Characterstics of seasonal variations of leaf n-alkanes and n-alkenes in modern higher plants in Qingjiang, Hubei Province, China

On the basis of GC and GC-MS analyses, the seasonal variation of leaf lipids is observed in five plant species in Qingjiang in Hubei Province. The CPI values （carbon preference index） of n-alkanes decrease gradually from May to November, though the carbon number distributions and the predominant carbon number in an individual species keep unchanged. The declined CPI values might be caused by the leaf fading, which is further supported by a comparison of the defoliated leaves with the fresh leaves. This observation infers the CPI values of n-alkanes in Quaternary sediments can be used as a tool to index the humification, and thus the climatic and the environmental conditions. The plants analyzed here show a remarkable difference in n-alkanes abundance, suggesting their differential contribution to the n-alkanes identified in sediments. The abundance and the compound species of the n-alkenes detected in the plant leaves change greatly with the seasons due to the influence of temperature, with the least compounds being identified in August.     

Molecular organic geochemical peculiarities of lacustrine core sediments in Fildes Peninsula, King George Island, Antarctica

The peculiarities of lipids in lacustrine core sediments from Fildes Peninsula, King George Island, Antarctica, are reported. The origin of high-molecular-weight n-alkanes, alkenes,fatty acids, alcohols is supposed to be related to the abundant moss occurring in the sediments.Abundant iso-and anteiso-fatty acids that occur in the sediments indicate a relatively strong bacterial activity in non-ice-cover zone than in other regions in Antarctica. The C18:2 unsaturated fatty acids mainly originate from autochthonous algae in the sediment pool, and the C18:2/C18:0ratios in the profile are controlled more by paleotemperatures than source assemblies. Long-chain alkenones were identified in freshwater lacustrine sediment in Antarctica for the first time, of which Prymnesiophyceae is assumed to be the source organism. High relative abundance of C37:4honologue in long-chain alkenone well correlates to the severely cold climate in Antarctica.     

Evidence from carbon isotope measurements for biological origins of individual longchainn-alkanes in sediments from the Nansha Sea, China

Carbon isotopes are measured for individual long-chain n-alkanes in sediments from the Nansha Sea. The features of carbon isotopic compositions of individual n-alkanes and their origins are studied. The results show that the long-chain n-aikanes have a light carbon isotopic composition and a genetic feature of mixing sources, and low-latitude higher plants and microbes are considered to be their main end member sources. Based on the abundances and carbon isotopic compositions of individual n-alkanes, the fractional contributions of the two end member sources to individual n-aikanes are quantitatively calculated by using a mixing model. The obtained data indicate that the fractional contributions of the two biological sources are different in the three samples. A trend is that the contribution of microbes increases with the depth. These results provide the theory basis and quantitatively studied method for carbon isotopic applied research of individual n-alkanes.     

High molecular weight (C35+)n-alkanes of Neogene heavily biodegraded oil in the Qianmiqiao region, North China

With wax content of 1.62%, heavy oil has been produced from the sandstone reservoirs of Neogene Guantao Formation (Ng1Ⅲ). In the GC and GC-MS RIC profiles of its aliphatic fraction, n-alkanes are totally lost, which shows the result of heavy biodegradedation. However, the remaining trace C13-C36 n-alkanes can be still seen from its m/z 85 mass chromatogram. In addition, a complete series of C35-C73 high molecular weight (HMW) n-alkanes was detected by high-temperature gas chromatography (HTGC). The HMW n-alkane series shows a normal distribution pattern, a major peak at nC43, obvious odd-carbon-number predominance, CPI37-55 and OEP45-49 values up to 1.17 and 1.16-1.20 respectively. The present study not only has conformed the strong resistibility of HMW n-alkanes to biodegradation in crude oils as concluded by previous researchers, but also has provided some significant information on source input and maturity for the heavily biodegraded oil in the Qianmiqiao region.     

植物品种净光合速率测定的取样技术——以苎麻(Boehmeria nivea(L.)Gaud.)为例

植物净光合速率(Pn)测定的取样技术决定结果的可靠性,但很少有文献专门论述.为此,分析苎麻Pn的日变化、个体间、叶位间和叶片不同位点的差异,结果表明:1天中苎麻Pn在11:00左右达到最高值,此后迅速降低,虽在下午可能回升,但不同品种有差异;品种内个体间Pn差异显著;不同叶位以顶部展开叶往下数第5～7叶Pn最高;叶片不同位点的Pn差异不显著.据此建议苎麻品种的Pn测定在上午9:00～11:00进行;每个品种/处理至少选择5个生长一致的正常植株,测定从植株顶部展开叶往下数第5～7叶近叶尖位置的Pn.还要特别注意植株的代表性和不同品种/处理/植株的叶位统一,叶片颜色、形状正常,无病虫危害.     

Molecular organic geochemical peculiarities of lacustrine core sediments in Fildes Peninsula,King George Island,Antarctica

The peculiarities of lipids in lacustrine core sediments from Fildes Peninsula, King George Island, Antarctica, are reported. The origin of high-molecular-weight n-alkanes, alkenes, fatty acids, alcohols Is supposed to be related to the abundant moss occurring in the sediments. Abundantiso- andanteiso-fatty acids that occur in the sediments indicate a relatively strong bacterial activity in non-ice-cover zone than in other regions in Antarctica. The C_18:2 unsaturated fatty acids mainly originate from autochthonous algae in the sediment pool, and the C_18:2C_18:0 ratios in the profile are controlled more by paleotemperatures than source assemblies. Long-chain alkenones were identified in freshwater lacustrine sediment in Antarctica for the first time, of whichPrymnesiophyceae is assumed to be the source organism. High relative abundance of C_37:4 homologue in long-chain alkenone well correlates to the severely cold climate in Antarctica.

     

Paleoecological implications of the nitrogen isotope signatures in the sediments amended by Antarctic seal excrements

The nitrogen isotope signatures in the sediments amended by seal excrements, from Fildes Peninsula of King George Islands, Antarctica, were examined for their paleoecological application potential. The contents of total organic carbon (TOC) and total nitrogen (TN) and the atomic C/N ratios in the sediments show that the organic carbon and nitrogen are predominantly of marine origin and derived from seal excrements. The remarkably high δ15N values in the sediments may be related to at least two important factors of trophic enrichment and NH3 volatilization, which requires further studies. The large variations in the seal hair abundances and the determinedδ15N values in the sediments signify similar changes of the historical seal populations around the study site. A significant negative correlation between the δ15N values and seal hair abundance was observed, and this suggests that the δ15N values, like the number of seal hairs,can be used as a paleoecological proxy for the historical seal populations. The time-integrated δ15N signatures in the sediments with predominantly animal-derived nitrogen source thus provide a new tool for estimating historical populations of seals and penguins and interpretlng the underlying paleoecological processes.     

优质稻穗部性状与农艺性状的相关性研究

对新育成的桂花香品系及目前广东优质稻生产中3个当家品种的主要穗部性状与农艺性状进行相关分析。研究表明，优质稻单株有效穗数与每穗实粒数呈极显著正相关。单株有效穗数、每穗总粒数、实粒数与冠层3片功能叶的叶宽、灌浆期叶面积指数（LAI）等显著或极显著的负相关；株高与千粒重呈极显著的正相关、与每穗实粒数和单株有效穗数呈负相关。试验结果说明，在一定株高范围内，适当增加冠层3片功能叶的叶宽、减小这3片功能叶的张角，同时增加叶面积指数、茎秆直径是优质稻株型改良的一个重点。     

漓江河岸植物功能性状的分类研究

对漓江河岸植物的功能性状(生活型、生态类群、叶片质地、花序类型、果实类型、种子传播方式)进行统计分析。结果表明,漓江河岸共有乔木37种,灌木63种,亚灌木6种,藤本15种,草本182种;中生植物201种,湿生植物55种,半湿生植物38种,两栖植物9种;草质叶122种,纸质叶121种,革质叶片53种,肉质叶4种,膜质叶3种;总状花序62种,圆锥花序56种,聚伞花序54种,头状花序37种,伞房花序、轮伞花序和肉穗花序均仅6种,团伞花序、复伞房花序及复二岐聚伞花序均仅1种;蒴果66种,瘦果53种,核果41种,颖果28种,胞果、角果、翅果、分果、柑果和梨果分别仅为8种、7种、5种、3种、2种和1种;动物传播有111种,风媒传播83种,水媒传播58种,自体传播51种。     

黑老虎植株不同部位木脂素和萜类成分分析

黑老虎(Kadsura coccinea)为传统中药材，为深入了解木脂素类和萜类成分在植株不同部位的分布和积累状况，采用广泛靶向代谢组学技术鉴定其叶、茎、根中的代谢物，基于结构配置解析木脂素和萜类的多样性和丰度。结果显示：在黑老虎植株中共鉴定出39个木脂素类化合物，根(32个，特有13个)>茎和叶(同为24个)，3个部位含17个相同的木脂素类化合物；同时，鉴定出41个萜类成分，根(39个)>茎和叶(同为36个)，3个部位含34个相同的萜类化合物。黑老虎根部木脂素类化合物丰度(114.62×10⁶)远高于叶(23.37×10⁶)和茎(25.96×10⁶),萜类化合物丰度为根(74.16×10⁶)>叶(37.06×10⁶)>茎(17.36×10⁶),根部与叶、茎相同及特有的木脂素和萜类化合物丰度均较高。日本南五味子木脂素G、乙酰表戈米辛R、Kadcoccilactone F等在黑老虎根中高度富集，在叶、茎、根中都鉴定出Kadcoccilactone Q-R、Kadcoccilactone M等三萜类化合物，表明黑老虎具有较高的研究与利用价值。     

海岸带不同复合农林业系统种群生态特性

通过对江苏沿海滩涂较具代表性的银杏采叶园（A）、银杏果－叶－农复合园（B）、银杏材－农复合园（C）等3种不同银杏－农作物复合系统种群复合结构、植物个体的生长结构、现实生态位、生物多样性的比较分析，研究了不同复合系统的种群动态特征。结果表明，银杏果用－叶用－豆科作物复合模式具有较大的生物多样性指数和较小的断面积密度指标值，同时具有利于间作种群共存的冠层结构和根系结构，便于调节种群动态和技术集成管理，是一种适宜的海岸带地区推广的优化复合经营模式。     

8种柏科植物叶表皮的扫描电镜观察

为了探讨柏科植物叶的微形态学特征和差异,应用扫描电子显微镜对8种柏科植物叶表皮的微形态特征进行了观察．结果发现,本实验所取8种柏科植物叶的气孔器均为椭圆形,副卫细胞5～7个,气孔器主要分布在叶的近轴面上,在刺形叶的远轴面上无气孔;8种柏科植物的叶表皮细胞上一般覆盖着较厚的角质层和蜡质层,不同种柏科植物的叶表皮具有不同的角质和蜡质纹饰;同种柏科植物同型叶的新叶和成熟叶、绿色叶和白色叶的微特征间也有区别,成熟叶的表皮细胞上角质和蜡质较新叶多;日本花柏白色鳞形叶的气孔分布和蜡质纹饰都有一定的特殊性．不同种柏科植物叶的微特征有较大的差别,可以为柏科植物的分类提供一定的依据．     

云南腾冲上新统Litsea cf.chunii的角质层微细构造特征

在云南省腾冲县上新统芒棒组发现了保存较好的被子植物压型化石高山木姜子(相似种)Litseacf.chunii Cheng.该化石叶片呈窄椭圆形,基部楔形,顶端短尖,叶全缘,中脉直,二级脉羽状,与中脉夹角为30°～50°,近叶边缘微弯曲,羽状脉。进一步分析了化石叶片的角质层微细构造,利用叶结构结合表皮特征的分析方法提高了对化石植物分类鉴定的准确性。化石叶片的角质层特征主要表现为:上表皮无气孔器,表皮细胞多为四或五边形,排列呈规则的网格状,垂周壁直或微弯,平周壁光滑,毛基较少;下表皮细胞排列同上表皮,具平列型气孔器,其长轴无定向性,气孔器由下陷的保卫细胞和两个上拱的副卫细胞组成,具有单细胞毛基,根部由5～6个辐射状的细胞组成。同现生高山木姜子Litseachunii相比,化石叶片具有更小的毛基密度,推测毛基的增加是由于气候变冷所致。由此通过化石和现生叶片角质层的对比分析推断滇西地区上新世气候比现在温暖湿润。     

中国东部城市森林阔叶树种叶绿素含量空间特征及其影响因素

选取中国东部样带9个城市27个公园,在生长季使用叶绿素仪（SPAD-502 Plus）测定了主要阔叶树种新叶与成熟叶的叶绿素相对含量（SPAD值）,探究了城市阔叶树种叶片叶绿素相对含量空间特征及其影响因素．结果表明:中国东部城市阔叶树种成熟叶SPAD值显著高于新叶,常绿阔叶树种叶片SPAD值显著高于落叶阔叶树种．中国东部城市阔叶树种新叶和成熟叶的叶绿素相对含量均随纬度降低而升高,主要是由树种组成（以常绿树种比例为指标）变化导致的．本研究相关结果增进了对城市环境中阔叶树种叶片属性大尺度空间规律的认识．      

不同水肥处理对梨枣几种形态指标的影响

研究了不同水肥处理(对照、浇水、浇完全营养液、施复合肥、施复合肥加浇水)对梨枣生长期叶片厚度、叶面积、百叶重、枣吊长度、枣吊叶片数的影响,结果表明:与对照相比,不同水肥处理均能增加梨枣的枣吊长度和枣吊叶片数,其中施复合肥加浇水效果最好;浇完全营养液、施复合肥、施复合肥加浇水处理后均能显著增加梨枣的百叶重,叶面积和叶片厚度。表明施肥结合灌溉能显著促进梨枣枣吊和叶片的生长,有利于提高梨枣的产量。     

植物动力2003对水稻秧苗素质影响的研究初报

本文探讨了植物动力2003对水稻秧苗苗高、绿叶数、叶挺长、总根数、白根数、分蘖数、秧苗最大叶片的长度和宽度等秧苗素质的影响。结果表明.喷施植物动力2003的水稻秧苗粗壮,分蘖多,根系发达,各项指标均明显优于对照。     

渤海柱状沉积物中烃类化合物的分布

本文测定了位于渤海中部的E3和E5两柱样中正构烷烃和脂肪酸的含量分布研究表明：渤海沉积物中有机质的重要来源是黄河的陆源物质输运,黄河的历史变迁在柱样中可通过轻重烃比值的变化记录体现。近年来黄河的断流和筑坝使得陆源物质的输入有明显的减少趋势。在讨论氧化环境(E5)和还原环境(E3)中脂肪酸的分布和行为中,脂肪酸作为较易改造降解的化合物,结合一些指标(BrC_15∶0/nC_15∶0和nC_18∶1/nC_18∶0参数),表明在还原环境中的脂肪酸的降解过程明显于氧化环境。     

镉胁迫下生物质炭对蔬菜生长特性的影响

采用盆栽试验,研究了施用生物质炭对外加镉污染土壤上小白菜生长性状和根系耐性指数的影响。结果表明,重金属镉加入时,抑制了小白菜根系的生长,随着镉污染浓度的增加,抑制趋势显著。但随着生物质炭浓度的增加,植物根长并没有因镉污染浓度的变化而显著变化,根长生长趋于稳定。镉污染对小白菜叶的生长有胁迫作用,无论是否有重金属污染,生物质炭对小白菜株高和叶宽的指标都有不同程度的促进作用。在施加生物质炭并且受镉污染的小白菜的根系耐性指数＞1.0。     

福州市江滨公园绿地木本植物色彩丰富度及多样性研究

采用典型抽样法,对福州市江滨公园绿地木本植物的种类构成、植物来源、色彩丰富度、物种多样性指数进行调查统计和分析,以期为福州市生物多样性保护提供基础数据,为福州生态城市建设提供科学依据.研究表明:福州市江滨公园绿地木本植物种类较为丰富,共120种,隶属于50科83属,其中,福州本地种26种,占总数的21.67%;国内引进种55种,占总数的45.83%;国外引进种39种,占总数的32.50%;彩叶树种19种,占总数的15.83%.频度指数较高的为秋枫(Bischofia javanica)、四季桂(Osmanthus fragrans)和红花檵木(Loropetalum chinense).福州市江滨公园5个园区绿地的乔木物种丰富度大于灌木.Simpson多样性指数和Shannon-Wiener多样性指数表现为相同趋势,且乔木的多样性指数大于灌木.Pielou均匀度在江滨公园5个园区的绿地之间差异较大,乔木均匀度仍大于灌木.