Ulysses radio and plasma wave observations in the jupiter environment

The Unified Radio and Plasma Wave (URAP) experiment has produced new observations of the Jupiter environment, owing to the unique capabilities of the instrument and the traversal of high Jovian latitudes. Broad-band continuum radio emission from Jupiter and in situ plasma waves have proved valuable in delineating the magnetospheric boundaries. Simultaneous measurements of electric and magnetic wave fields have yielded new evidence of whistler-mode radiation within the magnetosphere. Observations of aurorallike hiss provided evidence of a Jovian cusp. The source direction and polarization capabilities of URAP have demonstrated that the outer region of the lo plasma torus supported at least five separate radio sources that reoccurred during successive rotations with a measurable corotation lag. Thermal noise measurements of the lo torus densities yielded values in the densest portion that are similar to models suggested on the basis of Voyager observations of 13 years ago. The URAP measurements also suggest complex beaming and polarization characteristics of Jovian radio components. In addition, a new class of kilometer-wavelength striated Jovian bursts has been observed.     

跨文化交际在大学英语教学中的导入模式

语言是文化的载体, 是文化传播和继承的重要手段。 文章阐述了语言与文化之间的关系, 强调了英语语言教学中文化导入的重要性和必要性。作者针对大学英语教学中文化与语言融合之问题, 提出了跨文化在大学英语教学中的三种导入模式, 即从词汇的教学中导入文化、从语篇的分析中导入文化以及从目的语的文学作品研读中导入文化。     

小麦黑麦和油菜幼苗对稀土富集迁移规律的研究

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。     

烟草赤星病菌(Alternaria alternata)营养生理研究

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。     

中草药饲料添加剂在畜禽生产中的应用

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.     

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

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.     

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

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.     

Potato cultivar identification using simple sequence repeats markers (SSR)

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.     

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

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.