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1.
Samples of Rapistrum rugosum seeds were collected throughout the state of New South Wales in order to examine dormancy and germination requirements of the species. There were significant phenotypic differences in temperature response between samples. These did not obviously correlate with any environmental or geographic trends. Optimal temperature range for germination was between 10°C and 25°C, with a base temperature of about 5°C. The width of the temperature optimum increased during storage, with germination increasing particularly at higher temperatures. Seeds unable to germinate at low temperatures appeared to be induced into dormancy; this could be broken at least partly by dry storage at 35°C. There was slightly better germination in dark conditions, but this effect was lost during after-ripening. Seed samples varied in their ability to germinate at different soil depths. Losses of both distal and proximal seeds were rapid, even in the absence of successful germination. La germination de Rapistrum rugosum (L.) All. en provenance de Nouvelle Galles du Sud, Australie Des échantillons de graines de Rapistrum rugo sum ont été récoltés dans tout l'État de Nouvelles Galles du Sud pour etudier la dormance et les exigences de germination de cette espèce. Il y avail entre échantillons des différences phénotypiques significatives dans la réponse à la température. Elles n'étaient clairement corrélé'es avec aucune variable environnementale ou géographique. Les températures optimales de germination se situaient entre 10 et 25°C, avec une température de base 5°C. L'éventail des températures optimales s'accroissait durant le stockage, la germination augmentant particulièrement aux hautes temperatures. Les grainesé incapables de germer à basses températures se sont révélées en dormance; celle-ci pouvait être au moins partiellement levée par un stockage à sec %aG 35°C. La germination était légèrement meilleure àl'obscurité, mais cet effet était perdu pendant la post maturation. Les échantillons de graines variaient dans leur capacitéà germer à différentes profondeurs. Les pertes en graines distales et proximales étaient rapides. même en 1'absence de germination aboutie. Keimung von Rapistrum rugosum (L.) All. aus New South Wales, Australien In ganz New South Wales wurden Samenproben von Rapistrum rugosum gesammelt, um die Dormanz und die Keimungsansprüche der Art zu untersuchen. Zwischen den Proben gab es signifikante Unterschiede in der Reaktion auf verschiedene Temperatur, was offensichtlich weder mil den Umweltbedingungen noch mil der Herkunft korreliert war. Deroptimale Temperaturbereich für die Keimung lag zwischen 10 und 25°C, die niedrigste Temperatur lag bei 5°C. Während der Lagerung nahm der optimale Tempera turbereich zu, wobei die Keimung besonders bei höheren Temperaturen zunahm. Bei niedrigen Temperaturen nichtkeimfähige Samen schienen dormant geworden zu sein; diese Dormanz konnte zumindest teilweise durch trockene Lagerung bei 35 °C gebrochen werden. Im Dunkeln keimten die Samen etwas besser, doch ging diese Fähigkeit während des Nachreifens verloren. Je nach Herkunft variierte die Fähigkeit der Samen, aus verschiedenen Bodentiefen zu keimen.  相似文献   

2.
Alligator weed, Alternanthera philoxeroides (Martius) Grisebach, of the family Amaranthaceae, has become a weed in many countries outside of its natural range in South America. In Australia, it is classified as a weed of national significance because of its potential to devastate agricultural and natural ecosystems. In New South Wales, the weed management officers of local government areas are charged with its control. In 2007, we surveyed this group to determine the status of alligator weed in each jurisdiction and to determine the methods and resources used in its control. Half of the local government area officers who responded reported its presence. The age, number, and size of the infestations indicated that the weed continues to spread into new areas, and is well established in others, at least within local government areas. The resources provided for the weed's management across the local government areas was less than had been expended annually on its removal from a single swamp. The respondents acknowledged that the current approach was inadequate and the need for research into its management was identified. We conclude that, with current management, the weed will continue to spread and recommend that the community should be mobilized to identify new areas of infestation and appropriately train people (e.g. bush restoration consultants, Landcare groups) to remove the weed.  相似文献   

3.
Analaysis of organochlorine pesticides in soil, fish, and human blood samples from Holland Marsh, Ontario, indicates that although total DDT is present in detectable amounts, it does not constitute a hazard to human health and longevity. Among soils tested, residues were highest in surface samples. DDT levels in human blood samples were similar to those in U.S. and British studies.  相似文献   

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Black root rot disease of cotton seedlings caused by Thielavioposis basicola was first reported in New South Wales (NSW), Australia in 1990. In 2018, T. basicola was reclassified into a new genus Berkeleyomyces, accommodating two closely related species: B. basicola and B. rouxiae. However, species status of cotton-T. basicola in NSW remains unsolved. Ninety-five isolates recovered from black root rot diseased cotton seedlings sampled across NSW in 2017/18 season was subjected to morphological, multigene sequencing (ITS, MCM7, RPB2), and pathogenicity assessments for their species identification. Berkeleyomyces rouxiae was accurately identified as the causal agent of black root rot of cotton.

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6.
As part of the National Pesticide Monitoring Program, the U.S. Fish and Wildlife Service analyzed organochlorine contaminant residues in fish samples collected from about 100 stations each year from 1970 to 1974. During this period, mean residues of DDT and its metabolites declined nationally but remained widespread, and high concentrations continued to be present in areas where DDT use was extensive. Results of interlaboratory crosscheck analyses supported these conclusions, despite interpretation problems posed by intercompound analytical interferences in 1970 and 1971. Temporal trends in PCB residues were less obvious. Highest PCB residues were found in the industrialized areas of the Northwest and Midwest, and traces were present at most stations. Dieldrin and endrin residues remained essentially unchanged during this period; dieldrin residues were widespread and were highest in Hawaii and in areas of the Midwest where aldrin was used extensively. Toxaphene occurrence increased; it was formerly found only in fish from streams draining cotton-farming regions, but residues were detected in 1974 samples from other areas. According to the recommendation of the National Academy of Sciences' Water Quality Criteria, organochlorine residues in freshwater fish may have represented a hazard to piscivorous fish and wildlife at 71 percent of the stations sampled in 1970 and 66 percent in 1974.  相似文献   

7.
Historical records report Fusarium moniliforme sensu lato as the pathogen responsible for Fusarium diseases of sorghum; however, recent phylogenetic analysis has separated this complex into more than 25 species. During this study, surveys were undertaken in three major sorghum‐producing regions in eastern Australia to assess the diversity and frequency of Fusarium species associated with stalk rot‐ and head blight‐infected plants. A total of 523 isolates were collected from northern New South Wales, southern Queensland and central Queensland. Nine Fusarium species were isolated from diseased plants. Pathogenicity tests confirmed F. andiyazi and F. thapsinum were the dominant stalk rot pathogens, whilst F. thapsinum and species within the F. incarnatumF. equiseti species complex were most frequently associated with head blight.  相似文献   

8.
Summary Carthamus lanatus is a widespread and troublesome weed of crops and pastures in Australia. It is viewed as a target for both inundative and classical biological control. As fungal biological control agents are often specific in terms of their host range, the genetic variation within the host may be important in their successful deployment. The detection of genetic variation in populations of C. lanatus from New South Wales was studied using polymerase chain reaction (PCR)-based, intersimple sequence repeats (ISSR) analysis. DNA extracted from plant samples from 11 locations in New South Wales was compared with one sample from Western Australia and one accession of the closely related crop plant, safflower. The analysis indicated that there were two distinct groups of C. lanatus that correlated with location (northern and southern regions). Within-group genetic diversity, as determined by the Shannon genetic diversity index, was low at 0.33 in the southern group and 0.22 in the northern group. The presence of these groups may have implications for the biological control of C. lanatus using exotic fungi. In any screening of candidate agents, representatives of these populations should be included.  相似文献   

9.
D. J. SWAIN 《Weed Research》1974,14(3):185-191
In a series of experiments carried out in the Leeton-Yanco area of southern New South Wales, molinate was applied to drill-sown rice at rates ranging from 2.24 to 6.73 kg/ha, and at times ranging from pre-sowing to 36 days after sowing-Applications were made to dry soil, and pre-sowing applications were shallowly incorporated. All other treatments were followed within 24 h by either a flushing irrigation, or by permanent flooding All molinate applications reduced Echinochloa spp. populations but best results were obtained with early post-emergence applications. At this time of application 3.36 kg/ha was usually as effective as higher rates. Molinate caused no damage to the rice crop, and herbicide application resulted in yield responses where significant Echinochloa spp. infestations were present. Le molinate pour la lutte contre les Echinochloa spp. dans les cultures de riz en Nouvelle Galles du Sud Dans une série d'essais réalisés dans la région du Leeton-Yanco, dans la Nouvelle Galles du Sud, le molinate a été appliqué sur du riz semé en lignes à des doses allant de 2,24 à 6,73 kg/ha et à des époques se situant depuis le présemis jusquà 36 jours après le semis. Les traitements ont été effectués sur sol sec et les applications en présemis ont été suivies d'une incorporation superficielle. Tous les autres traitements ont été suivies dans les 24 heures soit par une irrigation temporaire soit par une submersion permanente. Toutes les applications de molinate ont réduit les populations d'Echinochloa spp. mais les meilleurs rédultats ont été obtenus avec les traitements en post levée précoce. A cette époque d'application, la dose de 3,36 kg/ha a été habituelle-ment aussi efficace que les doses supérieures. Le molinate n'a pas causé de dégâts sur le riz et les traitements n'ont provoqué des fluctuations du rendement que là où des infestations significatives d'Echinochloa spp étaient présentes. Bekämpfung von Echinochloa spp. in Reis mit Molinate in Neusüdwales In der Gegend von Leeton-Yanco im südlichen Neusüd-wales wurde in einer Reihe von Versuchen Molinate in ge-drilltem Reis in Aufwandmengen von 2,24 bis 6,73 kg/ha eingesetzt. Behandelt wurde im Zeitraum von vor der Saat bis 36 Tage nach der Saat. Es wurde auf trockenen Boden gespritzt und die s Vorsaatbehandlungen wurden flach ein-gearbeitet. Bei allen anderen Behandlungen folgte inner-halb von 24 Stunden entweder ein Überfluten oder ein ständiges Überstauen. Sämtliche Behandlungen mit Molinate verminderten den Besatz an Echinochloa spp., die besten Bekämpfungserfolge wurden jedoch mit früher Vorauflaufspritzung erzielt. Zu diesem Behandlungszeitpunkt waren im Normalfall 3,36 kg/ha genau so wirksam wie höhere Aufwandmengen. Molinate verursachte keine Schäden beim Reis. Die Herbizi-danwendung wirkte sich auf die Erträge aus, wenn starke Verunkrautung mit Echinochloa spp. vorhanden war.  相似文献   

10.
Abstract

Damage to tea plants due to a root infection was observed on an estate in southern Malawi. Initial symptoms on plants in the infected areas varied from yellowing of leaves on individual branches followed by dieback to a more frequent rapid wilting of the leaves of entire bushes. The bark surface of superficial roots and collar region was covered by a loose mat of coarse fungal mycelium varying from white or cream to pale or bright yellow in colour. Infection was well developed on a large proportion of roots of affected plants before foliage symptoms appeared. The causal agent was identified as Pseudophaeolus baudonii (Pat.) Ryv.; this is the first record of the fungus in Malawi and the first record of its occurrence anywhere on tea. The fungus is widely distributed in Africa on a range of hosts. It is not yet known how the fungus is transmitted and definite control methods cannot be recommended although it is suggested that entire tea crops in diseased areas be removed and the land used for tobacco production. It is unlikely thatP. baudonii will have serious economic effects on tea crops in the area.  相似文献   

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Various components of the aquatic ecosystem of Tuttle Creek Reservoir on the Big Blue River in northeastern Kansas were examined for organochlorine insecticide residues in 1970-71. Components examined were water, sediments, periphyton, zooplankton, insects, and whole-body samples of 10 common fish species. Only dieldrin and sigmaDDT residues were detected. Dieldrin was found in part of the nonfish samples at levels ranging up to 0.01 ppm and in 97 percent of the fish samples with a high level of 0.17 ppm. SigmaDDT residues were also detected in part of the nonfish samples at levels ranging up to 0.42 ppm, and in 98 percent of the fish samples at levels as high as 0.57 ppm. Authors' findings are roughly similar to those of other surveys of Kansas fishes. All levels are relatively low compared with those reported in surveys from other parts of the Nation.  相似文献   

14.
15.
Samples of breast muscle from 327 ducks collected from October 1970 to March 1971 in the conterminous United States were analyzed for total mercury by flameless atomic absorption spectrometry. Mercury levels for the entire collection ranged from less than 0.01 to 3.91 ppm wet weight with a median of 0.10 ppm. Twenty-five ducks had levels equalling or exceeding the 0.5 ppm guideline for fish and shellfish established by the Food and Drug Administration, U.S. Department of Health, Education, and Welfare. Dabbling ducks, which are shallow-water feeders and mostly vegetarian in fall, winter, and spring, usually had lower levels than diving and sea ducks. Levels were generally higher in ducks collected in areas where environmental mercury levels were known to be greater than in ducks from nonsuspect areas. Despite the mobility of the ducks, levels seemed more closely linked to local environmental contamination than to various factors associated with large geographic areas.  相似文献   

16.
Milk samples from 22 nursing mothers in the metropolitan area of Perth, Western Australia, have shown the presence of DDT, DDE, dieldrin, and HCB in amounts consistent with similar surveys in other countries. Although mean values tend to be slightly lower than expected, their wide range, 0.002-0.025 ppm for DDT, suggests that a much larger sample should be examined to obtain a more accurate mean. This view is supported by values obtained in another survey of the same area.  相似文献   

17.
The frequency with which chlorinated hydrocarbon insecticides appear in samples of southern Florida surface waters decreased sharply between 1968 and 1972. Sediment analyses attest to the earlier widespread use of chlordane, DDT, and dieldrin. Insecticide residues are more frequently detected in southern Florida than in other U.S. cropland soils. Transport of DDT, DDD, and DDE from the Everglades agricultural area into water conservation areas and undeveloped parts of the Everglades of southeastern Florida is facilitated by a system of water-management canals. Canal sediments within the urban area of southern Florida have high DDD, DDE, and dieldrin residue concentrations which may reflect local use of insecticides rather than their transport from adjacent agricultural areas.  相似文献   

18.
托木尔峰青冰滩72号冰川流域同位素特征及径流分割研究   总被引:1,自引:0,他引:1  
利用2010年8月在托木尔峰青冰滩72号冰川流域采集的不同水体样品,分析了典型冰川流域的氢氧同位素变化特征,并进行了初步的径流分割研究.结果表明,青冰滩72号冰川流域河水、冰川融水、降水中δ18O和δD含量存在显著差异;根据河水、冰川融水和降水中δ18O和δD比值关系,得出托木尔峰青冰滩72号冰川流域河水由冰川融水和降水组成;在夏季洪水期,进一步通过二元分割模型计算得出,冰川融水所占比率为74.8%,降水所占比率为25.2%,冰川融水是托木尔峰青冰滩72号冰川流域径流的主要补给来源.  相似文献   

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The potential of oilseed rape to suppress weed growth while maintaining optimal yield and quality is not well understood under field conditions in Australia. This study, conducted in Condobolin and Wagga Wagga, New South Wales (NSW), during 2015 and 2016, examined a diverse range of commercial oilseed rape cultivars for their inherent ability to suppress weeds and maintain yields when in competition with natural weed infestations, with and without pre-emergent herbicide treatment. Cultivar differences were observed in oilseed rape canopy architecture and yield; however, early-season biomass, light interception, leaf area index and visual vigour ratings exhibited both year and location interactions. Cultivars with the highest biomass, light interception, leaf area indices and visual vigour were typically also the most weed-suppressive, in particular GT-50 and Hyola 600RR. Although crop and weed biomass accumulation differed significantly among cultivars for both location and year, weed biomass was inversely related to cultivar biomass in both years and locations. Hybrid Hyola and GT-50 cultivars exhibited up to 50% less weed biomass while maintaining consistently high levels of dry crop biomass. In addition, pre-emergent herbicide applications reduced weed infestation and contributed to higher crop yield in both locations and years. Given the consistent aboveground competitive ability of certain oilseed rape cultivars, our study demonstrated that diverse cultivar-dependent competitive traits such as early growth vigour, biomass production, absorption of photosynthetically active radiation and production and retention of crop residue significantly impacted weed establishment and total weed biomass. Our findings suggest that cultivar selection offers potential as a tool for maintaining suitable grain yield in the presence of weeds while potentially delaying the development of herbicide resistance through efficacious weed suppression.  相似文献   

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