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1.
Biological control of thrips [Thysanoptera: Thripidae] on greenhouse cucumber byAmblyseius cucumeris
D. R. Gillespie 《BioControl》1989,34(2):185-192
The predatory miteAmblyseius cucumeris (Oudemans) [Acarina: Phytoseiidae] was evaluated as a biological control forThrips tabaci Lindeman andFrankliniella occidentalis (Pergande) [Thysanoptera: Thripidae] on greenhouse grown seedless cucumber.A. cucumeris spread throughout the greenhouses and provided control of both species of thrips.A. cucumeris adults persisted on plants for 7 weeks in the virtual absence of prey, and increased numerically in response to increases
in prey population. On the basis of these resultsA. cucumeris is recommended as a useful biological control forT. tabaci andF. occidentalis on greenhouse cucumber.
Publication No. 361, Agassiz Research Station, Agriculture Canada, Agassiz, B.C. Canada VOM 1AO. 相似文献
2.
Somaclonal variation as a tool to develop pest resistant plants of Torenia fournieri ‘Compacta Blue’
Callus cultures of Torenia fournieri Compacta Blue were initiated on a modified Murashige and Skoog salt medium (MS) with 2.26 M 2,4-dichlorophenoxyacetic acid. Shoots were regenerated from these cultures using MS medium amended with 2.46 M indolebutyric acid and 8.88 M benzyladenine. These shoot cultures were subjected to two-spotted spidermite (Tetranychus urticae Koch.) and the greenhouse whitefly [Trialeurodes vaporariorum (Westwood)]. Pests were allowed to feed until such time that their populations started to decrease due to lack of food. The remaining live tissue of the Torenia was placed on MS medium amended with 2.28 M zeatin to induce new adventitious shoots and plantlets. Newly regenerated plantlets were acclimated to greenhouse conditions and evaluated for resistance to the pest to which they were subjected in vitro. Highly significant differences in pest numbers were found in somaclones for both the two-spotted spidermite and greenhouse whitefly when compared to control plants. A wide range of variability was observed among the somaclonal population. There were significantly fewer mite eggs laid on plants regenerated from in vitro cultures screened with two-spotted spidermites than on seed sown controls. Regenerants from cultures screened with whiteflies in vitro had fewer eggs, immatures and live adults than controls.Abbreviations BA
benzyladenine
- IBA
indolebutyric acid
- 2,4-d
2,4-dichlorophenoxyacetic acid
- MS
Murashige and Skoog salt medium
Storrs Agricultural Research Station Scientific Publication 1641. 相似文献
3.
Summary Calculations indicate that the maximum daily solar radiation reaching the Martian surface is about 325 cal/cm2 during southern hemisphere summer at latitude of about 40°S. In the ultraviolet region of the spectrum, the radiation reaching the surface at wavelengths greater than 2800 Å is within 10% of the radiation incident on the atmosphere. There is significant extinction of radiation in the spectral region near 2500 Å in mid and high latitudes due to absorption of radiation by ozone; radiation reaching the surface may be reduced to one one-thousandth of that incident on the atmosphere during winter. Virtually no radiation of wavelengths less than 1900 Å reaches the surface because of absorption by the large column abundance of carbon dioxide. Daily and latitudinal distributions of radiation are presented for wavelengths of 3000, 2500 and 2000 Å. 相似文献
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5.
Summary Plant communities in the Mediterranean region have been analyzed with the emphasis on community processes regulating diversity trends. We want to know how several mechanisms that contribute to the maintenance or to the modification of species diversity, act: (i) in different communities, during an ecological succession (from old fields to forests), and (ii) in forest communities throughout the year. Some of these mechanisms were investigated through difference in stratification, life-form, phenology, dispersal agent, and microenvironmental gradient.The paper censists of two parts. The first one deals with the relationship between structural and biological diversity in conjunction with succession stages leading to a Quereus pubescens forest. It is concluded that diversity, however it is measured, fluctuates during the succession: it increases initially (15 years after abandonment) and also in later stages when trees appear in the fields; it decreases after 20 years when Brachypodium phoenicoides dominates and in the latest stages of the succession studied. These trends may be interpreted in relation to the evolution of life form and dispersal agents spectra during the succession.The second part concerns community-structure and biological diversity in relation to the organization of two Quercus pubescens forests. It appears that the species richness in the understory of the forests, may be explained by: (i) the tendency of the modal height of species foliage distribution to oceupy different positions, (ii) the quasicomplete asynchronism in the major phenophases of the dominant species, (iii) different horizontal patterns of species distribution along a light gradient.These schemes are discussed in relation to ecological hypotheses on diversity in relation to succession, and to community organization.Nomenelature follows: P. Fournier (1961). Les quatre flores de France for the Gramineae and Liliaceae, Flora Europea for the other taxa.The support of the Délégation de la Recherche Scientifique et Technique through the grants N567, N633, N674 (Structure et dynamique des formations à Chène pubescent en zone bioclimatique méditerranéenne) is acknowledged. We thank J. Biondel, R. Bonhomme and M. Dueray for technical and scientific assistance. We are greatly indebted to Dr. E. van der Maarel for his helpful improvements of this text. 相似文献
6.
高纬度和高海拔区为气候变化敏感区,该区域湿地碳循环与气候反馈关系倍受关注。为探究在全球变暖背景下高海拔区沼泽湿地碳源/汇功能是否发生了转化,以长白山高海拔区沿水分环境梯度分布的5种沼泽类型(草丛沼泽-C、灌丛沼泽-G、落叶松泥炭藓沼泽-LN、落叶松藓类沼泽-LX、落叶松苔草沼泽-LT)为对象,采用静态箱-气相色谱法和相对生长方程法,同步测定各沼泽类型全年尺度上的土壤异养呼吸碳排放量(CO2和CH4)、植被年净固碳量及相关环境因子(温度、水位和土壤有机碳等),并依据生态系统净碳收支平衡,量化各沼泽类型的碳源/汇作用,揭示其沿水分环境梯度变化规律及形成机制。结果表明:(1)5种沼泽类型土壤CO2年均通量((97.68±8.64)—(291.01±18.31)mg m-2 h-1)沿水分环境梯度呈阶梯式递增规律性(环境梯度上部生境地段的落叶松苔草沼泽和落叶松藓类沼泽最高,中部生境地段的落叶松泥炭藓沼泽和灌丛沼泽居中,草丛沼泽最低);(2)CH4年均通量((-0.... 相似文献
7.
微塑料因在土壤环境中广泛存在及其潜在的生态风险而受到越来越多的关注。微塑料的赋存会改变土壤理化性质,并对土壤微生物群落及其驱动的生物地球化学过程产生影响,而相关研究尚处于起步阶段。可生物降解塑料作为传统塑料的替代品,越来越多地应用于农业活动,并释放到土壤中。然而,可生物降解微塑料对土壤微生物特性产生影响的研究鲜有报道。基于此,本试验以我国三江平原水稻田土壤为研究对象,选取了2种常见的微塑料为试验材料,分别为传统型微塑料聚丙烯(Polypropylene,PP)和可降解微塑料聚乳酸(Polylactic acid,PLA),进行了为期41d的微宇宙培养实验,旨在分析不同浓度与类型的微塑料对土壤可溶性有机碳(Dissolved Organic Carbon,DOC)含量及官能团特征、温室气体排放以及微生物群落结构的差异性影响。结果表明,传统型微塑料PP与可降解微塑料PLA添加均对土壤理化性质与微生物群落产生显著影响。其中,微塑料添加大体上增加了土壤DOC含量,PLA的促进作用较为明显,且增加含量与微塑料添加量呈正相关;PP和PLA均影响土壤DOC分子结构,削弱了土壤团聚化程度并促进了大分子量DOC化合物的生成;微塑料的添加促进土壤CH4排放,而有效抑制了土壤CO2排放;微塑料显著改变了土壤细菌和真菌群落的丰富度与多样性。相关分析结果表明,土壤CO2累计排放量与芳香族化合物结构及疏水性等官能团特征、变形菌门(Proteobacteria)与放线菌门(Actinobacteria)均呈显著正相关关系。以上结果表明,微塑料添加改变了土壤DOC含量及官能团特征与微生物环境,进而影响土壤温室气体排放。本研究为今后微塑料对土壤地球化学和微生物特性的影响研究提供了科学的思路,同时也有助于评估微塑料对土壤生态系统的生态风险。 相似文献
8.
David S. Duncan Lawrence G. Oates Ilya Gelfand Neville Millar G. Philip Robertson Randall D. Jackson 《Global Change Biology Bioenergy》2019,11(2):416-426
Nitrous oxide (N2O) is a potent greenhouse gas and major component of the net global warming potential of bioenergy feedstock cropping systems. Numerous environmental factors influence soil N2O production, making direct correlation difficult to any one factor of N2O fluxes under field conditions. We instead employed quantile regression to evaluate whether soil temperature, water‐filled pore space (WFPS), and concentrations of soil nitrate () and ammonium () determined upper bounds for soil N2O flux magnitudes. We collected data over 6 years from a range of bioenergy feedstock cropping systems including no‐till grain crops, perennial warm‐season grasses, hybrid poplar, and polycultures of tallgrass prairie species each with and without nitrogen (N) addition grown at two sites. The upper bounds for soil N2O fluxes had a significant and positive correlation with all four environmental factors, although relatively large fluxes were still possible at minimal values for nearly all factors. The correlation with was generally weaker, suggesting it is less important than in driving large fluxes. Quantile regression slopes were generally lower for unfertilized perennials than for other systems, but this may have resulted from a perpetual state of nitrogen limitation, which prevented other factors from being clear constraints. This framework suggests efforts to reduce concentrations of in the soil may be effective at reducing high‐intensity periods—”hot moments”—of N2O production. 相似文献
9.
森林土壤是CO2、CH4和N2O等温室气体的主要排放源.本研究采用静态箱/色谱分析技术,对中国科学院鹤山丘陵综合开放试验站内厚荚相思林土壤CO2、CH4和N2O通量进行原位测定,研究剔除林下灌草和添加翅荚决明对土壤温室气体排放的影响.结果表明:厚荚相思林土壤CO2通量在湿季维持较高水平,在旱季则明显降低.CH4和N2O在9-11月波动幅度较大,峰值出现在10月.在不同处理下,厚荚相思林土壤可能是CH4的源也可能是CH4的汇,而于CO2和N2O则是源.林下剔除灌草能显著增大土壤CO2排放(P<0.05),而添加翅荚决明能加快土壤CH4的排放(P<0.05).林下剔除灌草及添加翅荚决明两种处理都能够加大N2O的排放通量.表层土壤温度、湿度、NO3--N和微生物生物量碳都是影响土壤温室气体排放的重要因子. 相似文献
10.