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排序方式: 共有92条查询结果,搜索用时 15 毫秒
1.
Improving Drought Tolerance of Rice by Designed QTL Pyramiding 总被引:4,自引:0,他引:4
Drought is the most important factor limiting rice yields in the rainfed areas of Asia. To overcome the problem we developed a new strategy ''''designed QTL pyramiding'''' to more efficiently develop drought tolerant 《分子植物育种》2007,5(2):205-206
Drought is the most important factor limiting rice yields in the rainfed areas of Asia. To overcome the problem, we developed a new strategy 'designed QTL pyramiding' to more efficiently develop drought tolerant (DT) rice cultivars. In the first phase of this strategy, we developed large numbers of introgression lines (ILs) in elite backgrounds using backcross (BC) breeding, each of which carries multiple genomic segments for improved DT from a known donor. Then, we genotyped all ILs with SSR markers to track the genomewide pattern of introgression in the DT ILs of 16 BC populations derived from crosses between 2 recipients (IR64 and Teqing) and four different donors. X^2 tests and linkage disequilibrium analyses of introgression in the DT ILs revealed significant frequency shifts at many loci across the genome and non-random associations at the multilocus level as a result of selection for DT in the ILs, which led us to the discovery of putative genetic networks underlying DT in the ILs. The networks each containing all DT loci detected in ILs from a BC population showed some interesting features. 相似文献
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Soil organic carbon stock variability in the Northern Gangetic Plains of India: interaction between agro‐ecological characteristics and cropping systems 下载免费PDF全文
V. K. Singh M. Rani B. S. Dwivedi S. K. Singh V. K. Gupta K. Majumdar R. P. Mishra 《Soil Use and Management》2015,31(4):461-473
Soil organic carbon (SOC) content and its spatial distribution in the Northern Gangetic Plain (NGP) Zone of India were determined to establish the cause–effect relationship between agro‐ecological characteristics, prevailing crop management practices and SOC stock. Area Spread Index (ASI) approach was used to collect soil samples from the NGP areas supporting predominant cropping systems. Exponential ordinary kriging was found most suitable geo‐statistical model for developing SOC surface maps of the NGP. Predicted surface maps indicated that 43.7% area of NGP had 0.5–0.6% SOC, while the rest of the area was equally distributed with high (0.61–0.75%) and low (< 0.5%) SOC content levels. Averaged across cropping systems, maximum SOC content was recorded in Bhabar and Tarai Zone (BTZ), followed by Central Plain Zone (CPZ), Mid‐Western Plain Zone (MWPZ), Western Plain Zone (WPZ) and South‐Western Plain Zone (SWPZ) of the NGP. The SOC stock was above the optimum threshold (> 12.5 Mg/ha) in 97.8, 57.6 and 46.4% areas of BTZ, CPZ and MWPZ, respectively. Only 9.8 and 0.4% area of WPZ and SWPZ, respectively, had SOC stock above the threshold value. The variation in SOC stock was attributed largely to carbon addition through recycling of organic sources, cropping systems, tillage intensity, crop or residue cover and land‐use efficiency, nutrient‐use pattern, soil texture and prevailing ecosystem. Adoption of conservation agriculture, balanced use of nutrients, inclusion of legumes in cropping systems and agro‐forestry were suggested for enhancing SOC stock in the region. 相似文献
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Roop Kishore Ashish Dwivedi Raghuvir Singh R. K. Naresh Vineet Kumar Priyanka Bankoti Dinesh Kumar Sharma Nishant Yadav 《Paddy and Water Environment》2017,15(1):49-58
Weeds caused serious problem on yield reduction of basmati rice worldwide. Losses caused by weeds varied from one country to another, depending on the presence of dominant weeds and the control methods practiced by farmers; therefore, suitable plant population and weed management practices should be adopted. Keeping these in mind, a field experiment was carried out during kharif seasons of 2009 and 2010 at crop Research Centre of SVPUA&T, Meerut, India comprising 4 planting geometries, viz. 20, 30, 40, and 50 hills m?2 as main plot factor, and 5 weed management practices (Butachlor @ 1.0 kg ha?1, Butachlor @ 1.0 kg ha?1 fb (followed by) one hand weeding, Butachlor @ 1.0 kg ha?1 fb Almix @ 4 g ha?1, two hand weedings and weedy check) in a split plot design with 3 replications. Experimental results revealed that plant population of 50 hills m?2 proved superior over that of 20 hills m?2 in respect of weed density, weed dry weight, number of tillers m?2, yield attributes, grain, straw, and biological yields. The maximum grain yield (29.00 and 31.00 q ha?1) and straw yield (51.30 and 52.50 q ha?1) were recorded in 50 hills m?2 followed by 40 hills m?2 during 2009 and 2010, respectively. In respect of nitrogen, phosphorus, and potassium removal, a reverse trend was observed: the highest in 20 hills m?2 followed by 30, 40, and 50 hills m?2. As far as the weed management practices are concerned, both chemical and mechanical methods of weed control were found superior over weedy check. The lowest weed density, dry weight, and highest weed control efficiency, maximum length of panicle?1, number of panicle (m2), and 1000-grain weight and grain yield of 30.40 and 32.60 q ha?1 were recorded with two hand weedings which was at par with Butachlor @ 1.0 kg ha?1 fb one hand weeding over rest of the weed management practices. 相似文献
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Summary A study of the several interspecific and inter-subspecific crosses indicated that albinism in groundnut is recessive and in these crosses is controlled by triplicate recessive loci.ICRISAT Paper No. JA-336 相似文献
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Ultrastructural study of the liver and kidney in ochratoxicosis A in young broiler chicks 总被引:1,自引:0,他引:1
Ultrastructural changes are reported in the kidney and liver of 20-day-old broiler chicks fed ochratoxin A (OA), incorporated in the diet at levels of 2 and 4 ppm. Changes in the kidney included the presence of abnormally shaped mitochondria in the proximal convoluted tubules. There was an increase in the size and number of mitochondrial dense granules and cytoplasmic peroxisomes. Intranuclear and cytoplasmic lipid droplets and electron dense round bodies in the dilated smooth endoplasmic reticulum were also noted. Regional thickening and degeneration of the glomerular basement membrane was observed in some cases. In the liver from OA fed birds there was an increased accumulation of cytoplasmic glycogen in the hepatocytes. Abnormal mitochondrial ring forms in the kidney and the accumulation of glycogen in the liver are considered to be of diagnostic significance in ochratoxicosis of young broiler chicks. The severity of the changes was found to be dose related. These results suggest that the mitochondria in the proximal convoluted tubules of kidney were most sensitive to OA toxicity. 相似文献
8.
Ultrathin sections of liver and kidney from 11-week-old quail fed, from day-old, ochratoxin A (OA) (mixed in the diet at levels of 4 and 8 ppm) were examined in the electron microscope. Pathological changes in the kidneys were limited to the proximal convoluted tubules (PCT) and glomeruli. In the PCTs, abnormal mitochondria and excessive numbers of lipid droplets were the principal findings with glomeruli showing thickened basement membranes. Swollen mitochondria and variable glycogen deposition were the chief features present in the livers. It is suggested that OA is more hepatotoxic in quail than in broilers, as well as being nephrotoxic. 相似文献
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Comparison of three techniques for the diagnosis of urinary tract infections in dogs with urolithiasis 总被引:1,自引:0,他引:1
OBJECTIVES: To identify an appropriate sampling technique(s) to accurately detect the bacteria causing urinary tract infections in dogs with urolithiasis. METHODS: Twenty-one dogs with urolithiasis were included in the study. Three types of samples were taken from each dog. Urine was collected by cystocentesis, and a urinary bladder mucosal biopsy and urolith were retrieved during cystotomy. The samples were then cultured on blood agar and MacConkey's agar to identify the bacteria associated with urinary tract infections. RESULTS: Bacterial urinary tract infection was found in 16 cases (76.19 per cent). The most prevalent bacteria found to cause urinary tract infection were Escherichia coli (n=7), followed by coagulase-positive Staphylococcus species (n=4), Klebsiella pneumoniae (n=2), Pseudomonas aeruginosa (n=2) and Proteus mirabilis (n=1). In the case of a positive urine culture, the same bacteria were also cultured from the urinary bladder mucosal biopsy alone or from both the urinary bladder mucosal biopsy and urolith. However, in the case of a negative urine culture, bacteria were found to be present in the urinary bladder mucosal biopsy or urolith cultures in 23.81 per cent of dogs. The uroliths that gave positive culture results were either infection-induced uroliths composed of struvite and calcium carbonate phosphate, ammonium acid urate only or metabolic uroliths composed of calcium oxalate and calcium phosphate, or calcium phosphate only. All the uroliths that gave negative culture results were metabolic uroliths composed of calcium oxalate and/or calcium phosphate, and uric acid and calcium phosphate. CLINICAL SIGNIFICANCE: When the culture from the urine obtained by cystocentesis is negative, cultures of urinary bladder mucosal biopsy and urolith are recommended in dogs with urolithiasis in order to accurately assess the microbiological status of the urinary tract. 相似文献