Biological and Physical Constraints on Maize Production in the Humid Forest and Western Highlands of Cameroon     

Z. Ngoko  K.F. Cardwell  W.F.O. Marasas  M.J. Wingfield  R. Ndemah  F. Schulthess 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(9):893-902

The aim was to identify biological and physical factors responsible for reducing maize yield in Cameroon. Two surveys were conducted in 137 fields in two agroecological zones in 1995–1997. In the Humid Forest (HF), Bipolaris maydis, Stenocarpella macrospora, Puccinia polysora, Rhizoctonia solani and soil fertility were factors that reduced maize production in 1995 and 1996. In the Western Highlands (WHL), Cercospora zeae-maydis, and the interaction between soil fertility and maize variety were the most important constraints to maize production in 1996. In 1997, C. zeae-maydis, S. macrospora, physiological spot and stem borer damage (Busseola fusca) were negatively related to ear weight. The combination of these biological factors (diseases and insects), and the physical parameter of soil fertility were responsible for reducing maize yield in these selected benchmarks of Cameroon. Maximum potential yield reductions were estimated at 68% due to B. maydis and 46% due to S. macrospora, respectively, in the HF in 1995. In 1996, maximum potential yield reductions in the HF were estimated at 34%, 41% and 30% due to S. macrospora, P. polysora and R. solani, respectively. In the WHL, C. zeae-maydis had the potential to cause a yield reduction of 79% in 1996. In the WHL in 1997, the interaction between C. zeae-maydis and B. fusca, stem diseases and the physiological spot caused potential reductions of 52%, 34% and 39%, respectively.  相似文献   

氧氟沙星药物的研究进展   总被引：2，自引：0，他引：2  

唐建华  姜波  刘昌林  邓开峰 《中国兽药杂志》2007,41(9):29-33

通过对氧氟沙星药物近十年来的检测方法、药代动力学、药效学、耐药性及抗菌后效应、联合应用及毒理学、残留及残留的检测方法等六个方面的大量研究资料进行综述,详细介绍并论述了氧氟沙星药物在这些方面的最新研究成果,对氧氟沙星药物及其他喹诺酮类药物的进一步研究、开发和应用具有指导意义。  相似文献   

Thermogravimetric analysis of pulps     

R. D. Cardwell Dr. Robert D. Cardwell  P. Luner 《Wood Science and Technology》1976,10(2):131-147

Summary A differential and an integral method of kinetic analysis of the data from isothermal pyrolysis of two pulps have shown that a cotton linters pulp has a lower activation energy throughout the entire reaction than has a bleached pine kraft pulp. In all cases, the activation energy decreases with increasing conversion. The mean values obtained were 30 and 36 kcal/mole by the differential and integral methods, respectively, for pyrolysis of the cotton linters pulp and 42 and 45 kcal/mole, respectively, for pyrolysis of the bleached pine kraft pulp. Neither method of analysis used in this work requires prior determination or empirical statement of the reaction order n. This is essential to a proper analysis since it has been shown that the reaction order cannot be regarded as a constant if the complete pyrolysis reaction is studied.Contribution No. 100 from the Empire State Paper Research Institute, State University of New York College of Environmental Science and Forestry, Syracuse, New York 13210.  相似文献   

Suspected poisoning of camels by Trema tomentosa (poison peach)     

KF TRUEMAN  MW POWELL 《Australian veterinary journal》1991,68(6):213-214

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Virulence characteristics of a new race of the parasitic angiosperm,Striga gesnerioides,from southern Benin on cowpea (Vigna unguiculata)     

J. A. Lane  T. H. M. Moore  D. V. Child  K. F. Cardwell  B. B. Singh  J. A. Bailey 《Euphytica》1993,72(3):183-188

An in vitro growth system was used to determine the virulence of two samples of Striga gesnerioides from Zakpota in southern Benin. Cowpea variety B301, previously considered resistant to all races of S. gesnerioides, was susceptible to both samples of the parasite. Two other cowpea varieties, 58–57 and IT81D-994, were totally resistant. Resistance in 58–57 was associated with a hypersensitive necrosis of infected roots, whilst IT81D-994 supported production of small S. gesnerioides tubercles with stems which failed to develop. Striga gesnerioides from southern Benin is the fourth race of the parasite to be identified, and the first with virulence on variety B301. The implications for breeding cowpeas with resistance to S. gesnerioides are discussed.Abbreviations IITA International Institute of Tropical Agriculture - LARS Long Ashton Research Station - SAFGRAD Semi-Arid Food Grain Research and Development  相似文献   

Assessing in vivo Fertilizing Capacity of Liquid-Preserved Boar Semen According to the 'Hanover Gilt Model'     

F Ardón  A Döhring  X Le Thi  KF Weitze  D Waberski 《Reproduction in domestic animals》2003,38(2):161-165

The goal of this study was to determine the ability of the Hanover gilt model to assess in vivo fertilizing capacity of preserved sperm and to consider whether any modifications to this model were needed. This model evaluates the fertilizing capacity of semen based on the fertilization rate, the rate of normal embryos and the accessory sperm count of 3–5‐day embryos. Its distinguishing characteristics are the use of one‐time insemination of sperm in reduced numbers, of spontaneously ovulating gilts and of ovulation detection through ultrasound examination of ovaries. Reduced sperm numbers allow for an accurate evaluation of the fertilizing potential of different semen treatments, thereby avoiding the compensatory effect of doses calibrated to maximize fertility. The model's usefulness was assessed in a trial run designed to compare the fertilizing capacity of liquid boar semen diluted into two different extenders. The diluent, the boar and the backflow, had no significant effect on any of the parameters studied. Gilts inseminated less than 24 h before ovulation had a significantly higher (p < 0.01) fertilization rate and accessory sperm cell count (p < 0.05) than those inseminated more than 24 h before ovulation. Very good/good embryos from homogeneous litters (only very good/good embryos were present) had a significantly higher (p < 0.01) accessory sperm count than those from heterogeneous litters (at least one embryo was of a different quality and/or oocytes were present). Both very good/good and degenerated/retarded embryos from heterogeneous litters had low accessory sperm numbers. This suggests that accessory sperm count is significantly related to the quality of the litter, but not to the quality of the embryo within gilts. It can be concluded that the Hanover gilt model is sensitive enough to show fertility differences (in this study, those associated with in vivo ageing of semen), while using relatively few gilts and little time.  相似文献   

An overview of study design     

Cardwell JM 《The Journal of small animal practice》2008,49(5):217-218

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Cobalt accumulation in horses following repeated administration of cobalt chloride     

RG Wenzel  D Major  KF Hesp  E Hall  P Doble 《Australian veterinary journal》2019,97(11):465-472

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Reaction of maize,sorghum and Johnson grass to Peronosclerospora sorghi     

G. Bigirwa  E. Adipala  J. P. Esele  K. F. Cardwell 《国际虫害防治杂志》2013,59(1):1-6

Development of sorghum downy mildew, incited by Peronoscleospora sorghi (Weston and Uppal) C.G. Shaw, on maize, sorghum and Johnson grass was investigated at two locations in Uganda during three seasons (1994 and 1995). More sorghum downy mildew developed on the Johnson grass and sorghum than on the maize at all locations and in all seasons. No significant differences were observed in sporulation of P. soghi on the three hosts. Leaf shredding occurred on the three hosts but was the least on maize. Cross-inoculation with both conidia and oospores was achieved on the three hosts. Since the fungal population formed oospores and sporulated readily on the three hosts, which is typical of the sorghum strain, the disease in Uganda is attributed to the sorghum strain.  相似文献   

The comparative pathogenicity of four serovars of Actinobacillus (Haemophilus) pleuropneumoniae   总被引：1，自引：0，他引：1  

RJ ROGERS  LE EAVES  PJ BLACKALL  KF TRUMAN 《Australian veterinary journal》1990,67(1):9-12

The pathogenicity of 2 isolates of each of serovars 7, 3, 1 and 2 of Actinobacillus pleuropneumoniae was tested by intranasal inoculation into 60, 6-week-old large white pigs. Four dose rates varying from 0.27 to 560 x 10(6) organisms per pig with 10-fold serial dilutions were used. Surviving pigs were necropsied 7 days after inoculation. The proportion of pigs dying and developing gross lesions following infection was significantly greater for pigs given serotype 1 than for each of the other 3 serotypes, which did not differ significantly from each other. Twelve of 16 pigs given either of the 2 isolates of serovar 1 died after acute illness and 1 of 44 pigs given either of the 2 isolates each of serovars 7, 3 and 2 died. Pigs given serovar 1 showed high temperatures, severe respiratory distress, frothy haemorrhagic nasal discharge and weight loss. Lung lesions were produced in all 16 pigs given serovar 1, in 7 of 14 pigs given serovar 7, 7 of 14 pigs receiving serovar 3 and in 5 of 16 pigs given serovar 2. The lethal infections were characterised by a severe acute fibrinohaemorrhagic necrotising pleuropneumonia, whereas non-lethal cases had lung lesions ranging from necrotising purulent pleuropneumonia to abscessation. Significant differences between isolates in proportions of tissues culture positive for A. pleuropneumoniae for serovars 7 and 2, but not for serovars 3 and 1 suggested that isolates may vary in virulence within serovars, but more detailed studies are needed to clarify this point.  相似文献