931 resultados para Seed morpholgy


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本文研究了茄科天仙子族7属以及有亲缘关系的颠茄属、茄参属和枸杞属的形态学、解剖学、孢粉学、种子形态学、胚胎学、花器官发生、分子系统学和分支系统学;论述了它们的结构、分化和系统关系。主要内容包括: 1.解剖学 在光学显微镜和扫描电镜下,观察了茄科天仙子族(Hyoscyameae)7属21种及邻近4属4种共25种植物的叶表皮特征,结果表明:气孔器在各种植物的上、下的表皮均有分布,多为无规则型,也有不等细胞型;叶表皮细胞形状有不规则形、十字形、近长圆形和不规则多边形,垂周壁较平直或各种波状。叶表皮气孔器外拱盖内缘近平滑、浅波状或波状;角质膜多为具条纹,也有同时具条纹和颗粒或鳞片,偶尔仅具颗粒和鳞片或光滑。气孔器类型可以作为区分部分属的依据之一。颠茄叶表皮细胞形状和垂周壁式样在一些属和种中有一定的规律性,并与外部形态、孢粉学性状或地理分布相关;叶片表面角质膜的特征对属和种的划分也有一定意义。 2.种子形态学 在扫描电子显微镜下首次全面研究了天仙子族及颠茄属和茄参属等共10属25种植物的种子形态学特征,结果表明: 该族植物种子表面纹饰有脑纹状或近脑纹状和网状两大类,除了山莨菪属Anisodus和Hyoscyamus.pusillus 外,其余类群均为网状。外种皮细胞形状和周壁式样有两大类,一类为多边形至近圆形,等径,周壁近平直,另一类为形状不规则,常不等径,周壁为各式波状;外种皮细胞周壁内侧有皱波状、瘤状、小颗粒、片状或小刺等各式附属物。各属植物的种子大小、形状及种脐着生位置的系统学意义不大。但是,种脐突出与否、种子外种皮细胞形状和周壁式样,尤其是周壁内侧附属物等性状具有较大的分类学意义。 3.孢粉学 在扫描电镜下研究了该族7属及其它3属共10属23种植物的花粉形态学特征。结果表明:天仙子族的花粉粒形状为球形、近球形、扁球形和长球形;萌发孔类型有无萌发孔、不规则的拟孔、3沟、4 沟、3- 4沟、散沟和3孔沟;外壁纹饰为小刺状、瘤状、各式条纹状、条纹-穴状、条纹-网状、皱波状、细网状和网状。沟膜近光滑、具小颗粒、具小刺状突起或具瘤状突起。各属植物的花粉形态在萌发孔的有无、萌发孔的类型和外壁纹饰等方面有较大的差异,可以作为探讨属间分类和系统关系的重要依据。天仙子族植物花粉萌发孔的演化趋势为:无萌发孔→ 3、4沟→3孔沟。无萌发孔的山莨菪属是原始类群,三孔沟的马尿泡和天仙子等属是进化类群。 4.胚胎学 本论文首次研究了天仙子族山莨菪Anisodus tanguticus的胚胎学特征,结果表明:山莨菪的小孢子形成为同时型,腺质绒毡层;胚珠半倒生,单珠被,薄珠心;蓼型胚囊;其胚胎发生类型可能为茄型;胚乳形成为细胞型。山莨菪的胚胎学性状与马尿泡十分相似。胚胎学证据支持山莨菪属与马尿泡属关系密切的观点。 5.花器官发生 首次全面研究了天仙子族的山莨菪属(山莨菪)、马尿泡属(马尿泡)、天仙子属(天仙子)及其邻近2属共5种植物的花器官发生特征,结果表明:山莨菪和天仙子的5个花萼裂片原基突起最早发生,且几乎是近同时环状发生,其排列方式从花发育早期直至花成熟后始终为轮状排列。而马尿泡和颠茄首先是5个花萼裂片原基突起依次螺旋状发生,但在其5个花萼裂片原基都出现后,其排列方式仍为轮状排列。不同之处是:马尿泡的花萼裂片原基在其花冠裂片原基刚刚不明显地发生时,就已经在基部联合并形成了一个环,而颠茄的花萼裂片原基直到雄蕊原基突起开始发生并较明显时,花萼裂片原基仍然是分离的,当花顶的中央开始出现很不明显的雌蕊原基的凹陷时,花萼裂片原基才开始联合。青海茄参与其它4种植物的不同之处在于柱头2裂或3裂,而后4者的柱头均为2裂。花器官发生的特征表明马尿泡与天仙子和山莨菪的关系较近。 6.基于叶绿体DNA trnL-F序列和核糖体DNA ITS序列的初步分析 以宁夏枸杞作为外类群,对代表天仙子族及其邻近3属的10种植物的ITS区和trnL-F序列进行了测定,将这两个序列结合构建系统树。将gaps作为fifth base处理时,马尿泡属和茄参属构成最基部的一支,赛莨菪属和天仙子属构成一支然后与泡囊草属构成姐妹群,另外一支由天蓬子属、颠茄属和山莨菪属组成,其中天蓬子属与颠茄属构成一支后与山莨菪属构成姐妹群。分子证据只是一个尝试,还不足以说明天仙子族各属的系统关系。 7.分支分析 以枸杞属为外类群,基于形态学、叶表皮、种子形态学、孢粉学等特征对天仙子族7属及颠茄属和茄参属进行了分支分析。结果表明:目前公认的天仙子族7属构成一个单系类群,而颠茄属和茄参属并没有包括在内,它们两者构成一支,并与天仙子族形成姐妹群的关系。这与该族传统的分类结果相一致。 8.天仙子族的分化和系统关系 基于上述研究结果,结合天仙子族各属的现代地理分布,讨论了各属的分化和系统关系。认为根据传统分类包括有7个属的天仙子族是一个自然的单系类群,目前还没有足够的证据说明是否应该将颠茄属和茄参属放在天仙子族中。

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Sequences of two chloroplast photosystem genes, psaA and psbB, together comprising about 3,500 bp, were obtained for all five major groups of extant seed plants and several outgroups among other vascular plants. Strongly supported, but significantly conflicting, phylogenetic signals were obtained in parsimony analyses from partitions of the data into first and second codon positions versus third positions. In the former, both genes agreed on a monophyletic gymnosperms, with Gnetales closely related to certain conifers. In the latter, Gnetales are inferred to be the sister group of all other seed plants, with gymnosperms paraphyletic. None of the data supported the modern ‘‘anthophyte hypothesis,’’ which places Gnetales as the sister group of flowering plants. A series of simulation studies were undertaken to examine the error rate for parsimony inference. Three kinds of errors were examined: random error, systematic bias (both properties of finite data sets), and statistical inconsistency owing to long-branch attraction (an asymptotic property). Parsimony reconstructions were extremely biased for third-position data for psbB. Regardless of the true underlying tree, a tree in which Gnetales are sister to all other seed plants was likely to be reconstructed for these data. None of the combinations of genes or partitions permits the anthophyte tree to be reconstructed with high probability. Simulations of progressively larger data sets indicate the existence of long-branch attraction (statistical inconsistency) for third-position psbB data if either the anthophyte tree or the gymnosperm tree is correct. This is also true for the anthophyte tree using either psaA third positions or psbB first and second positions. A factor contributing to bias and inconsistency is extremely short branches at the base of the seed plant radiation, coupled with extremely high rates in Gnetales and nonseed plant outgroups. M. J. Sanderson,* M. F. Wojciechowski,*† J.-M. Hu,* T. Sher Khan,* and S. G. Brady

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Within the Australian wet tropics bioregion, only 900 000 hectares of once continuous rainforest habitat between Townsville and Cooktown now remains. While on the Atherton Tableland, only 4% of the rainforest that once occurred there remains today with remnant vegetation now forming a matrix of rainforest dispersed within agricultural land (sugarcane, banana, orchard crops, townships and pastoral land). Some biologists have suggested that remnants often support both faunal and floral communities that differ significantly from remaining continuous forest. Australian tropical forests possess a relatively high diversity of native small mammal species particularly rodents, which unlike larger mammalian and avian frugivores elsewhere, have been shown to be resilient to the effects of fragmentation, patch isolation and reduction in patch size. While small mammals often become the dominant mammalian frugivores, in terms of their relative abundance, the relationship that exists between habitat diversity and structure, and the impacts of small mammal foraging within fragmented habitat patches in Australia, is still poorly understood. The relationship between foraging behaviour and demography of two small mammal species, Rattus fuscipes and Melomys cervinipes, and food resources in fragmented rainforest sites, were investigated in the current study. Population densities of both species were strongly related with overall density of seed resources in all rainforest fragments. The distribution of both mammal species however, was found to be independent of the distribution of seed resources. Seed utilisation trials indicated that M.cervinipes and R.fuscipes had less impact on seed resources (extent of seed harvesting) than did other rainforest frugivores. Experimental feeding trials demonstrated that in 85% of fruit species tested, rodent feeding increased seed germination by a factor of 3.5 suggesting that in Australian tropical rainforest remnants, small mammals may play a significant role in enhancing germination of large seeded fruits. This study has emphasised the role of small mammals in tropical rainforest systems in north eastern Australia, in particular, the role that they play within isolated forest fragments where larger frugivorous species may be absent.

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Abstract Seed-transmissibility of brood bean stain virus (BBSV) was investigated in a number of wild legume species. Genninating axes of seeds coliected from BBSV -infected plants were tested by the enzyme-linked immunosorbent assay (ELISA). The virus was found to be seedtransmitted in Vida pal«stina.

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Recent theoretical research has shown that ocean currents and wind interact to disperse seeds over long distances among isolated landmasses. Dispersal of seeds among isolated oceanic islands, by birds, oceans and man, is a well-known phenomenon, and many widespread island plants have traits that facilitate this process. Crucially, however, there have been no mechanistic vector-based models of long-distance dispersal for seeds among isolated oceanic islands based on empirical data. Here, we propose a plan to develop seed analogues, or pseudoseeds, fitted with wireless sensor technology that will enable high-fidelity tracking as they disperse across the ocean. The pseudoseeds will be precisely designed to mimic actual seed buoyancy and morphology enabling realistic and accurate, vector-based dispersal models of ocean seed dispersal over vast geographic scales.

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At St Thomas' Hospital, we have developed a computer program on a Titan graphics supercomputer to plan the stereotactic implantation of iodine-125 seeds for the palliative treatment of recurrent malignant gliomas. Use of the Gill-Thomas-Cosman relocatable frame allows planning and surgery to be carried out at different hospitals on different days. Stereotactic computed tomography (CT) and positron emission tomography (PET) scans are performed and the images transferred to the planning computer. The head, tumour and frame fiducials are outlined on the relevant images, and a three-dimensional model generated. Structures which could interfere with the surgery or radiotherapy, such as major vessels, shunt tubing etc., can also be outlined and included in the display. Catheter target and entry points are set using a three-dimensional cursor controlled by a set of dials attached to the computer. The program calculates and displays the radiation dose distribution within the target volume for various catheter and seed arrangements. The CT co-ordinates of the fiducial rods are used to convert catheter co-ordinates from CT space to frame space and to calculate the catheter insertion angles and depths. The surgically implanted catheters are after-loaded the next day and the seeds left in place for between 4 and 6 days, giving a nominal dose of 50 Gy to the edge of the target volume. 25 patients have been treated so far.

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The renovation of biomass waste in the form of date seed waste into activated carbon and biofuel by fixed bed pyrolysis reactor has been focused in this study to obtain gaseous, liquid, and solid products. The date seed in particle form is pyrolysed in an externally heated fixed bed reactor with nitrogen as the carrier gas. The reactor is heated from 400◦C to 600◦C. A maximum liquid yield of 50wt.% and char of 30wt.% are obtained at a reactor bed temperature of 500◦C with a running time of 120 minutes. The oil is found to possess favorable flash point and reasonable density and viscosity. The higher calorific value is found to be 28.636 MJ/kg which is significantly higher than other biomass derived. Decolonization of 85–97% is recorded for the textile effluent and 75–90% for the tannery effluent, in all cases decreasing with temperature increase. Good adsorption capacity of the prepared activated carbon in case of diluted textile and tannery effluent was found.

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The conversion of biomass waste in the form of date seed into pyrolysis oil by fixed bed pyrolysis reactor has been taken into consideration in this study. A fixed bed pyrolysis has been designed and fabricated for obtaining liquid fuel from these date seeds. The major component of the system are fixed bed pyrolysis reactor, liquid condenser and liquid collector. The date seed in particle form is pyrolysed in an externally heated 7.6 cm diameter and 46 cm high fixed bed reactor with nitrogen as the carrier gas. The reactor is heated by means of a biomass source cylindrical heater from 4000C to 6000C. The products are oil, char and gas. The reactor bed temperature, running time and feed particle size are considered as process parameters. The parameters are found to influence the product yield significantly. A maximum liquid yield of 50 wt.% is obtained at a reactor bed temperature of 5000 C for a feed size volume of 0.11- 0.20 cm3 with a running time of 120 minutes. The pyrolysis oil obtained at this optimum process conditions are analyzed for some fuel properties and compared with some other biomass derived pyrolysis oils and also with conventional fuels. The oil is found to possess favorable flash point and reasonable density and viscosity. The higher calorific value is found to be 28.636 MJ/kg which is significantly higher than other biomass derived pyrolysis oils.

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This work investigated the production of bio oil from plum seed (Zyziphus jujuba) by fixed bed pyrolysis technology. A fixed bed pyrolysis system has been designed and fabricated for production of bio oil. The major components of the system are: fixed bed reactor, liquid condenser and liquid collector. Nitrogen gas was used to maintain the inert atmosphere in the reactor where the pyrolysis reaction takes place. The feedstock considered in this study is plum seed as it is available waste material in Bangladesh. The reactor is heated by means of a cylindrical biomass external heater. Rice husk was used as the energy source. The products are oil, char and gas. The parameters varied are reactor bed temperature, running time and feed particle size. The parameters are found to influence the product yields significantly. The maximum liquid yield of 39 wt% at 5200C for a feed particle size of 2.36-4.75 mm and a gas flow rate of 8 liter/min with a running time of 120 minute. The pyrolysis oil obtained at these optimum process conditions are analyzed for some of their properties as an alternative fuel. The density of the liquid was closer with diesel. The viscosity of the plum seed liquid was lower than that of the conventional fuels. The calorific value of the pyrolysis oil is one half of the diesel fuel.

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The conversion of tamarind seeds into pyrolytic oil by fixed bed fire-tube heating reactor has been taken into consideration in this study. The major components of the system were fixed bed fire-tube heating reactor, liquid condenser and collectors. The raw and crushed tamarind seed in particle form was pyrolized in an electrically heated 10 cm diameter and 27 cm high fixed bed reactor. The products are oil, char and gases. The parameters varied were reactor bed temperature, running time, gas flow rate and feed particle size. The parameters were found to influence the product yields significantly. The maximum liquid yield was 45 wt% at 4000C for a feed size of 1.07cm3 at a gas flow rate of 6 liter/min with a running time of 30 minute. The pyrolysis oil was obtained at these optimum process conditions were analyzed for physical and chemical properties to be used as an alternative fuel.

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Among various thermo-chemical conversion processes, pyrolysis is considered as an emerging technology for liquid oil production. The conversion of biomass waste in the form of plum seed into pyrolysis oil by fixed bed pyrolysis reactor has been taken into consideration in this study. A fixed bed pyrolysis has been designed and fabricated for obtaining liquid fuel from this plum seeds. The major component of the system are fixed bed pyrolysis reactor, liquid condenser and liquid collectors. The plum seed in particle form is pyrolysed in an externally heated 7.6 cm diameter and 46 cm high fixed bed reactor with nitrogen as the carrier gas. The reactor is heated by means of a biomass source cylindrical heater from 4000C to 6000C. The products are oil, char and gas. The reactor bed temperature, running time and feed particle size are considered as process parameters. The parameters are found to influence the product yield significantly. A maximum liquid yield of 39 wt% of biomass feed is obtained with particle size of 2.36-4.75 mm at a reactor bed temperature of 520oC with a running time of 120 minutes. The pyrolysis oil obtained at this optimum process conditions are analyzed for some fuel properties and compared with some other biomass derived pyrolysis oils and conventional fuels. The oil is found to possess favorable flash point and reasonable density and viscosity. The higher calorific value is found to be 22.39 MJ/kg which is higher than other biomass derived pyrolysis oils.

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The renovation of biomass waste in the form of Mahogany seed waste into bio-fuel as well as activated carbon by fixed bed pyrolysis reactor has been taken into consideration in this study. The mahogany seed in particle form is pyrolyzed in an enormously heated fixed bed reactor with nitrogen as the carrier gas. The reactor is heated from 4000C to 6000C using a external heater in which rice husk and charcoal are used as the heater biomass fuel. Reactor bed temperature, running time and feed particle size have been varied to get the optimum operating conditions of the system. The parameters are found to influence the product yields to a large extent. A maximum liquid and char yield are 49 wt. % and 35 wt. % respectively obtained at a reactor bed temperature 5000C when the running time is 90 minutes. Acquired pyrolyzed oil at these optimal process conditions were analyzed for some of their properties as an alternative fuel. The oil possesses comparable flame temperature, favorable flash point and reasonable viscosity along with somewhat higher density. The kinematic viscosity of the derived fuel is 3.8 cSt and density is 1525 kg/m3. The higher calorific value is found 32.4 MJ/kg which is significantly higher than other biomass derived fuel. Moderate adsorption capacity of the prepared activated carbon in case of methyl blue & tea water was also revealed.