Comparing the yields of organic and conventional agriculture

Numerous reports have emphasized the need for major changes in the global food system: agriculture must meet the twin challenge of feeding a growing population, with rising demand for meat and high-calorie diets, while simultaneously minimizing its global environmental impacts. Organic farming—a system aimed at producing food with minimal harm to ecosystems, animals or humans—is often proposed as a solution. However, critics argue that organic agriculture may have lower yields and would therefore need more land to produce the same amount of food as conventional farms, resulting in more widespread deforestation and biodiversity loss, and thus undermining the environmental benefits of organic practices. Here we use a comprehensive meta-analysis to examine the relative yield performance of organic and conventional farming systems globally. Our analysis of available data shows that, overall, organic yields are typically lower than conventional yields. But these yield differences are highly contextual, depending on system and site characteristics, and range from 5% lower organic yields (rain-fed legumes and perennials on weak-acidic to weak-alkaline soils), 13% lower yields (when best organic practices are used), to 34% lower yields (when the conventional and organic systems are most comparable). Under certain conditions—that is, with good management practices, particular crop types and growing conditions—organic systems can thus nearly match conventional yields, whereas under others it at present cannot. To establish organic agriculture as an important tool in sustainable food production, the factors limiting organic yields need to be more fully understood, alongside assessments of the many social, environmental and economic benefits of organic farming systems.     

The cultural connotations of animal idioms among different countries

From the day that human beings came into existence,people began to encounter all kinds of animals.The primitive beings at an early age lived only on what the nature offered them and they hunted wild animals with stone implements.Instead of the essential maigre food,they took their own-made implements to capture animals in order to maintain their life.Through years of struggle with animals,human beings are closely related to animals and many customs and idiomatic usages about animals have come into existence,which makes the special culture based on them appear and the emotions human beings show to those animals have got deepened.From what has been mentioned above,we can see that ecological culture about animals has much to do with human society.So it can be said that the culture of human society originates from ecological culture.Different nations have their own totem,that is to say,every nation has its own preference for animals.Some quality and character is often associated with some sort of animal,but these associations seldom or have nothing to do with science.These associated character or quality with animals differ in different countries.The paper mainly talks about some idioms about animals and their translation and the same or different associations reflected by these idioms under the different cultural environment between China and English language.Chapter One mainly talks about the different cultural connotation and translation of idioms relating to the same animals between Chinese and English.Chapter Two mainly talks about the same cultural connotation and translation of idioms relating to the same animals between Chinese and English.     

按照统筹城乡发展的要求加快西藏农牧区经济发展步伐

西藏全面建设小康社会的重点、难点都在农牧区，由于受长期以来形成的“二元经济结构”的影响和制约，农牧区经济发展缓慢，农牧民生活质量不高。统筹西藏城乡发展，是缩小城乡差距，逐步消除“二元经济结构”，加快农牧区经济发展的必由之路。为此，必须大力推进农牧业结构调整，加大对农牧区的投入，创新产业化运行机制，加快小城镇建设，加强农牧区基础教育，积极推进移民扶贫行动，对农牧区的经济建设和农牧民生活质量的提高给予更多的关注。     

A plant receptor-like kinase required for both bacterial and fungal symbiosis

Most higher plant species can enter a root symbiosis with arbuscular mycorrhizal fungi, in which plant carbon is traded for fungal phosphate. This is an ancient symbiosis, which has been detected in fossils of early land plants. In contrast, the nitrogen-fixing root nodule symbioses of plants with bacteria evolved more recently, and are phylogenetically restricted to the rosid I clade of plants. Both symbioses rely on partially overlapping genetic programmes. We have identified the molecular basis for this convergence by cloning orthologous SYMRK ('symbiosis receptor-like kinase') genes from Lotus and pea, which are required for both fungal and bacterial recognition. SYMRK is predicted to have a signal peptide, an extracellular domain comprising leucine-rich repeats, a transmembrane and an intracellular protein kinase domain. Lotus SYMRK is required for a symbiotic signal transduction pathway leading from the perception of microbial signal molecules to rapid symbiosis-related gene activation. The perception of symbiotic fungi and bacteria is mediated by at least one common signalling component, which could have been recruited during the evolution of root nodule symbioses from the already existing arbuscular mycorrhiza symbiosis.     

耐盐碱油菜品种选育及修复利用盐碱地研究进展

 中国有1.0×10⁸ ha盐碱地资源,其中0.33×10⁸ ha有开发利用潜力。修复、利用盐碱地有重要的经济、生态和社会效益。经过10多年的研究,华中农业大学选育出耐盐碱甘蓝型油菜“华油杂62”等品种,在中国滨海盐碱地和内陆盐碱地均能生长良好,可收获青鲜油菜4.5×10⁴~7.5×10⁴ kg/ha,也可翻耕作绿肥。耐盐碱油菜具有“利用”与“改良”盐碱地相结合的特色,是改良利用盐碱地最有优势的大田作物。利用耐盐碱油菜、农牧结合等综合措施,是修复、利用盐碱地经济有效、可持续发展的途径。     

大熊猫膨化饼干饲料应用研究

对膨化饼干饲料饲喂大熊猫进行了研究，对日粮组合及饲喂方法作了重大改革。结果表明：使动物提高了日活动量，降低了排粘液次数有数量近一半，动物生长发育、营养状况、行为学及繁殖学各方面明显优于实验前，对提高动物健康与繁殖素质具有良好的作用。结果还表明动物对陌生环境和饲养因素的改变具有较强的适应能力，最长适应期为6个月，青年比老年个体适应性强。保持大熊猫的食竹特性十分重要。     

Reconstructing the food structure of ancient coastal inhabitants from Beiqian village: Stable isotopic analysis of fossil human bone

The Beiqian site located in Jimo city,Qingdao,a few kilometers from the modern coastline was excavated in 2007,2009 and 2011.A large number of human bones from the early Dawenkou period were unearthed.Through C and N stable isotopic analysis,the food structure of the "Beiqian" ancestors was reconstructed and the influence of terrestrial and marine resources on their lifestyle was discussed.Based on the δ13C and δ15N stable isotopic values of human bone collagen,the analytical results obtained through a ternary mixed model reveal that the food sources of the Beiqian ancestors included about 44.1% marine species(probably shellfish and fish),34.1% C4 plants(possibly millet),and 21.8% land animals.These results indicate that they lived mainly from fishing and farming,supplemented by hunting or poultry raising.Compared with other sites in the same period,the stable isotope results show that 5000-6000 years ago,the lifestyles of ancestors in the Yangtze River basin,Yellow River basin,Northern coastal area and inland area were very different.The ancestors from the Yangtze River basin focused on rice farming and fishing,whereas the ancestors in the Yellow River basin farmed millet and raised animals.Those in coastal areas relied mostly on farming and marine fishing.     

明至清初青藏高原畜牧业经济初探

文章以大量的历史文献论述了以饲养马、牛、羊等牲畜为主的畜牧业生产在青藏高原诸游牧民族的生产生活中占据着主导地位.明代至清前期,青藏高原地区的农业经济虽然有所发展,但由于自然条件的特殊性,畜牧业生产依然在社会经济生活中占据着主导地位,肩负着促进当地社会经济发展的任务,明清政府在高原地区和接近高原地区设置的官营茶马贸易和官办马场,客观上对民间畜牧产业的发展起到了推动作用.以史为鉴,如何在生态环境脆弱的条件下推动高原地区经济的发展,以满足当地人民日常生活所需也是我们当代人需要思考的问题.     

转基因作物在农业生产中的应用及发展趋势

将外源基因定向引入植物细胞,创造转基因作物新品种,已广泛应用于农业生产,产生了巨大的社会经济效益;在提高作物产量、改良作物品质、提高其抗旱、耐盐碱能力等方面将具有新的突破。     

Nodulation of legumes by members of the beta-subclass of Proteobacteria.

Members of the Leguminosae form the largest plant family on Earth, with around 18,000 species. The success of legumes can largely be attributed to their ability to form a nitrogen-fixing symbiosis with specific bacteria known as rhizobia, manifested by the development of nodules on the plant roots in which the bacteria fix atmospheric nitrogen, a major contributor to the global nitrogen cycle. Rhizobia described so far belong exclusively to the alpha-subclass of Proteobacteria, where they are distributed in four distinct phylogenetic branches. Although nitrogen-fixing bacteria exist in other proteobacterial subclasses, for example Herbaspirillum and Azoarcus from the phylogenetically distant beta-subclass, none has been found to harbour the nod genes essential for establishing rhizobial symbiosis. Here we report the identification of proteobacteria from the beta-subclass that nodulate legumes. This finding shows that the ability to establish a symbiosis with legumes is more widespread in bacteria than anticipated to date.     

Social feeding in Caenorhabditis elegans is induced by neurons that detect aversive stimuli

Natural Caenorhabditis elegans isolates exhibit either social or solitary feeding on bacteria. We show here that social feeding is induced by nociceptive neurons that detect adverse or stressful conditions. Ablation of the nociceptive neurons ASH and ADL transforms social animals into solitary feeders. Social feeding is probably due to the sensation of noxious chemicals by ASH and ADL neurons; it requires the genes ocr-2 and osm-9, which encode TRP-related transduction channels, and odr-4 and odr-8, which are required to localize sensory chemoreceptors to cilia. Other sensory neurons may suppress social feeding, as social feeding in ocr-2 and odr-4 mutants is restored by mutations in osm-3, a gene required for the development of 26 ciliated sensory neurons. Our data suggest a model for regulation of social feeding by opposing sensory inputs: aversive inputs to nociceptive neurons promote social feeding, whereas antagonistic inputs from neurons that express osm-3 inhibit aggregation.     

振兴徐州农业的七项措施

本文针对徐州市农业发展基本情况,具体提出专业化与综合发展相结合,建设各级农林牧渔商品基地;实行农牧轮作,大力发展畜牧业;加强水利建设与保护耕地等七项措施,以促进农业飞速发展。     

论"梅葛"的历史文化特点

“梅葛”是楚雄彝族最具有代表性的原始性史诗,与民族同生共长,并与原始宗教祭祀、节日庆典、礼仪民俗融为一体,蕴含着丰富的历史文化特点,如充满浓厚、神秘的原始宗教观念,展示了楚雄彝族家庭婚姻和传统伦理道德的演变过程,同时还揭示了彝族社会生产力从低到高不断发展变化的历史进程,阐述了彝族从游牧到旱稻兼作或稻作的农耕演变规律。     

中国西部地区草牧业发展的现状、问题及对策

 2015年中央一号文件《关于加大改革创新力度加快农业现代化建设的若干意见》和2016年中央一号文件《关于加大改革创新力度加快农业现代化建设的若干意见》要求加快发展草牧业,对中国草业和畜牧业建设意义重大。本文在对现有数据分析的基础上,对中国西部地区草牧业发展现状和潜力进行了分析,指出了西部地区农区、牧区、农牧交错带草牧业发展中存在的问题,提出了相关发展对策。     

Mealybug beta-proteobacterial endosymbionts contain gamma-proteobacterial symbionts

Some insects have cultivated intimate relationships with mutualistic bacteria since their early evolutionary history. Most ancient 'primary' endosymbionts live within the cytoplasm of large, polyploid host cells of a specialized organ (bacteriome). Within their large, ovoid bacteriomes, mealybugs (Pseudococcidae) package the intracellular endosymbionts into 'mucus-filled' spheres, which surround the host cell nucleus and occupy most of the cytoplasm. The genesis of symbiotic spheres has not been determined, and they are structurally unlike eukaryotic cell vesicles. Recent molecular phylogenetic and fluorescent in situ hybridization (FISH) studies suggested that two unrelated bacterial species may share individual host cells, and that bacteria within spheres comprise these two species. Here we show that mealybug host cells do indeed harbour both beta- and gamma-subdivision Proteobacteria, but they are not co-inhabitants of the spheres. Rather, we show that the symbiotic spheres themselves are beta-proteobacterial cells. Thus, gamma-Proteobacteria live symbiotically inside beta-Proteobacteria. This is the first report, to our knowledge, of an intracellular symbiosis involving two species of bacteria.     

青铜时代早期的不列颠

运用考古学材料论述青铜时代早期不列颠的社会状况。青铜时代早期的不列颠农耕畜牧经济持续不断的发展、青铜工业诞生、葬俗发生变化和巨石建筑的构筑,展示了史前不列颠社会不断进步的历史内涵和向前发展的历史进程。     

古代食人探源

一种观点认为,食人现象起源于旧石器时代晚期以后,原因是宗教的需要。然而大量的社会调查、考古发掘和古文献资料却证明:食人现象起源于旧石器时代早、中期,原因在于食物的缺乏。旧石器时代晚期出现的出于宗教需要的食人,原始社会末期及奴隶社会的人牺,都是早期食人现象的变态反映。就是在封建社会,在饥荒和战争的特殊环境中,"人相食"的现象仍然偶有发生。这些,都反过来证明了原始社会早期以人为食现象的存在。这个严酷的事实从一个侧面说明,原始社会尽管存在过原始的公有和平等,但它绝不是一个理想的社会。     

基于主导因素法的省级农业类限制开发区划分——以内蒙古自治区为例

在遵循国家主体功能区划结果的基础上,采用主导因素法对国内重要的农牧业生产基地——内蒙古自治区进行省级农业类限制开发区的划分.将全区的15个旗、县、市(区)划为省级农业类限制开发区,作为自治区主要的农畜产品供给区域,保障全区的食物安全.     

西藏农业跨越式发展战略与农村可持续发展

本文通过对农业跨越式发展与可持续发展之间的相互关系分析。认为要实现西藏农业的跨越式发展战略。必须从人口、经济、社会、环境和资源相互协调发展入手。将可持续发展作为跨越式发展战略的一项重要内容和目标贯穿始终。走可持续的农业发展道路。分析了当前西藏实现持续农业和农村可持续发展所面临的许多新问题和新的挑战。提出了从农村社区的可持续发展入手。以农牧区社区居民的全面发展为主体，以保护和改善生态环境，实现自然资源的合理、永续利用为基础。以经济、社会的协调发展为保障；通过思路创新、体制创新、科技创新，实现西藏农业可持续的跨越式发展战略。     

新疆农区农牧结合结构优化分析

农牧结合问题定性的研究已很多，而与其相应的定量方法的研究尚薄弱。本文以新疆干旱绿洲垦区１４８团农牧业生产调查分析为实证，运用农牧业多目标耦合动态模型法，优化农牧业结构，增强其功能，同时分析了目前存在的不足，并提出相应的发展对策。