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排序方式: 共有204条查询结果,搜索用时 15 毫秒
1.
While the toxic effects of neem, Azadirachta indica A. Juss, on Bemisia tabaci Genn. are well documented, few studies have evaluated other oils. We compared neem, sesame, citrus, castor, vegetable and mineral oils (1% v/v) to a chemical standard thiamethoxam (0.17 g A.I./L) against B. tabaci biotype B life stages on dry bean plants Phaseolus vulgaris L. under screenhouse conditions. Oils and thiamethoxam exhibited low ovicidal activity (<10% egg mortality). However, significant mortality occurred due to the residual activity to 1st instars that emerged from treated eggs. Overall, impacts of egg treatments were greatest for thiamethoxam (77% total mortality for eggs and 1st instars) compared with oils which were statistically similar (22–29% mortality). Larvicidal effect of oils (against 2nd instars) was greater than ovicidal effects. Highest nymphal mortality (>81%) was achieved with castor, sesame, citrus and neem oils, which was significantly greater than for thiamethoxam (65% mortality). Adult whiteflies were exposed to fresh and aged spray residues, rather than being sprayed directly. In this case, comparatively lower efficacy was achieved from oil treatments compared with thiamethoxam. While some mortality was observed from fresh residues of slow drying oils (up to 41% for castor oil), no significant control from any oil residues >3 days old was observed in our tests. The different route of exposure against adults likely reduced the effectiveness of oil treatments which act directly on the cuticle. In trials with viruliferous adult whiteflies exposed to fresh residues, none of the tested products completely prevented transmission of bean golden mosaic virus (BGMV). However, we noted reduced virus severity ratings from plants pre-treated with castor and citrus oil. We conclude that castor, sesame, citrus and neem oils have the potential to be used in whitefly management programs.  相似文献   
2.
An 8‐wk feeding trial was conducted to evaluate the effects of varying dietary protein and lipid levels with different protein‐to‐energy (P/E) ratios on growth, feed utilization, and plasma biochemical parameters of Sinocyclocheilus graham. Nine experimental diets were formulated to contain three protein levels (35, 40, and 45%), and each with three lipid levels (4, 8, and 12%), to produce a range of P/E ratios from 71.31 to 98.64 mg protein/kcal. Each diet was randomly assigned to triplicate groups of 25 fish. Fish grew best when fed the diet containing 45% protein and 12% lipid. However, fish fed the diet with 40% protein and 8% lipid had similar weight gain and specific growth rate as those fed the above diet but showed relatively better feed conversion ratio, protein efficiency ratio, and protein and energy retentions. Additionally, plasma total amino acids and blood urea nitrogen contents and γ‐glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase activities in fish fed the diet containing 40% protein and 8% lipid were relatively low among the dietary treatments. These results may indicate that a diet containing 40% protein and 8% lipid with P/E ratio of 84.05 mg protein/kcal would be suitable for the optimal growth, feed utilization, and health of S. graham.  相似文献   
3.
In order to investigate the dietary vitamin B6 (VB6) requirement for juvenile golden pompano, an experiment of six different diets with six dietary VB6 levels (0, 3.75, 7.47, 10.6, 13.7 and 18.5 mg/kg) was conducted. The results indicated that the content of dietary VB6 significantly increased weight gain rate (WGR), specific growth rate (SGR) and feed conversion ratio (FCR; p < 0.05). Golden pompano fed diet containing 7.47 mg/kg VB6 achieved the maximum ALT, AST, GPx, hepatic VB6 concentrations as well as the minimum MDA, however, the ALT, AST, GPx and hepatic VB6 concentrations decreased while MDA increased with a further increase in dieatry VB6. The highest values of GR and POD occurred at the 10.6 and 13.7 mg/kg dietary VB6 (p < 0.05) respectively. A diet supplemented with 7.47 mg/kg VB6 increased intestinal Na+, K+‐ATPase, Chymotrypsin, γ‐glutamyl transpeptidase, creatine kinase and amylase activities (p < 0.05). The relative abundance of Tenericutes and Bacteroidetes decreased while Proteobacteria and Firmicutes improved with an increase in dietary VB6 levels up to 7.47 mg/kg. Quadratic regression analysis on WGR, hepatic VB6 concentrations, AST and ALT indicated that the optimum dietary VB6 levels for juvenile golden pompano were 8.84–9.28 mg/kg.  相似文献   
4.
Summary The genetics of resistance to bean golden mosaic virus (BGMV) was studied in an 8×8 complete diallel cross of common bean, Phaseolus vulgaris L. The 28F1 hybrids, their reciprocals, and eight parents were artificially inoculated with BGMV under glasshouse conditions. Data were recorded and analyzed for foliar yellowing, plant dwarfing, flower abortion, and pod formation, using a randomized complete block design with two replications.General combining ability (GCA) mean squares were highly significant (P<0.01) and larger than values for specific combining ability for all traits. Reciprocal and maternal effects were nonsignificant. Cultivars Royal Red and Alubia Cerrillos possessed significant negative and positive GCA for all traits, respectively. Porrillo Sintetico also had negative GCA for all traits except plant dwarfing. None of the GCA effects were significant for Great Northern 31 and PVA 1111. Positive associations existed among all traits studied.  相似文献   
5.
Nutrient dynamics in a mangrove creek (North Brazil) during the dry season   总被引:1,自引:0,他引:1  
During the dry season, dissolved inorganic nutrients and organic carbon (DOC) in a mangrove tidal creek (Bragança, North Brazil) presented a clear tidal signature: silicate, phosphate, ammonium and DOC covaried with salinity, with minima at high tide and maxima at low tide. Hydrodynamical calculations explained most diel variability as dilution of nutrientrich groundwater input by estuarine water. Creek nutrients tended to lower concentrations towards the end of the dry season, probably due to changes in groundwater dynamics. Ammonium was about 44% higher in the night than during the day, while silicate, phosphate nitrate + nitrite showed differences < 5%, indicating preferential autotrophic uptake of ammonium as nitrogen source. Nitrification and/or nitrogen fixation are probably sources of nitrate + nitrite, which contributed only 12% to the dissolved inorganic nitrogen pool. Dissolved oxygen (7%) and DOC (11%) were lower during the night, suggesting the existence of a labile, algalderived DOC pool. There is a loose coupling between aquatic primary production, groundwater dynamics and tidal regime.  相似文献   
6.
张洪民 《计算机与农业》2010,(3):105-106,130
电子报税是我国税制改革的一个重要组成部分,根据电子报税的具体要求确定了系统的功能模块、开发及运行平台和网络拓扑结构,并按照系统工程原则,用现代软件技术设计了纳税申报电子信息采集系统。  相似文献   
7.
张洪民 《农业网络信息》2010,(3):105-106,130
电子报税是我国税制改革的一个重要组成部分,根据电子报税的具体要求确定了系统的功能模块、开发及运行平台和网络拓扑结构,并按照系统工程原则,用现代软件技术设计了纳税申报电子信息采集系统。  相似文献   
8.
Field experiments were made on a sandy clay loam soil at the Indian Agricultural Research Institute, New Delhi to study the effect of levels and sources of nitrogen on concentration and uptake of nitrogen by a high yielding variety Pusa 834 and a hybrid PRH3 of rice. Nitrogen concentration in hybrid PRH 3 remained lower than in Pusa 834, but N uptake was significantly more in the hybrid PRH 3. Nitrogen fertilization increased N concentration as well as N uptake by rice. At 30 days after transplanting (DAT) N uptake was more in Pusa 834, but at 60 DAT and at harvest hybrid PRH 3 recorded significantly more N uptake than Pusa 834. Use of neem oil blended urea (PNGU) and neem coated urea (NCU) increased N concentration and uptake by rice in both Pusa 834 and hybrid PRH 3. Use of neem coated/blended urea is recommended for rice.  相似文献   
9.
An outbreak of a Megalocytivirus infection was found in the golden mandarin fish Siniperca scherzeri during September and October 2016, in Korea. Phylogeny and genetic diversity based on the major capsid protein (MCP) and adenosine triphosphatase (ATPase) genes showed a new strain. Designated as GMIV, this strain derived from the golden mandarin fish was suggested to belong to the red sea bream iridovirus (RSIV)‐subgroup I. Additionally, this train clustered with the ehime‐1 strain from red sea bream Pagrus major in Japan and was distinguished from circulating isolates (RSIV‐type subgroup II and turbot reddish body iridovirus [TRBIV] type) in Korea. The infection level, evaluated by qPCR, ranged from 8.18 × 102 to 7.95 × 106 copies/mg of tissue individually, suggesting that the infected fish were in the disease‐transmitting stage. The diseased fish showed degenerative changes associated with cytomegaly in the spleen as general sign of Megalocytivirus infection. The results confirm that the RSIV‐type Megalocytivirus might have crossed the environmental and species barriers to cause widespread infection in freshwater fish.  相似文献   
10.
不同地区福寿螺繁殖力比较   总被引:4,自引:0,他引:4  
应用单对交配的方法对江苏、福建和广东3个不同地理群体福寿螺的繁殖力进行比较.结果显示,福寿螺的繁殖力变异较大;在个体产卵量方面,福建螺与江苏螺有显著差异(P<0.05);在雌螺个体体重的相对产卵量方面,广东螺与福建螺、广东螺与江苏螺有显著差异(P<0.05);不同地区、不同交配个体产卵块数差异不显著(P>0.05);不同壳色的福寿螺繁殖力差异不明显(P>0.05);交配个体雌雄大小不同其交配产卵量与雌螺个体大小呈正相关,与雄螺个体大小无关;雌螺个体越大产卵量越大,但相对产卵量反而越小;雌螺产卵量与卵块数呈正相关.福寿螺的繁殖力与环境条件、食物种类、温度等因素有密切的关系.  相似文献   
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