Combating viral mosaic disease of cassava in the Lake Zone of Tanzania by intercropping with legumes

Cassava (Manihot esculenta Crantz) production is constrained by many factors, including the viral cassava mosaic disease (CMD). This study was conducted to explore the potential of intercropping cassava with legumes to reduce CMD effects on cassava production. Local (Lyongo Kwimba) and improved (Suma) cassava varieties were intercropped with three types of grain legumes (groundnut, Arachis hypogea L. var. Upendo; cowpea, Vigna unguiculata (L.) Walp. var. Vuli; and green gram, Vigna radiata (L.) R. Wilczek var. Imara). Monocrops of cassava with and without NPK fertilizer were included as controls. The experiment was established using a randomized complete block design with four replications in a split-plot arrangement for three seasons. Cassava varieties intercropped with cowpeas, green gram, and groundnuts and cassava monocrops with and without NPK fertilizer constituted the main plot and sub-plots, respectively. Whitefly population counts and CMD severity and incidence were measured at regular intervals. Cropping system had a significant effect (P < 0.05) on whitefly populations and CMD severity. Small whitefly populations (0–7.5 individuals per leaf) and low CMD severity (1–2.4 on a 5-point scale) were recorded in improved and local cassava varieties intercropped with green gram. The local cassava variety intercropped with green gram showed low CMD incidences (0%–40%) in all seasons. Generally, growing cassava with green gram proved effective in reducing whitefly populations and CMD incidence and severity. Intercropping cassava with grain legumes may improve cassava production and food security in CMD-prone areas of the Lake Zone of Tanzania and areas with similar environments.     

大豆花叶病毒病转基因抗性研究进展

大豆是世界上重要的豆类作物,是人类植物性蛋白和食用油的主要来源.大豆花叶病毒(soybean mosaic virus,SMV)是大豆重要的病原物之一,广泛分布于世界各大豆产区,严重影响大豆的产量和品质.目前尚无有效的化学药剂可以防治大豆花叶病毒病,培育抗病品种是最经济、安全、有效的途径.然而,传统的抗病育种周期漫长,...     

Control of tobacco mosaic virus by Pseudomonas fluorescens CZ powder in greenhouses and the field

Pseudomonas fluorescens strain CZ has been reported to inhibit tobacco mosaic virus (TMV) by producing an antibiotic protein. In this study the effects of CZ powder on TMV infection were investigated on tobacco grown in greenhouses and in the field. CZ stocks were cultured in a mixture medium (5 g wheat bran, 1 g soybean flour, 1 g corn flour, 1 g peanut flour), and then mixed with silica white at a ratio of 6 ml:1 g to make CZ powder. The effective cell concentration in a 100-fold dilution of CZ powder was 49.8 × 10¹⁰ cfu ml⁻¹. In greenhouse experiments where Nicotiana tabacum cv. Samsun NN plants were challenged by mechanical inoculation with a mixture of the 100-fold diluted CZ powder and TMV, the in vitro suppression of the TMV infection was 88.3% compared to the controls in which a mixture of water and TMV was used as inoculum. Similarly when N. tabacum cv. NC89 plants were inoculated by cutting the leaves with virus-contaminated scissors, dipping the scissors in a 100-fold dilution of CZ powder before cutting showed a disinfection effect of 96.3% compared with water dipping controls. Drenching and spraying a 100-fold dilution of CZ promoted growth and inhibited virus infection by 59.2% on N. tabacum cv. NC89 plants in the greenhouse. In field trials, 100-fold dilution of CZ suppressed TMV infection by 58.2% and 47.6% in 2010 and 2011, respectively, which was similar to the effect of Ningnanmycin (antibiotic purified from Streptomyces noursei var. xichangensis), a registered antiviral agent in tobacco. All these results indicated that CZ has a potential to be used as a hand tool disinfector and an antiviral agent against TMV.     

番茄斑驳花叶病毒海南分离物全基因组序列分析

本研究采用小RNA深度测序及RT-PCR检测技术鉴定海南省陵水县冬种番茄(圣女果)病株受到烟草花叶病毒属的番茄斑驳花叶病毒(Tomato mottle mosaic virus,ToMMV)侵染。通过机械摩擦接种,将该病原病毒保存于本生烟植株上,命名为番茄斑驳花叶病毒海南分离物(ToMMV-HN)。采用RT-PCR分段扩增获得了该病毒分离物的全基因组序列。测序结果表明,该病毒分离物基因组全长6399 nt,含有4个开放阅读框,编码4种蛋白,与已报道的ToMMV9个分离物核苷酸和编码产物氨基酸序列相似性分别为98.0%～100%和99.2%～100%;与同属的番茄花叶病毒(Tomato mosaic virus,ToMV)、番茄棕色皱果病毒(Tomato brown rugose fruit virus,TBRFV)和烟草花叶病毒(Tobacco mosaic virus,TMV)代表分离物核苷酸序列相似性分别为84.7%、80.7%和79.0%。系统进化分析结果表明,ToMMV-HN与该病毒中国西藏和云南辣椒分离物亲缘关系最近,与美国加州和南卡州番茄分离物次之,与西班牙和巴西番茄分离物亲缘关系相对较远。本研究为我国番茄病毒病诊断和防控,尤其是抗病品种选育提供了基础资料。     

Biotinylated DNA probes for detecting virus Y and aucuba mosaic virus in leaves and dormant tubers of potato

Summary Detection of potato virus Y (PVY) in dormant potato tubers using the enzyme-linked immunosorbent assay (ELISA) has been reported not to be accurate and reliable and it requires breaking of the dormancy of tubers prior to testing. We describe a simple, practical and highly sensitive hybridization method based on the use of biotinylated DNA probes for detecting PVY and potato aucuba mosaic virus (PAMV) in dilutions made of crude extracts of infected potato leaves and dormant tubers. As little as 50 fg of RNA can be detected by this method, and the probes are highly specific for their targets, even in crude plant extracts. The presence of one virus did not interfere with the detection of the other.     

Developing cultivars of the common bean (Phaseolus vulgaris L.) for southern Africa: bean common mosaic virus resistance, consumer preferences and agronomic requirements

The requirements that must be met by bean common mosaic virus (BCMV)-resistant cultivars of the common bean in Zimbabwe, and the feasibility of developing such cultivars, were investigated by a survey among farmers, evaluation of resistant and locally adapted inbred genotypes, and backcrossing to transfer the bc-3 resistance gene to the genetic background of the locally adapted genotypes. Genotypes were evaluated by field trials in a range of environments, by consumer assessment and by measurement of seed size, water absorption capacity (WAC) and cooking time. Backcross generations were evaluated in the field and by measurement of the same seed characters.

Most farmers produced beans in monoculture, using bush or semi-climbing cultivars and a single seed type, the most common colour type being cream with red mottles. This is in strong contrast to the production system in many parts of eastern and central Africa, where intercropping, climbing types and seed-type mixtures are common. The BCMV-resistant genotypes had a similar range of flowering dates, maturity dates and canopy heights to locally adapted genotypes, and a similar range of environmental responses with respect to these variables, but were generally small-seeded. Consumers preferred large seeds, and seed colours that were not generally found in the resistant genotypes. However, the bc-3 gene was readily combined with large seed by backcrossing. The resistant genotypes generally had shorter cooking times than the locally adapted genotypes.

It is concluded that it will not be difficult to combine BCMV resistance with the other characteristics required of bean cultivars in Zimbabwe, with the possible exception of seed colour, and that the same is probably true for other production regions in southern Africa.     

油菜品种和资源材料 对芜菁花叶病毒的抗性鉴定

在人工接种高病害压条件下,对当前生产上应用的13个油菜双低和杂交品种及14份资源材料进行了 对芜菁花叶病毒( TuMV)的抗性鉴定。结果表明,参试的13个油菜品种均不抗TuMV,但感病性低于对照品种中油 821。14份油菜资源材料间抗性差异显著,有3份材料表现高抗和中抗。大部分油菜推广品种表现的高发病率和 病情指数表明在病害流行地区和年份,这些品种不足以抵挡病毒病造成的损失。     

安徽省SMV株系的鉴定及其抗源筛选

为明确安徽省大豆花叶病毒（Soybean mosaic virus,SMV）株系的最新组成、分布及消长动态,以及筛选对流行株系的抗性种质。2009-2010年广泛采集安徽省各大豆主要产区疑似SMV病样461份,采用生物学及血清学方法鉴定得到83个SMV分离物。用全国统一的10个鉴别寄主对这些分离物进行鉴定,共鉴定出14个SMV株系,如SC3-SC9、SC11、SC13-SC15、SC17、SC19和SC22,其中SC5、SC11、SC14、SC15、SC17、SC19和SC22是本研究大豆主产区新发现的。进一步比较分析发现,SMV株系SC3和SC7仍为目前安徽省大豆产区的流行株系,分别占分离物总数的16.9%和25.3%;其次为新发现的强毒株系SC15,在安徽省也有较为广泛的分布,比率为12.1%。针对流行株系SC3和SC7的抗源筛选结果表明,来自参加安徽省区试的149份资源中有中作J8023、中黄45、L85-2308、中涡47号和濉科13等5份材料对SC3表现高抗,中黄45、宿03-4-1-4和鲁06-7等9份材料对SC7表现高抗;来自参加我国南方区试的95份种质资源中有13份对强毒株系SC15表现抗病,占鉴定品种的13.7%。本研究明确了安徽省大豆产区的流行株系及变化趋势,筛选出针对SMV流行株系的抗源,为培育抗病品种和抗病品种布局提供了依据。     

皖豆33对SMV株系SC3的抗性遗传分析及分子标记定位

大豆花叶病毒(soybean mosaic virus, SMV)病严重影响我国大豆产量及品质。本研究利用抗病高产稳产大豆品种皖豆33配制抗×感和抗×抗杂交组合,接种SMV优势株系SC3,研究皖豆33的抗性遗传方式及其与不同品种抗性基因间的等位性关系。结果表明:接种SC3后,抗感组合(W illiams82×皖豆33)及(皖豆33×南农1138-2)的F1单株均表现抗病,卡方测验结果显示F2群体符合3抗∶1感的分离比,F2∶ 3家系分离比符合1抗∶2分离∶1感,表明皖豆33对SC3的抗性由1对显性基因(命名为RSC3(w))控制;抗×抗组合科丰1号、齐黄1号和大白麻×皖豆33的抗性基因等位性研究显示,科丰1号与皖豆33携带对株系SC3的抗性基因是等位的或紧密连锁的,齐黄1号、大白麻与皖豆33携带抗SC3的基因是不等位且独立遗传。利用皖豆33×南农1138-2的392株F2群体将皖豆33携带SC3的抗性基因RSC3(w)定位在大豆2号染色体SSR标记BARCSOYSSR_02_0610和ZL-52之间,遗传距离分别为0.29cM和0.35 cM,物理距离约为175 kb。     

An evaluation of gains in breeding for resistance to the cocoa swollen shoot virus disease in Ghana

The present study examines the gains in resistance to cocoa swollen shoot virus (CSSV) infection from investments in breeding over the past seven decades. The general susceptibility to CSSV infection of the West African Amelonado that dominated plantings prior to the start of formal research in 1938 necessitated the introduction of germplasm of Upper Amazon origin to better contain the disease spread. Included in this study are findings of two recent experiments. In the first, the genetic basis for resistance in the clone mvT85, developed from gamma radiation of clone T85/799 and putatively resistant to CSSV disease was investigated. In the second experiment, the comparative levels of resistance in sets of old, current and new cocoa varieties were tested following inoculations with the severe CSSV strain 1A. Absence of nucleotide differences at 29 single nucleotide polymorphism (SNP) loci between mvT85 and T85/799, and lack of segregation for resistance in the full-sib and backcross populations derived from mvT85 indicated that mvT85 did not carry novel genes for improving cocoa for CSSV disease resistance. Moreover, there were no differences in resistance to CSSV disease between mvT85 and T85/799. These observations conflict with the previous report that mvT85 is immune to CSSV disease, and distinct from T85/799. Between variety groups, disease severity scores based on three successive leaf flushes after inoculation were not effective in discriminating among them. Disease severity assessed eight months after inoculation was the most important criterion for separating varieties for resistance to CSSV disease. As expected, the older varieties were the most sensitive to infection. No differences were found between current varieties derived exclusively from Upper Amazon clones and new varieties. Contrary to the generally held opinion of a higher level of resistance in existing inter Upper Amazon cultivars, varieties derived from crosses using Catongo, RB 49 and C-SUL 7 (all of Lower Amazon origin) as males with specific Upper Amazon varieties were among the most resistant. A re-appraisal of variety recommendations for areas of mass infection and for less affected areas is advocated.     

CAP Analysis of the Distribution of the Introduced Bemisia tabaci (Hemiptera: Aleyrodidae) Species Complex in Xinjiang,China and the Southerly Expansion of the Mediterranean Species

Bemisia tabaci (Gennadius) cryptic complex has invaded Xinjiang, China, since 1998. The distribution of Mediterranean (MED) and Middle East-Asia Minor 1 (MEAM1) B. tabaci substrains has been gradually identified due to the development of molecular technology. In this study, the distribution of MED and MEAM1 in Xinjiang was determined by cleaved amplified polymorphic sequence (CAPs). Results showed that MED dominated in northern Xinjiang (84%), whereas MEAM1 was dominant in southern Xinjiang (72%). Five pairs of simple sequence repeat (SSR) primers were used to analyze the genetic diversity of B. tabaci among 36 geographic populations. The genetic diversity of MED and MEAM1was low and varied little among populations in Xinjiang (0.09 ± 0.14 and 0.09 ± 0.13, respectively). Based on ∆K statistic, 13 populations of MEAM1 could be classified into two subgroups at K = 2, whereas the 23 populations of MED could be classified into four subgroups at K = 4. However, Mantel t-test demonstrated no correlation between geographical and genetic distances among B. tabaci complex (R = 0.42, P = 1.00). Neighbor-joining and principal coordinate analysis showed that geographical isolation and interspecific differences were the main causes of the genetic variation. Gene flow predicted that MEAM1 was most likely introduced from Urumqi to the southern Xinjiang. Meanwhile, a large proportion of MED in Kashi region came from Changji and Yining. To block ongoing dispersal, strict detection and flower quarantine regulations need to be enforced.     

Economic injury levels for Bemisia tabaci (Homoptera: Aleyrodidae) in cotton: impact of crop price, control costs, and efficacy of control

Field studies were conducted during 1993 and 1994 in the Imperial Valley, California and Maricopa, Arizona to examine relationships between densities of Bemisia tabaci (Gennadius) populations and cotton (Gossypium hirsutum L.) yields, and to estimate economic injury levels (EILs) for pest management application. Populations of B. tabaci were manipulated by applying different numbers of insecticide applications in replicated plots. Resulting insect populations and cotton lint yields were used to develop damage functions and to estimate EILs for all life stages in relation to variable cotton prices, insecticide costs, and pest control efficacy. Economic injury levels declined with increasing cotton prices and increased as the cost of control increased, however, these changes were relatively small, based on typical ranges in price and control costs. In contrast, the efficacy of control provided by insecticide applications had a large influence on EILs, with lower efficacies being associated with higher injury levels. We developed a multiple regression model that accounted for the dynamic changes in the EIL in relation to crop price, control costs, control efficacy, and potential yield. Based on average prices and reasonable control costs and efficacy, EILs ranged from 5.9–15.2 adults/leaf, 6.1–19.8 eggs cm⁻², and 1.7–4.7 nymphs cm⁻² of leaf area. Additional research is needed to more closely relate the costs of control to the suppression of insect populations, and to define economic thresholds that will enable pest managers to maintain pest populations below EILs.     

一种E.coli-Free的酵母同源重组系统稳定快速构建PLDMV侵染性克隆的新方法

侵染性克隆是研究病毒的重要工具,而偏大的病毒基因组及其在大肠杆菌中的不稳定给构建侵染性克隆造成很大困难。通常采用插入内含子和酵母同源重组等方式可以获得稳定克隆,但本实验最初利用酵母同源重组系统并未成功构建番木瓜畸形花叶病毒(PLDMV)的侵染性克隆。经研究证实,该不稳定现象确实存在于大肠杆菌中,而非酵母和农杆菌细胞。通过改良酵母同源重组方法,成功构建了有/无内含子intron 2的PLDMV侵染性克隆p35S-FL和p35S-FL-In2,农杆菌注射接种番木瓜均发病,侵染效率达64.7%~69.7%。本研究通过酵母同源重组质粒直接转化农杆菌,建立了一种10 d内即可稳定快速构建PLDMV侵染性克隆的E.coli-Free酵母同源重组新方法。该方法对其他在大肠杆菌中不稳定的植物病毒侵染性克隆的构建具有重要意义。     

Occurrence of Telosma mosaic virus causing passion fruit severe mosaic disease in Thailand and immunostrip test for rapid virus detection

The cause of leaf and fruit severe mosaic disease in purple passion fruit (Passiflora edulis) in Chiang Mai province, Thailand, was identified and virus diagnostic kit was developed. Symptomatic plants collected from diseased mother plants in the nursery at the Royal Pangda research station (RPRS) was used for virus isolation through single lesion transfer in Chenopodium amaranticolor, followed by virus propagation for purification in Nicotiana benthamiana, and back inoculation to purple passion fruit. Electron microscopy of leaves with typical symptoms revealed potyvirus-like flexuous rod particles, ca. 750 nm long and pinwheel inclusion bodies in the cytoplasm of infected cells. The deduced amino acid sequence of the complete coat protein revealed that the isolated virus was a strain of Telosma mosaic virus with which it shared 84% identity. A rabbit polyclonal antiserum was produced against purified virions, and used to develop a gold-labeled immunostrip for rapid virus diagnosis. The test strip could detect the virus in diseased passion fruit sap up to a dilution of 1: 640, and positive test line could be read within 3–5 min. Application of strip test for virus assay in RPRS nursery's mother plants help screen clean stocks. This strip test kit supports RPRS program of producing virus-free planting materials for farmers.     

Reducing the spread of potato leaf roll virus,alfalfa mosaic virus and potato virus Y in seed potatoes by trapping aphids on sticky yellow polyethylene sheets

Summary Trials were made in an attempt to reduce the spread of the aphid-transmitted viruses, potato leaf roll virus, potato virus Y and alfalfa mosaic virus in seed potatoes. The experiments were carried out on the coastal plain of Israel, at Bet-Dagan. Seed potatoes which had been protected by ‘sticky’, yellow polyethylene sheeting showed a marked reduction in the incidence of virus-infected tubers. The percentage of potato leaf roll virus-affected tubers from protected plots, compared to that from the unprotected, control plots, was as follows: for 1974, 2 and 17.2%, for 1975, 6 and 29%, respectively. The higher infection rates for the period 1975–76 being explained by the longer aphid trapping time used which continued until 20 June in 1975, but only to 10 May in 1974. There was also a reduction in the spread of both potato virus Y and alfalfa mosaic virus.

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Zusammenfassung Es wurde untersucht, ob die Ausbreitung von Blattlaus-übertragbaren Viren-Blattrollvirus (PLRV). Alfalfa-Mosaik virus (AMV) und Kartoffel-Y-Virus (PVY)- in Pflanzkartoffełbest?nden durch den Gebrauch von Farbk?dern kontrolliert werden k?nnte. Diese Versuche beruhen auf den Ergebnissen, dass L?use von reflektiertem Licht im Bereich zwischen 500 und 700 nm stark angezogen werden (Moericke, 1969). In den Jahren 1974–1975 und 1975 1976 wurden im Frühjahr (Hauptkartoffelanbauzeit) in Bet-Dagan. Israel zwei getrennte Versuche durchgeführt. Abb. 1 zeigt zwei Parzellen 10 m × 10 m. die 30 m von einander getrennt sind. Eine ist von klebrigen gelben Poly?thylenfolien umgeben, die andere nicht- unbehandelte Kontrolle. Jeder dieser Parzellen wurde am 2. M?rz 1974 und am 5. M?rz 1975 mit irischem zertifiziertem Pflanzgut der Sorte Up-to-date bepflanzt, insgesamt 260 Knollen pro Parzelle, wobei der Abstand zwischen den Reihen 90 em und innerhalb der Reihe 35 cm betrug. Vor dem Auflaufen der Kartoffeln wurde in einem Abstand von 4 m von den Parzellenkanten bis zu einer H?he von 70 cm über dem Erdboden 4 m×0.5 m grosse Poly?thylenfolien gespannt. Diese Folien wurden mit ‘Rimi foot glue’ (R. Yewnin and M. Joffe. Technochemical factory. Tel Aviv. Israel) bedeckt, das durchsichtig ist und lange Zeit klebrig bleibt. W?hrend der Wachstumszeit wurden die Symptome beobachtet und mit Hilfe einer Wasserfalle nach Moericke, die nahe der Kartoffeln aufgestellt war, wurden die geflügelten Blattlauspopulationen gefangen, um darüber Daten zu erhalten. Die gefangenen Blattl?use wurden w?chentlich gesammelt (Zimmerman-Gries & Swirski, 1960). Vom Gesamtfang wurde nurMyzus persicae bestimmt und gez?hlt. Das Auftreten von Prim?rinfektionen durch PLRV, AMV und PVY wurde durch regelm?ssige Feldbeobachtungen erfasst. Von jeder Pflanze wurden für sp?tere Kontrollen zwei Kartoffelknollen in den für sp?tere Kontrollen zwei Kartoffelknollen in Pflanzgutgr?sse geerntet. Diese Kartoffelknollen wurden 6 Monate bei 2 3 C gelagert und dann in einem insektengeschüzten Gew?chshaus ausgepflanzt. Das Blattrollivrus wurde bestimmt, in demM. persicae von Pflanzen, in denen dieses Virus vermutet wurde, aufDatura stramonium umgesetzt wurden (Zimmerman-Gries et al., 1973). AMV, PVY und PVX wurden durch mechanische Inokulation auf Testpflanzen identifiziert. Die Abbildungen 2 und 3 zeigen die enge Verbindung zwischen der Verteilung des Gesamtfanges w?hrend der Saison und der vonMyzus persicae. Tabelle 1 zeigt die Anzahl infizierter Knollen in Prozent im ersten Nachbau von geschützten und ungeschützten Parzellen. In den Jahren 1974 und 1975 waren in den ungeschützten Parzellen viel mehr PLRV-infizierte Knollen als in den geschützten (2 und 17.2% bzw. 6 und 29%). Der h?here PLRV-Befall im Jahre 1975 kann durch die l?ngere Fangperiode fürM. persicae in diesem Jahr erkl?rt werden. Ein ?hnlicher Einfluss der klebrigen, gelben Poly?thylenfolien wurde bei der Ausbreitung von AMV (1974: 16 und 7.2%. 1975: 2.5 und 6%) beobachtet. Der Befall durch PVY war nicht so hoch wie der von Cohen & Marco (1973) festgestellte (1974: 0 und 2.4% und 1975: 1 und 3.5%). Sie fanden in 90% ihrer Pfefferproben PVY. Diese Technik, mit entsprechender Weiterentwicklung, k?nnte der Ausbreitung persistenter und nicht persistenter Viren in Pflanzkartoffelbest?nden entgegenwirken.

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Résumé La possibilité de réduire le taux de contamination du plant de pommes de terre par le virus de l'enroulement (PLRV), le virus de la mosa?que de la luzerne (AMV) et le virus Y de la pomme de terre (PVY) a été testée et la réduction a pu être possible par l'utilisation d'appats de couleur’. Ces essais ont été basés sur le fait que les pucerons sont fortement attirés par la lumière réfléchie dans la zone des 500–700 nm (Moericke, 1969). Deux expérimentations différentes ont été conduites durant le printemps (principale période de culture de la pomme de terre) des années 1974–75 et 1975–76 à Bet-Dagan en Isra?l. Deux parcelles de 10 m×10 m, séparées par une distance de 30 m, ont été retenues comme l'indique la figure 1. L'une est entourée avec des baches en polyéthylène jaune qui sont collantes, l'autre n'est pas entourée et sert de témoin non traité. Chacune de ces parcelles a été plantée avec des semences certifiées en provenance d'Irlande de la variété Up-to-Date le 2 mars 1974 et le 5 mars 1975. 260 tubercules ont été plantés dans chaque parcelle à des distances de 90 cm×35 cm. A une distance de 4 m de chaque c?té, et avant la levée des pommes de terre, une bache de polyéthylène jaune de 4 m ×0.5 m a été déployée à une hauteur de 0.7 m au-dessus du sol. Ces baches ont été recouvertes de ‘glue Rimi-foot’ (R. Yewmin et M. Joffe, usine technochimique. Tel Aviv, Isra?l) qui est transparente et qui reste collante assez longtemps. Les sympt?mes ont été observés pendant la période de croissance et un échantillonnage de la population aphide ailée a été réalisé au moyen de piège à eau du type Moericke, placé près des pommes de terre afin d'obtenir des données sur la population de pucerons ailés. Les pucerons piégés ont été collectés chaque semaine (Zimmerman-Gries & Swirski, 1960). Sur le total d'ailés recueillis, il n'y a eu queMyzus persicae d'identifier et de dénombrer. L'incidence de l'infection en cours de saison par le PLRV, AMV et PVY a été déterminée par des observations au champ à intervalles réguliers. Au moment de la récolte, il a été prélevé 2 tubercules par pied pour le test de préculture. Ces tubercules ont été conservés à 2–3 C pendant 6 mois: la mise en culture a eu lieu en l'absence de tout insecte. Le virus de l'enroulement a été identifié après acquisition parM. persicae sur des plantes suspectées être contaminées et après transmission àDatura stramonium (Zimmerman-Gries et al., 1973). AMV, PVY et PVX ont été identifiés par inoculation mécanique à des plantes tests. Peu de plantes infectées en cours de saison ont été observées. L'étroite correspondance entre la distribution saisonnière pour l'ensemble des pucerons recueillis et pourM. persicae est indiquée par les figures 2 et 3. Le pourcentage de tubercules-fils contaminés par les virus pour les parcelles protégées et non protégées est résumé dans le tableau 1, II y a eu plus de tubercules contaminés par le PLRV dans les parcelles non protégées que dans les parcelles protégées pour les deux années 1974 et 1975 (2 et 17.2%, 6 et 29% respectivement). Le pourcentage plus élevé du PLRV en 1975 peut être expliqué par la période de capture deM. persicae, plus longue cette année. Une influence similaire des baches de polyéthylène jaune qui sont collantes a été observée sur la dissémination du AMV (1974: 16 et 7.2%. 1975: 2.5 et 6%). L'incidence du PVY (1974: 0 et 2.4% et 1975: 1 et 3.5%) n'a pas été aussi grande que celle observée par Cohen & Marco (1973). Ces auteurs ont trouvé 90% de PVY dans leurs échantillons de poivre. Cette technique, avec davantage de données, peut être efficace pour lutter contre la dissémination des virus persistants et non persistants dans les parcelles de plants de pommes de terre.

     

The Use of Saline Water in Agriculture in the Near East and North Africa Region: Present and Future

SUMMARY

Salinity is a major problem that negatively impacts agricultural activities in many regions in the world, and especially the Near East and North Africa region. Generally, salinity problems increase with increasing salt concentration in irrigation water. Crop growth reduction due to salinity is generally related to the osmotic potential of the root-zone soil solution. This will lead to certain phenological changes and substantial reduction in productivity. Salinity also affects the soil physical properties. Sewage treated wastewater is an alternative water source for irrigation. Using such wastewater will provide a new water resource to expand agricultural activities as well as reduce the environmental pollution. Each country in the region has a unique system of rules and regulations to protect the quality of water resources. Important aspects that should be taken into account when using wastewater for irrigation are discussed, including some information on the different irrigation systems used in the region, and the factors leading to success of using saline water for economic crop production. Information on the use of saline water or marginal saline soils for wheat production and improvement of irrigation systems, including old land irrigation systems, under Egyptian conditions is also presented. The regional experiences and the future prospects of using saline water for crop production that vary greatly among countries in the Near East and North Africa region are summarized. This article also presents information on special cultivation methods, such as protected agriculture and soilless culture that can help in alleviating the salinity effects. Finally, the article includes some examples on the inherited knowledge for saline agriculture that conveys the grower's experience in the Near East and North Africa region where several living examples for unique and sustainable cultivation system are still in operation. One of the most impressive cultivation techniques for bio-saline crop management in Egypt is the Edkawy production system.     

大豆新品系抗SMV鉴定及其抗性来源分析

大豆花叶病毒(soybean mosaic virus,SMV)病是危害我国大豆生产的主要病害之一。利用黄淮大豆产区的SMV优势株系SC3和SC7对选育的394份大豆高世代新品系进行抗病性评价并分析其抗性来源。结果表明:对SC3株系表现高抗的品系有120份,占试验品系总数的30.46%;高抗SC7株系的品系有80份,占20.30%;对SC3和SC7株系都表现高抗的品系有64份,占鉴定品系数的16.24%。如大豆新品系H20443、H21660、H22501、Y50574和Y52933等通过审定后用于大田的生产将对SMV的流行起到控制作用。对选育的大豆新品系进行抗性来源分析可以发现,RT(抗病型)×RT组合获得抗病型后代品系的概率最高,其后依次为RT×IT(中间型)RT×ST(感病型)IT×RTIT×ITST×RTST×IT,后代品系出现抗病型概率最低的组合是ST×ST。这些结果可为大豆新品系的选育和抗病育种亲本的组配提供参考依据。     

Investigation of Thrips tabaci Lind. as a cotton pest and the development of strategies for its control in Punjab

Thrips tabaci Lind. migrates from the lower to the upper portion of the cotton plant as the season progresses and plants increase in size. The population level of thrips on seedlings should be determined by visual observations of leaf damage instead of scouting. The crop should be sprayed before the damage level is such that seedling leaflets have a cup-like appearance. Combined attack by thrips (14.6 per leaf) and jassid (4.6 per leaf) caused a 37.6% loss in the yield of seed cotton. Granule application at the seedling stage and foliar sprays at later stages is suggested as a control strategy. Thrips and jassids appear to be mutually exclusive but the exact mechanism is not known.     

江苏省夏大豆褐斑粒率与病毒病病害程度及大豆主要性状关系的研究

用抗性不同（抗、高抗、中抗和不抗）的１６个大豆品种,组成１７个杂交组合。以其杂种二代为材料,研究其褐斑粒率与病毒病发病程度的相关性及与大豆主要农艺性状的关系。结果表明：大豆花叶病毒是籽粒发生褐斑的前提,在大多数情况下,褐斑率大小与病害程度呈正相关。一般情况下,在组合内,褐斑率与百粒重呈负相关,褐斑率高的品种,脐色一般较深,生育期越长,褐斑率越大,在育种中选择低褐斑率品种作亲本时,相关性状也应予考虑