Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) or poro (Erythrina poeppigiana) in Costa Rica     

J. Beer  A. Bonnemann  W. Chavez  H. W. Fassbender  A. C. Imbach  I. Martel 《Agroforestry Systems》1990,12(3):229-249

Predictive models were developed for Cordia alliodora branch and Theobroma cacao branch or leaf biomass,based on branch basal areas (r² 0.79) but the model of C. alliodora leaf biomass, although significant, was of very low accuracy (r² = 0.09) due to annual leaf fall. At age 10 years, shade tree stem biomass accounted for 80% of the total above-ground biomass of either tree. However, between the ages of 6 and 10 years, the biomass increment of T. cacao branches (3–4t.ha^–1.a^–1) was similar to that of the shade tree stems. During the same period, the net primary productivity was 35 and 28 t.ha^–1.a^–1, for the Erythrina poepigiana and and C. alliodora systems, respectively.Cocoa production under either of the shade trees C. alliodora or E. poeppigiana was 1000 kg.ha^–1.a^–1 (oven-dry; ages 6–10 yr). During the same period, C. alliodora timber production was 9 m³.ha^–1.a^–1 whilst the leguminous shade tree E. poeppigiana does not produce timber. Litterfall over the same 5 years, including crop and/or shade tree pruning residues, averages 11 and 23 t.ha^–1.a^–1, respectively. The main difference was due to E. poeppigiana pruning residues (10t.ha^–1.a^–1).Soil organic material reserves (0–45 cm) increased over 10 years from 198 to 240 t.ha^–1 in the E. poeppigiana plots and from 168–184 t.ha^–1 in the C. alliodora plots. These values, together with the productivity indices presented, provide evidence that the systems are sustainable.For economic reasons, the use of C. alliodora is recommended under the experimental conditions. however, on less fertile soils without fertilization, the greater biomass and hence nutrient return to the soil surface under E. poeppigiana, might make this the preferable shade tree.  相似文献   

Litter production and nutrient cycling in coffee (Coffea arabica) or cacao (Theobroma cacao) plantations with shade trees     

John Beer 《Agroforestry Systems》1988,7(2):103-114

The relative importance of N fixation, organic material inputs and nutrient inputs in litterfall, as justifications for including shade trees in plantations of coffee or cacao, is discussed. According to existing data, N fixation by leguminous shade trees does not exceed 60 kg.N/ha/a. However, these trees contribute 5,000–10,000 kg. organic material/ha/a.Comparisons are made between the leguminous shade tree Erythrina poeppigiana and the non-leguminous timber tree Cordia alliodora. The former, when pruned 2 or 3 times/a., can return to the litter layer the same amount of nutrients that are applied to coffee plantations via inorganic fertilizers, even at the highest recommended rates for Costa Rica of 270 kg.N, 60 kg.P, 150 kg.K/ha/a. The annual nutrient return in this litterfall represents 90–100 percent of the nutrient store in above-ground biomass of E. poeppigiana, and hence the consequences of competition with the crop should not be a serious limitation. In the case of C. alliodora, which is not pruned, nutrient storage in the tree stems, especially of K, is a potential limiting factor to both crop and tree productivity.It is concluded that, in fertilized plantations of cacao and coffee, litter productivity is a more important shade tree characteristic than N fixation.An early version of this review was presented at the CATIE-IUFRO meeting Los Arboles de Uso Multiple en Sistemas Agroforestales, June 1985, Turrialba, Costa Rica.  相似文献   

Analysis of 151 agricultural driveline-related incidents resulting in fatal and non-fatal injuries to U.S. children and adolescents under age 18 from 1970 through 2004     

Beer SR  Deboy GR  Field WE 《Journal of agricultural safety and health》2007,13(2):147-164

Agricultural driveline-related incidents have been identified as an important cause of farm-related injury resulting in death and permanently disabling conditions to children and adolescents. A database of driveline-related injuries, including both PTO drivelines and secondary shafts and drivelines on agricultural equipment, developed at Purdue University was mined to identify all cases involving children and adolescents under age 18 who had been involved in a driveline-related incident from 1970 through 2004. Although these incidents did not account for a high percentage of all childhood farm-related injuries, this age group was found to make up nearly one in four documented agricultural driveline incidents. Of the 685 cases in the database with known ages, 151 were identified as youth under age 18. Findings indicated that these incidents often resulted in catastrophic injuries including amputation, spinal cord injuries, and compound bone fractures. Over the period studied, the trend in documented cases is declining, with recent years reporting below the yearly average and 2004 reporting no fatalities. Youth, primarily males, age 13 had the highest frequency of incidents, and over 50% of all cases occurred to youth ages 12 to 17. Fall was identified as the season with the most reported incidents. Amputations were documented in nearly 50% of all cases, and augers, elevators, and conveyors were the machines most frequently identified as being involved in the incident. Recommendations and strategies that specifically target the childhood injury problem related to agricultural drivelines are provided.  相似文献   

Characterization of C-strain "Riems" TAV-epitope escape variants obtained through selective antibody pressure in cell culture     

Leifer I  Blome S  Blohm U  König P  Küster H  Lange B  Beer M 《Veterinary research》2012,43(1):33

ABSTRACT: Classical swine fever virus (CSFV) C-strain "Riems" escape variants generated under selective antibody pressure with monoclonal antibodies and a peptide-specific antiserum in cell culture were investigated. Candidates with up to three amino acid exchanges in the immunodominant and highly conserved linear TAV-epitope of the E2-glycoprotein, and additional mutations in the envelope proteins ERNS and E1, were characterized both in vitro and in vivo.It was further demonstrated, that intramuscular immunization of weaner pigs with variants selected after a series of passages elicited full protection against lethal CSFV challenge infection. These novel CSFV C-strain variants with exchanges in the TAV-epitope present potential marker vaccine candidates. The DIVA (differentiating infected from vaccinated animals) principle was tested for those variants using commercially available E2 antibody detection ELISA. Moreover, direct virus differentiation is possible using a real-time RT-PCR system specific for the new C-strain virus escape variants or using differential immunofluorescence staining.  相似文献   

Schmallenberg virus challenge models in cattle: infectious serum or culture-grown virus?     

Kerstin Wernike  Michael Eschbaumer  Angele Breithaupt  Bernd Hoffmann  Martin Beer 《Veterinary research》2012,43(1):84

Schmallenberg virus (SBV), discovered in Europe in 2011, causes mild transient disease in adult ruminants, but fetal infection can lead to severe malformation in cattle, sheep and goats.To elucidate the pathogenesis of this novel orthobunyavirus, considerable efforts are required. A reliable and standardized infection model is essential for in vivo studies. In the present study, two groups of four cattle were inoculated with either serum passaged in cattle only or cell culture-grown virus. The replication of culture-grown SBV in cattle was reduced compared to virus inoculated via infectious serum. In a second experiment, the infectious serum was titrated in calves; the tested batch contained 10^2.83 infectious doses per mL. Hence, serum-borne virus that was only passaged in the natural host is a suitable option for a standardized SBV infection model.  相似文献   

Experimental infection of South American camelids with bluetongue virus serotype 8     

Schulz C  Eschbaumer M  Rudolf M  König P  Keller M  Bauer C  Gauly M  Grevelding CG  Beer M  Hoffmann B 《Veterinary microbiology》2012,154(3-4):257-265

Bluetongue (BT) is an infectious, non-contagious disease of wild and domestic ruminants. It is caused by bluetongue virus (BTV) and transmitted by Culicoides biting midges. Since 1998, BT has been emerging throughout Europe, threatening not only the na?ve ruminant population. Historically, South American camelids (SAC) were considered to be resistant to BT disease. However, recent fatalities related to BTV in captive SAC have raised questions about their role in BTV epidemiology. Data on the susceptibility of SAC to experimental infection with BTV serotype 8 (BTV-8) were collected in an animal experiment. Three alpacas (Vicugna pacos) and three llamas (Lama glama) were experimentally infected with BTV-8. They displayed very mild clinical signs. Seroconversion was first measured 6-8 days after infection (dpi) by ELISA, and neutralising antibodies appeared 10-13 dpi. BTV-8 RNA levels in blood were very low, and quickly cleared after seroconversion. However, spleens collected post-mortem were still positive for BTV RNA, over 71 days after the last detection in blood samples. Virus isolation was only possible from blood samples of two alpacas by inoculation of highly sensitive interferon alpha/beta receptor-deficient (IFNAR(-/-)) mice. An in vitro experiment demonstrated that significantly lower amounts of BTV-8 adsorb to SAC blood cells than to bovine blood cells. Although this experiment showed that SAC are generally susceptible to a BTV-8 infection, it indicates that these species play a negligible role in BTV epidemiology.  相似文献   

Harpin-elicited hypersensitive cell death and pathogen resistance require the NDR1 and EDS1 genes     

J. -L. Peng  H. -S. Dong  H. -P. Dong  T. P. Delaney  J. M. Bonasera  S. V. Beer   《Physiological and Molecular Plant Pathology》2003,62(6):317-326

Plants sprayed with harpin, a bacterial protein that induces hypersensitive cell death (HCD), develop systemic acquired resistance (SAR) without macroscopic necrosis. HCD sometimes accompanies the development of resistance conferred by resistance (R) genes. In Arabidopsis, some R genes require one or both of the signalling components NDR1 and EDS1 for function. This study addresses whether HCD, NDR1 and EDS1 are required for induction of SAR by harpin. When Arabidopsis and tobacco leaves were sprayed with harpin, microscopic hypersensitive response (micro-HR) lesions developed. Systemic expression of PR genes and the development of resistance were accompanied by micro-HR, except in the ndr1-1 mutant, in which harpin induced micro-HR without the development of resistance or expression of the PR-1 gene. Cell death and resistance did not occur following treatment with harpin in plants that could not accumulate salicylic acid. Harpin also failed to induce resistance in Arabidopsis eds1-1 mutants. Therefore, harpin-induced resistance seems to develop concomitantly with cell death and resistance requires NDR1 and EDS1.  相似文献   

Black root rot: a long known but little understood disease     

W. J. Nel  T. A. Duong  Z. W. de Beer  M. J. Wingfield 《Plant pathology》2019,68(5):834-842

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生产菌DAB啤酒酵母选育技术研究     

郝建国  杨秀炯  李晨  姜雪林 《河北北方学院学报(自然科学版)》2000,(3)

生产性状发生退化的DAB酵母,采用30％致死率的紫外线处理,经高糖培养基筛选及单细胞分离等手段,得到一株性能优良的啤酒生产酵母菌种。  相似文献   

Arbeitsergebnisse aus der Projektgruppe ?Krankheiten im Getreide“ der Deutschen Phytomedizinischen Gesellschaft e. V.     

Eckard Beer 《Gesunde Pflanzen》2005,3(1):59-70

In den Jahren 1989 bis 1992 wurde in bundesweit durchgeführten Feldversuchen eine Bekämpfungsschwelle für Blatt- und Ährenkrankheiten in unterschiedlich widerstandsfähigen Winterweizensorten überprüft. Nach vergleichbarem Muster lief die Überprüfung verschiedener Schwellenwerte in Winterroggen, Winter- und Sommergerste von 1992 bis 1995 ab.Mit von 1995 bis 1998 ebenfalls mehrfaktoriell angelegten Feldversuchen beteiligte sich die Projektgruppe an dem Vorhaben der Bundesanstalt für Landwirtschaft und Ernährung (BLE) Untersuchungen zum Einfluss unterschiedlicher Pflanzenschutzmaßnahmen auf den Mykotoxingehalt und den Fusarium-Besatz im Erntegut von Getreide (1997–2000). Ergänzt um Beiträge der Projektgruppenteilnehmer aus dem eigenen Forschungs- und Entwicklungsbereich wurden die Erkenntnisse der Projektgruppe zu diesem Themenkomplex im Rahmen eines Workshops im November 2002 vorgestellt und mit ca. 120 Fachleuten aus Ministerien, der Produktionstechnik sowie den vor- und nachgelagerten Bereichen diskutiert.  相似文献