Het toetsen van aardappelknollen op de aanwezigheid van YN-virus     

J. A. De Bokx 《European journal of plant pathology / European Foundation for Plant Pathology》1961,67(5):333-342

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Effect of day and night temperatures during long photoperiods on the vegetative growth and flowering of Chrysanthemum morifolium Ramat     

J. De Jong  L. Smeets 《Scientia Horticulturae》1982,17(3):271-275

The influence of day and night temperatures in the range of 10–17°C on the vegetative growth under long days of 17 year-round cultivars of chrysanthemum was studied. The after-effect of the temperature regime on the time of flowering at 17°C under short days was also recorded.A decrease of the day or night temperature reduced growth, but the effect of the day temperature was much stronger than that of the night temperature. The temperature during the vegetative period had hardly any effect on the time of flowering at 17°C.The consequences for production and breeding are discussed.  相似文献   

Levels of some reproductive diseases in the dairy cattle of Colombia     

I. B. Griffiths  M. I. Gallego  Ligia S. De Leon 《Tropical animal health and production》1984,16(4):219-223

Of 4,144 serum samples collected from cows on 113 farms from eight areas of Colombia 3.3% had positive and 8.8% inconclusive titres to Brucella abortus, 21.7, 6.3, 1.6, 0.6 and 0.7% of cows had positive titres to Leptospira serovars hardjo, pomona, canicola, icterohaemorrhagiae and grippotyphosa respectively. Questionnaires completed on 110 farms revealed that 6, 2.5 and 4.6% of cows had had metritis, aborted or retained their placentas respectively in the previous 12 months. Trichomonas foetus and Campylobacter fetus were isolated from 13.7% and 15% of the bulls sampled on 103 farms. Six and two bulls had inconclusive and positive titres to Brucella abortus. Eight and 23 bulls had positive titres to pomona and hardjo. The results were discussed and remedies for control suggested.  相似文献   

Detection of soluble antigens of Erwinia salicis in leaves of Salix alba by Enzyme-linked Immunosorbent Assay     

M. De Kam 《Forest Pathology》1982,12(1):1-6

Soluble antigens of Erwinia salicis are transported through the xylem vessels to the leaves of Salix species. These antigens can be detected by the use of the Enzyme-linked Immunosorbent Assay (ELISA) in willow trees in the absence of bacterial cells and are also produced in pure cultures. In this way populations of E. salicis occurring in stem or branches can be traced in the leaves. The possibilities for more general application in the detection of vascular parasites is discussed.  相似文献   

Bud necrosis,a storage disease of tulips. III. The influence of ethylene and mites     

W. J. De Munk 《European journal of plant pathology / European Foundation for Plant Pathology》1972,78(4):168-178

Experiments demonstrated that bud necrosis in tulip bulbs is caused by mites that penetrate the flower bud during storage. This penetration is only possible if the buds, which are normally closed, are open at their tips. Such buds were found after administration of ethylene (3 ppm) during storage at 20°C shortly after lifting and in Red Champion also after storage at higher temperatures (20 to 23°C) in ethylene-free atmospheres. Open buds, caused by ethylene, resulted from unequal growth inhibition of the young leaves and stamens. The difference in sensitivity of both organs to ethylene decreased during storage. later on, the growth inhibition of stamens and leaves became equal, and the buds remained closed. Then ethylene caused blasting of the flower buds. Open buds in Red Champion, caused by higher storage temperatures, resulted from aberrant differentiation of the tips of the young leaves.The production of ethylene by tulip bulbs infected withFusarium oxysporum f.tulipae was measured and proved to be sufficiently high to cause open buds in non-infected bulbs stored in the same room if ventilation is not adequate. The highest production of ethylene, averaging 140 l/24 h/bulb was found at a storage temperature of 20°C.Samenvatting Proeven toonden aan dat kernrot in tulpebollen wordt veroorzaakt door mijten (Rhizoglyphus echinopus Fumouze & Robin enTyrophagus spp.) als deze tijdens de bewaring in de bloemknoppen binnendringen (Tabel 2 en 3). Dit konden mijten alleen bij knoppen die aan de top open waren; normaal zijn de knoppen gesloten. Open knoppen ontstonden door blootstelling van de bollen aan ethyleen (3 dpm) bij 20°C vlak na het rooien (Tabel 1 en Fig. 2) en bij bollen van Red Champion ook door bewaring bij hoge temperaturen (20 tot 23°C) in een ethyleen-vrije atmosfeer. Dit laatste berustte op een afwijkende differentiatie in de top van de pas aangelegde bladeren (Fig. 3). Ethyleen kon open knoppen doen ontstaan, doordat de lengtegroei van de jonge bladeren sterker werd geremd dan die van de meeldraden (Fig. 1). De snellere groei van de binnenste delen van de knop resulteerde dan in open knoppen. Het verschil in gevoeligheid van beide organen voor ethyleen was het grootst vaak na het rooien en nam af gedurende de bewaring. Later in het seizoen (na augustus) was de remming van meeldraden en jonge bladeren gelijk (100%) en ontstonden geen open knoppen meer. Ethyleen veroorzaakte toen verdroging van de bloemknoppen.De door ethyleen geïnduceerde groeiremming was ten dele reversibel. De groei van de jonge bladeren herstelde gedeeltelijk; de groei van de meeldraden geheel, tenzij verdroging van deze organen had plaats gehad als gevolg van blootstelling aan ethyleen laat in het seizoen. Door het verschil in reversibiliteit van de groeiremming van meeldraden en loofbladen kan de toename van de mate van knopafwijking tijdens verdere bewaring na de toediening van ethyleen verklaard worden (Tabel 1).De ethyleenafgifte van bollen die metFusarium oxysporum f.tulipae waren geïnfecteerd, is gemeten. De geproduceerde hoeveelheden ethyleen bleken afhankelijk te zijn van de bewaartemperatuur. Gemiddeld werd de grootste hoeveelheid gevonden bij 20°C, namelijk: 140 l per dag per bol (Fig. 4). Deze hoeveelheid blijkt voldoende te zijn om in slecht geventileerde ruimten bij bollen die niet doorFusarium zijn aangetast, bovengenoemde abnormale groei te veroorzaken.  相似文献   

Genital lesions in an outbreak of caprine contagious agalactia caused by Mycoplasma agalactiae and Mycoplasma putrefaciens     

Gil MC  Peña FJ  Hermoso De Mendoza J  Gomez L 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2003,50(10):484-487

This paper reports on the genital lesions observed in adult male and female goats from a commercial flock in the Extremadura region of southwestern Spain, following an outbreak of contagious agalactia syndrome caused by Mycoplasma agalactiae and M. putrefaciens. Although both species were isolated from several organs, M. putrefaciens was the only agent isolated from the genital lesions reported here, characterized by desquamative salpingitis and cystic catarrhal metritis in females and by testicular degeneration in males. Mycoplasma putrefaciens was isolated from the testes of only one of the males examined.  相似文献   

Detection of foot-and-mouth disease virus from culture and clinical samples by reverse transcription-PCR coupled to restriction enzyme and sequence analysis   总被引：4，自引：0，他引：4  

Sáiz M  De La Morena DB  Blanco E  Núñez JI  Fernández R  Sánchez-Vizcaíno JM 《Veterinary research》2003,34(1):105-117

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甘肃省泾川县三元杂交肉牛生长发育的研究报告   总被引：1，自引：1，他引：0  

王德春  胡拴祥  董格平  王宗德 《中国牛业科学》2003,29(1):30-39

本研究测定并对比研究了德秦黄、德利黄、德西黄、利西黄、利秦黄等三元杂交牛及二元杂交牛初生 ,3月龄、6月龄、1 2月龄、1 8月龄的生长发育指标 ,结果表明 :三元杂交牛比二次杂交牛体尺、体重均有较大幅度的增长、初步筛选出适宜泾川养殖习惯的较佳杂交组合。在农户饲养条件下 ,三元杂交初生重 38kg,比二元杂交牛提高 1 2 .8%～ 5 6.6% ;1 8月龄母牛体重 377.8kg,提高 1 5 .2 %～94.1 % ;1日龄～ 1 8月龄日增重 5 2 8.2 g,增长 9.2 %～ 68.7% ;管围提高幅度为 2 4 .1 %～ 32 .3% ;臀围为 1 .7%～ 32 .3% ;体高为 2 .9%～ 1 5 3% ,体斜长为 5 .5 %～ 1 3.9% ,胸围为 1 1 .4%～ 2 0 .5 %。尻长为 5 .1 %～ 1 1 .8% ,腰角宽为 0～ 2 1 .4% ,髋宽为 0～ 3%。适宜的杂交组合为德秦黄、德利黄、德西黄。三元杂交牛 6～ 1 2月龄生长发育受阻 ,主要是饲料营养水平低所致 ,建议从 2月龄开始用优质饲草和配和配合饲料 ,1 8月龄体重达到 40 0 kg以上 ,再经 3个月育肥 ,2 1月龄达到体重 5 0 0 kg的出栏标准。  相似文献   

What is your diagnosis? Plasma cell podoermatitis and plasma cell dermatitis of the nose apex in cat     

De Man M 《Journal of Feline Medicine and Surgery》2003,5(4):245-247

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Risk assessment models for wheat fusarium head blight epidemics based on within-season weather data     

De Wolf ED  Madden LV  Lipps PE 《Phytopathology》2003,93(4):428-435

ABSTRACT Logistic regression models for wheat Fusarium head blight were developed using information collected at 50 location-years, including four states, representing three different U.S. wheat-production regions. Non-parametric correlation analysis and stepwise logistic regression analysis identified combinations of temperature, relative humidity, and rainfall or durations of specified weather conditions, for 7 days prior to anthesis, and 10 days beginning at crop anthesis, as potential predictor variables. Prediction accuracy of developed logistic regression models ranged from 62 to 85%. Models suitable for application as a disease warning system were identified based on model prediction accuracy, sensitivity, specificity, and availability of weather variables at crop anthesis. Four of the identified models correctly classified 84% of the 50 location-years. A fifth model that used only pre-anthesis weather conditions correctly classified 70% of the location-years. The most useful predictor variables were the duration (h) of precipitation 7 days prior to anthesis, duration (h) that temperature was between 15 and 30 degrees C 7 days prior to anthesis, and the duration (h) that temperature was between 15 and 30 degrees C and relative humidity was greater than or equal to 90%. When model performance was evaluated with an independent validation set (n = 9), prediction accuracy was only 6% lower than the accuracy for the original data sets. These results indicate that narrow time periods around crop anthesis can be used to predict Fusarium head blight epidemics.  相似文献