Development and Application of Cotton InDel Markers Based on High Throughput Sequencing

[Objective] Dimorphic InDel markers can be used for cotton variety identification and purity detection, to improve the accuracy and efficiency of cotton seed testing, and to play a role in molecular breeding of cotton. [Method] Based on the whole genome sequencing of 121 cotton varieties from different sources, the InDel markers with high polymorphism were developed according to polymorphism information content(PIC) and were applied in the genetic distance analysis and cluster analysis by using 66 cotton varieties in China. [Result] Totally 10 967 InDel were identified based on the next generation sequencing data of 121 cotton varieties. Among the 85 pairs of InDel primers synthesized, 64 were selected including 35 from At group and 29 from Dt group. The minimum average allelic frequency(MAF) of At and Dt chromosomes were 0.45 and 0.32, respectively, while the PIC were 0.49 and 0.40, respectively. The genetic distances of the 66 cotton varieties ranged from 0.04 to 0.65 centimorgan (cM), with an average of 0.39 cM. The two varieties with the largest genetic distance were Simian 3 and CCRI 36, and the two varieties with the smallest genetic distance were Xumian 18 and Xuza 3. [Conclusion] The 64 cotton dimorphic InDel markers can effectively reveal the relationships among varieties based on the genetic distance, and distinguish cotton varieties from different sources, which has certain theoretical significance and application value.     

我国池塘养殖业发展现状与对策

新中国成立70多年来，我国池塘养殖业取得了举世瞩目的发展成就。随着供给侧结构性改革的不断深入，池塘养殖绿色发展的新格局逐步形成，产业转型升级初见成效。深入分析了当前我国池塘养殖业的产业发展状况和养殖技术现状，指出了池塘养殖业存在的问题，在此基础上提出了通过深化产业结构调整、完善法律法规、加强标准和技术体系建设、加快新技术和新模式应用，以及培养新型科技人才等具体策略，推动和促进我国池塘养殖业的现代化进程与绿色发展。     

我国刺参养殖产业发展现状与对策研究

在国家政策的正确引导和支持下,随着国民经济的持续增长和人民生活水平的不断提高,我国刺参养殖产业获得了前所未有的大发展,刺参已经成为海水养殖业的支柱性经济品种之一。分析了刺参养殖产业的发展现状,从全国传统主产区、南移养殖区的养殖状况和技术应用水平等方面深入剖析了产业发展的结构与格局,指出了当前刺参养殖产业存在的问题和不足,并在此基础上提出了以"五大发展理念"为指导,通过加强宏观调控、建立健全法律法规与标准体系、构建良种资源和病害防控体系、重视科技人才培养和加快新技术应用等具体发展策略,推动和促进"新常态"下我国刺参养殖产业的可持续健康发展。     

冷却EGR开度影响共轨柴油机排放性能研究

结合某增压中冷小型直列4缸直喷式柴油机,引入电控高压共轨和冷却EGR系统,试验研究了不同EGR开度对柴油机的CO、HC和NOx排放的影响,并结合不同共轨压力和喷油提前角条件分析了冷却EGR对降低柴油机排放的作用机理。研究结果为联合采用高压共轨、增压中冷和EGR技术降低柴油机排放提供理论指导。     

Fisheries independent assessment of a returning fishery: Abundance of juvenile white seabass (Atractoscion nobilis) in the shallow nearshore waters of the Southern California Bight, 1995–2005

Nearshore, coastal and embayment areas off southern California were sampled to determine the spatial and temporal patterns abundance and size distributions of young white seabass in the shallow (5–14 m) waters from Santa Barbara south to Imperial Beach off San Diego. A total of 19 stations, 13 in nearshore coastal waters and 6 in embayments, dispersed along the Southern California Bight were surveyed in each sampling month using 45.7 m variable mesh, monofilament gill nets. In the 11-year period of sampling (April 1995–June 2005), a total of 8075 juvenile white seabass was captured in 42 sampling months. The mean catch-per-unit-effort (CPUE: 2.0 fish/net ± 0.2) for juvenile white seabass varied significantly among stations during the 10-year period (1996–2005) of the full station sampling. Stations located near large rocky headlands, such as Palos Verdes, Santa Barbara, Newport, and La Jolla yielded the highest catches. Although CPUE peaked in August 1999 as a result of strong year classes in 1996–1998, overall, catches tripled over the 11-year sampling period at seven coastal sites increasing significantly at a rate equivalent to 0.22 fish/(net year). These relatively high catches of wild, juvenile fish over the last decade, along with significant increases in commercial CPUE and increased recreational catches overall, indicate that the natural population of white seabass is in the process of recovery. Commercial catches are again comparable to levels attained prior to the fishery collapse in the 1970s and 1980s. Therefore, we propose that the white seabass now represents one of the first documented cases of a recovering, demersal species of commercial importance. The ban of nearshore commercial gill net fishing by Proposition 132 probably contributed greatly to the increase in the population size that led to this recovery. In addition, the succession of warm water years that occurred from 1983 to the strong El Niño event of 1997–1998 also played an important role in the successful recruitment of white seabass.     

1980—2018年江苏里下河平原景观格局时空变化及其热点分析

  目的  探讨景观格局时空变化及其冷热点,为区域生态安全与高质量发展提供科学依据。  方法  以江苏里下河平原1980、1990、2000、2010与2018年共5期景观类型数据为基础,采用景观格局指数、景观转移矩阵、景观综合动态度等方法,分析里下河平原近40 a景观格局的时空变化特征,基于热点分析探究景观变化的冷热点区域。  结果  研究区耕地、湖荡湿地和建设用地为优势景观类型,耕地是面积占比最多的景观,但整体上持续减少了1 000.67 km2,湖荡湿地和建设用地面积不断扩张,建设用地扩张面积达679.83 km2,草地和未利用地面积有所减少,林地面积有所增加。近40 a来,研究区各景观类型之间发生了复杂的相互转化,最显著的是耕地与湖荡湿地、建设用地之间的相互转化。研究期间格网景观综合动态度变化幅度为0~5.43%。里下河平原景观变化具有明显的方向性和聚集性,以“东南—西北”方向为主轴发生倾斜,兴化市、高邮市、盐都区及江都区是景观变化的热点区域。  结论  里下河平原景观格局变化显著,景观多样性增加、破碎化加剧,人类活动对景观格局的影响增强。自然湿地恢复政策的实施对研究区景观生态安全产生了积极影响。图4表4参32     

探析提高常见螺栓联接强度的方法

主要探讨了影响螺栓联接强度的因素,提出提高联接强度的措施,并结合具体实例加以分析说明。     

LQ-18型锯链切削性能试验台进给系统设计

为适应LQ-18型锯链切削性能试验台木材进给速度要求,确定了进给系统的进给方式和传动方案,优化设计了进给系统床鞍、溜板箱的结构。保证了进给系统具有足够刚度和精确的传动速度,速度可调范围为2.44￣31.88cm/s,达到试验台无级调速的要求。     

Barley–hairy vetch mixture as cover crop for green manuring and the mitigation of N leaching risk

Adopting mixtures of legumes and non-legumes can be an efficient tool to merge the advantages of the single species in the fall-sown cover crop practice. Cover crop mixtures are supposed to provide an additional benefit in reducing N leaching risks as compared to pure legume thanks to the N trapping skill of the non-legume companion, but to our knowledge no data are available on the effect of mixed cover crops on N leaching. For this reason, in a three-year study we investigated the effect of barley (Hordeum vulgare L.) and hairy vetch (Vicia villosa Roth.) grown in 100% pure stands or in 50:50 mixtures on the N leaching below the rooting zone as compared to the bare soil. The NO₃-N concentration in the soil solution was monitored by suction cup lysimeters placed at 0.9 m depth during the whole growing cycle and after cover crop incorporation into the soil and the amount of leached N was calculated on the basis of estimated drainage.The mixture showed variable biomass accumulation and proportion in the biomass accumulated by companion species across years, but a rather constant N accumulation, with a biomass C/N ratio intermediate between those of the pure crops. In all years, the N trapping effect of the mixture was clear as it decreased NO₃-N leaching at the same level of pure barley, both during its own growing cycle and after cover crop incorporation into the soil. Pure vetch showed the highest N source potential as green manure but no NO₃-N leaching mitigation effect as compared to the bare soil. Thus we demonstrate here that a mixture of barley and vetch, which was already known to be a “self-buffered system” able to guarantee a good and rather stable N accumulation, is also a “buffering system” for the agroecosystems in the Mediterranean conditions by acting as a N trapping crop able to reduce N leaching.     

生态恢复视角下海滨湿地景观模拟 ——以江苏盐城湿地珍禽国家级自然保护区为例

选择盐城典型淤泥质海滨湿地区,从生态恢复的视角,模拟预测未来海滨湿地景观可能的变化结果,为海滨湿地的科学管理提供决策参考。盐城海滨湿地是区域重要的生态屏障,近年来,在人类与自然的双重作用下,区域湿地景观变化显著。为维护区域生态安全,发挥湿地应有的功能,以2000年和2011年遥感影像为基础,结合土壤水分和盐度数据,采用景观过程模型,从生态恢复的视角,对2020年盐城海滨湿地景观演变进行模拟,研究结果表明:(1)人工围堰、互花米草扩张和碱蓬沼泽退化是研究区面临的主要生态问题。(2)人工管理区,至2020年,碱蓬沼泽比现状条件下模拟结果增加了18.46倍,互花米草沼泽减少了66.04%;景观多样性指数从1.007增加到1.150,景观均匀度指数从0.626增加到0.715。(3)自然条件区,至2020年,互花米草沼泽的面积比现状条件下模拟结果减少了82.32%,碱蓬沼泽增加了19.65倍;景观多样性指数从1.082增加到1.237,景观均匀度指数从0.780增加到0.892。