日光温室黄瓜生长积温研究     

马凤莲  魏瑞江  王鑫  吴显春  孙庆川 《气象与环境学报》2019,35(4):85-92

为定量研究黄瓜生长发育对积温的需求,提高日光温室黄瓜生长的预测能力和种植效益,本文利用多年日常管理下日光温室内小气候和黄瓜生长的观测数据,采用数理统计方法,分析不同年度不同茬口下日光温室黄瓜叶片和果实的生长规律,以及黄瓜叶片和果实生长与所需有效积温的关系,并确定黄瓜植株致死的积温指标。结果表明:整个生育期内,黄瓜叶片数随生育进程呈S型变化,一根黄瓜生长遵循先慢后快的规律;不同茬口的黄瓜叶片每增加一叶所需有效积温均呈不对称“U”型,即叶片生长初期和生长中后期,每增加一叶所需的有效积温多于叶片生长中期所需的有效积温,整个生育期内平均每增加一叶所需8—40℃有效积温为33—37℃·d;一根黄瓜从坐果到采收需要15—35℃的有效积温为110—130℃·d;若温室内反复出现10℃以下、5℃以上的温度条件时,且反复过程所累积的10—5℃有效积温达8℃·d左右时,黄瓜植株即会死亡。上述积温指标在日光温室黄瓜生产中具有现实的指导意义。  相似文献   

~(13)C/~(12)C比值在海洋生态系统营养关系研究中的应用──海洋植物的同位素组成及其影响因素的初步探讨   总被引：6，自引：0，他引：6  

蔡德陵  毛兴华  韩贻兵 《海洋与湖沼》1999,(3)

于1993年2月-1995年5月,采用生物显微镜鉴定并计数和高温氧化的方法,对崂山湾海洋植物的种类组成及其有机碳同位素组成的季节性变化作了5个季度月的研究。结果表明,该区同采浮游植物全年以硅藻为主,甲藻在夏季也可成为优势种之一。浮游植物的碳同位素组成在夏季较重,冬季和春季较轻,并与海水温度有弱的正相关性。浮游植物δ13C值的变化范围为-259ｘ10-3—-19.2ｘ10-3,全年平均值为（-23.2±2.4）ｘ10-3。该生态系统的另一碳源为底栖藻类,其δ13C平均值为（-18.5±2.4）ｘ10-3,明显区别于浮游植物。对除温度以外的其它影响海洋植物同位素组成的因素,诸如植物种类组成、海水中溶解无机碳δ13C值、CO2供应速率以及CO2固定过程中不同验化酶的同位素分馏作用等也作了初步探讨。  相似文献   

豫西鲁山洛峪口组宏观藻类的发现及地质意义   总被引：6，自引：1，他引：5  

尹崇玉  高林志 《地质学报》2000,74(4):339-343

本文报道在华北地台南缘豫西鲁山下汤九女洞剖面洛峪群洛峪口组下部灰绿色粉砂质页岩中发现可靠的宏观碳质印膜化石,包括Ｃｈｕａｒｉａ,Ｓｈｏｕｈｓｉｅｎｉａ,Ｔａｗｕｉａ,Ｏｖｉｄｉｓｃｉｎａ等属。通过同国内外已发现的前寒武纪宏观藻类资料广泛对比,并结合其他化石资料的综合分析,对华北地台南缘晚前寒武纪地层对比及新元古代地层格架进行探讨。  相似文献   

Advances in the Effects of Wind on Plants     

Zhang Linlin  Zhao Xiaoying  Yuan Hui 《地球科学进展》2013,28(12):1349-1353

Wind is a important factor. It can strongly affect development, growth and reproduction of terrestrial plants. The plant in wind environment can adapt to wind by special mechanism to decrease damage. This paper reviews the effects of wind on plant in phenotype, anatomy and root archetecture. Some plant species show a resistance strategy, but other species show an avoidance strategy. After the analysis of the restriction of current research in this area, the authors suggest that studies in the area should be extended to taking the whole plant as an integrated system rather than focusing on specific tissue level. Furthermore to understand the general mechanism across species, it is required to study different species from different environmental conditions. Advances in bioinformatics, molecular and physiological research will facilitate cross disciplinary studies to understand the complicated responses of plants to wind.  相似文献   

我国酸沉降地区硫源的硫同位素组成研究   总被引：1，自引：0，他引：1       下载免费PDF全文

胡菲菲  张良 《江苏地质》2013,37(4):675-680

我国同世界大部分地区的酸雨类型一致,均为典型的硫酸型酸雨,因此硫同位素组成是示踪酸雨来源的重要手段。在前人研究的基础上,对酸雨硫同位素组成研究的思路和实验方法进行综述,重点介绍燃煤过程中硫同位素的分馏效应和大气SO2、气溶胶、大气降水、苔藓和小麦等植物中的硫同位素组成等,对环境地球化学的研究具有重要意义。  相似文献   

基于微博的芦山地震前后宏观异常信息筛选与分析     

苏晓慧  张群燕  张晓东  张旭  李林  刘峻明  黄健熙  苏伟 《震灾防御技术》2013,8(4):451-458

地震宏观异常是指地震前后人的感觉能直接察觉到的自然界异常现象,本研究在芦山地震后,针对公众通过微博发布的异常信息进行搜集,提出从真实性、完整性、信誉度和关联度四方面对公众提供的微博宏观异常信息进行筛选的方法,并根据筛选后的信息从时间角度、空间分布等方面进行芦山地震前后宏观异常信息的分析研究.结果表明,芦山地震前后是有宏观异常出现的,公众关注的异常种类主要为动物异常与天气异常;震前发生宏观异常占宏观异常总数的67％,但仅有30％被发布;微博发布的宏观异常信息中,大多位于距离震中较远的成都市,而非震中地区.微博信息可以作为宏观异常信息的一个主要的及时信息来源,有助于发挥群测群防在防震减灾工作中的作用.  相似文献   

Soil charcoal stability over the Holocene across boreal northeastern North America     

Guillaume de Lafontaine  Hugo Asselin 《Quaternary Research》2011,76(2):196-200

The analysis of macroscopic wood charcoal fragments extracted from soils is frequently used as a palaeoecological tool for reconstructing stand-scale forest composition and fire history. Here we explored the putative loss of palaeoecological information due to charcoal degradation through time and in different biogeographical settings. We compared the relationship between charcoal mass and abundance for soil samples from five biogeographical regions of boreal northeastern North America spanning most of the Holocene period. We verified whether charcoal (Ø ≥ 2 mm) conservation differed as a consequence of different taphonomical processes between organic and mineral soil types. We also assessed the mass/abundance relationship as a function of charcoal residence time in soil. Overall, the slope of the regression between charcoal particles mass (g) and abundance (number of particles) was 0.0042. The slope was not significantly different in samples from organic and mineral soil, and all biogeographical regions had similar slope values except one (higher charcoal fragmentation, probably due to high colluvial activity). Charcoal conservation also did not vary according to residence time in soil. This study shows that macroscopic soil charcoal particles resist fragmentation over millennia in different biogeographical settings and under the influence of various taphonomical processes.  相似文献   

Factors controlling the heterogeneous distribution of Cr(VI) in soil, plants and groundwater: Evidence from the Assopos basin, Greece     

Maria Economou-Eliopoulos  Ifigenia Megremi  Charalampos Vasilatos 《Chemie der Erde / Geochemistry》2011,(1):39-52

The effective influence of industry or ultramafic rocks by natural processes to soil, plants and groundwater contamination by chromium, which is often a subject of debate, was investigated for the case of the Assopos basin, Greece. The Neogene Assopos basin, is mainly composed by Tertiary and Quaternary sediments of more than 400 m thick and is characterized by brittle type deformation (fault zones, faults). Chromium in soil, ranging from 67 to 204 ppm, is mostly hosted in chromite, Fe-chromite, Cr-bearing goethite and silicates.Special attention was given to the plants, which are a major source of organic matter that serves as the driving force for Cr(VI) reduction. The increase of the Fe, Mn and Ni contents, with the increasing Cr content in the plant-roots, in particular at the external parts of roots and those of bulb-type plants, suggest reduction and immobilization of Cr(VI) and that redox reactions play a significant role to the translocation processes from root to shoot.Groundwater samples from the Assopos aquifer showed a wide spatial variability, ranging from <2 to 180 ppb Cr_total content [almost same to the Cr(VI)-values] despite their spatial association. The presence of Cr(VI)-contaminated groundwater at depths >200 m is attributed to a direct injection of Cr(VI)-rich industrial wastes at depth rather than that Cr(VI) is derived from the Assopos river or by the interaction between water and Cr-bearing rocks. The heterogeneous distribution of Cr in groundwater may be related with the intense neotectonic deformation, as is exemplified by several sharp tectonic contacts between sediment types, while the Cr content in soil is mostly depend on the transported chromite grains.  相似文献   

东天山海相火山岩型铁矿区域成矿规律研究   总被引：7，自引：0，他引：7  

徐仕琪  赵同阳  冯京  高永峰  田江涛  杨在峰  刘德权 《新疆地质》2011,29(2):173-177

选择东天山阿齐山-雅满苏-沙泉子一带海相火山岩型铁矿区作为研究区,从区域成矿地质背景入手,首先分析古火山机体成矿构造聚敛场、海盆成矿构造聚敛场对海相火山岩型铁矿的控制作用,依次总结了沉积岩相建造、火山岩建造、侵入岩、变质作用对铁矿的控制作用,最后全面系统的总结出东天山地区海相火山岩型铁矿在时间和空间上成矿规律和演化过程,指明该类型铁矿在宏观场和微观场中的识别标志,对该区域海相火山岩型铁矿勘查工作提供一定技术指导.  相似文献   

Hydrology and plant survival in excavated depressions near an earthen dam in north-central Texas     

Lynde L. Williams  Paul F. Hudak 《Environmental Geology》2005,48(6):795-804

This investigation examined plant survival and water sources for small depressions excavated to build an earthen dam and nature trail in north-central Texas, USA. These “inadvertent wetlands” occupy part of an outdoor education facility, overlying alluvial deposits of the Trinity River. A large lake behind the earthen dam strongly influences surface water and groundwater levels in the area. Excavated depressions receive direct precipitation, runoff, and groundwater inputs, losing water by seepage and evapotranspiration. Hydroperiods varied with location and water input: excavations receiving groundwater held water year round; others periodically desiccated. Groundwater-fed depressions had higher salinity; however, the highest average value (1,304 μS/cm) was within the freshwater range. A total of 66 to 75% of emergent and floating wetland species planted in three depressions survived after 2 years. The developing wetlands appear viable under hydrologic conditions typical of the study period. Ultimately, variable hydroperiods among wetlands, and water level fluctuations within individual wetlands, may foster diverse plant-species compositions. Depressed lake levels following long-term drought or increased water demands pose the greatest threat to the developing wetlands.  相似文献