不同温度下黄岗仓花蝽实验种群生命表     

文必然  邓望喜 《华中农业大学学报》1988,(2)

在五种不同恒温条件下,观察了黄岗仓花蝽各世代的存活率及成虫的繁殖力。结果表明,该虫的世代存活率及成虫的繁殖力均以28℃下的为最高,36℃下的为最低。进而根据不同温度条件下的实验数据,组建了该虫实验种群生命表,并用数学模型描述了温度与种群增长的关系,可用以预测该虫在不同温度下的种群增长趋势。  相似文献   

Use of urea-molasses-multinutrient block and urea-treated rice straw for improving dairy cattle productivity in Vietnam     

Vu DD  Cuong LX  Dung CA  Hai PH 《Preventive veterinary medicine》1999,38(2-3):187-193

After conducting a preliminary survey, a feeding trial was carried out to determine the effect of urea-molasses-multinutrient block (UMMB) and urea-treated rice straw (UTRS) as a feed supplement on the productivity of dairy cows. Sixty Holstein-Friesian crossbred cows on 11 smallholder farms were divided equally into control, UMMB and UTRS supplementation groups. Milk yield and feed intake were recorded daily. Milk fat content, body weight and body condition score (BSC) of each cow were determined at two week intervals. Milk samples for progesterone analysis were collected once a week commencing one month after parturition. Data were recorded for date of onset of ovarian activity, estrus, insemination, and conception rate. Milk production increased by 10.3-11.9% and milk fat content increased by 3-5%, therefore, profit for farmers increased by US $0.55-0.73 per cow per day (exchange rate US $1 = VN $11,000). The intervals from calving to onset of ovarian activity (91-94 days), to estrus (110-114 days), to conception (121-122 days) and the calving interval (13.4-13.6 months) in the trial groups were significantly shorter than those in the control group (112, 135, 152 days and 14.4 months, respectively.  相似文献   

天山云杉优势木对比法选优中有关遗传参数的估算方法的探讨     

董玉芝  白根本  朱小虎 《新疆农业大学学报》1995,(2)

本研究为克服优势木对比法在天山云杉的选优工作中的一些缺陷，采用双重逐步筛选回归的方法，建立了由三株优势木对比法所得候选树性状的优良度、均值、缩差、标准差和变异系数对标准地上的林分和候选材相应性状参数的估测方程。使优势木对比法和标准地法有机的结合起来．用前者的资料得到后者的信息．从而间接的估算出期望遗传增益。  相似文献   

Continued freedom from blue-tongue virus infection in cattle and sheep in Western Australia south of latitude 26° S     

TM ELLIS  R. TURNOR  TT NGUYEN  U. TARNOWSKI 《Australian veterinary journal》1996,74(4):317-319

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褐飞虱及白背飞虱空中迁飞规律的研究   总被引：32，自引：2，他引：30  

邓望喜 《植物保护学报》1981,8(2):73-82

为了研究褐飞虱、白背飞虱的迁飞规律,作者于1977～1979年夏季和秋季,在华中地区,用运五型飞机,携带自行设计的活动型捕虫装置,进行空中捕捉褐飞虱、白背飞虱的试验。三年间共飞行91小时58分,计13000公里,共捕获褐飞虱、白背飞虱1915头,占捕虫总数的53.71%。试验结果证实了这两虫具有明显的季节性的中、长距离的迁飞特性,并探明了其空中迁飞的垂直高度、水平分布、虫口密度和迁飞种群的型式、姿态、生理状况、回迁动态以及迁飞起飞与气象条件的关系。  相似文献   

High yield and nutritional quality of rice for animal feed achieved by continuous irrigation with treated municipal wastewater     

Tran  Lanh Danh  Phung  Luc Duc  Pham  Dung Viet  Pham  Dong Duy  Nishiyama  Masateru  Sasaki  Atsushi  Watanabe  Toru 《Paddy and Water Environment》2019,17(3):507-513

Paddy and Water Environment - Two consecutive pilot-scale experiments were conducted to investigate the potential reuse of treated municipal wastewater (TWW) as an irrigation source for cultivating...  相似文献   

Larvicidal activity of natural and modified triterpenoids against Aedes aegypti (Diptera: Culicidae)          下载免费PDF全文

Gloria NS da Silva  Frances TT Trindade  Francine dos Santos  Grace Gosmann  Alexandre A e Silva  Simone CB Gnoatto 《Pest management science》2016,72(10):1883-1887

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Seed size and chloroplast DNA of modern and ancient seeds explain the establishment of Japanese cultivated melon (Cucumis melo L.) by introduction and selection     

Katsunori Tanaka  Chris J. Stevens  Shiho Iwasaki  Yukari Akashi  Etsuyo Yamamoto  Tran Phuong Dung  Hidetaka Nishida  Dorian Q. Fuller  Kenji Kato 《Genetic Resources and Crop Evolution》2016,63(7):1237-1254

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Small-Scale Shrimp Grower–Collector Relationships: The Case of Thua Thien Hue Province,Central Vietnam     

Dung Q. Truong  Anoma Ariyawardana 《Aquaculture Economics & Management (Blackwell Science)》2013,17(4):404-422

Small-scale shrimp-culture is an important livelihood for rural residents in Thua Thien Hue (TTH) province, central Vietnam. However, they are facing the risk of exclusion from the food system due to globalization and trade liberalization. To keep these farmers in modern supply chains, their relationships with other chain actors, foremost the collectors, need to be improved. Thus, this study explores the characteristics and constructs of the relationships between the small-scale shrimp growers and their collectors. Data was based on a survey on 83 small-scale shrimp growers, together with 16 unstructured interviews with growers (10) and collectors (6). It was revealed that the relationships between small-scale shrimp growers and collectors in TTH province are short-term and price-driven and are influenced by the power of collectors. The relationship strength was measured by five intercorrelated constructs including reliability, willingness-to-maintain, desire-fulfilment, negotiation capacity, and discussion capacity. Although some constructs were positively correlated, the strength of the relationships was weak. Both business linkages and social connections affected the grower-collector relationships. Female traders had stronger relationships with collectors than males. Therefore, interventions should be focused on business and social linkages as well as females’ involvement in shrimp trade.  相似文献   

Determinants and correlates of above-ground biomass in a secondary hillside rainforest in Central Vietnam     

Roland Cochard  Yen Thi Van  Dung Tri Ngo 《New Forests》2018,49(3):429-455

Despite inception of carbon-conservation forestry programs, information about total above-ground woody biomass (TAGB) in Vietnamese secondary lowland rainforests is still scarce. We elucidated major factors influencing local variation of TAGB within an anthropogenically modified hillside forest in Th?a Thiên-Hu? Province. On forty 400 m² sized plots all tree species were recorded, and their biomass was calculated using allometric equations. In addition, bio-physical parameters relating to terrain and soils were measured. Effects of bio-physical variables on forest TAGB were assessed using multivariate regression methods. Forest TAGB (average 117 Mg ha^?1) was primarily explained by forest structural variables, i.e. tree densities and average heights, in particular presence of large trees. TAGB was largely determined by the biomass of a few species which dominated different forest parts (ridges or hill base); TAGB was hardly influenced by species diversity. Many dominant trees were light-demanding species; these were characterised by scarce rejuvenation and high tree mortality. Bio-physical patterns indicated that previous logging impacts persisted and continued to influence seedling establishment, sapling growth/survival, and—ultimately—species composition. Nutrient patterns were mostly explained by interactions with certain tree species and tree foliage cover, as modulated by terrain and logging impacts. Development trajectories of TAGB over the next 10–20 years could not be predicted easily since (1) many functionally important late-succession species (e.g. dipterocarps) were very scarce; (2) the sizes of initially established light-demanding species appeared to meet limits, including increasing tree mortality; and (3) rejuvenation and species succession differed locally and proceeded along largely unpredictable pathways. Some suggestions for further research are made.  相似文献