阿克苏市灰枣园净生态系统碳交换特征及其对气象因子的响应

为了解枣园与大气之间净生态系统碳交换(NEE)特征,运用涡度相关系统、小型自动气象站及HemiView冠层分析系统分别对2017年阿克苏市郊区灰枣园CO2通量、气象因子及叶面积指数进行观测,研究了枣园NEE变化特征、NEE和叶面积指数及气象因子之间的日动态相关性。结果表明:NEE日动态为“U”形曲线。白天NEE为负值,表现为碳吸收,夜间NEE为正值,表现为碳排放。枣园各生育期的晴天与阴天NEE变化特征基本一致。枣园各生育期按照NEE及阶段NEE强度由高到低排序依次为果实发育期、果实成熟期、花期、萌芽期。枣园全生育期叶面积指数和气象因子按照与枣园NEE的相关性由高到低排序依次为叶面积指数、相对湿度、空气温度、光合有效辐射、饱和水汽压差。果实发育期碳交换速率和NEE最大,因此在枣树果实发育期应保证水分和无机盐的供应,对枣园NEE影响最大的因素是叶面积指数。     

干旱绿洲区微喷灌枣园蒸散量时空尺度转换研究

为探究干旱绿洲区不同时空尺度单棵枣树蒸散量向枣园尺度蒸散量的转换关系,通过涡度系统、茎流计和微型蒸渗仪对枣园蒸散量、枣树蒸腾量和土壤蒸发量进行了监测.通过对茎流系统与涡度系统测量的不同时间、空间尺度的枣园蒸散量进行分析,分析从点(枣树)尺度蒸散量向面(枣园)尺度蒸散量的转换关系得出:(1)全生育期蒸腾量为403.2 m...     

Variance–covariance structure and its influence on variety assessment in regional crop trials

The primary method used to analyze regional crop variety trials is based on the analysis of variance (ANOVA), which requires a homogenous variance–covariance of data. While other models are available, the problem of how the models should be assessed and which model is more suitable for a given trial's data has not been solved. This restricts the applicability of the models. Therefore, a mixed linear model with flexible variance–covariance structures is proposed. Relationships are introduced for various variance–covariance structures of mixed models, and other models for analyzing crop regional trials. Using data from regional corn trials in northeastern and northern China, an assessment was made of the information criterion and likelihood-ratio-test, along with the goodness of fit of variance–covariance structures. This regional trial data facilitated comparison between an ANOVA model and a mixed linear model with an optimal variance–covariance structure. The results showed that the variance–covariance of varietal effects over environmental influences was not homogeneous, as is required in the ANOVA model. Instead, it was found to be heterogeneous in all trials considered. On average, the ratio of significant varietal differences for the same variety was only 86% when comparing the ANOVA model and the optimal mixed linear model. Also, there were obvious differences in the yield ranking of varieties between the two models. The mean standard error of a difference of varietal effects in the optimally-fitted mixed linear model was smaller than that in the ANOVA model.     

Computer simulations of the effects of the Sitka eddy on the migration of sockeye salmon returning to British Columbia

The Sitka eddy is a mesoscale eddy, 300 km in diameter, that develops off SE Alaska in about one year in two. The eddy has surface currents exceeding 50 km day⁻¹ and it has been suggested that the eddy could deflect migrating salmon to the south, thereby reducing the proportion of British Columbia (BC) sockeye salmon accessible to Alaskan fishers. We modelled its effects on the migration of sockeye salmon ( Oncorhynchus nerka ) returning to northern BC, using an individual-based model to simulate migration paths, migration timing and metabolic costs of salmon with different migration behaviours. Except when their migration behaviour included positive rheotaxis, salmon that encountered the eddy had faster migration times and lower metabolic costs than those that did not. The least complex migration behaviour, compass orientation with no rheotaxis, was only slightly less efficient in metabolic terms than the optimal migration paths determined by dynamic programming. Our simulations show that the Sitka eddy itself does not deflect migrating salmon to the south or south-east regardless of migration behaviour, but that by interrupting the normal northward flow of the Alaskan Current, the eddy could influence latitude of landfall of migrating salmon.     

基于流场数值仿真的人工鱼礁组合优化研究

基于特征礁水槽集鱼实验,研究了不同结构人工鱼礁和不同背景速度下黑鲷幼鱼在各流速区段出现频度,以鱼类出现频度高、水平流速为背景速度的0.7倍和0.8倍以下的流场空间体积作为背涡流范围指标,以垂向上升流速为水平来流速度的0.1倍和0.2倍以上的空间体积作为上升流范围指标,基于Fluent、采用大涡模拟法(LES)的湍流模型,进行数值水槽建模,以4种单位鱼礁组合方案为例来分析不同组合流场效应的差异和优劣。研究表明,边长3 m的正方体鱼礁,以20～30个单礁、1～2倍礁距进行五点式、对称型单位鱼礁组合投放为宜,这样既能发挥礁体的协同效应,又能使单位鱼礁的调控范围达到最大化。     

公交投币鉴伪清分系统研究

针对目前公交系统收到大量假硬币的现状,在比较了常用硬币检测方法的基础上,提出了使用双电涡流传感器检测硬币的材质的方案,给出了硬币检测系统的结构框图,选用高性能的STC单片机、电涡流传感器、红外光电开关和语音芯片及电磁铁构成了检测系统,可以实现对乘客所投硬币及时鉴别并剔除假币的功能。系统成本低廉,便于操作,具有一定的应用前景和推广价值。     

不同地理来源草鱼群体杂交后代的生长性能分析

为评估10 个不同地理来源草鱼群体（佛山群体、肇庆群体、荆州群体1、荆州群体2、荆州群体3、鄂州群体、益阳群体、长沙群体1、长沙群体2 和江苏群体）杂交后代的生长性能,对该10 个群体为亲本构建的15 个杂交组合进行同塘生长对比。对其4 月龄、7 月龄、8 月龄、10 月龄、12 月龄、15 月龄和18 月龄的体质量进行测量。以4 月龄体质量为协变量,运用协方差分析对不同杂交组合后代进行生长性能分析。结果显示,在18 月龄时荆州群体2♀×佛山群体♂杂交组合后代平均体质量最高,为1892.90 g,比其他杂交组合平均体质量分别高3.51%~32.36%。经多重比较分析结果显示,荆州群体2♀×佛山群体♂和荆州群体1♀×佛山群体♂杂交组合后代的体质量显著高于其他杂交组合(P＜0.05)。生产上,应用这2 个具有生长优势的组合生产优质苗种进行推广,可大幅度提高渔民的经济效益,另外该结果可为快速生长草鱼核心群体的确定奠定基础。     

Seasonal and inter-annual variations in carbon fluxes and evapotranspiration over cotton field under drip irrigation with plastic mulch in an arid region of Northwest China

 Xinjiang is the largest semi-arid and arid region in China, and drip irrigation under plastic mulch is widely used in this water-limited area. Quantifying carbon and water fluxes as well as investigating their environmental drivers over cotton fields is critical for understanding regional carbon and water budgets in Xinjiang, the largest cotton production basin of China. In this study, an eddy covariance (EC) technique was used to measure the carbon and water fluxes of cotton field under drip irrigation with plastic mulch in the growing seasons of 2009, 2010, 2012 and 2013 at Wulanwusu Agrometeorological Experiment Station, a representative oasis cropland in northern Xinjiang. The diurnal patterns of gross primary production (GPP), net ecosystem exchange (NEE) and evapotranspiration (ET) showed obviously sinusoidal variations from June to September, while the diurnal ecosystem respiration (Res) was stable between daytime and nighttime. The daytime hourly GPP and ET dis-played asymptotic relationships with net solar radiation (Rnet), while showed concave patterns with raising vapor pressure deficit (VPD) and air temperature (Ta). The increases in hourly GPP and ET towards the maximum occurred over half ranges of VPD and Ta. The seasonal variations of GPP, NEE and ET were close to the cotton phenology, which almost reached the peak value in July. The cumulative GPP averaged 816.2±55.0 g C/m² in the growing season (from April to October), and more than half of GPP was partitioned into NEE (mean value of –478.6±41.4 g C/m²). The mean seasonal ET was 501.3±13.9 mm, and the mean water use efficiency (WUE) was 1.0±0.1 (mg C/g H2O)/d. The agro-ecosystem behaved as a carbon sink from squaring to harvest period, while it acted as a carbon source before the squaring time as well as after the harvest time.     

典型草原区草地潜热通量特征

为研究局地小气候和草地生态系统变化提供依据。利用2010年6月1日—8月31日开路涡度相关系统和常规气象观测系统资料,分析锡林浩特典型草原区草地潜热通量变化特征及其与环境因子的关系。结果表明,6—8月总体能量平衡闭合很好,闭合度达83.9%。晴天闭合度为81.4%,阴天闭合度为95.0%,处于国内外同类观测闭合度范围的上等水平;潜热通量日变化呈单峰型二次曲线,日出后逐渐升高,中午左右达到峰值,然后逐渐降低,日落后趋于稳定。晴天和阴天的潜热通量日变化趋势相同,但阴天波动性较大,变幅大于晴天,且峰值滞后于晴天;潜热通量与净辐射、气温、地表温度、地表温度与气温差、呈极显著正相关,与相对湿度呈极显著负相关,而与水平风速的相关性相对较弱。其中,净辐射是最大的影响因素。     

水稻稻米Hg累积的遗传生态特性研究

选用6个不同类型的水稻品种（系）,按完全双列杂交设计（6×5）配成一套亲本、F1和F2 3个世代的遗传材料。采用包括种子、细胞质、母体植株三套遗传体系的种子性状遗传模型和统计分析方法,系统分析了稻米汞含量性状的遗传特点。主要结果如下：遗传方差分析结果表明,Hg元素含量除了受制于种子基因效应、细胞质基因效应和母体植株基因效应等遗传主效应外,还会明显受到各遗传效应与环境互作效应的影响,汞元素含量主要以遗传主效应为主。在各遗传体系中,汞元素含量以显性效应及其与环境互作效应为主,种子基因效应也有一定作用。遗传率和选择响应分析结果表明,汞总狭义遗传率较高,世代的遗传传递力较强,在鉴定筛选淘汰时,需要加大群体才能达到降低Hg元素含量的育种目标。