Soil biodiversity and DNA barcodes: opportunities and challenges

Soils encompass a huge diversity of organisms which mostly remains to be characterized due to a number of methodological and logistical issues. Nonetheless, remarkable progress has been made in recent years toward developing strategies to characterize and describe soil biodiversity, especially thanks to the development of molecular approaches relying on direct DNA extraction from the soil matrix.Metabarcoding can be applied to DNA from any environment or organism, and is gaining increasing prominence in biodiversity studies. This approach is already commonly used to characterize soil microbial communities and its application is now being extended to other soil organisms, i.e. meso- and macro-fauna.These developments offer unprecedented scientific and operational opportunities in order to better understand soil biodiversity distribution and dynamics, and to propose tools and strategies for biodiversity diagnosis. However, these opportunities also come with challenges that the scientific community must face. Such challenges are related to i) clarification of terminology, (ii) standardisation of methods and further methodological development for additional taxonomic groups, (iii) development of a common database, and (iv) ways to avoid waste of information and data derived from metabarcoding. In order to facilitate common application of metabarcoding in soil biodiversity assessment, we discuss these opportunities and challenges and propose solutions towards a more homogeneous framework.     

Dahlin控制器的根轨迹的绘图方法

财产保险公司绝大部分业务来自于车险业务，因而车险业务的绩效关系到财险公司的经营业绩，甚至整个保险业的稳定和健康发展。从承保、理赔、续保及财务四个方面选取17个具体指标构建车险业务绩效评价指标体系进行有效性检验，计算某财险公司湖南分公司车险业务绩效水平指数，评价其车险业务经营状况。结果显示：该公司财务指标对车险业务影响的权重最大，综合车险指数呈上升趋势，表现出较好的经营状况。     

Relationship between calving difficulty and fertility traits in first‐parity Iranian Holsteins under standard and recursive models

The main objective of this study was to estimate the genetic and phenotypic relationships between calving difficulty (CD) and fertility traits, including success at first service (SF), number of inseminations to conception (INS), interval from calving to first service (CTFS), interval between first and last service (IFL) and days open (DO), in first‐parity Iranian Holsteins under standard (SMMs) and recursive (RMMs) mixed models. The data analysed in this paper included 29 950 records on CD and fertility traits, collected in the time period from 1995 to 2014 by the Animal Breeding and Improvement Center of Iran. Under all observed SMMs and RMMs, five bivariate sire‐maternal grandsire models (ten bivariate analyses in total) were used for the analyses. Recursive models were applied with a view to consider that CD influences the fertility traits in the subsequent reproductive cycle and the genetic determination of CD and fertility traits by fitting CD as covariate for any of the fertility traits studied. The existence of such cause‐and‐effect is considered in RMMs but not in SMMs. Our results implied a statistically non‐zero magnitude of the causal relationships between CD and all the fertility traits studied, with the former influencing the latter. The causal effects of CD on SF (on the observed scale, %), INS, CTFS, IFL and DO were ?2.23%, 0.10 services, 1.93 days, 3.76 days and 5.61 days, respectively. Direct genetic correlations between CD and the fertility traits under both models were not statistically different from zero (95% HPD interval included zero), except for the correlation between CD and CTFS, which were 0.197 and 0.134 under SMM and RMM, respectively, indicating that genes associated with difficult births also increase intervals between calving and the first insemination afterwards. Comparison of both models by the deviance information criterion (DIC) demonstrated the plausibility of RMMs over SMMs.     

吉林省玉米产业的运行机制研究

吉林省由于区位因素、资源禀赋造成玉米成为吉林省农业不可替代的主导产业。玉米生产又出现销售难、收储难、农民收入增长难,摆脱这种状况的现实的选择是以玉米生产为基础,构建一个全方位、系列化、具有多重产业关联度的玉米产业框架,建立合理的玉米产业运行机制,提高玉米产业的运行效率。     

植保无人飞机喷施叶面肥作业参数对枇杷冠层雾滴沉积分布的影响

为探究植保无人飞机（大疆T30）作业参数对枇杷冠层雾滴沉积分布的影响。本文利用3个因素（作业高度、作业速度、亩用液量）,3因子的正交实验,进行植保无人飞机喷洒枇杷树的喷雾试验。试验结果表明：从雾滴沉积密度、雾滴覆盖率和雾滴穿透性等因素来看,植保无人飞机对枇杷树的最佳作业参数为：作业高度2.0m、作业速度4.5m·s-1、亩用液量2.0L。对雾滴穿透冠层的影响最大的因素是工作高度;在1.5m的作业高度下雾滴沉积穿透性最佳。本研究对指导植保无人飞机枇杷树精准喷施叶面肥具有重要意义。     

基于HVI测试的标准化操作规范

为了规范大容量棉花测试仪的使用、校准及维护,提高检测结果准确性.作者根据HVI应用手册和实际操作经验,总结了大容量棉花测试仪的标准化工作各项要求.主要包括样品管理、气电及空间要求、恒温室、标准化仪器、校准与核查、比对试验、测试人员、健康安全、消防安全等.供业内同仁参考.     

对国有林场管理体制和经营机制改革问题的思考

分析了国有林场改革试点工作中所面临的重点难点问题,并从搞活经营机制、多渠道妥善安置富余职工、解决历史欠账、优化资源配置、整合生产要素等方面提出了发展建议。     

梅花鹿剖腹产诊治研究

本文是笔者在近年养鹿实践中 ,对梅花鹿剖腹产进行了诊治研究的总结。较详尽地阐述了梅花鹿剖腹产的适应症、剖腹产的手术方法和术后护理等问题。通过 1 5例难产手术证明 ,仔鹿成活率达 80 % ,母鹿成活率达 1 0 0 %。     

广元市油橄榄产业运行模式探讨

为加快广元市油橄榄产业的健康、快速发展，通过调查研究，对油橄榄产业建设中“公司 基地 农户”运作模式在运行机制、政策、资金、生产技术、农村经济合作组织等方面的现状进行了分析，指出了油橄榄产业发展尚存在的问题，并结合实际对油橄榄产业今后发展的思路和在“公司 基地 农户”利益联结机制、农村经济合作组织建设、标准化生产等方面的对策措施提出了建议。     

Genetic parameters for direct and maternal calving ease in Walloon dairy cattle based on linear and threshold models

Calving ease scores from Holstein dairy cattle in the Walloon Region of Belgium were analysed using univariate linear and threshold animal models. Variance components and derived genetic parameters were estimated from a data set including 33 155 calving records. Included in the models were season, herd and sex of calf × age of dam classes × group of calvings interaction as fixed effects, herd × year of calving, maternal permanent environment and animal direct and maternal additive genetic as random effects. Models were fitted with the genetic correlation between direct and maternal additive genetic effects either estimated or constrained to zero. Direct heritability for calving ease was approximately 8% with linear models and approximately 12% with threshold models. Maternal heritabilities were approximately 2 and 4%, respectively. Genetic correlation between direct and maternal additive effects was found to be not significantly different from zero. Models were compared in terms of goodness of fit and predictive ability. Criteria of comparison such as mean squared error, correlation between observed and predicted calving ease scores as well as between estimated breeding values were estimated from 85 118 calving records. The results provided few differences between linear and threshold models even though correlations between estimated breeding values from subsets of data for sires with progeny from linear model were 17 and 23% greater for direct and maternal genetic effects, respectively, than from threshold model. For the purpose of genetic evaluation for calving ease in Walloon Holstein dairy cattle, the linear animal model without covariance between direct and maternal additive effects was found to be the best choice.