Carbon isotopic ratios of wetland and terrace soil sequences in the Maya Lowlands of Belize and Guatemala     

Timothy Beach  Sheryl Luzzadder-Beach  Richard Terry  Nicholas Dunning  Stephen Houston  Thomas Garrison 《CATENA》2011

This article provides new data and synthesizes earlier findings on the carbon isotope ratios of the humin part of soil organic matter from a range of sites in the central Maya Lowlands. Changes down the soil profile in carbon isotope ratios can provide an important line of evidence for vegetation change and erosion over time, especially in well dated aggrading profiles. Research thus far has provided substantial evidence for significant inputs from C₄ vegetation in buried layers from the Ancient Maya periods in depositional soils but equivocal evidence from sloping soils. We present new findings from soil profiles through ancient Maya wetland fields, upland karst wetlands, ancient Maya aguadas (reservoirs), and ancient Maya terraces. Most of the profiles exhibited δ¹³C enrichment greater than the 2.5–3‰ typical from bacterial fractionation. Seven of nine ancient Maya wetland profiles showed δ¹³C enrichment ranging from 4.25 to 8.56‰ in ancient Maya-dated sediments that also contained phytolith and pollen evidence of grass (C₄ species) dominance. Upland karst sinks and ancient reservoirs produced more modest results for δ¹³C enrichment. These seasonal wetland profiles exhibited δ¹³C enrichment ranging from 1 to 7.3‰ from the surface to ancient Maya-period sediments. Agricultural terraces produced mixed results, with two terraces having substantial δ¹³C enrichment of 5.34 and 5.66‰ and two producing only equivocal results of 1.88 and 3.03‰ from modern topsoils to Maya Classic-period buried soils. Altogether, these findings indicate that C₄ plants made up c. 25% of the vegetation at our sites in the Maya Classic period and only a few percent today. These findings advance the small corpus of studies from ancient terraces, karst sinks, and ancient wetland fields by demonstrating substantial δ¹³C and thus C₄ plant enrichment in soil profile sections dated to ancient Maya times. These studies are also providing a new line of evidence about local and regional soil and ecological change in this region of widespread environmental change in the Late Holocene.  相似文献   

鸡粪改良对铜尾矿基质中无机氮组分及3种豆科植物生长发育的影响     

张宏  沈章军  阳贵德  安宗胜  孙庆业 《农业环境保护》2011,(11):2285-2293

基质改良和耐性物种选择是重金属矿业废弃地生态修复的关键。本文通过室内盆栽试验,以4kg尾矿为植物盆栽基质,分别加入腐熟鸡粪0、8、16、32g混匀,记作MA0（CK）、MA8、MA16、MA32处理方式,研究不同比例腐熟鸡粪改良对铜尾矿基质中无机氮组分及3种豆科植物决明（Cassia tora）、田菁（Sesbania cannabina）、菽麻（Crotalaria juncea）生长发育的影响。结果表明,添加鸡粪改良处理后,3种豆科植物生长的尾矿基质中均以硝态氮为有效氮的主要形态,总无机氮含量为17.96～44.82mg·kg-1。其中菽麻MA32处理组尾矿基质中铵态氮含量（5.31mg·kg-1）最高,菽麻MA16处理组尾矿基质中硝态氮含量（43.06mg·kg-1）和总无机氮含量（44.82mg·kg-1）最高。MA16处理时,田菁和菽麻叶绿素a、叶绿素b、叶绿素a＋b值均表现最大。3种豆科植物叶绿素a/b为0.92～1.08。在同一鸡粪比例处理中,菽麻叶绿素a、叶绿素b、叶绿素a＋b值均显著高于决明和田菁（P〈0.05）。鸡粪改良铜尾矿基质能够促进3种豆科植物生长,植物株高、冠幅、根长均增加,并且随着生长期延长,增加明显。其中MA32处理菽麻70d株高（94.40cm）最大,阻止尾矿风蚀水蚀的效果最好。综合分析表明,MA16处理方式可作为鸡粪改良铜尾矿基质理想的比例模式,菽麻可作为铜尾矿生态修复优选植物种。  相似文献   

园林植物模型在Quest3D中的应用研究     

刘蓓蓓  赵晓春  张永帅  仇锦绣  唐特 《计算机与农业》2011,(1):13-16

随着计算机软硬件水平的提高和可视化技术的不断发展更新,虚拟现实技术在园林中应用的领域越来越广,对园林设计的影响也越来越大。作为主流的虚拟现实软件,Quest3D在园林表现中越来越多地被应用,而园林植物对园林设计效果的表现起着重要的作用。对园林植物模型在Quest3D中的应用提出了优化的方法,以改进和完善基于Quest3D的园林虚拟漫游系统的表现效果。  相似文献   

基于机器视觉的红掌检测分级方法     

李恺  杨艳丽  刘凯  辜松  张青  赵亮 《农业工程学报》2013,29(24):196-203

中国盆花销售量随着消费水平的提高而迅速攀升,四大盆花之一的红掌在规模化生产中存在分级标准掌控不统一、分级结果不稳定以及效率低下等问题,制约了红掌产品的规模化生产,影响了红掌的出品质量。该研究提出基于机器视觉技术的红掌分级检测方法,对90株红掌的水平和竖直方向图像采集,经过二值化等处理,从侧视轮廓、俯视轮廓及佛焰苞轮廓特征三方面获取红掌植株的高度、冠幅、佛焰苞片数、苞片横径4项指标的信息, 针对每一项指标提出检测方法。试验结果表明,该方法对植株高度测量误差小于5.4 mm;针对植株冠幅提出了当量直径测量方法,佛焰苞片数测量正确率可达98.9%,苞片横径相对误差最大为6.52%。针对试验所选90盆红掌分级成功率达到97.8%。研究表明,利用机器视觉技术能够很好地实现对红掌盆花的在线检测分级。  相似文献   

Respiration pattern and microbial use of field-grown transgenic Bt-maize residues     

Markus Raubuch  Katja Roose  Florian Wichern 《Soil biology & biochemistry》2007,39(9):2380-2389

A 49-day incubation experiment was carried out with the addition of field-grown maize stem and leaf residues to soil at three different temperatures (5, 15, and 25 °C). The aim was to study the effects of two transgenic Bt-maize varieties in comparison to their two parental non-Bt varieties on the mineralization of the residues, on their incorporation into the microbial biomass and on changes in the microbial community structure. The stem and leaf residues of Novelis-Bt contained 3.9 μg g⁻¹ dry weight of the Bt toxin Cry1Ab and those of Valmont-Bt only 0.8 μg g⁻¹. The residues of the two parental non-Bt varieties Nobilis and Prelude contained higher concentrations of ergosterol (+220%) and glucosamine (+190%) and had a larger fungal C-to-bacterial C ratio (+240%) than the two Bt varieties. After adding the Bt residues, an initial peak in respiration of an extra 700 μg CO₂-C g⁻¹ soil or 4% of the added amount was observed in comparison to the two non-Bt varieties at all three temperatures. On average of the four varieties, 19-38% of the maize C added was mineralized during the 49-day incubation at the three different temperatures. The overall mean increase in total maize-derived CO₂ evolution corresponded to a Q₁₀ value of 1.4 for both temperature steps, i.e. from 5 to 15 °C and from 15 to 25 °C. The addition of maize residues led to a strong increase in all microbial properties analyzed. The highest contents were always measured at 5 °C and the lowest at 25 °C. The variety-specific contents of microbial biomass C, biomass N, ATP and adenylates increased in the order Novelis-Bt ? Prelude<Valmont-Bt ? Nobilis. The mineralization of Novelis-Bt residues with the highest Bt concentration and lowest N concentration and their incorporation into the microbial biomass was significantly reduced compared to the parental non-Bt variety Nobilis. These negative effects increased considerably from 5 to 25 °C. The transgenic Bt variety Valmont did not show further significant effects except for the initial peak in respiration at any temperature.  相似文献   

水土流失区马尾松垦复施肥与混交固氮植物措施对比分析   总被引：2，自引：0，他引：2  

林红强 《亚热带水土保持》2005,17(3):59-60,62

水土流失区马尾松“老头林”采用一般的垦复施肥措施，对促进马尾松生长有显著效果，但施肥作用只能持续3年左右。而采用混交固氮树种杨梅、胡枝子的措施，随着固氮植物固氮能力及生物生长量的增加，土壤养分状况、土壤结构等得到不断改善，马尾松高生长量也在逐步上升，效果十分显著，且作用持久。  相似文献   

镍胁迫对玉米幼苗氮、磷、钾积累与分配的研究   总被引：2，自引：0，他引：2  

王丽娜  杨靖民  刘金华  张忠庆  谢韩丹  周米平 《中国农学通报》2014,30(27):139-144

研究发现吉林省黑土中镍含量逐年增加,造成土壤理化性质恶化和玉米产量、品质降低,因此,了解镍胁迫对玉米植株生长特性的影响有重要意义。采用盆栽试验,研究了不同镍浓度（0、50、100、200、400 mg/kg）胁迫处理下玉米植株各部位的生物量、生物量分配格局以及氮、磷、钾积累和分配特征。结果表明,（1）镍浓度为50 mg/kg时,增加了玉米幼苗根、茎、叶生物量和总生物量,镍浓度大于50 mg/kg时,减少了各部位生物量及总生物量;（2）各部位对镍的吸收和积累随土壤外源镍浓度的增加而增加;（3）镍浓度为50 mg/kg时,增加了各部位的钾含量和根、茎钾的积累比例,而植株中的氮、磷含量随土壤中镍含量的增加呈降低趋势。因此得出,镍浓度为50 mg/kg的处理增加了玉米植株的生物量、根茎叶中钾含量及养分积累,改变了养分在玉米植株内的分配格局,而浓度大于50 mg/kg时抑制了玉米生长,降低了根茎叶中氮和磷的含量及积累。  相似文献   

药用植物填料减轻卷烟危害机理的研究进展     

刘慧慧  赵昶灵  丁灿  卢红 《中国农学通报》2015,31(28):270-279

卷烟中药用植物填料的运用形式不同、填料在卷烟及其相关产品的使用位置不同,药用植物减害的目标指向及其理化和药理机理就不同,主要机理涉及3个方面。首先,中草药与烟草同源,药用植物用于卷烟减害契合中医的烟熏疗法,体现了中医的配伍理论,药用植物具备能预防、缓解或治疗吸烟所致疾病的特定类群。其次,药用植物填料通过直接截留、物理吸附、化学吸附和催化解毒来降低烟气中焦油、烟碱、稠环芳烃、亚硝胺、自由基、挥发性酚类、巴豆醛、氰化氢、一氧化氮、一氧化碳、氨和重金属元素的含量。再者,卷烟中药用植物成分的特定熔点、沸点或气化点和吸燃烟支的温度条件决定了成分具备烟气转移属性,能缓解、治疗吸烟所致的呼吸道疾病、血管损伤及癌变,并具一般性的消炎和提高机体免疫力的功效,可为卷烟的药用植物减害实践和中国特色卷烟的研发提供依据。  相似文献   

园林植物高新技术育种研究综述和展望   总被引：13，自引：0，他引：13  

季孔庶 《分子植物育种》2004,2(2):295-300

随着我国园林绿化市场的持续升温,园林植物育种领域的研究不断得到重视,在传统育种技术的基础上,以现代生物技术、航天和离子注入诱变育种为核心的高新技术育种得到较大程度的发展。本文阐述了基因工程和细胞工程技术在园林植物株型和花型、花色和香味、生长发育、延缓衰老、抗病虫、抗逆境等方面的研究现状;综述了航天育种和离子注入育种等高新技术的研究基础,及其在园林植物种质创新领域的研究进展;并介绍了国内有关研究单位的一些相关研究情况。分析了园林植物育种技术的发展趋势,并重点对园林植物现代生物技术、航天和离子注入育种作了展望。  相似文献   

功能性inositol类物质在不同植物中的含量分析     

姜斌  沈明浩 《农产品加工．学刊》2011,(9):87-91

利用乙醇抽提不同植物中的inositol类物质,将其抽提物中的水溶相部分依次通过ODS柱和阴离子交换柱后,用HPLC法进行分析。结果表明,D-pinitol含量多的植物有槐树叶、红花三叶草、白花三叶草、繁缕、银杏叶、婆婆指甲菜;D-chiro-inositol含量多的植物有蒲公英、白背;ononitol含量多的植物有槐树和婆婆指甲菜;myo-inositol含量多的植物有金银花、柿子叶、蒲公英、桑树叶。  相似文献