江苏省4个太湖新银鱼种群遗传多样性和遗传结构分析

太湖新银鱼(Neosalanx taihuensis)是我国特有的银鱼种类,主要分布在长江和淮河中下游及其附属湖泊,近年来其资源量呈明显下降趋势。为了解太湖新银鱼遗传背景,本研究采用线粒体细胞色素b (Cytochrome b, Cyt b)基因序列,分析了江苏省太湖、高邮湖、洪泽湖和骆马湖4个太湖新银鱼野生群体共144尾样本的遗传多样性及遗传结构。结果显示,太湖新银鱼Cyt b基因序列共发现29个变异位点,定义25个单倍型;平均单倍型多样性(Hd)为0.682±0.037,核苷酸多样性(π)为0.00231±0.00021;4个群体中,高邮湖群体的遗传多样性最高(Hd: 0.609±0.078; π: 0.00094± 0.00027),太湖群体的遗传多样性最低(Hd: 0.343±0.107; π: 0.00075±0.00033)。分子方差分析(AMOVA)显示,太湖新银鱼群体间遗传差异(71.53%)大于群体内遗传差异(28.47%),遗传变异主要来自于群体间。遗传分化指数Fst值统计检验表明,骆马湖群体与太湖、高邮湖和洪泽湖群体之间有显著性差异。分子系统树和单倍型网络进化图分析显示,25个单倍型形成2个明显的地理分支,一支由太湖群体、高邮湖群体和洪泽湖群体组成,另一支由骆马湖群体组成。中性检验和错配分布图分析表明,太湖新银鱼历史上发生过群体扩张。整体来看,太湖新银鱼野生种群遗传多样性较低,应加强种质资源保护。建议将太湖、高邮湖群体和洪泽湖群体作为整体进行管理和保护,骆马湖群体单独管理和保护。     

稻草不同途径还田对土壤结构及有机质特征的影响

通过3年的田间定位试验,系统的研究了稻草不同途径还田对稻田土壤容重、孔隙度、团聚体、有机碳总量、腐殖质组成及腐殖质结合形态的影响。结果表明,与无肥(CK)及纯施化肥(NPK)对照相比,稻草直接深埋还田(NPK+S)及利用后的菌渣、牛粪、沼渣深埋还田(NPK+FD、NPK+CD、NPK+BD)均能一定程度的降低土壤容重、增加孔隙度、增加>0.25 mm水稳性团聚体的数量和提高土壤团聚体的稳定性,有利于形成和保持良好的土壤结构;同时能提高土壤腐殖质中胡敏酸含量和HA/FA比值,增加松结态腐殖质含量和提高松/紧腐殖质比值,能一定程度的改善土壤腐殖质的组成、性质及结合形态,提高腐殖质品质,不过这4个处理间的差异不明显。稻草焚烧还田(NPK+S′)在以上方面效果均不显著,且带来严重的大气污染,并不可取。     

荒坡地新建果园作物问种模式生态结构及功能研究

通过分析荒坡地新建果园5种优化模式的生态结构和功能表明,随重复种植的增加,5种间种模式土壤的有机质年均增加5％～20％,全N年增加7％～40％,全P年增加8％～70％,全K年增加15％～80％;顺坡垦植的土地水土流失严重,土壤侵蚀和地表径流第1年平均达1415.2t/km~2和790.7m~3/hm~2,花生-秋大豆水土保持最好,其次为春大豆-秋大豆、西红柿-白菜和辣椒-西红柿,其土壤平均侵蚀量和地表径流量与对照相比分别降低44.19％、38.24％、39.52％、37.56％和22.40％、9.28％、24.11％、21.16％。5种模式中辣椒-西红柿生物量最高,年均达10.028万kg/hm~2,其次是花生-秋大豆,年均达7.703万kg/hm~2,西红柿-白菜的生产力最高,达1.539万kg/hm~2,其次是辣椒-西红柿,达1.380万kg/hm~2;辣椒-西红柿投能效率最高,年均达2.96,其次为花生-秋大豆、西红柿-白菜、春大豆-秋大豆和早稻-红萝卜,分别为2.08、2.01、2.00和0.96,与对照相比辣椒-西红柿产出能最高,其次为花生-秋大豆、春大豆-秋大豆、西红柿-白菜和早稻-红萝卡,分别提高614.77％、433.01％、390.39％、316.07％和133.24％。     

不同灌溉处理寒地井灌稻田地温和产量构成要素研究

通过田同试验研究了浅水-间歇灌溉（SIT）、湿润-间歇灌溉（MIT）、淹灌（CSF）条件下寒地稻田的0～ 15 cm地温和水稻产量构成因素.结果表明,SrT、MIT田间建立浅水层或无水层,有利于0～ 15 cm的土壤温度的提升.由于Srr和MIT处理显著提高了每穴有效穗数,因而最终分别较CSF增产8.6％和11.9％,但SIT和MIT处理间差异不显著.     

基于线粒体控制区部分序列的大青鲨种群遗传结构研究

基于线粒体DNA ( mtDNA)控制区部分序列对采集自太平洋、大西洋、印度洋的5个大青鲨Prion-ace glauca群体165尾成鱼样本进行遗传多样性与遗传结构分析。结果表明：165尾大青鲨的mtDNA控制区片段长为694 bp,共得到110个变异位点,定义了145个单倍型,碱基组成中A为33.46%, T为36.40%, C为18.61%, G为11.53%, G+C含量为30.14%;单倍型多样性指数( Hd )在各个采样点都较高,平均值为0.9973±0.0014,核苷酸多样性指数(π)为0.01510±0.00091,这表明大青鲨群体的遗传多样性水平很高,遗传资源丰富;分子方差分析表明,99.28%的遗传变异出现在种群内,0.72%的遗传变异来自于种群间;采用邻接法构建的系统发育树表明,5个群体间未形成显著的遗传结构,群体间的高基因交流值( Nm )和低遗传分化指数( Fst )揭示了三大洋的大青鲨群体间基因交流频繁,不存在显著的遗传分化。     

蓝果树种群径级结构与生命表分析

蓝果树是重要的乡土彩叶树种之一。为全面了解其种群数量时空动态变化规律,采用空间代时间法和匀滑技术编制种群静态生命表。结果表明:蓝果树种群径级结构处于稳定状态。死亡率和损失率2个死亡高峰分别出现在第3,4和8龄级,存活曲线属于Deevey-Ⅱ型。生存分析4个函数曲线表明,蓝果树种群具有前期衰退,中后期稳定的特点。该研究可为蓝果树的经营管理和种群未来动态预测提供参考。     

Do plant species encourage soil biota that specialise in the rapid decomposition of their litter?

Plants are often nutrient limited and soil organisms are important in mediating nutrient availability to plants. Thus, there may be a selective advantage to plants that alter the soil community in ways that enhance the decomposition of their litter and, hence, their ability to access nutrients. We incubated litter from three tree species (Fagus sylvatica, Acer pseudoplatanus and Picea sitchensis) in the presence of biota extracted from soil beneath a stand of each species to test the hypothesis that litter decomposes fastest in the presence of biota derived from soil where that species is locally abundant. We found that respiration rate, a measure of decomposer activity and carbon mineralisation, was affected by litter type and source of soil biota, whereas, mass loss was only affected by litter type. However, litter from each tree species did not decompose faster in the presence of indigenous soil biota. These findings, therefore, provide no support for the notion that woodland plants encourage the development of soil communities that rapidly decompose their litter.     

大型液化气低温储罐结构及其保冷设计

根据储存液化气大容量储罐的超低温特点，对液化石油气和液化天然气低温储存储罐的隔冷保温材料及其保温结构设计进行了研究，并对几种大型圆筒型立式储罐的结构设计及其技术经济特性进行了讨论和比较。     

耕地利用视角下全国粮食生产时空特征演变

为综合考虑耕地数量及各项因素对粮食生产的影响,基于对数平均迪式分解方法(LMDI)将影响粮食产量的因素分解为耕地面积、复种指数、种植结构和粮食单产四大因素,研究1996—2016年其对全国粮食产量变化的作用机制。结果表明:1)我国耕地数量持续减少,空间上呈现南部地区减少、北部地区增加的趋势,导致全国粮食产能重心北移。2)粮食单产、复种指数这些技术因素均是促进因素,其中单产提高对总产量提升贡献最大;期间耕地面积下降与种植结构调整则是粮食产量的抑制因素。研究认为,城市化过程中耕地面积减少不可避免,保证粮食安全不但需要严格保护耕地,而且必须强化"藏粮于技"战略实施,不断提高粮食单产与复种指数,以稳定与优化粮食生产。     

Effect of selection under cultivation on morphological traits and yield of Ladino white clover landraces

One reason for the relatively low genetic advance realized in forage legumes may be the possible selection, under the severe intraspecific competition occurring naturally during cultivation, of a few high-yielding genotypes that would be of similar value in a broadly-based landrace or old cultivar and a narrowly-based, modern variety. The effect of selection under cultivation was assessed in two Ladino white clover farm landraces. Genotypes collected from each farm after a three-year crop cycle (survivor populations), or obtained from the seed used to establish each meadow (original populations), were multiplied clonally and evaluated in isolation and monoculture conditions for one year. The occurrence of directional selection was observed only in the landrace featured by greater intra-population variation in favour of genotypes with longer petioles (+11%), larger leaf size (+13%), less stolons (–14%) and lower production of heads (–16%). Selection for the first two traits would imply an increase of competitive ability, whilst that for the fourth trait appeared mainly as a correlated response. The trade-off between leaf gigantism and head production could act as a buffering mechanism against rapid change in genotype frequencies following random mating. A slight trend towards directional selection for higher yield (+6%) in the same landrace was not statistically significant. No disruptive or stabilizing selection was observed for any trait in either landrace.