,在较深土层影响小.沟垄处理均可提高水分利用效率,其中土垄与平作差异不明显,而膜垄水分利用率宽膜垄沟(40.85 kg·hm-2·mm-1)、窄膜垄沟(39.03 kg·hm-2·mm-1)均显著高于平作(30.27 kg· hm-2· mm-1)(P＜0.05),宽垄比窄垄水分利用率高,但差异不显著.不同沟垄处理对南瓜的产量影响较大,产量增加4.23％～32.39％,增产效益176.2～1 210.4元·hm-2,两膜垄组南瓜产量与对照平作差异显著(P＜0.01),尤以宽膜垄沟增产效益为最高.综上所述,宽膜垄沟的栽培方式对南瓜水分利用和增产增效作用显著,是目前坡耕旱地南瓜生产中较为理想的田间沟垄微型集雨种植模式.  相似文献   

3.
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   

4.
通过旱棚小车模拟小麦/玉米垄沟套作种植试验,研究了3种不同垄沟部位(垄顶、垄底和沟中)施肥对小麦/玉米生长和产量及土壤水氮分布的影响。结果表明:相同灌水条件下,施肥部位对垄沟套作水分分布影响不显著,但土壤硝态氮的分布差异较大;垄顶施肥和垄底施肥处理下,由于水肥异区,其垄上小麦生长带的硝态氮主要分布在0~30 cm土层,有效地减少了硝态氮向土壤深层淋溶,而后期沟内玉米生长带的水氮处理相同,因此其硝态氮分布差异较小;在相同灌水条件下,垄沟套作可以有效降低水分流失,减少氮肥损失,因此较传统平作更有利于作物生长,提高小麦、玉米的产量,且以垄顶施肥和垄底施肥效果最显著,小麦产量较平作分别增加11.47%、10.81%,玉米产量较平作分别增加18.87%、22.70%。  相似文献   

5.
为了提高旱作农区降雨利用效率,并解决春旱问题,在西北半干旱地区设置了秋季地膜全覆盖(PA)和秋季沟垄集雨半膜覆盖(RH)两种覆膜方式,以裸地不覆盖(CK)为对照,对土壤水分、春玉米功能叶片的光合参数、荧光参数和籽粒产量进行了研究。结果表明:与对照(CK)相比,不同秋覆膜方式显著增加了春玉米播前0~100 cm土壤储水量,2013年春旱严重,PA和RH处理分别提高了26.15%和13.40%;2014年春季有雨雪,两种覆膜方式分别提高了10.44%和11.20%。不同秋覆膜处理的春玉米净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、最大荧光(Fm)、最大光化学量子产量(Fv/Fm)、PSII的潜在活性(Fv/F_0)和光化学猝灭系数(q P)较对照有不同程度提高,且2014年增幅高于2013年。2013年PA和RH处理的籽粒产量较CK分别提高了40.98%和25.83%,水分利用效率增加了29.70%和22.87%;2014年两个处理春玉米籽粒产量分别提高了74.60%和48.64%,水分利用效率增加了64.87%和47.08%。试验表明,不同秋覆膜方式在西北半干旱地区均可提高春玉米叶片的光合性能,并显著提高春玉米籽粒产量及水分利用效率,在偏旱的年份效果尤为明显,且秋季地膜全覆盖优于秋季沟垄集雨半膜覆盖,是西北半干旱区春玉米一种高效的栽培模式。  相似文献   

6.
针对晚播对夏玉米生长发育造成的不利影响,采用垄覆膜沟不覆盖（LN）、垄覆膜沟覆秸秆（LJ）和垄沟全覆膜（LM）3种垄沟种植方式,以常规播期平作不覆盖（CK1）和晚播平作不覆盖（CK2）为对照,分析了不同垄沟种植方式对晚播夏玉米农田土壤水分、土壤温度及玉米生长和产量的影响,对比不同垄沟覆盖种植方式对晚播玉米生长的补偿效应。结果表明：垄沟种植显著提升了夏玉米0~25 cm土层土壤温度,促进了晚播夏玉米生长;生育期内多雨导致各处理0~200 cm土层土壤含水率一直在18%（75%田间持水率）或更高水平,覆膜对土壤水分的影响不明显;垄沟种植夏玉米整体生长状态在8月中下旬（抽雄~灌浆阶段）与CK1处理达到相同水平;地上部干物质量在成熟期达到或超过CK1处理水平;低温多雨导致晚播夏玉米生育期延长了8~9 d;垄沟种植处理倒伏率较低,最高值仅为3%,平作处理倒伏严重,CK1和CK2处理倒伏率分别达73.1%和20.1%;CK2处理全生育期各项生长及产量指标均较低,LJ处理前期生长状态差,后期贪长,最终相对CK1处理减产7.9%;LN处理产量9 783.8 kg·hm-2,与CK1处理持平,LM处理达到最高产量11 101.7 kg·hm-2,相对CK1处理增产12.2%。综合考虑土壤水热、夏玉米生长、产量等各方面因素,多雨条件下垄沟全覆膜方式对晚播玉米生长达到了最好的补偿效果。  相似文献   

7.
旱地春小麦集雨补灌增产机制初探   总被引：7，自引：3，他引：7  
为查明集雨补灌对不同种植模式小麦的增产机理，于1998年在甘肃中部旱农区进行了田间试验。结果表明：少量灌水使沟播春小麦出苗率提高，小穗数及穗粒数增加；在植株生长的需水关键期补灌，小麦叶面积增大，叶绿素含量提高，地上部干物质及籽粒干物质积累量增加，有效小穗数及穗粒数增多，穗粒千重及千粒重增大，最终经济产量和生物产量提高。籽粒平均灌浆速率和最大灌浆速率提高是旱田补灌作物增产的主要机制。  相似文献   

8.
垄膜沟播与平膜侧播对冬小麦光合特性及产量的影响   总被引：5，自引：0，他引：5  
为了探索我国西北半湿润易旱区合理覆膜种植方式,为该区作物生产及覆膜种植制度的建立提供参考,本研究以传统平作为对照,设两种覆膜方式:垄膜沟播(R)与平膜侧播(F).结果表明,与传统平作(CK)相比,垄沟宽均为40 cm(R40)和60 cm(R60)的沟播处理全生育期0-200 cm土壤平均含水量分别提高8.82％(P ＜0.05)和10.84％ (P＜ 0.01),膜宽为40 cm(F40)和60 cm(F60)的侧播处理提高4.40％和3.96％,沟播处理较侧播处理平均提高了5.42％(P＜0.05).不同覆膜方式处理的旗叶叶绿素相对含量(SPAD)、净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均较传统平作(CK)显著增加,同宽度的沟播处理较对应的侧播处理提高幅度明显,但胞间CO2浓度显著低于传统平作(CK).不同覆膜方式处理的小麦经济产量和水分利用效率均较传统平作(CK)显著提高,平均提高幅度达21.52％和30.97％,同宽度沟播处理的生物产量、经济产量和作物水分利用效率显著(P＜0.05)高于对应的侧播处理.试验表明,在半湿润旱作区冬小麦垄膜沟播是一种高效栽培模式.  相似文献   

9.
以陇薯6号为试验材料,研究了不同覆盖种植模式对甘肃定西马铃薯田土壤温度、水分和产量的影响,并对其经济效益进行分析比较。结果表明,全地面覆盖双垄垄作侧播和全地面覆盖垄上微沟穴播处理在马铃薯整个生育期0~30 cm平均土壤温度较CK增加2.2℃和2.5℃,秸秆带状覆盖处理平均土壤温度较CK降低了1.0℃。覆膜垄沟集雨和秸秆带状覆盖技术都能明显改善土壤水分状况,在马铃薯生长前期集雨保墒效果尤为明显,出苗期全地面覆盖双垄垄作侧播、全地面覆盖垄上微沟穴播、秸秆带状覆盖在0~100 cm平均土壤含水量分别较CK提高2.6%和2.2%和1.6%。各处理马铃薯土壤温度和含水量垂直变化随着土壤深度的增加而减弱。全地面覆盖双垄垄作侧播、全地面覆盖垄上微沟穴播和秸秆带状覆盖增产效果明显,产量分别较CK增加33.6%、28.6%和23.2%。全地面覆盖双垄垄作侧播纯收益最高,秸秆带状覆盖次之,纯收益较CK分别增加7 201.56元·hm~(-2)和5996.04元·hm~(-2)。因此,黑膜全覆盖双垄垄作侧播技术在改善土壤水温效应的同时能显著增产增收,是定西地区马铃薯种植的高效栽培模式。  相似文献   

10.
为寻求半干旱地区垄沟集雨环保沟覆盖材料,探究垄沟集雨种植增产机理,在半干旱黄土高原区通过大田试验,以传统平作为对照,研究不同沟覆盖方式(无覆盖、生物可降解地膜覆盖和秸秆覆盖)对土壤含水量、玉米根干重、根长、根表面积和根体积的影响。结果表明:垄沟集雨种植沟中的土壤含水量、玉米根干重、根长、根表面积和根体积明显大于垄中;与平作相比,无覆盖、生物可降解地膜覆盖和秸秆覆盖耕层沟中作物生育期平均土壤含水量分别增加6.9%、10.6%和9.3%,垄中平均土壤含水量分别降低13.8%、10.9%和5.6%;玉米总根干重(沟中+垄中)分别降低15.9%、6.1%和16.8%,总根长分别增加37.6%、43.7%和34.8%,总根表面积分别增加10.5%、33.6%和15.0%。无覆盖和秸秆覆盖玉米总根体积分别降低34.5%和16.3%,生物可降解地膜覆盖玉米总根体积增加13.2%。与传统平作相比,垄沟集雨种植增加土壤水分、玉米根长和根表面积,降低玉米根干重。在不同沟覆盖方式中,生物可降解地膜覆盖具有较高土壤含水量、根长、根表面积和根体积。  相似文献   

11.
Fifteen species of dermestid beetles were recorded at ‘Evolution Canyon’ (EC), Lower Nahal Oren, Mt. Carmel, Israel. They represent ~35% of known Israeli dermestid species. The following three species were recorded for the first time in Israel:Trogoderma svriaca Dalla Torre, 1911;Ctesias svriaca Ganglbauer, 1904; andAnthrenus (s.str.) jordaniens Pic, 1934. Adults of 13 species were collected on the more solar radiated, warmer and climatically more fluctuating south-facing slope (SFS); ten species were collected on the opposite, north-facing slope (NFS), which was cooler and climatically more stable. The abundance of adult dermestid beetles was 1.9 times higher on the SFS than on the NFS (86 and 47, respectively). Species richness and abundance distribution at EC (three collecting stations on each slope and one at the valley bottom) were significantly negatively correlated with the plant cover that consisted of trees and bushes (Spearmanr s ,P=0.007 and 0.039, respectively) and perennials (Spearmanr s ,P=0.039 and 0.077, respectively), indicating that non-woody plants were preferred by adult dermestid beetles.  相似文献   

12.
Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.  相似文献   

13.
The genera ofMicrogaster Latreille 1804 andHygroplitis Thomson 1895 from China are presented systematically in this paper. Thirty-two species ofMicrogaster and three species ofHygroplitis are known in China. Diagnosis, character variation, distribution and host of each species among the two genera are presented, including its host and distribution. Keys to the species ofMicrogaster andHygroplitis are given. http://www.phytoparasitica.org posting Dec. 19, 2006.  相似文献   

14.
Plant Viruses Transmitted by Whiteflies   总被引：18，自引：0，他引：18  
One-hundred and fourteen virus species are transmitted by whiteflies (family Aleyrodidae). Bemisia tabaci transmits 111 of these species while Trialeurodes vaporariorum and T. abutilonia transmit three species each. B. tabaci and T. vaporariorum are present in the European–Mediterranean region, though the former is restricted in its distribution. Of the whitefly-transmitted virus species, 90% belong to the Begomovirus genus, 6% to the Crinivirus genus and the remaining 4% are in the Closterovirus, Ipomovirus or Carlavirus genera. Other named, whitefly-transmitted viruses that have not yet been ranked as species are also documented. The names, abbreviations and synonyms of the whitefly-transmitted viruses are presented in tabulated form together with details of their whitefly vectors, natural hosts and distribution. Entries are also annotated with references. Whitefly-transmitted viruses affecting plants in the European–Mediterranean region have been highlighted in the text.  相似文献   

15.
Broad bean mottle virus (BBMV) was transmitted from infected to healthy faba-bean plants by the curculionid weevilsApion radiolus Kirby,Hypera variabilis Herbst,Pachytychius strumarius Gyll,Smicronyx cyaneus Gyll, andSitona lineatus L. The latter appeared to be an efficient vector: acquisition and inoculation occurred at the first bite, the rate of transmission was c. 41%, and virus retention lasted for at least seven days.S. lineatus transmitted the virus from faba bean to lentil and pea, but not to the three genotypes of chickpea tested. This is the first report on the generaHypera, Pachytychius, andSmicronyx as virus vectors, and onA. radiolus, H. variabilis, P. strumarius, andS. cyaneus as vectors of BBMV.Out of 351 samples of food legumes with symptoms suggestive of virus infection, 16, 11, 19, and 17% of the samples of chickpea, lentil, pea, and common bean, respectively, were found infected when tested for BBMV in DAS-ELISA. This is the first report on the natural occurrence of BBMV in chickpea, lentil, pea, and common bean. The virus should be regarded as a food-legume virus rather than a faba-bean virus solely, and is considered an actual threat to food legume improvement programmes.  相似文献   

16.
A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVYN strain and six to the PVYO strain. No PVYC was found. Two other isolates reacted serologically like PVYO, but were unable to elicit a hypersensitive response from the Nytbr gene and probably represent the PVYZ group. At the molecular level, these two isolates showed a combination of both PVYO and PVYN and could be recombinants of these strains. Another isolate reacted serologically like PVYO, but induced vein necrosis in tobacco, like PVYN-Wilga. Some PVYN isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVYNTN group. The PVYNTN, PVYN-Wilga and PVYZ groups probably represent pathotypes within strains PVYN and PVYO, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.  相似文献   

17.
The phenology of the autumn leafroller,Syndemis musculana, a local pest of apple, was studied in order to forecast larval emergence. From 1983–1986, peak flight as determined with sexpheromone traps was always between 13–18 May. The duration of embryonic development was determined at various constant temperatures and used to estimate the periods of egg hatch in these four years. Each year, most eggs should have hatched in the second decade of June.Differences in attack rates between apple cultivars seem to be explained largely by the variation in picking time. Larvae are only half grown at the beginning of harvest (cv. James Grieve), and have gone into hibernation when the latest variety (cv. Golden Delicious) is picked. Moreover, the varieties Cox's Orange Pippin and Belle de Boskoop, picked about half time, are liable to receive additional damage by caterpillars brought with the picked fruits into storage.Various hymenopterous parasites were reared from caterpillars. As the only leafroller in the orchard which hibernates as mature larva,S. musculana may promote winter survival of some parasitoids, like the eulophidColpyclypeus florus.Samenvatting De fenologie van de herfstbladroller (Syndemis musculana Hübner), een incidentele plaag op appel, werd nader bepaald met het doel het uitkomen van de eieren te kunnen voorspellen. In 1983–1986 viel de piekvlucht, bepaald met behulp van feromoonvallen, steeds tussen 13 en 18 mei.De ontwikkelingsduur van de eieren bij verschillende constante temperaturen werd gebruikt om de periode van uitkomen te schatten. De meeste eieren zullen ieder jaar in de eerste helft van juni uitkomen.Geconstateerde verschillen in schade tussen appelrassen blijken goeddeels terug te voeren op verschillen in pluktijdstip. De rupsen van de herfstbladroller zijn pas half-was als de eerste appels eind augustus geplukt worden, terwijl tegen het einde van de oogst begin oktober de meeste al in winterslaap zijn. Met name tussentijdse rassen, als Cox's Orange Pippin and Schone van Boskoop, lopen extra schade op doordat grotere rupsen met de geplukte vruchten in de kist terecht komen.Uit de rupsen werden negen, al van andere boomgaardbladrollers bekende, sluipwespen gekweekt, Omdat deze bladrollersoort, als enige in de boomgaard, als volgroeide rups overwintert, lijkt zij bij uitstek geschikt als winterwaard.This study was carried out at the Experimental Orchard De Schuilenburg, Schuilenburg 3, 4041 BK Kesteren, the Netherlands, to which address correspondence should be addressed.  相似文献   

18.
Molecular diagnostic techniques have been developed to differentiate the Ascochyta pathogens that infect cool season food and feed legumes, as well as to improve the sensitivity of detecting latent infection in plant tissues. A seed sampling technique was developed to detect a 1% level of infection by Ascochyta rabiei in commercial chickpea seed. The Ascochyta pathogens were shown to be genetically diverse in countries where the pathogen and host have coexisted for a long time. However, where the pathogen was recently introduced, such as A. rabiei to Australia, the level of diversity remained relatively low, even as the pathogen spread to all chickpea-growing areas. Pathogenic variability of A. rabiei and Ascochyta pinodes pathogens in chickpea and field pea respectively, appears to be quantitative, where measures of disease severity were based on aggressiveness (quantitative level of infection) rather than on true qualitative virulence. In contrast, qualitative differences in pathogenicity in lentil and faba bean genotypes indicated the existence of pathotypes of Ascochyta lentis and Ascochyta fabae. Therefore, reports of pathotype discrimination based on quantitative differences in pathogenicity in a set of specific genotypes is questionable for several of the ascochyta-legume pathosystems such as A. rabiei and A. pinodes. This is not surprising since host resistance to these pathogens has been reported to be mainly quantitative, making it difficult for the pathogen to overcome specific resistance genes and form pathotypes. For robust pathogenicity assessment, there needs to be consistency in selection of differential host genotypes, screening conditions and disease evaluation techniques for each of the Ascochyta sp. in legume-growing countries throughout the world. Nevertheless, knowledge of pathotype diversity and aggressiveness within populations is important in the selection of resistant genotypes.  相似文献   

19.
In the summer of 2004 an epidemic of sclerotinia blight of peanut, a disease caused by Sclerotinia minor, occurred in Texas in fields where the disease was never previously detected. The disease was observed on many plants within one of the fields (>3000 disease foci), although most foci were <1 m. It is hypothesized that these observations were inconsistent with the recent introduction of a monocyclic pathogen, even if disease developed under conducive environmental conditions. The pattern of disease is most suggestive of the presence of foliar (ascospore) infections, although air temperature was above the known limits for apothecia development if the pathogen had arrived in the field in 2004 peanut seed. To further examine this epidemic, 232 isolates were collected, across a variety of spatial scales spanning this field and other Texas peanut fields, and evaluated for aggressiveness, fungicide sensitivity and genotypic diversity. There was wide variation among isolates for the phenotypic characteristics measured, but there was no evidence that a genotypically unique, highly aggressive, and fungicide resistant isolate had been introduced or evolved. The predominant genotype, TX1, which contained 154 isolates, was found in every county and field population.  相似文献   

20.
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   

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