不同水肥条件对间作花生和谷子水分养分利用的影响

采用水、氮、磷"3414"试验设计,研究了花生和谷子间作不同水肥条件对作物水分、养分利用的影响。结果表明:当氮素和磷素均处于丰富水平,随着土壤水分的提高,花生叶片水分利用效率呈下降趋势,谷子呈先升高后下降的趋势;在水分和其中一种肥料因素处于丰富水平时,花生和谷子叶片水分利用效率均随着另一肥料因素的增加呈先升高后下降趋势。花生氮素积累量与施氮量,花生磷素积累量与施磷量,谷子氮素、磷素和钾素积累量与土壤水分含量具有明显相关性。花生氮积累量与钾积累量、磷积累量与钾积累量之间具有较高相关性;谷子氮积累量、磷积累量和钾积累量,三者中两因素之间均具有较高相关性;花生氮积累量与谷子钾积累量和磷积累量、花生磷积累量与谷子磷积累量、花生钾积累量与谷子钾积累量和磷积累量具有较高的协同相关性。在其他两因素处于丰富水平,随着土壤水分的提高,花生和谷子氮素、磷素和钾素利用效率均呈先升高后下降趋势;随着施氮量的增加,花生和谷子氮素和钾素利用效率呈先升高后降低的趋势,谷子磷素利用效率呈增高趋势;随着磷素水平的不断提高,花生和谷子氮素、磷素和钾素利用效率均呈先升高后降低趋势。     

土壤速效磷浓度对立架甜瓜生物量和磷素累积特征的影响

以喀什地区立架伽师瓜为研究材料,试验设置6个水平(0、150、225、300、375和450 kg·hm-2)施磷量的田间试验,研究土壤速效磷(Olsen_P)浓度对立架甜瓜生物量和磷素累积特征的影响。结果表明,施磷条件下立架甜瓜田间土壤Olsen_P浓度的动态变化可用三次函数方程模拟,立架甜瓜生物量、磷素累积动态遵循Logistic曲线;土壤Olsen_P浓度快速下降期的平均速率、持续时间分别与立架甜瓜生物量、磷素快速累积期的最大相对累积速率、持续时间存在显著或极显著的相关性;在150~225 kg·hm~(-2)施磷量条件下,土壤Olsen_P浓度快速下降期的平均速率(0.078~0.108 mg·d~(-1))和持续时间(36.1~52.0 d)最佳,立架甜瓜生物量和磷素快速累积期的累积特征值,生物量、磷素累积特征值、产量以及品质均最优,其中生物量和磷素累积理论最大值以及产量分别达515.8~529.2 g·株~(-1),1 791.4~1 895.2 mg·株~(-1)和68 972.0~71 037.6 kg·hm~(-2)。高施磷量(450 kg·hm~(-2))和不施磷(0 kg·hm~(-2))均不利于立架甜瓜生物量和磷素的累积。土壤Olsen_P浓度的动态变化能响应立架甜瓜生物量和磷素的累积状况,尤其是合理施用磷肥(150~225 kg·hm~(-2))可调节立架甜瓜田间土壤Olsen_P浓度的动态变化,优化立架甜瓜生物量和磷素的累积以及提高其产量和品质。     

不同水氮水平对马铃薯产量和水氮利用效率的影响

为了给马铃薯生产提供科学合理的水氮管理依据,以品种"大西洋"脱毒组培苗为材料,通过3个水分水平(90%,70%和50%的土壤田间持水量)和3个氮肥水平(不施氮,施N 0.2 g·kg~(-1),施N 0.4 g·kg~(-1))完全组合的盆栽试验研究了不同水氮水平对马铃薯产量和水氮利用效率的影响。结果显示:在同一水分水平下,中氮处理的块茎产量、整株生物量和水氮利用效率明显高于低氮和高氮处理;在同一施氮量下,随着土壤含水量的增加,马铃薯的块茎产量、整株生物量和氮肥利用率明显提高。在9种水氮组合方式下,正常水分和中氮处理下的块茎产量、整株生物量、氮肥农学利用率和氮肥偏生产力最高,分别为273 g·株~(-1)、359 g·株~(-1)、52.5 g·g~(-1)和143.9 g·g~(-1)。这说明90%的田间持水量和0.2 g·kg~(-1)土有利于马铃薯植株获得较高的产量和水氮利用效率。此外,中氮下较高的整株生物量和较低的收获指数说明:适量施用氮肥增加产量主要是因为其增加了整个植株同化物的积累,而非增加了同化物向块茎的分配。     

不同氮肥用量对春油菜产量及养分吸收分配的影响

在青海省春油菜主产区开展田间小区试验,采用随机区组设计,每公顷分别施用纯氮0、75、150、225 kg,研究氮肥水平对甘蓝型春油菜新品种青杂12号的产量、养分吸收量、不同部位分配比例和氮素利用效率的影响。结果表明,在施用磷肥、钾肥和硼肥的基础上,增施氮肥75～225 kg·hm~(-2)可显著增加春油菜地上各部位产量,其中籽粒平均增产量为1 274 kg·hm~(-2),平均增产率为77%,地上部分生物量平均增加3 116 kg·hm~(-2),平均增产率为79%。增施氮肥可显著提高地上部氮素累积量(P0.05),平均增加69%;在施氮水平为150～225 kg·hm~(-2)时,施氮可以显著促进春油菜磷、钾素的累积,累积量平均增加69%和239%。青杂12号成熟期氮素、磷素和钾素吸收分配均表现为:籽粒茎秆角壳,分配比例平均为74.7%、19.5%和5.8%。随着施氮量的增加青杂12号的氮肥偏生产力显著降低,从28.2 kg·kg~(-1)下降到15.3 kg·kg~(-1),增施氮肥后氮肥农学效率、表观利用率、生理利用率、地力贡献率平均值分别为8.2 kg·kg~(-1) N、32.8%、25.6 kg·kg~(-1) N和59.1%。根据产投比结果分析,本试验条件下青海省春油菜推荐氮肥用量为150 kg·hm~(-2)。     

水肥供应对番茄生长及产量形成的影响

以"金鹏1号"番茄为试验材料,通过盆栽试验,对处于不同灌水量和氮、磷、钾肥用量条件下的番茄生长及产量进行分析。在此试验条件下,各因素对叶片数的因子贡献率的主次关系为:施氮量=施磷量灌水量施钾量;对叶果比的影响表现为:灌水量施氮量施磷量施钾量;坐果率表现为:灌水量施氮量施磷量施钾量;60%~83.78%的灌水量有利于降低叶果比进而促进产量的增加;氮肥、磷肥用量达到0.96 g·kg~(-1)、P_2O_50.528 g·kg~(-1)土时会导致叶片数和叶果比增加,坐果率和产量下降;随着灌水量、施氮量、施钾量的增加番茄产量呈先增后减的趋势,在灌水量为83.78%W,施氮量为0.77N g·kg~(-1)土,施磷量为P_2O_50.421 g·kg~(-1)土,施钾量为K2O 0.670g·kg~(-1)土时产量达到最大值为467.5 g·株~(-1)。     

不同盐度下施氮量对甜菜生长发育及氮素吸收利用特性的影响

本研究以Na Cl为盐分模拟不同盐度环境(轻度S1:2.5 g·kg~(-1);中度S2:5.0 g·kg~(-1);重度S3:7.5g·kg~(-1)),研究了施氮对盐环境下甜菜生长发育与氮素吸收利用状况的影响。结果表明:(1)在实验的三种盐度条件下,在N1(0.3 g·kg~(-1))~N4(2.4 g·kg~(-1))的范围内施氮可显著缓解盐胁迫对甜菜造成的伤害或显著增强其在盐胁迫下的生存能力,甜菜在轻度与中度盐胁迫下的最佳施氮量均为N3(1.2 g·kg~(-1)),在重度盐胁迫下的最佳施氮量为N2(0.6 g·kg~(-1));(2)在轻、中、重三种盐度下,随着施氮水平(0~2.4 g·kg~(-1))的提高,甜菜叶片渗透势随之降低,渗透调节能力呈增强趋势;(3)在各盐度环境下,施氮均可促进甜菜叶片(同化枝)光合色素的合成,增加光合色素含量,从而提高光合效率,同时增强其对盐渍环境的适应能力;(4)在三种盐度下,随着施氮量的增加甜菜氮素生产力与氮肥农学利用效率均呈现出下降的趋势,在N1(0.3 g·kg~(-1))~N3(1.2 g·kg~(-1))水平下表现为大幅度下降,并且氮素生产力与氮肥农学利用效率均随着盐度的增加而下降;(5)在三个盐度环境下,甜菜块根、叶柄、叶的含氮量均随着施氮量(0~2.4 g·kg~(-1))的增加而升高,且同一施氮水平下甜菜各部位含氮量总体表现为:叶叶柄块根;(6)在轻、中、重三种盐度胁迫下的最高施氮限量分别为1.39、1.33 g·kg~(-1)和1.24 g·kg~(-1)(其最高干物质产量分别为90.09、72.86 g·pot~(-1)和32.47 g·pot~(-1))。     

风沙土区黄柳根系及其碳储量分布特征

以内蒙古敖汉旗风沙土区15 a、25 a和35 a林龄的黄柳(Salix gordejevii)林为研究对象,分别设置3个样地,采用分层分段挖掘法,测定不同土层、土段的根系生物量、含碳率,计算根系碳储量,分析不同林龄黄柳根系及根系碳储量分布特征变化。随着土层深度的增加,黄柳根系生物量呈现先增加后减少的趋势,主要分布在0~100cm土层,均占根系总量的80%以上;15 a、25 a和35 a生黄柳根系总生物量分别为516.50、4 448.60 g·株~(-1)和7 257.7 g·株~(-1),随着林龄的增加,黄柳根系生物量呈增长趋势。根系碳储量分布特征呈梭形,15 a、25 a和35 a生黄柳根系总生物量分别为30.81、158.56 g·株~(-1)和229.9 g·株~(-1);随着林龄的增加呈增加趋势。     

缓释尿素对土壤和玉米植株氮素及干物质和产量的影响

试验在等量普通尿素、磷、钾肥(纯N 60、P_2O_5120、K_2O 90 kg·hm~(-2))作种肥一次性施入玉米种下8 cm基础上,在拔节期前施入不同类型缓释尿素(纯N记160 kg·hm~(-2)),采用随机区组设4个施氮处理:树脂包膜尿素(A);硫包膜尿素(B);植物油包膜尿素(C);普通尿素(CK)。测定玉米整个生育期0～20 cm土层中硝态氮、铵态氮和全氮含量,测定植株不同器官干物质量和氮含量。结果表明缓释尿素可以提高玉米生育后期土壤硝态氮和铵态氮含量,与普通尿素相比处理A、B、C灌浆期分别提高硝态氮20.37、29.76、5.18 mg·kg~(-1)和铵态氮8.19、2.31、1.85 mg·kg~(-1),成熟期分别提高硝态氮5.50、5.93、2.04 mg·kg~(-1)和铵态氮7.12、3.39、1.02 mg·kg~(-1);土壤全氮含量灌浆期提高0.22、0.11、0.05 mg·kg~(-1),成熟期提高0.20、0.20、0.01 mg·kg~(-1);与对照相比树脂包膜尿素(A)、硫包膜尿素(B)、植物油包膜尿素(C)干物质积累量和氮素积累量分别提高89.41、60.92、48.97 g·株-1和73.12、51.60、34.84 kg·hm~(-2),成熟期籽粒氮素吸收量提高56.98、43.58、29.36 kg·hm~(-2);缓释尿素处理较普通尿素处理增产2.22%～18.82%。三种缓释尿素处理相比较,树脂包膜尿素施用有效提高了生育后期土壤氮素含量、植株干物质积累、氮素积累和产量,施用效果最佳。     

不同开垦年限土壤养分和盐分时空分布特征研究

为了研究干旱区绿洲农业不同开垦年限耕地土壤养分的时间和空间变化规律,选取玛纳斯流域内5个开垦年限(荒地、2 a、4 a、6 a、8 a)的土地,结合地统计学、3S技术,利用空间置换时间的方法对研究区土壤养分和盐分的时空分布特征进行分析研究。结果表明:研究区耕地随着开垦年限的增加,各层土壤的总盐、有效钾含量呈现明显下降的趋势。总盐含量由开垦前11.9~25.2 g·kg~(-1)下降至开垦8 a后的1.7~3.0 g·kg~(-1),尤其是表层土壤总盐的含量在开垦种植6~8 a后基本维持在非盐化-轻盐化水平;而土壤有效钾含量在各个层次均呈现出不断的消耗趋势,由开垦前225~499 mg·kg~(-1)下降至开垦8 a后的138~225 mg·kg~(-1);随着开垦年限的增加,研究区土壤有机质、碱解氮和有效磷含量呈现出先下降再升高的趋势,基本上在开垦4 a左右的时候会出现一个较低值,然后随着开垦种植年限的增加而逐渐上升,如有效磷含量由开垦前3.7~8.1 mg·kg~(-1)下降至开垦4 a后的1.9~5.7 mg·kg~(-1),随后上升至开垦8 a后的3.37~13.5 mg·kg~(-1)。研究表明,研究区农业用地开垦时间的长短对土壤养分、盐分含量的影响表现出一定的规律。     

生物炭对谷子幼苗生长及光合特性的影响

为揭示生物炭在谷子种植中的应用潜力和价值,以祥谷3号为材料,采用室内盆栽试验的方式,在土壤中添加3种不同比例的生物炭(10、50、90 g·kg~(-1)),于播种后30 d对谷子幼苗进行生物量、根系形态和地上形态及叶片光合的测定分析。结果表明:与未施用生物炭(BC0)对照相比,不同剂量的生物炭均显著改善了谷子幼苗地上和地下生物量、形态指标以及除胞间CO_2浓度以外的其他光合参数指标,且以中等剂量生物炭(50 g·kg~(-1))对谷子生长和光合指标的影响效果最为明显。与对照相比,中等剂量生物炭(50 g·kg~(-1))处理谷子幼苗地上部分和地下部分鲜重、干重分别提高了220%、181%和500%、350%,根冠比增加41.7%;谷子幼苗地下部分主根长、总根长、总根表面积、根尖数、分枝数分别提高124%、215%、323%、86.4%、279%;谷子地上部分幼苗株高、茎粗和叶面积分别提高48.28%、50%、159%;叶片相对叶绿素含量和净光合速率分别提高21.01%和167%。研究表明,生物炭添加可以改善地下根系和地上茎叶形态,改善叶片光合和根系对水分和矿质元素的吸收能力,从而促进谷子生物量的积累,可为后期产量的形成奠定基础。     

Dermestid beetles in ‘evolution Canyon’, lower Nahal Oren, Mt. Carmel, including new records for Israel

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.     

Diagnostics,genetic diversity and pathogenic variation of ascochyta blight of cool season food and feed legumes

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.     

Epidemiology of Toxigenic Fungi and their Associated Mycotoxins for Some Mediterranean Crops

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.     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

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.     

A survey of the genera of<Emphasis Type="Italic">Microgaster</Emphasis> latreille and<Emphasis Type="Italic">Hygroplitis</Emphasis> thomson (Hymenoptera: Braconidae: Microgastrinae) from China

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.     

Plant Viruses Transmitted by Whiteflies

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.     

Brief Guide for Authors

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     

The use of Solacol® (validamycin) as a growth retardant in the isolation of soil fungi

Solacol^®, a formulation of the antibiotic validamycin, at 0.33% in 2% malt extract agar, reduced the spread of fungi on dilution plates drastically and allowed twice as much incubation time before subculturing; this resulted in an elevated number of species isolated. Using pure cultures of 62 common soil fungi, it was shown that all fast-growing species (exceptPythium ultimum) were efficiently inhibited but not completely suppressed. Inhibition was comparable to that by 0.5% oxgall, though, while this substance completely suppressed several species, Solacol very strongly inhibited onlyGaeumannomyces graminis, Gerlachia nivalis, Harzia acremonioides, Verticillium biguttatum andRhizoctonia solani. In a further experiment each separate constituent of Solacol was tested against 22 fungi at equivalent concentrations. Validamycin strongly inhibitedChaetomium globosum and two Basidiomycetes, though hardly more than the non-ionic detergent which mainly inhibited the other fungi. A few species were, however, more inhibited by Solacol than by the detergent alone. Solacol at 0.33% is a suitable aid in dilution plating of soil fungi, by increasing the number of colonies and species observed.Samenvatting Solacol^®, een formulering van het antibioticum validamycine, remde de groei van schimmels in verdunningsplaten met een concentratie van 0.33% in 2% moutagar en maakte het mogelijk de periode tot afenten met een factor 2 te verlengen; daardoor was het aantal geïsoleerde soorten duidelijk toegenomen. Met reincultures van 62 algemene grondschimmelsoorten werd aangetoond, dat alle snelgroeiende soorten (met uitzondering vanPythium ultimum) voldoende geremd, maar niet volkomen onderdrukt werden. Het remmingspercentage was vergelijkbaar met dat van 0.5% ossegal, hoewel dit laatste sommige soorten volkomen onderdrukte; Solacol remde alleenGaeumannomyces graminis, Gerlachia nivalis, Harzia acremonioides, Verticillium biguttatum enRhizoctonia solani zeer sterk. In een volgend experiment werden de componenten van Solacol t.o.v. 22 fungi apart getoetst in concentraties equivalent aan 0.33% Solacol. Validamycine remde alleenChaetomium globosum en twee basidiomyceten behoorlijk, maar nauwelijks meer dan de niet-ionische uitvloeier, die in hoofdzaak de overige remeffecten veroorzaakte. Enkele soorten werden echter door het complete Solacol veel sterker geremd dan door de uitvloeier alleen. Solacol in een verdunning van 0,33% wordt aanbevolen bij verdunningsplaten voor het isoleren van grondschimmels ten einde het aantal kolonies en soorten te verhogen.     

Broad bean mottle virus in Morocco; curculionid vectors,and natural occurrence in food legumes other than faba bean (Vicia faba)

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.     

Characterization of potato potyvirus Y (PVY) isolates from seed potato batches. Situation of the NTN, Wilga and Z isolates

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 PVY^N strain and six to the PVY^O strain. No PVY^C was found. Two other isolates reacted serologically like PVY^O, but were unable to elicit a hypersensitive response from the Ny_tbr gene and probably represent the PVY^Z group. At the molecular level, these two isolates showed a combination of both PVY^O and PVY^N and could be recombinants of these strains. Another isolate reacted serologically like PVY^O, but induced vein necrosis in tobacco, like PVY^N-Wilga. Some PVY^N isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVY^NTN group. The PVY^NTN, PVY^N-Wilga and PVY^Z groups probably represent pathotypes within strains PVY^N and PVY^O, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.