首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper reports on the search for inoculum sources of Mycocentrospora acerina on caraway (Carum carvi L.). Obvious suspects are cover crops of biennial caraway and preceding crops of annual caraway. Other suspects are weeds in or alongside the field. Finally, survival structures of the fungus, chlamydospore chains, packed in plant debris or naked, are suspected. M. acerina is able to infect many plant species, including cover crops of caraway such as spinach for seed production and peas. However, the agronomical suitability of a crop to serve as a cover crop of biennial caraway proved to be a more important factor in determining caraway yield than the susceptibility of the cover crop to M. acerina. This finding was corroborated by the fact that spinach and peas as preceding crops had no significant effects on M. acerina development in spring caraway sown the next year. Dill, barley and four weed species were found as new hosts of M. acerina. The role of weed hosts, susceptible crops and plant debris in the survival of the fungus in years without caraway is discussed. Caraway sown on soil containing infested caraway straw, infested debris of other plant species or chlamydospores grown in pure culture, became infected by M. acerina. Only high inoculum densities of chlamydospores in the soil caused severe damping-off of caraway seedlings. The opportunity for disease management by agronomical means is quite limited.  相似文献   

2.
Habitat diversification can influence the interactions of insects with plants and this can be used in agroecosystems for the management of pest populations. Plant diversification can be achieved through planting crops, such as trap crops, or by adjusting weed management. Aster leafhopper, Macrosteles quadrilineatus Forbes (Hemiptera: Cicadellidae), is a polyphagous species that uses cereals, vegetables, and weeds as host plants. The influence of weeds on M. quadrilineatus abundance was investigated experimentally in carrot [Daucus carota L. cv. Canada (Apiaceae)] field plots by adjusting the level of management of two groups of weeds (broadleaf and grass) and by comparing it to weed‐free plots. The preference of M. quadrilineatus for different cereal and weed species relative to carrots was tested in choice test assays. Habitat context influenced the abundance of M. quadrilineatus in the field experiments. The presence of border crops such as oat, rye, barley, wheat, and triticale did not significantly attract or repel this insect to carrot plots compared to the no‐border treatment. However, spelt‐bordered plots had 42% fewer M. quadrilineatus than three treatments, triticale, wheat, and barley, that had the highest insect abundance. The type of weed management affected M. quadrilineatus abundance in carrot plots, but not the frequency of herbicide application. Plots that had carrot growing with broadleaf‐weeds had about 59% fewer M. quadrilineatus compared with those growing with crabgrass or carrot alone. In the greenhouse choice tests, grasses (e.g., cereals) attracted and broadleaf‐weeds repelled M. quadrilineatus relative to carrots. In summary, carrot growers may be able to manage this pest by reducing the interaction of cereal cover crops with carrots and eliminating grassy weeds in commercial production fields.  相似文献   

3.
报道了甘肃省菊科植物的3个分布新记录属,母菊属(Matricaria),联毛紫菀属(Symphyotrichum)和艾纳香属(Blumea),以及3个甘肃省分布新记录种,同花母菊[Matricaria matricarioides(Lessing)Porter ex Britton],钻形紫菀[Symphyotrichum subulatum(Michaux)G.L.Nesom]和柔毛艾纳香[Blumea axillaris(Lamarck)Candolle]。  相似文献   

4.
Seedbanks and seedling emergence, resulting from seeds shed in wheat crops and ploughed in, were monitored in two experiments for 3–4 years in successive autumn sown crops, in which herbicides were used to prevent re-seeding. Populations of Galium aparine, Papaver rhoeas, Lamium purpureum, Myosotis arvensis, Veronica persica, Viola arvensis and Veronica hederifolia were studied in separate plots. The numbers of viable seeds in the soil declined exponentially; G. aparine and V. hederifolia declined most, and P. rhoeas and V. arvensis least rapidly. Total weeds (all species) over the 3–4 years, (obtained by adding successive numbers of seedlings recorded in each autumn or winter), represented 3–4% of the first year seedbank for the combined species. Few seedlings emerged in the first year after seeding due to effective burial by the initial ploughing. The species showing the greatest emergence in the first year, relative to seedbank size, were G. aparine and V. hederifolia. Other, smaller seeded, species produced their main seedling flushes in the second and third years after seeding. It is concluded that poor weed control in one year is likely to result in large weed infestations for up to four years and probably longer for some species.  相似文献   

5.
Achenes of 12 species of Compositae were collected in each of 3 years and mixed with the top 7.5 cm of sterilised soil which was confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Seedling emergence was recorded for 5 yr and the numbers of viable seeds remaining then determined. Emergence of Arctium lappa, A. minus, Picris hieracioides, Taraxacum officinale, Sonchus arvensis and S. asper was mainly in spring. Seedlings of Chrysanthemum segetum, Lapsana communis, Anthemis cotula and Sonchus oleraceus were often most numerous in spring but also emerged at other times, while Matricaria matricarioides and M. recutita showed no consistent seasonal pattern of emergence. Except for C. segetum and A. cotula, in which there was evidence of innate dormancy imposed by the seed coat, the numbers of seedlings were greatest in the first year and thereafter decreased approximately exponentially from year to year. Few viable seeds of A. lappa or A. minus remained after 5 yr and those of T. officinale, P. hieracioides and S. arvensis accounted for less than 1.5% of the seeds sown. Seed survival was greatest in the annual weeds and ranged from 2.1% (S. asper) to 8.6% (M. matricarioides) after 5 yr.  相似文献   

6.
Four carabid species,Anisodactylus santaecrucis, Bembidion quadrimaculatum oppositum, Pterostichus lucublandus andPterostichus melanarius, abundant in carrot fields in southwestern Quebec, were tested for predation against the carrot weevil,Listronotus oregonensis, on host plants. The largest species,Pterostichus melanarius, consumed the greatest number of carrot weevil larvae and pupae.Bembidion quadrimaculatum oppositum did not prey on carrot weevil eggs laid on carrot leaves.   相似文献   

7.
Plant species differing in susceptibility to 2,4-dichlorophenoxyacetic acid (2,4-D) were examined as to the level of phylloquinone (K) in the leaves. The K level was found to be considerably higher in several plants resistant or moderately resistant to 2,4-D (Aegopodium podagraria L., Galium mollugo L., Lamium album L., Matricaria chamomilla L., Oxalis acetosella L., Stellaria media (L.) Vill., Viola arvensis Murr.) than in Chenopodium album L. and Sinapsis arvensis L. which are susceptible to 2,4-D. Capsella bursa-pastoris (L.) Med. and Plantago major L. (both moderately susceptible) and a few resistant or moderately resistant species (Agropyron repens (L.) PB., Anthriscus silvestris (L.) Hoffm., Triticum aestivum L.) had intermediate K levels. Cirsium arvense (L.) Scop. (susceptible) had a relatively high level of K. It is possible that a high K level in the plant can be of importance in the resistance to 2,4-D.  相似文献   

8.
Miscanthus, is a promising bioenergy crop, considered superior to other bioenergy crops because of its higher water and nutrient use efficiency, cold tolerance, and higher production of biomass. Broadleaf weeds and grass weeds, cause major problems in the Miscanthus field. A field experiment was conducted in 2018 and 2019, to assess the effects of pre-emergence (alachlor and napropamide) and post-emergence herbicides (nicosulfuron, dicamba, bentazon, and glufosinate ammonium) on broadleaf and grass weeds in M. sinensis and M. sacchariflorus fields. The weed control efficiency and phytotoxicity of pre- and post-emergence herbicides were evaluated at 30 days after treatment (DAT) and compared to those of the control plots. The results showed wide variations in the susceptibility of the weed species to the treated herbicides. Treatment with nicosulfuron 40 g.a.i.ha−1 provided the most effective overall weed control (with 10% visual injury), without affecting the height and biomass of neither Miscanthus species in the field. Post-emergence herbicides such as glufosinate ammonium 400 g.a.i.ha−1 and dicamba 482 g.a.i.ha−1 were effective and inhibited the growth and density of the majority of weeds to a 100%; however, they showed significant phytotoxicity (toxicity scale of 1–10) to both species of Miscanthus. The application of glufosinate ammonium caused severe injuries to the foliar region (90% visual injury) of both Miscanthus sps. Comparatively, M. sinensis showed a slightly higher tolerance to the herbicides nicosulfuron, bentazon and napropamide with 10% visual injury at the recommended dose than M. sacchariflorus. The present study clearly showed that infestation of broadleaf and grass weeds in Miscanthus fields can cause significant damage to the growth and biomass of Miscanthus and applying pre-emergence and post-emergence herbicides effectively controls the high infestation of these weeds.  相似文献   

9.
Abstract

The uptake and distribution of arsenic (As) and some heavy metals was determined in three Viola endemic species from As‐overloaded soil in an abandoned mine at Alchar, Republic of Macedonia (FYROM – The Former Yugoslav Republic of Macedonia). Some essential elements were also analyzed in order to characterize the common geochemical properties of this site. Total As content in soil ranged from 3347 to 14,467 mg kg?1, and plant available As from 23 to 1589 mg kg?1. The concentration of As in roots ranged from 783 mg kg?1 in Viola macedonica to 2124 mg kg?1 in Viola arsenica. Only a small amount of As accumulated in the aboveground parts of these species (<100 mg kg?1), while in shoots of Viola allchariensis, As accumulated in the range 187–439 mg kg?1. Arsenic accumulation in the roots of these Viola species may make these plants valuable tools for the bioindication and phytoremediation (phytostabilization) of As in naturally loaded and anthropogenically contaminated soils.  相似文献   

10.
In an epidemiological study conducted on commercial agricultural plots affected by stolbur phytoplasma in Northern and Central Spain, different species of leafhoppers and planthoppers were identified as potential vectors of the phytoplasma. They included individuals of Macrosteles quadripunctulatus infected by stolbur phtytoplasma in most of the locations. The potential of this species as a vector of stolbur was evaluated in this work. The transmission trials were carried out on healthy plants of Catharanthus roseus (periwinkle), Lycopersicon esculentum (tomato), Daucus carota (carrot), Lactuca sativa (lettuce) and Vitis vinifera (grapevine). The first symptoms of infection in these plants were observed 2 weeks after the inoculation period in tomato and periwinkle, and after 4 weeks in carrot. Only one of five grapevines showed phytoplasma symptoms. PCR analysis was used to verify the ability of M. quadripunctulatus in transmitting stolbur phytoplasma in the plant species tested. The phytoplasma was not detected in lettuce or in the healthy control plants. Studies of stolbur transmission to insect‐feeding medium were also conducted and indicated that M. quadripunctulatus acquires and was capable of transmitting the phytoplasma after it fed during a single day on infected plants followed by a 19‐day latent period on healthy plants.  相似文献   

11.
Abstract. The distribution, density and cover of small-scale natural disturbances was surveyed in semi-natural and set-aside vegetation in a hilly landscape in Central Germany in the spring of 1995. More of the landscape was disturbed on set-aside agricultural land in valley s (1.02 %) and on warm south-facing slopes(1.33 %) than on rocky hilltops (0.3 %) and cool north-facing slopes (0.56 %). The major agents of disturbance on set-aside fields were moles, rodents (and their predators) and wild boars. In surrounding semi-natural grasslands, rabbit warrens were common on south-facing slopes and mound-building ants on north-facing slopes. Disturbances were significantly clustered and frequently superimposed. In order to investigate the effects of disturbance quality on plant assemblages in set-aside fields, two common types of disturbances were compared. These were grazing lawns (0.4–1.0 m2) maintained throughout the summer by common voles (Microtus arvalis), and excavations, 0.7–1.6 m2 in area, where wild boars (Sus scrofd) grubbing for food had removed vegetation and top soil in early spring. Both types of disturbances increased plant species richness on the local scale. Wind-dispersed annual and pauciennial forbs of ruderal habitats (e.g. Carduus acanthoides, Cirsium vulgare, Matricaria maritima, Senecio vernalis) were most abundant on the superficial disturbances made by voles, whereas small, ephemeral field weeds (e.g. Polygonum aviculare, Anagallis arvensis, Chenopodium album, Fallopia convolvulus) predominated on patches grubbed by boars. This study confirms that small-scale disturbances by animals provide a variety of regeneration niches for field weeds and ruderals. The rate of decline in plant species richness on set-aside land is likely to be reduced where land is utilized by a variety of herbivorous and soil-moving mammals.  相似文献   

12.
Crops and weeds were tested for their ability to host Clavibacter michiganensis ssp. sepedonicus (Cms), the causal agent of bacterial ring rot in potato. Ten crops grown in rotation with potato in Europe, namely maize, wheat, barley, oat, bush bean, broad bean, rape, pea and onion and five cultivars of sugar beet were tested by stem and root inoculation. About 6–8 weeks after inoculation, Cms could be detected in most crops except onion and sugar beet, in larger numbers in stems (105–106 cells/g of tissue) than in roots (≤103 cells/g of tissue) in immunofluorescence cell‐staining (IF). Cms was successfully re‐isolated only from IF‐positive stem samples of maize, bush bean, broad bean, rape and pea, but not from roots. Twelve solanaceous weeds and 13 other weeds, most commonly found in potato fields in Europe, were tested in IF as hosts of Cms by stem and root inoculations. Only in Solanum rostratum, a weed present in northern America, Cms persisted in high numbers (108 cells/g tissue) in stems and leaves, where it caused symptoms. In the other solanaceous weeds, Cms persisted at low numbers (approximately 105 cells/g of tissue) in stems but less so in roots. The bacteria could be frequently re‐isolated from stem but not from root tissues. In 2 consecutive years, plants from 14 different weed species were collected from Cms‐contaminated potato field plots and tested for the presence of Cms by dilution plating or immunofluorescence colony‐staining (IFC), and by AmpliDet RNA, a nucleic acid‐based amplification method. Cms was detected in roots but not in stems of Elymus repens plants growing through rotten potato tubers, and in some Viola arvensis and Stellaria media plants, where they were detected both in stems and roots, but more frequently by AmpliDet RNA than by IFC.  相似文献   

13.
Summary A survey of selected crop species and weeds was conducted to evaluate the inhibition of the enzyme acetohydroxyacid synthase (AHAS) and seedling growth in vitro by the sulfonylurea herbicides chlorsulfuron, DPX A7881, DPX L5300, DPX M6316 and the imidazolinone herbicides AC243,997, AC263,499, AC252,214. Particular attention was given to the Brassica species including canola cultivars and cruciferous weeds such as B. kaber (wild mustard) and Thlaspi arvense (stinkweed). Transgenic lines of B. napus cultivars Westar and Profit, which express the Arabidopsis thaliana wild-type AHAS gene or the mutant gene csr1-1 at levels similar to the resident AHAS genes, were generated and compared. The mutant gene was essential for resistance to the sulfonylurea chlorsulfuron but not to DPX A7881, which appeared to be tolerated by certain Brassica species. Cross-resistance to the imidazolinones did not occur. The level of resistance to chlorsulfuron in transgenic canola greatly exceeded the levels that were toxic to the Brassica species or cruciferous weeds. Direct selection of transgenic lines with chlorsulfuron sprayed at field levels under greenhouse conditions was achieved.  相似文献   

14.
In the present paper we deal with the possibility of morphogenesis induction in callus tissue cultures of some representatives ofMatricaria andAchillea species. Shoot regeneration from calli ofMatricaria chamomilla andM. inodora has been induced by 0.1 mg l-1 kinetin or by combination of 0.5 mg l-1 kinetin and 0.5 mg l-1 NAA added to Murashige-Skoog culture medium. Rhizogenesis took place without any other addition of auxin. In callus tissue cultures ofAchillea ptarmica cultivated on Murashige-Skoog medium with 1 mg l-1 2,4-D after a year long cultivation the whole plant has been regenerated without any change of nutrient requirements. In callus tissue ofA. nobilis under the same conditions only roots wore regenerated.  相似文献   

15.
No‐till cropping systems that include cover crops could lead to important changes in weed communities by decreasing some annual weed populations. In this study, we predicted that seed burial depth and the presence of cover crop would affect the emergence and initial growth success of annual weed species. We tested two factors on 14 weed species in a greenhouse: the seed burial depth of weeds (buried versus soil surface) and the presence/absence of a cover crop (ryegrass). We counted the emerged seedlings and measured the height of weeds and cover crops (Hweed, Hcover), the dry matter content of weeds and cover crops (DMCweed, DMCcover) and the number of leaves of weeds (NLweed) on 1433 weed and 390 ryegrass individuals. Emergence of five weed species (AMBEL, ANGAR, BROST, CENCY and EPHHE) was affected by the seed location (?10.3% on average for unburied seeds), five other weed species (ALOMY, CAPBP, SONAS, VERPE and VLPMY) were affected by cover (on average ?9.5% for seeds emerged in the presence of cover crop), and four weed species (GERDI, LAMPU, POAAN and VIOAR) were not affected by either. Weed growth of all weed species also decreased with the presence of a cover crop (on average Hweed: ?49.9%, DMCweed: ?87.2% and NLweed: ?55.4%) and for unburied seeds (on average Hweed: ?33.7%, DMCweed: ?70.6% and NLweed: ?43.3%), with various responses according to species. This study indicates that annual weeds could be disadvantaged by no‐till systems using cover crops.  相似文献   

16.
长期有机无机肥配施对稻田杂草生长动态的影响   总被引:1,自引:0,他引:1  
利用中国农业科学院红壤实验站红壤稻田长期定位试验,于2011年研究了在以无机肥(化肥NPK)与有机肥(M)氮磷钾养分等量条件下,长期有机无机肥配施水稻生育期间杂草种类和生物量变化。结果表明:30a后,早稻和晚稻施肥处理中:PK+M处理下杂草种类最多,NPK+M处理下杂草种类和优势杂草种类较少,且种类数量稳定,早稻和晚稻杂草种类数量前者比后者分别高出19.7%和9.8%;施肥处理中:两季杂草总生物量NPK+M处理最高,NP+M处理最低,且NPK+M、NK+M、PK+M和CK处理比NP+M处理分别高出31.3%、26.5%、8.3%和5.6%,早稻NPK+M处理杂草总生物量和浮生杂草总生物量最多,NK+M处理湿生杂草总生物量最多,晚稻NK+M处理杂草总生物量和湿生杂草总生物量最多,NPK+M处理浮生杂草总生物量最多;土壤碱解氮和有效磷与杂草总生物量、湿生杂草总生物量、浮生杂草总生物量显著正相关(相关系数依次分别为0.508*和0.578**、0.552*和0.453*、0.410*和0.802**),p H值与三者显著负相关(相关系数依次分别为-0.516*、-0.531*和-0.698*)。土壤p H受土壤有效磷和碱解氮及其他因子的共同作用对杂草总生物量产生影响。通过施肥措施调节土壤适宜p H及碱解氮和有效磷含量,能有效调控农田中湿生和浮生杂草生长,使杂草种类和生物量在农业生产中达到有益平衡。  相似文献   

17.
Allchar mine is an abandoned arsenic-antimony-thallium deposit located on the north-western part of Ko?uf Mt., Republic of Macedonia. Allchar is a unique deposit within the world, due to the variety of its mineral composition especially and in the high content of thallium. The aim of this work was to assess the level of contamination at this post-mining area as well as to determine the intensity of accumulation of various elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sr, Tl, V, and Zn) with focus on As, Sb and Tl, in two endemic Viola species from this locality (Viola allcharensis G. Beck, Viola arsenica G. Beck) and one Balkan endemic species (Viola macedonica Boiss. &; Heldr.). Samples of different plant parts and soil were digested and then analysed by ICP-AES. It was found that the accumulation of As, Sb, and Tl in these endemic species is significantly high. In this study a systematic investigation of the As-Sb-Tl contamination of soils and their bioavailability was carried out using the extraction procedure in order to explore the mobility and potential bioavailability of the As, Sb, and Tl.  相似文献   

18.
Zusammenfassung 1. An Hand von 101 Aufnahmen wird das Aphano-Matricarietum typicum and scleranthetosum im Unteren Eichsfeld in eine typische, eineRanunculus repens-, eineGnaphalium uliginosum-und eineJuncus bufonius-Variante gegliedert.2. Durch Bestimmungen des Bodenwassergehaltes und des pflanzenverfügbaren Wassers sowie durch Berechnung des W-Wertes nachEllenberg wird die Reihe der Varianten als Reihe zunehmender Feuchtigkeit charakterisiert.3. Bei zunehmender Dichte des Getreidebestandes nehmen die dominierenden Unkräuter stark ab, die schwach deckenden Unkräuter dagegen zu.4. Aus den Deckungswerten der soziologischen Tabelle werden Konkurrenzwirkungen zwischenMatricaria chamomilla, Aphanes arvensis undStellaria media belegt.
Summary 1. In two subassociations of a weed community (Aphano-Matricarietum typicum and scleranthetosum) 101 relevés are used for distinguish three subunits: a var. ofRanunculus repens, ofGnaphalium uliginosum and ofJuncus bufonius.By estimating the water contents and pF values of the soil and by calculating the water figure afterEllenberg this series of subunits is shown to be a series of increasing humidity.2. With increasing density of the cereal grasses, the stronger dominant weeds decrease, while the weaker ones increase.3. A method is described to calculate competition between the dominant weeds from the figures of the sociological relevés. Interactions have been found betweenMatricaria chamomilla at the one side andAphanes arvensis andStellaria media at the other side and vice versa.
  相似文献   

19.
Viola mirabilis is abundant in Estonia; Viola elatior is rare. We tested whether these species differ in their competitive responses to a common grass. We used a pot experiment in which individuals of each violet species grew with 0, 2, 4, or 8 individuals of Festuca ovina in natural soil. The response patterns of shoot and root mass and leaf numbers of the two species were similar: the biomass and leaf number of both violet species decreased with increasing grass density. The decrease of root mass of the rare V. elatior was significantly greater, and the decrease of leaf number tended to be greater, than that of the common V.␣mirabilis. We conclude that the stronger competitive response of V. elatior compared to V. mirabilis might be one reason behind its lower regional and local abundance.  相似文献   

20.

The presence of weeds in the margins of strawberry crops can enhance populations of predatory mites as a measure to support conservation biological control. The aims of this study were (i) to assess the composition of the acarofauna associated with strawberries and the accompanying herbaceous plants in an organic farming system, and (ii) to evaluate the possible relationships between phytophagous and predatory mites occurring in this system. Strawberry leaves and whole plants of weeds were sampled biweekly from August 2014 to February 2015 in Lapa (Paraná, Brazil). In total, 23 weed species belonging to 10 families were identified; 3768 mite individuals (from 15 families and 4 suborders) were recovered, 77% on strawberries and 23% on weeds. Abundance of predatory mites on weeds was greater than on strawberry cultivars. On strawberries, the most abundant family was Tetranychidae (84%) followed by Phytoseiidae (11.6%). In total, 16 predatory mite species from the Phytoseiidae family were identified, 13 of them occurring on strawberry leaflets. Typholodromalus aripo, Neoseiulus californicus and Typhlodromips mangleae were the most abundant mite species on strawberry leaves. On weeds, most individuals were predatory mites (59%), whereas phytophagous mites represented 17.2%. The most abundant family was Phytoseiidae (36.4%). On weeds, the phytoseiid mite T. aripo was the most abundant species, representing 34.7%. Besides being found on strawberry leaflets, T. aripo was associated with 15 weed species. Among the weeds, Bidens pilosa showed the highest values of the Shannon index (1.97), Margalef index (3.04), and Pielou’s evenness index (0.95). This study emphasizes the importance of surrounding weeds as a shelter for beneficial mitefauna in strawberry fields, likely contributing to enhance conservation biological control.

  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号