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In recent years several varieties of wheat, such as Rothwell Perdix and Maris Envoy, have shown good resistance to yellow rust when first produced, but because their resistance was determined by simply inherited major genes, they have later been severely attacked by newly arising physiologic races of the pathogen. Other varieties, such as Little Joss, Atle and Maris Widgeon, though slightly attacked by several races, have never suffered severe damage even when exposed to high levels of inoculum. The inheritance of this non-race-specific type of resistance was studied in a cross between Little Joss and a susceptible but shorter-strawed variety, Nord Desprez. Resistance appeared to be under complex control. It was found possible to select short-strawed resistant plants, using simple techniques in the field. 相似文献
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Fine needle aspiration cytology of salivary gland lesions 总被引:1,自引:0,他引:1
Eighty-eight fine needle aspirates from 79 salivary gland lesions in 77 patients were examined. The overall diagnostic sensitivity was 84% and the specificity 98.41%. When the 14 unsatisfactory specimens were excluded the sensitivity rose to 95.45%. Correct identification of the disease process was possible in nearly 80% of cases with a final benign diagnosis. The histological tumour type was correctly predicted in 75% of the malignancies. In the others the cytological diagnosis was anaplastic malignant neoplasm. 相似文献
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Does gall diameter affect the parasitism rate of Asphondylia borrichiae (Diptera: Cecidomyiidae)? 总被引:1,自引:0,他引:1
ANTHONY M. ROSSI PETER D. STILING DONALD R. STRONG† DEREK M. JOHNSON 《Ecological Entomology》1992,17(2):149-154
Abstract. 1. Fertilized field plots of Borrichia frutescens (L.) de Candolle produced plants with a higher apical-leaf nitrogen content than control plots.
2. Gall frequency of the cecidomyiid Asphondylia borrichiae Rossi & Strong on stems of B.frutescens , increased significantly on fertilized plots after approximately 3 months.
3. Fertilizer treatment did not result in changes in stem density but did tend to increase proportion of stems flowering and overall plant size. Galls are not normally found on flowering stems.
4. Galls grew at a faster rate and to a larger final size on fertilized plots.
5. On three sampling dates, per cent parasitism of galls was the same on fertilized and control plots; therefore, this study does not support the galldiameter hypothesis. 相似文献
2. Gall frequency of the cecidomyiid Asphondylia borrichiae Rossi & Strong on stems of B.frutescens , increased significantly on fertilized plots after approximately 3 months.
3. Fertilizer treatment did not result in changes in stem density but did tend to increase proportion of stems flowering and overall plant size. Galls are not normally found on flowering stems.
4. Galls grew at a faster rate and to a larger final size on fertilized plots.
5. On three sampling dates, per cent parasitism of galls was the same on fertilized and control plots; therefore, this study does not support the galldiameter hypothesis. 相似文献
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