加入WTO后中欧水产品贸易特点、问题和对策     

骆乐  陈凡华  吕祥 《世界农业》2007,(5):37-39

欧盟是中国第三大贸易伙伴,也是中国水产品出口的重要地区。自中国加入WTO以来,中欧贸易往来频繁,水产品出口增长较快。至2005年中欧水产品贸易额达12.8亿美元,数量为54.5万t,与2001年相比,分别增长了139%和87.9%。但中欧水产品贸易在快速发展中还存在许多波折和摩擦,本文回顾了加入WTO后中欧水产品贸易的发展进程,从现状出发分析了双边水产品贸易的主要特征。针对存在的主要问题,进行了较全面的分析,并且提出了相应的对策。对今后进一步扩大中欧水产品贸易有重要的现实意义。  相似文献   

小麦黑麦和油菜幼苗对稀土富集迁移规律的研究     

胡忻  陈逸君  戴乐美  王晓蓉 《农业环境科学学报》2002,21(2):97-99

选择小麦(troticumaestivumL.)、黑麦(SecaleCerealeL.)、油菜(BrassicarapaL.)作为试验作物,研究其对稀土镧迁移累积的时间效应和浓度效应。结果表明:(1)镧能在3种作物中迅速累积。随着试验液镧浓度的增加,作物中镧的积累量也增加,但与镧的暴露浓度不呈线性相关性。(2)积累效应主要发生于暴露早期。随着暴露的延长,作物体内的镧含量逐渐稳定。(3)镧在3种作物中的积累具有明显的种属特异性。镧积累量油菜远高于小麦和黑麦,但3种作物的茎叶和根中的镧积累量的比值差异较大,其中小麦远高于其它两种作物,表明小麦对镧的输送作用比其他两种作物强。  相似文献   

烟草赤星病菌(Alternaria alternata)营养生理研究     

张乐  王革  高智谋  杜雷  许峰 《勤云标准版测试》2007,(5)

研究了6种碳源和6种氮源对烟草赤星病菌[Alternaria alternata(Fr)Keissler]菌丝生长和产孢量的影响。结果表明,不同的碳源和氮源对该病菌菌丝生长和产孢量均有显著影响。病菌在以淀粉为碳源的培养基上菌丝生长最快,乳糖次之;菌丝干重以果糖培养基上最大,乳糖、葡萄糖、麦芽糖、蔗糖、淀粉次之,无碳对照最低;产孢量以在麦芽糖为碳源的培养基上最高,乳糖次之,无碳对照最低。病菌在以蛋白胨为氮源的培养基上菌丝生长最快,菌丝干重最大,硝酸铵次之,脲最慢;产孢量以在蛋白胨为氮源的培养基上最高,硝酸铵、硫酸铵上次之,脲最低。脲和氯化铵对病菌生长和孢子形成均有抑制作用。  相似文献   

中草药饲料添加剂在畜禽生产中的应用   总被引：8，自引：0，他引：8  

乐其新 《安徽农业科学》2007,35(4):1046-1046,1110

简述了中草药饲料添加剂在畜禽生产中的应用,阐述了中草药饲料添加剂的作用机理、应用效果、目前存在的问题和发展前景.  相似文献   

In winter wheat (Triticum aestivum L.), post-anthesis nitrogen uptake and remobilisation to the grain correlates with agronomic traits and nitrogen physiological markers     

Thomas Kichey  Bertrand Hirel  Emmanuel Heumez  Frédéric Dubois  Jacques Le Gouis 《Field Crops Research》2007

In wheat, nitrogen (N) uptake and remobilisation after flowering contributes largely, in Northern countries, to grain yield and grain protein content. The aim of our study was first to estimate the proportion of N taken up and remobilised to the grain as well as their relative efficiency using ¹⁵NO₃⁻-labelling at flowering. The validity of the technique was assessed in comparison to the N budget calculation method on five winter wheat cultivars grown for 2 years at low and high fertilization input. We estimated that on average 71.2% of grain N originates from remobilisation with significant genotypic differences. Among the five genotypes, significant differences were also found for both N remobilisation efficiency (from 69.8 to 88.8%) and N translocation efficiency (from 89.7 to 93.4%). In parallel, during 1 year, we monitored physiological markers representative of N assimilation and recycling at two sampling dates during the grain filling period. We then examined if there was any relationship between these physiological markers, N absorption and remobilisation estimates and agronomic traits related to yield and grain N content. Nitrate reductase (NR) activity was highly correlated to N absorbed post-flowering and to grain protein content. Glutamine synthetase (GS) activity was even more highly correlated than NR activity to the amount of N remobilised and grain yield. The use of physiological traits such as NR and GS activities as markers of the wheat N status is discussed.  相似文献   

Feasibility of Improving Unmanned Aerial Vehicle-Based Seeding Efficiency by Using Rice Varieties with Low Seed Weight     

Wang Xinyu  Yang Guodong  Pan Xiangcheng  Xiang Hongshun  Peng Shaobing  Xu Le 《水稻科学》2022,29(4):299-303

Unmanned aerial vehicle (UAV) has offered a promising platform for rice direct seeding that can substantially reduce labor input in the crop establishment process. However, the insufficient payload capacity of UAV-based seeders is currently limiting its intensive and large-scale use for rice direct seeding. This study indicated a large variation in seed weight across varieties, ranging from 15.0 to 36.5 mg and 14.0 to 31.3 mg for inbred and hybrid varieties, respectively, with average seed weights of 25.3 mg for inbred and 24.7 mg for hybrid varieties. Seed weights of 160 out of 4 106 inbred varieties and 17 out of 311 hybrid varieties ranged from 15.0 to 20.0 mg. Reducing seed weight from 25.0 to 15.0 mg increased the seeding area per UAV flight by 67% regardless of inbred and hybrid varieties, although the absolute increase in seeding area for hybrid variety was greater than that for inbred variety because of the difference in seeding rate. The grain yield of inbred varieties was reduced when the seed weight was less than 24 mg. Moreover, 87% of inbred varieties with a seed weight ≤ 20 mg were distributed in South China where rice consumers prefer small rice grains. Therefore, the use of low-seed-weight inbred varieties for improving UAV seeding efficiency might be considered in South China. Unlike inbred rice, 64% of hybrid varieties had higher grain weights compared with their seed weights, and reducing seed weights did not necessarily cause yield loss. Therefore, the small-seed-and-large-grain strategy in hybrid rice could be used for improving UAV seeding efficiency without yield loss. This strategy can be considered for improving UAV seeding efficiency in rice production regions other than South China.  相似文献   

Potato cultivar identification using simple sequence repeats markers (SSR)   总被引：2，自引：0，他引：2  

M. Moisan-Thiery  S. Marhadour  M. C. Kerlan  N. Dessenne  M. Perramant  T. Gokelaere  Y. Le Hingrat 《Potato Research》2005,48(3-4):191-200

Summary Identification of potato cultivars is currently based on phenotypic characters. Crop inspections are needed at different stages and the increasing number of cultivars means the process is becoming more and more complex. Molecular markers are a possible complementary tool to identify potato cultivars and to rapidly check the identity of seeds lots. In this study 286 potato cultivars produced in France were characterized by Polymerase Chain Reaction (PCR) using Simple Sequence Repeats (SSR) markers. Sequential amplifications with 4 to 5 of the chosen SSR markers enabled complete discrimination between all the cultivars. The patterns were registered in a database and the procedure is now used routinely in France.  相似文献   

Assessing the genetic resources to improve drought tolerance in sugar beet: agronomic traits of diverse genotypes under droughted and irrigated conditions     

Eric S. Ober  Chris J. A. Clark  Mich Le Bloa  Andy Royal  Keith W. Jaggard  John D. Pidgeon 《Field Crops Research》2004,90(2-3):213-234

Drought is the major cause of sugar beet (Beta vulgaris L.) yield losses in the UK and many other regions where the crop is not normally irrigated. However, drought tolerance has not been a breeding target partly because the extent of the problem was not understood, it is difficult to design effective selection screens, and because of the suspicion that few varietal differences existed. The aim of this study was to evaluate the genetic resources necessary to improve drought tolerance. Specific objectives were to assess the degree of genotypic diversity for drought tolerance, characterise genotypic differences in response to drought, and identify sources of germplasm with greater drought tolerance than current commercial varieties. Over 3 years, 46 beet genotypes representing diverse genetic backgrounds were tested in the field under large polythene covers to impose a drought beginning approximately 40 days after emergence until harvest. Sugar, root and total dry matter yields were measured under drought and irrigated conditions. The percentage green crop cover was measured at regular intervals and used in the calculation of radiation use efficiencies for each genotype. Drought tolerance index (DTI) was computed as the fraction of irrigated yield maintained under drought, normalised by the mean yield across all genotypes in the trial. Seven genotypes were tested in all years, and the data on these were used to calculate yield stability statistics and to estimate broad-sense heritability. There were more than two-fold differences in droughted and irrigated yields between genotypes, and nearly a two-fold difference in DTI. According to an index that combines yield potential and drought tolerance, some genotypes performed better than the three locally adapted commercial varieties included in the test. There were significant effects for genotype, treatment and G×E interactions for yield components and radiation use efficiency. There were also significant genotype differences in harvest index but few significant G×E interactions. Droughted and irrigated yields were positively associated, but there was no close relation between yield potential and DTI. The seven genotypes common to all years differed in yield stability and in sensitivity to water availability. Thus, the genetic resources exist for germplasm improvement. Both yield potential and DTI (which may ensure better yield stability) should be considered simultaneously as breeding targets for drought-prone areas.  相似文献   

Determination of grayanotoxins in biological samples by LC-MS/MS     

Holstege DM  Puschner B  Le T 《Journal of agricultural and food chemistry》2001,49(3):1648-1651

A rapid LC-MS/MS method was developed for the quantitative determination of grayanotoxins I, II, and III in rumen contents, feces, and urine. The grayanotoxins were extracted from solid samples with methanol. The methanol extract was diluted with water and cleaned up using a reversed phase solid phase extraction column. HPLC separation was performed by reversed phase HPLC using a gradient of water and methanol containing 1% acetic acid. Determination was by positive ion electrospray ionization and ion trap tandem mass spectrometry. Grayanotoxin I quantitation was based on fragmentation of the sodium adduct ion at m/z 435 to a product ion at m/z 375. Grayanotoxins II and III were quantitated on the basis of fragmentation of the ion at m/z 335 to the product ion at m/z 299. The method detection limits were 0.2 microg/g in rumen contents and feces and 0.05 microg/g in urine. Fortifications at the detection limits and 10 times the detection limits of bovine rumen contents, caprine feces, and ovine urine were recovered in the range 80-114%. The diagnostic utility of the method was tested by analyzing samples submitted to the veterinary toxicology laboratory.  相似文献   

Reproductive phenology ofStenocereus gummosus (Engelm.) Gibson & Horak. Implications for its cultivation     

J.L. de la Luz León  R. Domínguez-Cadena  M. Cruz-Estrada  R. Rodríguez-Estrella 《Genetic Resources and Crop Evolution》1995,42(1):61-67

Summary Stenocereus gummosus (“pitaya agria”, Cactaceae) is a wild native species of the Baja California Peninsula, Mexico. The fruit of these plants is harvested by ranchers for public consumption. There has been no attempt to cultivate this species or to enhance fruit production by selecting highly productive lines with desirable characteristics. Nevertheless, it is relatively easy to propagate asexually. Seed propagation is not practical in spite of its regular flower, fruit, and viable seed generation. Here, the “pitaya agria” was studied over 4 years (1988–1991) to generate basic information that may be useful for its induction to cultivation. A sample of plants was monitored during phenological events of budding, flowering, fruiting, and abortion. Among the results, we found that a third of the original buds developed into fruit, and the first 40 cm of the branches yielded more buds where the conversion into fruit was higher than in the rest of the branch. A statistical analysis revealed slight differences in the phenological events, despite dissimilar rainfall over the four years. In view of its successful asexual propagation, this species can be considered commercially promising.  相似文献