Weed seeds in long-term dryland tillage and cropping system plots   总被引：2，自引：0，他引：2  

Unger  Miller  & Jones 《Weed Research》1999,39(3):213-223

Successful crop production depends on effective weed control. Weed seedbanks were determined after 12 years of dryland cropping with winter wheat and grain sorghum under different tillage methods (no- and stubble mulch) and cropping sequences. Seeds of 12 species were detected. Amaranthus retroflexus was most abundant, but seed numbers were similar under all conditions. Portulaca oleracea , Panicum capillare , Setaria viridis and Sorghum halepense seed numbers differed because of some factors, with those for P. oleracea being greatest. For others, seed numbers were low (≤0.11 kg⁻¹ soil), except for Digitaria sanguinalis with 7.8 kg⁻¹ soil and Bromus japonicus with 1.3 kg⁻¹ soil. Most seeds were near the surface with both tillage methods, with enough present under most conditions to cause a problem if proper control measures were not used, especially with continuous cropping. When a weed problem occurs under conditions as in this study, the results indicate that it could be reduced by growing winter and summer crops in rotation, which permits controlling weeds with tillage and/or herbicides when a crop is not growing. Other possibilities for controlling weeds under conditions as in this study are to alternate between dicotyledonous and monocotyledonous crops, which would permit use of a wider range of herbicides, and to use selective in-crop herbicides.  相似文献   

Evaluation of the isoflurane‐sparing effects of fentanyl,lidocaine, ketamine,dexmedetomidine, or the combination lidocaine‐ketamine‐dexmedetomidine during ovariohysterectomy in dogs     

Eduardo Gutierrez‐Blanco  José M Victoria‐Mora  Jose A Ibancovichi‐Camarillo  Carlos H Sauri‐Arceo  Manuel E Bolio‐González  Carlos M Acevedo‐Arcique  Gabriela Marin‐Cano  Paulo VM Steagall 《Veterinary anaesthesia and analgesia》2013,40(6):599-609

ObjectiveTo evaluate the isoflurane‐sparing effects of an intravenous (IV) constant rate infusion (CRI) of fentanyl, lidocaine, ketamine, dexmedetomidine, or lidocaine‐ketamine‐dexmedetomidine (LKD) in dogs undergoing ovariohysterectomy.Study designRandomized, prospective, blinded, clinical study.AnimalsFifty four dogs.MethodsAnesthesia was induced with propofol and maintained with isoflurane with one of the following IV treatments: butorphanol/saline (butorphanol 0.4 mg kg^?1, saline 0.9% CRI, CONTROL/BUT); fentanyl (5 μg kg^?1, 10 μg kg^?1 hour^?1, FENT); ketamine (1 mg kg^?1, 40 μg kg^?1 minute^?1, KET), lidocaine (2 mg kg^?1, 100 μg kg^?1 minute^?1, LIDO); dexmedetomidine (1 μg kg^?1, 3 μg kg^?1 hour^?1, DEX); or a LKD combination. Positive pressure ventilation maintained eucapnia. An anesthetist unaware of treatment and end‐tidal isoflurane concentration (Fe′Iso) adjusted vaporizer settings to maintain surgical anesthetic depth. Cardiopulmonary variables and Fe′Iso concentrations were monitored. Data were analyzed using anova (p < 0.05).ResultsAt most time points, heart rate (HR) was lower in FENT than in other groups, except for DEX and LKD. Mean arterial blood pressure (MAP) was lower in FENT and CONTROL/BUT than in DEX. Overall mean ± SD Fe′Iso and % reduced isoflurane requirements were 1.01 ± 0.31/41.6% (range, 0.75 ± 0.31/56.6% to 1.12 ± 0.80/35.3%, FENT), 1.37 ± 0.19/20.8% (1.23 ± 0.14/28.9% to 1.51 ± 0.22/12.7%, KET), 1.34 ± 0.19/22.5% (1.24 ± 0.19/28.3% to 1.44 ± 0.21/16.8%, LIDO), 1.30 ± 0.28/24.8% (1.16 ± 0.18/32.9% to 1.43 ± 0.32/17.3%, DEX), 0.95 ± 0.19/54.9% (0.7 ± 0.16/59.5% to 1.12 ± 0.16/35.3%, LKD) and 1.73 ± 0.18/0.0% (1.64 ± 0.21 to 1.82 ± 0.14, CONTROL/BUT) during surgery. FENT and LKD significantly reduced Fe′Iso.Conclusions and clinical relevanceAt the doses administered, FENT and LKD had greater isoflurane‐sparing effect than LIDO, KET or CONTROL/BUT, but not at all times. Low HR during FENT may limit improvement in MAP expected with reduced Fe′Iso.  相似文献   

Academic freedom and the classified information system     

Rosenbaum RA  Tenzer MJ  Unger SH  Van Alstyne W  Knight J 《Science (New York, N.Y.)》1983,219(4582):257-259

Executive Order 12356, signed by President Reagan on 2 April 1982, prescribes a system for classifying information on the basis of national security concerns. The order gives unprecedented authority to government officials to intrude at will in controlling academic research that depends on federal support. As such, it poses a serious threat to academic freedom and hence to scientific advances and the national security.  相似文献   

Worm control practice against gastro-intestinal parasites in Norwegian sheep and goat flocks     

Atle VM Domke  Christophe Chartier  Bj?rn Gjerde  Nils Leine  Synn?ve Vatn  Olav ?ster?s  Snorre Stuen 《Acta veterinaria Scandinavica》2011,53(1):29

Background

Anthelmintic treatment is the most common way of controlling nematode infections in ruminants. However, several countries have reported anthelmintic resistance (AR), representing a limitation for sustainable small ruminant production. The knowledge regarding worm control management represents a baseline to develop a guideline for preventing AR. The aim of the present study was therefore to improve our knowledge about the worm control practices in small ruminant flocks in Norway.

Methods

A questionnaire survey regarding worm control practices was performed in small ruminant flocks in Norway. Flocks were selected from the three main areas of small ruminant farming, i.e. the coastal, inland and northern areas. A total of 825 questionnaires, comprising 587 sheep flocks (return rate of 51.3%) and 238 goat flocks (52.6%) were included.

Results

The results indicated that visual appraisal of individual weight was the most common means of estimating the anthelmintic dose used in sheep (78.6%) and goat (85.1%) flocks. The mean yearly drenching rate in lambs and ewes were 2.5 ± 1.7 and 1.9 ± 1.1, respectively, whereas it was 1.0 (once a year) in goats. However, these figures were higher in sheep in the coastal area with a rate of 3.4 and 2.2 in lambs and ewes, respectively. Benzimidazoles were the predominant anthelmintic class used in sheep flocks (64.9% in 2007), whereas benzimidazoles and macrocyclic lactones were both equally used in dairy goat flocks. In the period of 2005-2007, 46.3% of the sheep flocks never changed the anthelmintic class. The dose and move strategy was practiced in 33.2% of the sheep flocks.

Conclusions

The present study showed that inaccurate weight calculation gives a risk of under-dosing in over 90% of the sheep and goat flocks in Norway. Taken together with a high treatment frequency in lambs, a lack of anthelmintic class rotation and the common use of a dose-and-move strategy, a real danger for development of anthelmintic resistance (AR) seems to exist in Norwegian sheep and goat flocks. This risk seems particularly high in coastal areas where high treatment frequencies in lambs were recorded.  相似文献   

More precise map position and origin of a durable non-specific adult plant disease resistance against stripe rust (Puccinia striiformis) in wheat     

E. K. Khlestkina  M. S. Röder  O. Unger  A. Meinel  A. Börner 《Euphytica》2007,153(1-2):1-10

Recently a major gene determining non-specific adult plant disease resistance against stripe rust (Puccinia striiformis) designated Yrns-B1 was mapped in wheat Triticum aestivum L. by using a cross between ‘Lgst. 79-74’ (resistant) and ‘Winzi’ (susceptible). Linkage to five Gatersleben wheat microsatellite (GWM) markers was discovered, previously mapped on chromosome arm 3BS. In the present study this map was improved by the incorporation of four additional GWM markers. QTL-analysis revealed high LOD values for the resistance at all nine loci, whereas the largest LOD (20.76) was found for the newly mapped marker Xgwm1329. Microsatellite analysis and resistance tests of a collection of old German/UK wheat varieties, including probable ancestors of ‘Lgst.79-74’ were carried out. A high coincidence of non-specific adult plant disease resistance against stripe rust and the presence of ‘Lgst. 79-74’ allele (117 bp) of the marker Xgwm533 was observed among the varieties tested. Linkage during the inheritance of both the resistance and the 117 bp allele of Xgwm533 was demonstrated. The probable origin of Yrns-B1 is discussed. Carriers of this resistance gene were grown on large areas since more than 100 years. To estimate the capability of Xgwm533 as a diagnostic marker for non-specific adult plant disease resistance against stripe rust, microsatellite analysis and resistance tests of a collection of Russian spring wheat varieties were performed. The 117 bp allele of Xgwm533 was found in about 35% of the Russian cultivars analysed, however, none of them possessed the expected disease resistance. Thus, the utilisation of Xgwm533 as diagnostic marker seems to be restricted to certain genepools.  相似文献   

Hypoglycin A Concentrations in Seeds of Acer Pseudoplatanus Trees Growing on Atypical Myopathy‐Affected and Control Pastures     

L. Unger  A. Nicholson  E.M. Jewitt  V. Gerber  A. Hegeman  L. Sweetman  S. Valberg 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2014,28(4):1289-1293

Background

Hypoglycin A, found in seeds of Acer negundo, appears to cause seasonal pasture myopathy (SPM) in North America and is implicated in atypical myopathy (AM) in Europe. Acer negundo is uncommon in Europe. Thus, the potential source of hypoglycin A in Europe is unknown.

Hypothesis and Objectives

We hypothesized that seeds of Acer pseudoplatanus were the source of hypoglycin A in Europe. Our objective was to determine the concentration of hypoglycin A in seeds of A. pseudoplatanus trees located in pastures where previous cases of AM had occurred.

Animals

None.

Methods

University of Berne records were searched to retrospectively identify 6 farms with 10 AM cases and 11 suspected AM deaths between 2007 and 2011. During October 2012, A. pseudoplatanus seeds were collected from 2 to 6 trees per pasture on 6 AM farms (7 pastures) from trees in or close to 2 pastures on 2 control farms where AM had not been previously reported. Hypoglycin A in seeds was analyzed by GC–MS.

Results

Acer pseudoplatanus trees were identified on all AM pastures. Hypoglycin A was detected in all A. pseudoplatanus seeds in highly variable concentrations ranging from 0.04 to 2.81 μg/mg (mean 0.69) on AM farms and 0.10 to 9.12 μg/mg (mean 1.59) on control farms.

Conclusion and Clinical Importance

Preventing horses from grazing pastures containing A. pseudoplatanus seeds during late fall and early spring might be the best means to prevent AM.  相似文献   

Identification of microsatellite markers for a leaf rust resistance gene introgressed into common wheat from Triticum timopheevii     

I. Leonova    A. Borner    E. Budashkina    N. Kalinina    O. Unger    M. Röuder  E. Salina 《Plant Breeding》2004,123(1):93-95

The tetraploid wheat Triticum timopheevii Zhuk (A^tA^tGG) is known as a source of genes determining resistance to many diseases. An introgressive line 842, with durable resistance to leaf rust was established by crossing T. aestivum cv. ‘Saratovskaya29’ with T. timopheevii ssp. viticulosum and used for mapping leaf rust resistance genes. Molecular analysis of the line 842 with polymorphic microsatellite markers detected introgressions of T. timopheevii into the homoeologous group 2 chromosomes of common wheat. Transloca‐tion breakpoints of introgressed fragments were localized between the markers Xgwm95 and Xgwm817 on chromosome 2A, as well as Xgwm1128 and Xgwm1067 on chromosome 2B. Linkage analysis demonstrated the association of disease resistance at the seedling stage with chromosome 2A. The gene was found to be linked with marker Xgwm817 at a genetic distance of 1.5 cM. The alien leaf rust resistance gene was temporarily designated as lrTt1.  相似文献   

Isolation and characterization of structurally novel antimutagenic flavonoids from spinach (Spinacia oleracea).     

R Edenharder  G Keller  K L Platt  K K Unger 《Journal of agricultural and food chemistry》2001,49(6):2767-2773

Thirteen compounds, isolated from spinach (Spinacia oleracea), acted as antimutagens against the dietary carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline in Salmonella typhimurium TA 98. The antimutagens were purified by preparative and micropreparative HPLC from a methanol/water (70:30, v/v) extract of dry spinach (commercial product) after removal of lipophilic compounds such as chlorophylls and carotenoids by solid-phase extraction (SPE). Pure active compounds were identified by instrumental analysis including FT-IR, (1)H and (13)C NMR, UV-vis spectroscopy, and mass spectrometry. All of these compounds were flavonoids and related compounds that could be attributed to five groups: (A, methylenedioxyflavonol glucuronides) 5,3'-dihydroxy-4'-methoxy-6,7-methylenedioxyflavonol 3-O-beta-glucuronide (compound 1), 5,2',3'-trihydroxy-4'-methoxy-6,7-methylenedioxyflavonol 3-O-beta-glucuronide (compound 2), 5-hydroxy-3',4'-dimethoxy-6,7-methylenedioxyflavonol 3-O-beta-glucuronide (compound 3); (B, flavonol glucuronides) 5,6,3'-trihydroxy-7,4'-dimethoxyflavonol 3-O-beta-glucuronide (compound 4), 5,6-dihydroxy-7,3',4'-trimethoxyflavonol 3-O-beta-glucuronide (compound 5); (C, flavonol disaccharides) 5,6,4'-trihydroxy-7,3'-dimethoxyflavonol 3-O-disaccharide (compound 6), 5,6,3',4'-tetrahydroxy-7-methoxyflavonol 3-O-disaccharide (compounds 7 and 8); (D, flavanones) 5,8,4'-trihydroxyflavanone (compound 9), 7,8,4'-trihydroxyflavanone (compound 10); (E, flavonoid-related compounds) compounds 11, 12, and 13 with incompletely elucidated structures. The yield of compound 1 was 0.3%, related to dry weight, whereas the yields of compounds 2-13 ranged between 0.017 and 0.069%. IC(50) values (antimutagenic potencies) of the flavonol glucuronides ranged between 24.2 and 58.2 microM, whereas the flavonol disaccharides (compounds 7 and 8), the flavanones (compounds 9 and 10), and the flavonoid-related glycosidic compounds 11-13 were only weakly active. The aglycons of compounds 7 and 8, however, were potent antimutagens (IC(50) = 10.4 and 13.0 microM, respectively).  相似文献   

Tillage implement disturbance effects on soil properties related to soil and water conservation: a literature review     

P. W. Unger  D. K. Cassel 《Soil & Tillage Research》1991,19(4):363-365

The effects of tillage implement distrubance on the physical properties of soil have been widely studied. However, because soil properties resulting from the use of a given implement vary due to implement factors (depth and speed of tillage) and soil factors (water content, texture, residue cover, etc.), soil properties for a given operation are difficult to visualize, let alone predict. This report summarizes the ranges of selected soil property responses observed in previous tillage studies and identifies factors that must be considered in developing useful models to predict the effects of tillage on soil properties that are related to soil and water conservation. Considered are soil mechanical properties (surface micro-relief, aggregate size distribution and bulk density) and hydraulic properties and processes (water retention, saturated conductivity, infiltration and evaporation). For future literature reports on tillage to be useful for developing comprehensive relationships between tillage and soil properties, the reports should include information on: soil classification, texture, water content (or time of precipitation), bulk density, mechanical impedance and organic matter concentration; tillage method, depth and speed of operation; previous crop, including availability of crop residues; and previous soil management history (compacted soil, irrigated or dryland, etc.).  相似文献   

The short-term effects of wood-ash amendment on forest soils     

Yvonne L. Unger  Ivan J. Fernandez 《Water, air, and soil pollution》1990,49(3-4):299-314

In the heavily forested regions of the northeastern U.S. the potential for producing electricity from wood-fired boilers is also creating a growing supply of wood-ash requiring disposal. Landfill space is expensive and limited, which has resulted in an interest in spreading wood-ash on forest sites. This greenhouse study was designed to provide information on soil and seedling response to wood-ash applications. Red maple (Acer rubrum) seedlings were grown in either O or B horizon forest soil material and amended with six levels of ash (0, 4, 8, 12, 16, and 20 Mg ha^?1) and two levels of N fertilizer (0 and 224 kg ha^?1). Ash amendments increased pH and exchangeable base cations, and decreased extractable Al and Fe concentrations, in both soil materials. Ash treatments increased seedling foliar K and Na concentrations in O horizon soils, but had little effect on growth. No significant effects on seedling properties from ash in B horizon soils were found. Fertilizer N treatments did not improve seedling growth in either soil material. Soil and seedling response to N were notably different for the different soils used. Based on this short-term study it appears that (a) land applications of wood-ash at the rates used may be a viable approach to recycling this solid waste, and (b) long-term studies are required to evaluate this practice under field conditions.  相似文献