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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
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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
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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
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Cardwell JM 《The Journal of small animal practice》2008,49(5):217-218
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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
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Summary This paper surveys the different kinetic schemes that have been employed with dynamic thermogravimetric analysis and discusses their advantages and shortcomings with particular reference to cellulose. It is concluded that the differential method of Friedman [1965] and the integral method of Flynn and Wall [1966] are the best approaches for kinetic analysis in each category. Both these methods are consistent with and analogous to the isothermal kinetic methods previously given by Cardwell and Luner [1975].Contribution No. 101 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
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An increased risk of urinary incontinence in bitches has often been associated with previous ovariohysterectomy but remains controversial. The objective of this study was to evaluate the strength of evidence for an association between neutering or age at neutering and urinary incontinence in bitches and to estimate the magnitude of any effect found. A systematic review of peer-reviewed original English analytic journal articles was conducted, based on Cochrane guidelines (Higgins and Green 2009) Of 1,853 records screened, seven studies were identified that examined the effect of neutering or age at neutering on the risk of urinary incontinence but four were judged to be at high risk of bias. Of the remaining three studies, which were at moderate risk of bias, there was some weak evidence that neutering, particularly before the age of three months, increases the risk of urinary incontinence. However, overall the evidence is not consistent nor strong enough to make firm recommendations on the effect of neutering or age at neutering on the risk of urinary incontinence. 相似文献
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Factors affecting the production of conidia of Peronosclerospora sorghi , causing sorghum downy mildew (SDM), were investigated during 1993 and 1994 in Zimbabwe. In the field conidia were detected on nights when the minimum temperature was in the range 10–19°C. On 73% of nights when conidia were detected rain had fallen within the previous 72 h and on 64% of nights wind speed was < 2.0 m s−1 . The time period over which conidia were detected was 2–9 h. Using incubated leaf material, conidia were produced in the temperature range 10–26°C. Local lesions and systemically infected leaf material produced 2.4–5.7 × 103 conidia per cm2 . Under controlled conditions conidia were released from conidiophores for 2.5 h after maturation and were shown to be well adapted to wind dispersal, having a settling velocity of 1.5 × 10−4 m s−1 . Conditions that are suitable for conidia production occur in Zimbabwe and other semi-arid regions of southern Africa during the cropping season. 相似文献
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