The effect of organic and chemical fertilizers on oilseed rape productivity and weed competition in short rotation     

Ruhollah Naderi  Ehsan Bijanzadeh  Todd P. Egan 《Journal of plant nutrition》2020,43(16):2403-2410

Abstract

A two-year field experiment was conducted to investigate the impact of short crop rotation and organic amendments on rapeseed yield under weed competition conditions. The primary experimental plots consisted of either triticale or pea as a prior crop, consisting of four subplots with either 25 tons of composted cattle manure (CCM), 150?kg urea N ha^?1 (N), 25 tons composted cattle manure + 75?kg urea N ha^?1 (CCM?+?N), or no urea N or manure added as the control (C0). Rapeseed seed yield was not significantly affected by previous crops, except for rapeseed grown after pea which had slightly higher seed yield (2058?kg ha^?1) than those grown after triticale (1942?kg ha^?1). Plants that received CCM?+?N produced the highest amount of seed yield (2447?kg ha^?1), but were not significantly different from plants that received just urea N (2218?kg ha^?1). Weeds gained more biomass when the previous crop was pea compared to those whose previous crop was triticale. Weeds in plots that received CCM?+?N produced the greatest biomass, followed by N, and CCM plots, respectively.  相似文献   

Detection and quantification ofSpongospora subterranea f. sp.subterranea by PCR in host tissue and naturally infested soils     

Xinshun Qu  James A. Kavanagh  Damian Egan  Barbara J. Christ 《American Journal of Potato Research》2006,83(1):21-30

A polymerase chain reaction (PCR) assay using primers SsF and SsR designed from the internal transcribed spacer (ITS) regions ofSpongospora subterranea f. sp.subterranea was developed for the specific identification and quantification ofS. subterranea. These primers amplified a 434 bp product from DNA ofS. subterranea spore balls, but not from DNA of healthy potato, common scab tuber, and taxonomically related plasmodiophorids. This PCR assay was successfully used for the detection ofS. subterranea in naturally infected symptomatic and asymptomatic potato tubers.Spongospora subterranea in other infected symptomless host plants was detected by PCR. The PCR assay was modified with improved soil DNA extraction methods to detectS. subterranea in soil. The assay was sensitive, and one spore ball per gram of soil could be detected. Following the design of a heterologous competitor DNA template from the sequence of λDNA, a competitive PCR assay for the quantification ofS. subterranea in soil was developed and provided accurate quantification in the range of 1 to 10⁴ spore balls per 0.25 g of soil. In a preliminary survey of naturally infested field soil samples, spore ball concentrations were estimated to vary from ca 0 to 3600 spore balls per 0.25-g soil sample by this competitive PCR assay. The spore ball levels were compared with the powdery scab disease incidence of potatoes in these fields, and a correlationship between spore ball levels and subsequent disease incidence was found. The PCR assays developed in this investigation can be routinely used to detect and quantifyS. subterranea in diseased plant tissue, asymptomatic plant tissue, and infested soil.  相似文献   

The effectiveness of cypermethrin in the control of summer mastitis     

J Egan 《The British veterinary journal》1987,143(6):531-536

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Blood,plasma, and serum inorganic and organic reference values for two-year old Irish Thoroughbreds during the racing season     

D. A. Egan  J. Cullen  J. G. McLaughlin 《Veterinary research communications》1980,4(1):107-111

The concentration of 13 inorganic and organic components in the blood, plasma, and serum of 51 two-year old Irish Thoroughbreds were measured on seven occasions over a ten-month period including the racing season. Reference values were established for calcium, magnesium, inorganic phosphorus, potassium, copper, iron, zinc, total protein, albumin, globulin, urea, glucose, and alkaline phosphatase. The components measured were those usually considered to be useful aids in clinical diagnosis. No significant differences were established between the best and worst eight track performers with the exception of inorganic phosphorus which in the best eight was significantly lower (P<0.01).  相似文献   

Comparison of the microtitration agglutination test and the enzyme-linked immunosorbent assay for the detection of herds affected with swine dysentery   总被引：1，自引：0，他引：1  

I T Egan  D L Harris  L A Joens 《American journal of veterinary research》1983,44(7):1323-1328

A method was designed to evaluate and compare the microtitration agglutination test (MAT) and the enzyme-linked immunosorbent assay (ELISA) to detect antibodies in swine sera to Treponema hyodysenteriae and thereby establish a method for determining the prevalence of swine dysentery (SD) in herds. According to sampling criteria based on the hypergeometric distribution, sera were collected from 3 age groups of swine from farms having a history of SD on the premises (SD+) recently or being free of the disease (SD-). The highest degree of test sensitivity was obtained when sera from market age swine were evaluated with the ELISA. Of 14 SD+ herds from which sera were obtained from market-age swine, 13 were positive with the ELISA (93%); none of the 8 SD- herds was positive. The detection rates of individual swine in the SD+ herds for the 2 tests by age group were as follows: MAT--adult swine 1.4%, market-age swine 6%, and weaned pigs 0.8%; ELISA--adult swine 16%, market swine 31%, and weaned pigs 0.5%.  相似文献   

An investigation into human pandemic influenza virus (H1N1) 2009 on an Alberta swine farm     

Krista J. Howden  Egan J. Brockhoff  Francois D. Caya  Laura J. McLeod  Martin Lavoie  Joan D. Ing  Janet M. Bystrom  Soren Alexandersen  John M. Pasick  Yohannes Berhane  Margaret E. Morrison  Julia M. Keenliside  Sonja Laurendeau  Elizabeth B. Rohonczy 《The Canadian veterinary journal. La revue veterinaire canadienne》2009,50(11):1153-1161

On May 2, 2009 the Canadian Food Inspection Agency notified the World Organization for Animal Health that an emerging novel influenza A virus (pandemic H1N1 2009) had been confirmed on a swine farm in Alberta. Over a 4-week period pigs in this farrow-to-finish operation were clinically affected by respiratory disease consistent with an influenza A virus infection and the presence of active viral infection was confirmed in all production areas by real-time polymerase chain reaction (RT-PCR). Despite clinical recovery of animals, there was reluctance by purchasers to receive animals from this operation due to concerns about the effect on both domestic and international markets. The owner decided to depopulate the entire herd due to impending welfare issues associated with overcrowding and economic concerns resulting from the inability to market these animals. Carcasses were rendered or composted and did not enter the human food or animal feed chain. The source of virus in this herd was determined to be an infected human. Zoonotic transmission to 2 individuals responding to the outbreak was suspected and recommendations to prevent occupational exposure are discussed.  相似文献   

Effect of different salts of sodium and potassium on the growth of Atriplex prostrata (Chenopodiaceae)     

Todd P. Egan  Irwin A. Ungar 《Journal of plant nutrition》2013,36(10):2193-2205

Although there are a variety of ions occurring in the soil throughout most of North America, the majority of halophyte literature focuses on the effects of NaCl on plants. In this study, a comparison is made of the effects of NaCl, KC1, Na₂SO₄, and K₂SO₄, on growth of the halophyte Atriplex prostrata Boucher ex DC (SYN: A. triangularis Willd.) at 0, ‐0.75, ‐1.00, and ‐1.50 MPa. Plant survival, height, number of leaves, nodes, and branches were recorded weekly. Photosynthesis was measured once before plants were harvested and dry mass was determined after one month. Content of Na⁺, K⁺,‐Mg²⁺, and Cl^‐ in plant tissue was also measured. A general trend observed was that all plant growth parameters decreased with a lowering of the medium osmotic potential, and that K⁺ salts were more inhibitory than Na⁺ salts. Ion content of plant tissue generally increased with a lowering of osmotic potential. Our data indicated that K⁺, a plant macronutrient, was more inhibitory to plant growth than Na⁺. It is possible that halophytes such as Atriplex prostrata could use Na⁺ as an osmoticum to adjust the vacuolar water potential, but were unable to use K⁺ for this function because of a specific ion toxicity. The inhibitory effect of salt on plant growth parameters and survival follow the pattern; K₂SO₄ >KCl>Na₂SO₄=NaCl.  相似文献   

Corn nitrogen management using NDVI and SPAD sensor-based data under conventional vs. reduced tillage systems     

Mohsen Edalat  Ruhollah Naderi  Todd P. Egan 《Journal of plant nutrition》2013,36(18):2310-2322

Present analyses to calculate nitrogen fertilizer recommendations are time consuming and costly. Therefore, a field study determining the efficiency of SPAD and NDVI meters to calculate soil N deficiency and guide fertilizer application timing and rate was completed. Reduced vs. conventional tillage at various N application rates was studied. Regardless of tillage system, both NDVI and SPAD were able to detect N deficiency at early growth stages, however, SPAD measurements better reflected plant N status regarding N application rates. A modified Michaelis-Menten model was used to illustrate the relationship between N rates and grain yield, as well as grain N content and leaf N content, and both showed acceptable goodness of fit. Grain yield under reduced tillage was significantly higher than that of conventional tillage. The combination of leaf nitrogen, SPAD, and NDVI data may become a tool to manage corn field nitrogen status and predict grain yield.  相似文献   

A comparative assessment of culture and serology in the diagnosis of brucellosis in dairy cattle     

D. O’Grady  W. Byrne  P. Kelleher  H. O’Callaghan  K. Kenny  T. Heneghan  S. Power  J. Egan  F. Ryan 《Veterinary journal (London, England : 1997)》2014,199(3):370-375

To investigate the usefulness of culture for the confirmation of brucellosis in cattle, a comparison of culture and serology was undertaken on 248 animals in four dairy herds where the disease was active. Paired supramammary (SM), retropharyngeal (RP), and internal iliac (IL) lymph nodes were cultured, and five serological tests were deployed: the microserum agglutination test (MSAT), complement fixation test (CFT), the indirect (iELISA) and competitive ELISA, and the fluorescence polarisation assay (FPA). Brucella abortus was isolated from 86.8% of animals on combined culture of all three lymph nodes. Individually, the highest isolation rate was from the RP (90.5% of culture positives). Of culture positive animals, 13.7% and 6.2% were positive from the RP and SM alone, respectively.Approximately half of the positive cultures yielded <10 colonies/culture plate. Although 80.9% of animals were positive in at least one serological test, only 45.2% were positive in all five. For culture-positive animals, the MSAT was the most sensitive test (71.8%). Of the culture-negative animals 67.7% were positive in at least one test, while 12.9% were positive in all five. Titres were higher in animals culture-positive from the SM, and there was a direct correlation between higher titres and higher colony counts in SM cultures. Only 8.9% of animals were both culture-negative and seropositive (in at least one test), while 16.5% were culture-positive and seronegative in all five tests. The results highlight and validate the sensitivity of bacteriological culture in confirming a diagnosis of bovine brucellosis. While the MSAT and FPA were the most sensitive serological tests, a significant percentage of infected animals were undetectable using these standard serological assays.  相似文献   

Assessing the Effectiveness of Functional Genetic Screens for the Identification of Bioactive Metabolites     

Anahit Penesyan  Francesco Ballestriero  Malak Daim  Staffan Kjelleberg  Torsten Thomas  Suhelen Egan 《Marine drugs》2013,11(1):40-49

A common limitation for the identification of novel activities from functional (meta) genomic screens is the low number of active clones detected relative to the number of clones screened. Here we demonstrate that constructing libraries with strains known to produce bioactives can greatly enhance the screening efficiency, by increasing the “hit-rate” and unmasking multiple activities from the same bacterial source.  相似文献