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以黄旦、福鼎大白茶、肉桂、毛蟹、铁观音鲜叶为原料,对其驻芽一、二、三叶进行力学特性及粗纤维含量的测定,研究表明,茶树嫩梢的弹性模量在4 158.88~14 849.11 kPa,最大应力在870.00~1 842.97 kPa,断裂应力在673.33~1 639.62 kPa,叶位对弹性模量、最大应力与断裂应力的影响达到极显著水平,大小排序为:三叶>二叶>一叶。茶树嫩梢最大力点应变在10.61%~18.36%,断裂应变在12.19%~26.95%,叶位对最大应力与断裂应力的影响达到极显著水平,大小排序为:三叶>二叶>一叶,不同品种有所差异。茶树嫩梢力学参数为茶叶加工机械设计提供了一定的参考价值。 相似文献
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叶片是茶树进行光合作用、蒸腾作用和气体交换的主要营养器官,也是栽培茶树的目的物。叶片的解剖结构是茶树一系列生理活动的基础,与物质代谢有密切的关系,因此,研究茶树不同叶位的解剖结构及其变化规律,具有重要意义。一般红绿茶的采摘标准,是当新梢长至一芽三叶时,采一芽二、三叶。笔者于今年春季,当福鼎大白茶(11足龄)春梢长至一芽三叶时,取芽下第一叶、第二叶、第三叶、鱼叶,和去年秋梢第一叶、第二叶、第三叶。经石蜡切片后,在光学显微镜下进行观察研究。现将观察研究的初步结果整理成文,供参考。 相似文献
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茶树离体春梢萎凋失水规律初步研究 总被引：2，自引：0，他引：2
茶鲜叶在萎凋过程中的水分变化是茶叶品质工艺调控的重要参数指标。为了解茶树离体春梢的萎凋失水特性,本文选用14份茶树品种的春茶鲜叶（一芽二、三叶和中小开面二至四叶）为供试原料,对其在控温控湿（20～22℃、RH35%～45%）条件下的萎凋失水变化进行跟踪监测。结果表明,伴随水分的不断散失,不同嫩度茶鲜叶失水速率逐步减小,趋近于匀减速变化;茶树新梢萎凋失水速率存在明显的品种差异,但不同茶树品种新梢失水快慢与采摘嫩度无明显相关性。相同采摘嫩度的茶树品种或名枞鲜叶按失水特性可初步划分为“失水较快”和“失水较慢”两种类型,其中具有亲缘关系品种（茗科1号、金牡丹、黄观音和黄棪）一芽二、三叶的萎凋失水表征基本相似,然而茶鲜叶萎凋失水速率并非完全由茶树品种或名枞的资源特性所决定。 相似文献
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茶树对铬、镉的吸收积累特性研究 总被引：3，自引：1，他引：2
通过水培实验,研究了茶树(3个品种)受铬(Cr3+)、镉(Cd2+)毒害的表观症状以及铬、镉在茶树体内的分布、积累特性。结果表明:铬(20~100mg/L)、镉(1~5mg/L)胁迫下,茶树出现的毒害症状和对新梢生长的抑制效应因胁迫浓度、时间和品种而异。茶树各器官的铬、镉含量总体随铬、镉胁迫浓度的增加而增加,并且与胁迫浓度呈极显著或显著正相关。铬在茶树体内由高到低的分布次序是:吸收根>主根>主茎>枝条>老叶>新梢(一芽二叶);镉则为:吸收根>主根>主茎>新梢(一芽二叶)>枝条>老叶。根部吸收的铬、镉元素大部分被吸收根所固定,向地上部运输的比例较低,但镉在茶树体内的活性和迁移能力强于铬,运输到地上部的镉极易迁移到新梢中。新梢不同叶位镉含量的高低顺序为:第一叶>第二叶>第三叶>第四叶,新梢中的镉有明显向上富集的趋势。不同品种的茶树对铬、镉的吸收、积累和迁移能力有一定差异。 相似文献
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用火焰原子吸收分光光度计测定茶树各不同部位铅的累积量。结果表明,茶树品种间和部位间的铅含量差异极显著,大叶种茶树的铅含量显著或极显著高于中小叶种茶树。茶树不同部位中铅含量地上部:生产枝>成熟叶>嫩梢,地下部:吸收根>细根,对于整株茶树而言,铅含量:生产枝>根>成熟叶>嫩梢。 相似文献
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测试分析不同适制乌龙茶品种(系)小至中开面的对夹二、三叶嫩梢茶叶铝含量,分析采摘时期对茶树新梢及茶汤铝含量的影响,阐明不同茶树品种及采摘时期对茶叶铝累积的影响并评价茶叶饮用安全.结果表明,福建省主栽适制乌龙茶品种(系)小至中开面的对夹二、三叶嫩梢茶叶铝含量在445.17~814.51 mg·kg-1之间,肉桂、黄玫瑰和紫玫瑰茶树品种茶叶铝含量较高,梅占、金牡丹和佛手茶叶铝含量较低.茶树新梢茶叶铝含量随着生长时间的延长迅速提高,采用指数方程可以很好模拟茶树新梢铝累积与生长时间的关系,控制茶叶采摘时期是控制茶叶铝含量的有效措施;随着新梢生长时间的延长,茶汤铝含量、茶叶铝溶出量及茶叶铝溶出率迅速升高,但日常饮用乌龙茶铝摄入量在安全限量范围内,不会对人体造成伤害. 相似文献
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茶树不同叶位叶片功能性状与光合特性研究 总被引：2，自引：0，他引：2
以5个茶树品种(系)为研究对象,分析了茶树新梢不同叶位叶片的叶面积(LA)、叶形指数(LI)、比叶面积(SLA)、干物质含量(LDMC)、叶绿素a(Chla)、叶绿素b(Chlb)、叶绿素总量(Chl)、类胡萝卜素(Car)及光合特性,并研究了叶片功能性状和光合特性之间的相关性。结果表明,不同叶位叶片的LA、LMDC、净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)由第1叶至第6叶基本呈现先增加后降低趋势,新梢中部3~4叶达到峰值,第1叶和第6叶显著降低(P0.05);不同叶位叶片LI和SLA基本呈现随着叶位增加而增加的趋势,第6叶的SLA均显著高于其他叶位(P0.05);第1~4叶的Chla、Chlb和Chl含量较高,第6叶Chla、Chlb和Chl含量显著低于其他叶位(P0.05),Car变化趋势不明显。LA与LI、LDMC、Chla、Chlb、Chl和Car之间存在显著或极显著正相关,与胞间CO2浓度(Ci)之间呈显著负相关,与其他指标相关性不显著;LI与其他指标不相关(LA除外);SLA与LDMC、Chla、Chlb、Chl、Car和Pn之间存在显著或极显著负相关,与Ci之间呈极显著正相关,与其他指标相关性不显著;LDMC与Chla、Chl和Pn之间存在显著或极显著正相关;Chla、Chlb、Chl和Car两两之间均存在极显著正相关,且均与Pn存在显著或极显著正相关;Gs和Tr与叶片功能性状不相关。分析以上结果可以得出,茶树新梢第3~4叶具有相对较大的LA和较强的光合能力,LDMC积累较大,可以作为表征茶树光合能力的供试叶片;SLA、LDMC和光合色素含量与Pn存在密切相关性,可作为评价茶树光合能力的指标。 相似文献
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《Journal of Crop Improvement》2013,27(2):81-114
Summary The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices. 相似文献
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Lakshman Lal 《Potato Research》1987,30(2):329-334
Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong
(1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage,
sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over
45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield
of a subsequent crop. 相似文献
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Joseph E. Laferriere Charles W. Weber Edwin A. Kohlhepp 《Plant foods for human nutrition (Dordrecht, Netherlands)》1991,41(3):277-282
Teas of plant origin traditionally consumed by the Mountain Pima of Chihuahua, Mexico, were analyzed for mineral nutritional content. Fe, Cu, Zn, Ca, and Mg composition was determined for native teas made from shoots ofTagetes lucida, T. filifolia, Elytraria imbricata, andHolodiscus dumosus, and from root xylem ofCeanothus depressus andPhaseolus ritensis. Native uses of these teas are also described. 相似文献
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M. I. Siri P. Villanueva M. J. Pianzzola L. Franco Fraguas G. Galván M. Acosta F. Ferreira 《Potato Research》2004,47(3-4):127-138
Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results
for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin
presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear
relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins
and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds. 相似文献
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Novel food and non-food uses for sorghum and millets 总被引：4，自引：3，他引：4
Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity. 相似文献
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Alejandro Carlos Tozzini María Fernanda Ceriani María Verónica Saladrigas H. Esteban Hopp 《Potato Research》1991,34(3):317-324
Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets
that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and
slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging
toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta.
Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X1 (also called RXact). 相似文献
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Rita Favas Janaína Morone Rosrio Martins Vitor Vasconcelos Graciliana Lopes 《Marine drugs》2022,20(3)
The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O2•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O2•− scavenging, (IC50 = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC25 = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC50 = 863 µg/mL; elastase, IC50 = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O2•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms. 相似文献
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Alejandro M. S. Mayer Abimael D. Rodríguez Orazio Taglialatela-Scafati Nobuhiro Fusetani 《Marine drugs》2013,11(7):2510-2573
The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories. 相似文献