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1.
通过宁夏引黄灌区田间小区试验,研究施磷量分别为0、60、120、180 kg/hm2对春小麦产量、磷肥利用率、吸氮特性和土壤中硝态氮累积的不同影响,旨在明确该区合理施磷量.结果表明:合理施用磷肥(60~120 kg/hm2)能提高春小麦籽粒产量和生物量.当施磷量为120 kg/hm2,小麦籽粒产量最高,为6 215 kg/hm2.春小麦氮素累积动态呈先增加后降低的趋势,增施磷肥能增加小麦吸氮量,但到成熟期春小麦地上部氮素累积出现损失,损失量达7.7%~13.4%.当施磷量分别为60、120、180 kg/hm2时,0~150 cm土层中的NO3--N累积量分别比对照减少了50.6、58.5、62.9 kg/hm2.综合考虑磷肥利用率、小麦产量和降低土体中NO3--N残留等方面的因素,磷肥当季施用量应该控制在60~120 kg/hm2.  相似文献   

2.
不同灌水量对阿拉尔垦区棉田土壤硝态氮淋失量的影响   总被引:3,自引:0,他引:3  
以阿拉尔垦区棉田为试验地点,在棉花全生育期分别设8 100、6 600、5 100、3 600 m3/hm2 4个灌水水平,5次灌水,测定棉田0~100 cm土壤NO3--N含量变化和灌水后105 cm处渗漏液NO3--N浓度.结果表明,灌水对硝态氮淋失有明显的影响,在4~9月整个种植周期内,土壤浅层硝态氮浓度都呈下降趋势,深层硝态氮浓度缓慢上升;灌水量越大,深层土壤硝态氮浓度越高.在种植期间渗漏水硝态氮浓度变化趋势为:NO3--N基本上呈现低-高-低的变化趋势,且变化幅度较大;NO3--N淋失量为2.18~21.23 kg/hm2,与灌水量呈对数相关.  相似文献   

3.
为了有效利用氮肥,减少残留NO3^--N在土壤剖面中的累积,在位于半干旱半湿润地区的陕西岐山、杨凌、澄城和甘肃的定西,我们连续几年对不同试验处理条件下土壤剖面中残留NO3^--N的累积强度及其影响因子进行了系统研究。研究结果表明,在半干旱半湿润农田生态系统石灰性土壤剖面中累积着大量的残留NO3^--N。在所有测定土壤剖面中,NH4^4-N含量和累积量不仅在不同土层中差异不大,而且在不同生态系统和管理条件土壤剖面中的差异也不大,其含量变化在1~3μgN/g之间,累积量相当于14~42kg/hm^2,平均28kg/hm^2,显著小于残留NO3^--N。残留NO3^--N累积量平均占总矿质氮(NO3^--N NH4^ -N)累积量的75%以上,是土壤剖面中可浸取态矿质氮的主体。在岐山测定的129个土壤剖面中,O~100cm土层残留NO2^--N累积量小于50kg/hm^2的有26个,占20%,大干70kg/hm^2的有86个,占66.7%,大于100kg/hm^2的有47个,占36%,大干140kg/hm^2的有13个,占10%,每季作物吸氮量大约是70kg/hm^2,说明在目前施肥和生产水平下,有66.7%田块O~100cm土层中的残留NO3^--N最少与1季作物吸氮量相当;在杨凌、澄城、定西等地大部分试验小区(与当地一般施肥水平相当的小区),甚至有些不施氮肥对照小区土壤剖面中残留的.NO3^--N与1季作物的吸氮量也基本一致。这些结果充分说明,在半干旱农田生态系统石灰性土壤剖面中残留累积的NO3^--N是不可忽视的有效氮库。因此,在估计土壤供氮水平和确定施氮量,或者在制定这一地区土壤供氮指标测定方法时,必须要充分考虑在一定土层土壤剖面中的残留NO3^--N。土壤剖面中的残留NO3^--N通过对流(Convection)和扩散(Diffusion)等途径,逐渐向深层移动,脱离根区。在杨陵灌溉试验站和蔬菜试验站的测定结果表明,O~1000cm土层累积的NO3^--N分别高达1295.6kg/hm^2和710.4kg/hm^2,O~600cm土层累积的NO3^--N分别为。706.1kg/hm2和435.1kg/hm^2。在200cm土层以下累积着大量NO3^--N。在以上观测的2个剖面中,200~400cm、400~600cm、600~800cm和800~1000cm各土层累积的NO3^--N数量显著大干0~200cm土层,说明在上层(特别是在耕层)以各种途径增加的NO3^--N,通过长期淋溶,完全有可能脱离根区,淋溶到1000cm以下土层。在不同试验区进行的所有试验结果均表明,与不施氮对照小区相比,施氮小区在作物收获时,土壤剖面中残留.NO3^--N累积量呈增加趋势,并随施氮量增加,残留累积量增加。在杨凌和澄城进行的长期定位试验表明,连续施用氮肥,特别是高量氮肥田块,土壤剖面中残留NO3^--N与不施氮对照之间的差异很大:在杨凌长达25a的长期定位试验中,NP处理O~120cm土层残留NO3^--N累积量(163.4kg/hm。)比不施肥对照(51.8kg/hm^2)增加111.6kg/hm^2,如果在施NP的基础上休闲,残留NO3^--N增加效果更加突出,比对照增加156.5kg/hm^2;试验还发现,在施NP的基础上,配施玉米秸秆,一定程度上能够降低残留NO3^--N累积量,并随秸秆用量增加,残留NO3^--N累积量下降;在澄城,连续4季作物施用氮肥后,从2个灌水处理平均结果看,与不施氮对照相比,在每季作物施氮量低(<75kg/hm^2)时,不会发生NO3^--N残留累积,而当施氮量高于112.5kg/hm^2时,在O~120cm土层中残留NO3^--N累积量显著增加。在杨凌进行的2次大田试验表明,无论是在降雨丰富年份,还是在干旱年份,休闲都能够显著增加土壤剖面中NO3^--N的累积量,并且不管在任何采样时期,休闲小区100~120cm土层的NO3^--N含量均比复种玉米小区高,复种玉米能够减少残留NO3^--N在土壤剖面中的累积。由于地膜覆盖改变了土壤水热状况和生物性质,因而也必然影响土壤氮素转化过程,从而影响NO3^--N在土壤剖面中的累积。在定西进行的2a试验结果表明,如果在春小麦播种后全生育期覆膜,能够显著增加收获时土壤剖面中残留NO3^--N的累积:1999年,不施氮时,增加9.4kg/hm^2,施氮后,增加88.9kg/hm^2;2000年,不施氮时,增加17.9kg/hm^2,施氮后,增加39.9kg/hm^2;定西试验还表明作物生育前期覆膜,后期揭膜,有利于减少残留NO3^--N在土壤剖面中的累积。在作物生长后期,地膜覆盖处理耕层土壤水分条件较好,温度较高,有利于土壤有机氮的矿化。而在这一时期,小麦对NO3^--N的吸收能力减弱,需要量减小,因而在土壤剖面中易产生残留NO3^--N的大量累积。小麦收获后,值降水较多期,累积的NNO3^--N非常容易通过淋溶和反硝化损失,从这一角度考虑,在春小麦栽培中,不宜提倡全生育期地膜覆盖。  相似文献   

4.
蔬菜日光温室栽培条件下土壤养分累积特性研究   总被引:9,自引:0,他引:9  
测定了陕西杨凌示范区不同日光温室栽培土壤剖面的养分含量及变化。结果表明,日光温室土壤有机质、硝态氮、有效磷和速效钾含量呈现显著累积趋势,其中以0~20 cm土层有机质、0~40 cm土层有效磷和速效钾以及0~200 cm土层硝态氮累积量尤为突出。蔬菜生长过程中温室土壤剖面中铵态氮含量的变化相对较小,而硝态氮含量呈逐渐降低趋势。蔬菜收获后土壤剖面(0~200 cm)硝态氮残留量在707~1 161 kg/hm2之间,平均达954kg/hm2,明显高于农田土壤。温室栽培条件下土壤电导率明显高于农田土壤,以土壤表层尤为突出。土壤硝态氮、有效磷和速效钾与土壤电导率之间的关系均达显著水平,其中硝态氮含量与土壤电导率间的关系最为密切,说明过量施用肥料特别是氮肥,是引起土壤盐分累积的主要原因。  相似文献   

5.
本试验在片麻岩新成山地土壤上,设置0(CK)、N 120kg/hm2(N120)、N 225 kg/hm2(N225)、N 300kg/hm2(N300)4个施氮水平,布置田间微区试验,小区面积为10m2,研究了尿素不同施用量对旱地谷子生长及土壤硝态氮时空分布的影响。定位试验第二年的结果表明:在该试验条件下,N120处理谷子产量达到最高为4.76 kg/10m2,之后提高施肥量N225和N300处理的谷子产量并没有显著增加;从0~60 cm土壤剖面中硝态氮时空分布的差异可以看出:在施肥20 d后,N120、N225和N300处理NO3--N含量在0~40 cm土层显著增加,其中N225和N300处理NO3--N已经下移到40~60 cm土层。施肥80 d后,各施肥处理的硝态氮有一部分已经移出60 cm土层。到施肥96 d(谷子收获),N120、N225和N300处理比CK处理土壤剖面中NO3--N含量显著增加,且氮肥用量越高,土壤中NO3--N含量越高。  相似文献   

6.
为了解不同氮肥用量对土壤NO3--N淋洗的风险程度, 合理指导温棚蔬菜施肥和灌溉,2005~2006年在宁夏引黄灌区滴灌条件下,以轮作体系下的温棚黄瓜-番茄为研究对象,采用田间土壤溶液定位提取、田间试验与室内分析相结合的方法,设化肥施氮量150 kg/hm2(低氮)、300 kg/hm2(中氮)、450 kg/hm2(高氮1)、600 kg/hm2(高氮2)及有机肥和不施肥(CK)处理,研究滴灌条件下施氮量对土体中NO3--N淋洗的影响.结果表明:无论是低、中或高氮处理下,黄瓜-番茄轮作周期中,滴灌施肥对0~30 cm土壤溶液NO3--N含量变化的影响明显;在高氮处理下,由于番茄季较强的滴灌量,土体中NO3--N不断向下淋洗至90 cm土层;与CK处理相比,单施有机肥会造成的土壤NO3--N向深层淋洗.因此,提出每茬蔬菜推荐施氮量控制在300 kg/hm2左右为宜,在冬春茬后期4~6月份减少滴灌次数是减少土体NO3--N向下淋洗的措施.  相似文献   

7.
以22年定位试验为基础,研究了长期施用氮磷化肥(NP)下不同种植体系土壤交换性钙在剖面上分布与累积状况。结果表明:研究区为石灰性土壤,交换性钙含量较高;不同种植体系交换性钙在土壤剖面上发生淋溶累积现象,在140~180 cm土层产生累积峰,累积峰值:玉米-小麦(2a)+糜子轮作为13 180mg/kg、豌豆-小麦(2a)+糜子轮作为12597mg/kg、红豆草-小麦(2a)轮作为11 960mg/kg、豌豆-小麦(2a)+玉米轮为11 778mg/kg、小麦连作为11 590mg/kg、小麦(2a)+糜子-玉米轮作为11 290mg/kg;不同种植体系0~200cm土壤交换性钙的总累积量以玉米-小麦(2a)+糜子轮作最高,为269.67 t/hm2,小麦连作最低,为218.78 t/hm2。不同种植体系交换性钙在土壤剖面上分布不同主要是由作物和种植方式不同引起,不同种植体系0~200 cm土壤交换性钙的总累积量差异不显著。  相似文献   

8.
采取大田结合小区试验的方法,研究了不同水肥管理措施对春玉米产量和土壤硝态氮时空分布的影响。结果表明:水肥一体管理区春玉米产量为17 107 kg·hm-2,显著高于传统水肥管理区(13 349 kg·hm-2);从春玉米出苗期到收获期,无肥区0~90 cm各土层硝态氮含量不断降低,累积总量也从452.5 kg·hm-2降低到279.1 kg·hm-2,传统水肥管理区和水肥一体管理区0~90 cm各土层硝态氮含量和累积总量均呈先上升后下降的趋势,但水肥一体管理区分次追肥避免了传统水肥管理大喇叭口期过量追氮带来的淋溶风险;春玉米大喇叭口期和收获期随着土层深度的增加,0~180 cm土层硝态氮含量呈下降趋势;不同水肥管理措施0~180 cm土层硝态氮累积总量传统水肥管理区最高,大喇叭口期和收获期分别达到1 119.3 kg·hm-2和945.5 kg·hm-2,淋溶风险最大。因此以水肥一体化为核心的水肥管理措施可实现冀西北地区春玉米高产和环境友好。  相似文献   

9.
通过半开顶式CO2人工气候室,研究了CO2浓度升高(360、540μmol·mol-1和720μmol·mol-1)与不同氮肥营养(0、150、300 kg·hm-2和450 kg·hm-2)相互作用对蕾铃期棉花-土壤氮含量变化及棉花氮素吸收的影响,结果显示:大气CO2浓度增加,高氮肥处理下棉花叶片、蕾铃中氮含量显著降低,茎秆、根系中氮含量增加,棉花整株氮含量表现为下降;相同的CO2浓度下,随着氮素营养的增加棉花各器官氮积累量呈增加趋势,其中蕾铃、叶片氮积累量较高,茎秆、根系氮积累量相对较少,说明CO2浓度增加与增施氮肥促进了土壤氮素向植株叶片和生殖器官运输。通过对土壤无机氮含量的测定分析,CO2浓度升高为540μmol·mol-1,各施氮水平下棉田土壤NO3--N含量显著降低,NH4+-N含量在低氮水平下有少量增加,在高氮水平下表现为降低;CO2浓度升高为720μmol·mol-1,土壤NO3--N含量表现为降低,NH4+-N含量呈增加趋势。研究表明:大气CO2浓度增加且浓度范围在500~720μmol·mol-1,增加氮肥施用量可有效促进棉花对氮素养分尤其是NO3--N的吸收利用。  相似文献   

10.
半干旱区农田生态系统石灰性土壤施入的氮肥和有机氮矿化产物,除植物吸收、微生物固定、粘土矿物固定、挥发损失和反硝化损失外,有相当一部分最终以NO3--N形态残存在土壤中。土壤剖面中的残留NO3--N通过对流和扩散等途径,逐渐向深层移动,脱离根区。影响土壤剖面NO3--N残留累积和淋溶的主要因素包括施氮量、植物吸氮量、前作收获后的植物残留物、氮肥种类、施氮方式和降雨量等。残留NO3--N本身具有很高的生物有效性,但能否被植物吸收利用,关键在于残留NO3--N所在深度及其是否能够到达根区。在半干旱区降雨量较高的雨季,NO3--N向深层移动,而在较干旱条件下即使土壤剖面深层NO3--N,也可随水分上移供根系利用,因此土壤剖面中累积的残留NO3--N显著影响氮肥肥效果,许多地方用一定深度土层中累积的NO3--N作为土壤供氮指标,以减少NO3--N的淋溶损失和提高氮肥肥效。过去对半干旱地区土壤剖面中NO3--N的研究主要涉及3方面,一是土壤剖面中NO3--N的残留累积及其影响因素,二是与根系分布深度相适应土层中残留NO3--N对氮肥肥效的影响,三是根据土壤剖面中的残留NO3--N确定农田作物施氮量。在分析过去研究结果的基础上,提出了今后需进一步深入研究的科学问题。  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.
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   

13.
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   

14.
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   

15.
We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.  相似文献   

16.
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   

17.
《干旱区科学》2014,(6):782-782
正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad  相似文献   

18.
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   

19.
Zusammenfassung Verbände des ökologischen Landbaus wie z. B. Bioland, Gäa, Demeter; Naturland, Ernte für das Leben oder Bio Suisse beschränken ihre Mitglieder bei der Wahl von Vorratsschutzmaßnahmen. Vorrang besitzen Maßnahmen zur Vermeidung von Schädlingen gegenüber Bekämpfungsmaßnahmen. Fallen müssen zur Befallsüberwachung eingesetzt werden, um einen Befall durch Vorratsschädlinge frühzeitig zu erkennen. Diese Maßnahmen sollen den weitgehenden Verzicht auf chemisch-synthetische Mittel ermöglichen. In diesem Beitrag werden die Empfehlungen der Verbände mit den derzeit verfügbaren chemischen Mitteln für den Vorratsschutz abgeglichen. Erfahrung in der praktischen Umsetzung von physikalischen und biologischen Verfahren werden diskutiert und Defizite bei der Befallsüberwachung und Bekämpfung beschrieben.  相似文献   

20.
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   

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