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1.
亚热带丘陵茶园间作白三叶草的生态效应   总被引:33,自引:0,他引:33  
在亚热带丘陵区1a生幼龄茶园通过连续4a的大田对比试验,研究了茶园间作白三叶草的生态效应,结果发现:茶园间作白三叶草降低了土壤容重,提高了土壤孔隙度、有机质、全N、水解N的含量、K的活性、蚯蚓的数量和生物量,消耗了部分有效P;增加了土壤关键层次(0—20cm)和关键时期(4~6月)的水分含量,延缓和缩短了夏季高温干旱与秋季持续干旱时间;获得了土壤降温时增温、保温与升温时降温的双向动态调控效果,增加了同一层次土壤温度的稳定性,延缓了高温和低温的出现时间,缩短了过度高温时间,减少了高温对茶树生长产生的影响;抑制了杂草生长,增加了天敌的种类和种群数量,减少了虫害发生率。从而形成了立地环境.茶树.伴生生物群落系统自我调节的动态平衡,促进了茶树生长,改善了茶叶品质,显著增加了茶叶产量。与清耕茶园相比,茶园间作白三叶草后,春秋茶的酚氨比分别下降了17.10%和30.90%,产量提高了32.65%。  相似文献   

2.
伊克昭盟项目区水土保持的生态效益   总被引:4,自引:0,他引:4  
根据对伊克昭盟世行项目区的监测数据,分析了项目实施后水土保持的生态效益。结果表明,项目实施后,改善了土壤的理化性质,增加了土壤肥力;同时,提高了当地的林草植被覆盖度,改善了局地气候,促进了生物多样性的恢复和保护。  相似文献   

3.
亚热带丘陵茶园间作白三叶的土壤环境调控效果   总被引:16,自引:1,他引:15  
在亚热带丘陵区1年生幼龄茶园通过连续4年间作白三叶大田试验,研究了其对茶园土壤环境及茶叶品质、产量的影响,结果表明,茶园间作白三叶降低了土壤容重,提高了土壤孔隙度、有机质、全氮、水解氮的含量及钾的活性,消耗了部分有效磷;增加了土壤关键层次(0~20cm)和关键时期(4~6月)的水分含量,延缓和缩短了夏季高温干旱与秋季持续干旱时间;获得了土壤降温时增温、保温与升温时降温的双向动态调控效果.增加了同一层次土壤温度的稳定性,延缓了高温和低温的出现时间,缩短了过度高温时间。从而促进了茶树生长,改善了茶叶品质,显著增加了茶叶产量。与清耕茶园相比,茶园间作白三叶后,春秋茶的酚氨比分别下降了17.10%和30.90%,产量提高了32.65%。  相似文献   

4.
花菇的冷冻干燥技术研究   总被引:1,自引:0,他引:1  
实验研究用板层导热法研究了花菇的冻干特性,获得了新鲜花菇的冻干曲线,分析了花菇冻干过程,测定和比较了新鲜花菇和冻干花菇的营养成份。证实试验机的适应性并确定了花菇的冻干工艺,为工业生产提供了理论依据和参考价值。  相似文献   

5.
对华北落叶松鞘蛾和兴安落叶松鞘蛾的形态特征进行了研究,与容易混淆的欧洲落叶松鞘蛾进行了比较。更正了兴安落叶松鞘蛾的学名,肯定了华北落叶松鞘蛾的分类学地位,并进行了重新描述。文中提供了以上3种落叶松鞘蛾的成虫、雌雄外生殖器等特征图,给出了它们的区别要点。  相似文献   

6.
由于鸡本身的众多优点,转基因鸡的研究逐渐受到了研究者的重视,简要介绍了转基因鸡的发展史,对各种转基因技术方法进行了比较和分析,提出了每种方法的优缺点,尤其在精子介导法上作了较为详细的论述,并展望了转基因鸡的应用前景。  相似文献   

7.
远程教育培训给生物教学带来新的生机。夯实了专业知识,梳理了生物知识,使我认识到应该如何把握生物课堂教学,提高了课堂教学设计能力,凝聚了生物教师的力量,使老师们学到了很多知识和教学技能,解决了平时教学中的一些难题,提升了生物的教学水平。  相似文献   

8.
上海市细胞生物学学会于1986年12月26日至27日在上海召开了年会。26日上午举行了年会开幕式,会上由庄孝僡理事长致开幕词,胡兆庆秘书长作了学会的工作报告。大会并邀请了细胞生物学研究所王亚辉所长作了细胞生物学的趋向和发展战略的报告。有150余人参加了会议。26日下午和27日上午进行了分组论文报告,共报告了64篇论文,年会显示了近年来上海市细胞生物学研究取得的成就。会议期间还邀请了下述同志作了小组专题报告。庄孝僡:关于中胚层的决定和分化的问题;顾国彦:胞质分裂时蛙卵表面运动;鲍璿:体外培养神  相似文献   

9.
降脂红曲的菌学性质及化学成分的分析   总被引:4,自引:0,他引:4  
本文对No.4降脂红曲的生理特性进行了分析,测定了其一般的化学成分,将No.4红曲米的色调和色价与其它红曲米进行了对比,确定了该红曲的最适培养条件,制定了No.4红曲米的质量标准,并验证了它可作为糖化酶的生产菌。  相似文献   

10.
合理施肥对银杏园土壤肥力和酶活性的影响   总被引:2,自引:0,他引:2  
首次研究合理施肥对银杏园土壤肥力和酶活性的影响,结果表明合理施肥,改善了土壤理化性状,显著地提高了土壤肥力和土壤酶的活性;从而培育了银杏发达的根群,促进了树体的生长。增加了银杏鲜根重和百叶鲜重,减少了银杏黄化株率,提高了银杏挂果株率及种核的产量和品质。  相似文献   

11.
Phylogenetic definitions and taxonomic philosophy   总被引:4,自引:0,他引:4  
An examination of the post-Darwinian history of biological taxonomy reveals an implicit assumption that the definitions of taxon names consist of lists of organismal traits. That assumption represents a failure to grant the concept of evolution a central role in taxonomy, and it causes conflicts between traditional methods of defining taxon names and evolutionary concepts of taxa. Phylogenetic definitions of taxon names (de Queiroz and Gauthier 1990) grant the concept of common ancestry a central role in the definitions of taxon names and thus constitute an important step in the development of phylogenetic taxonomy. By treating phylogenetic relationships rather than organismal traits as necessary and sufficient properties, phylogenetic definitions remove conflicts between the definitions of taxon names and evolutionary concepts of taxa. The general method of definition represented by phylogenetic definitions of clade names can be applied to the names of other kinds of composite wholes, including populations and biological species. That the names of individuals (composite wholes) can be defined in terms of necessary and sufficient properties provides the foundation for a synthesis of seemingly incompatible positions held by contemporary individualists and essentialists concerning the nature of taxa and the definitions of taxon names.  相似文献   

12.
The fossil record of bryophytes is generally poor and infertile plants attributable to liverworts and mosses could also be thalloid vascular plant gametophytes or herbaceous lycophytes respectively. The paucity of the bryophytic record could be the result of relatively rapid degradation of bryophytic material in comparison to that of vascular plants, the absence of lignified cells in bryophytes sustaining this belief. However, certain organs of bryophytes are as robust as those of vascular plants (e.g. spores) and the hydroxybenzofuran polymers produced by some mosses could be of similar preservational resistance to lignins. A simplistic experiment to test the relative resistance to decay of bryophytic material has been undertaken. Its findings suggest that bryophytic plant material has a similar preservational potential to that of a selected vascular plant, particularly in organic rich sediments. This result may be construed to imply that bryophytes were indeed less abundant in the preservational environments of the Coal Measures than might be expected on the basis of current palaeoenvironmental reconstructions.  相似文献   

13.
Research on the influence of sea level variations on the benthic faunas have been carried out in the Upper Ordovician of Sardinia. Study of the depositional facies and sequence analysis of the upper part (Lower Ashgill) of the Portixeddu Formation led to the identification of the sedimentary environments. Cystoids and crinoids are associated to bryozoans and brachiopods in most levels. The numerical analysis of associations and megaguilds shows that crinoids and cystoids have a higher frequency in the proximal and median facies of the upper offshore. The columnal association characterized by Conspectocrinus celticus and the coronoid Mespilocystites tregarvanicus has been discovered in the upper part of the formation. This material and complementary samples from Upper Ordovician of Sardinia and Kabylia (Algeria) bring additional data on the systematic and show the wide distribution of this fauna outside of the Ibero-armorican domain. The distribution of this echinoderm association supports a palaeogeographical position of the Ibero-armorican domain and Sardinia within the north gondwanan margin during the Lower Palaeozoic.  相似文献   

14.
Found in Chiapas (South-East of Mexico), Praealveolina michaudi nov. sp. and Chubbina jamaicensis (of Campanian-Maestrichtian age) are described, both evolved from Nummoloculina sp. while Raadshoovenia guatemalensis (upper Paleocene-lower Eocene) arises from Quinqueloculina. We precisely analyze and modelize the nepionic coiling during the evolutionary change from Miliolacea to Alveolinacea. During ontogenesis as well as during phylogenesis, quinqueloculine coiling progresses to streptospiral and then to planispiral chamber arrangement with the increase of volume of embryo and of chambers. Appearance of these large foraminifers are understood as a consequence of the rise of K-strategies in their mode of life, following the development of photosynthetic symbioses.  相似文献   

15.
突变文库的构建是定向进化研究过程中一个关键步骤,主要利用天然存在的系统或者人工合成的分子技术来产生多样性核酸分子文库,为制备和筛选具有一定特性的蛋白酶、多肽、人工抗体等提供庞大的遗传基因库,也可用于合成生物学中相关基因元件的研究与筛选,为目标生物制品的高效工业化生产提供动力。随着对突变文库构建技术研究的日益深入,各种文库构建策略相继被开发出来,并在生物能源、生物化工、生物医药、生物试剂和食品工业等方面得到了广泛的应用。然而,定向进化中的文库构建策略多有不同,各种突变文库构建技术的核心方法也在不断创新。主要介绍近年来实验室中人工合成多样性文库的前沿技术,并对文库构建技术在自动化和智能化方向的发展进行了展望。  相似文献   

16.
A phylogenetic analysis of 123 morphological characters of basal waterfowl (Aves: Anseriformes) and other selected avian orders confirmed that the screamers (Anhimae: Anhitn-idae) are the sister-group of other waterfowl (Anseres), and that the magpie goose (Anseranatidae: Anseranas semipalmata) is the sister group of other modern waterfowl exclusive of screamers (Anatidae sensu stricto). The analysis also supports the traditional hypothesis of the gallinaceous birds (Galliformes) as the sister group of the Anseriformes. Presbyornis, a fossil from the early Eocene of Wyoming and averred by Olson & Feduccia as showing that the Anseriformes were derived from shorebirds (Charadriiformes), was found to represent the sister group of the Anatidae. Associated hypotheses by Olson & Feduccia concerning the implications of Presbyornis for the phylogenetic relationships of flamingos (Phoenicopteriformes), the position of the Anhimidae within the waterfowl, relationships among modern Anatidae, and a plausible evolutionary scenario for waterfowl also are rejected. Analyses revealed that cranial characters were critical to the establishment of the Galliformes as the sister group of the Anseriformes; exclusion of the Anhimidae, especially in combination with Anseranas, also undermined the support for this inference. Placement of Presbyornis as the sister group of the Anatidae casts doubt on the role suggested by Feduccia of ‘transitional shorebirds' in the origin of modern avian orders, and calls into question the concept of ‘fossil mosaics’. The phylogenetic hypothesis is used to reconstruct an evolutionary scenario for selected ecomorphological characters in the galliform-anseriform transition, to predict the most parsimonious states of these characters for Presbyornis, and to propose a phylogenetic classification of the higher-order taxa of waterfowl. This re-examination of Presbyornis also is used to exemplify the fundamental methodological shortcomings of the intuitive approach to the reconstruction of phylogenetic relationships.  相似文献   

17.
The archaeological excavation of the cave of the Gardon has brought to light a dilated and nearly continuous stratigraphy for the Neolithic era. The analysis of lithic industry has showed the existence of variations between those neolithic layers, which are independents of the technological processes of tools productions. Four criteria allow us to characterize the occupation’s type of each layer. Compared to the excavations data and to sedimentological analysis, these results allow us to display the evolution of the intensity of occupations of the cave throughout the whole Neolithic.  相似文献   

18.
The natural host range of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis can be defined as the range of insects which indigenous nematode populations use for propagation. Information on the natural host range is rare. However, based on records of insects found to be naturally infected with nematodes, some conclusions regarding the natural host range of some Steinernema spp. and Heterorhabditis spp. are presented. Reports of indigenous nematode populations impacting on insect populations can be divided between relatively balanced, long-lasting nematode-host associations and unbalanced, short-lasting epizootics. Examples of the augmentation and inoculative introduction of nematodes in agriculture and forestry ecosystems are presented. Based on current knowledge, nematode reproduction strategies are discussed and indications of the risk involved in the release of non-indigenous nematodes are given.  相似文献   

19.
The reference ranges of the trace elements Al, As, Be, B, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Li, Rb, Se, Sr, and Zn were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in sera of a group of free-ranging plains viscachas of the pampa grasslands of Argentina. The values were compared with those of a small group of captive plains viscachas of the Zurich Zoo with diabetes and bilateral cataracts. In addition, a method for digestion of whole-blood samples is described for the trace element determination. Significant differences in the concentration of trace elements in the two groups of animals are discussed. No correlation was found between the levels of selenium and of other trace elements compared to the formation of cataracts.  相似文献   

20.
The field slug, Deroceras reticulatum (Muller), is probably the most damaging and widespread species of slug, causing severe economic losses in a broad range of crops in temperate zones throughout the world. Investigations into the role of predation in the population dynamics of this species required a biochemical system which was capable of identifying the remains of this slug in the crop contents of predators, and distinguishing them from those of other molluscs. A monoclonal antibody was developed (IgM isotype). This was capable of separating, in an enzyme-linked immunosorbent assay, D. reticulatum from the related D. caruanae (Pollonera) and all molluscs and other invertebrates tested, with the unexpected exceptions of New Zealand flatworms, Artioposthia triangulata (Deny) and the millipede Polymicrodon polydesmoides (Leach). Characterization of the antibody and assay demonstrated that the system could clearly detect as little as 11.6 ng of D. reticulatum protein in 200 mu l of buffer. Slug remains could be identified as such in the crops of the carabid predator Pterostichus melanarius Illiger for 38.1 h, while the antibody-antigen reaction declined to half of that measured immediately following consumption, after 12.9 h. A practical and highly sensitive system was therefore developed, using the first species-specific monoclonal antibody available for the investigation of predation on slugs.  相似文献   

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