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排序方式: 共有28条查询结果,搜索用时 15 毫秒
1.
天葵"块根"是由主根及下胚轴共同膨大形成,天葵药材的形态本质应为肉质直根。天葵肉质直根的增粗主要原因是由于木薄壁细胞产生三生形成层,形成大量三生维管束;以及次生韧皮部和次生木质部中薄壁细胞的不断增加。  相似文献   
2.
邹毅  方基胜  高伟 《湖北农业科学》2016,(16):4193-4197
为比较制造橡木桶用木材的微观结构特征,选用10种橡木(Quercus L.)为试验材料,通过显微镜观察橡木的导管、木射线和轴向薄壁组织,分析常见橡木的共性与个性。结果表明,栓皮栎(Q.variabilis Bl.)导管内侵填体较少,液体流透性比较高;美国红橡(Q.rubra L.)管孔较大,与外界的空气接触过多,二者均不适合制造橡木桶。夏橡(Q.robur L.)、卢浮橡(Q.sessiliflora Salisb)、孚日橡(Q.pendunculata L.)、无梗花橡[Q.petraea(Matt.)Liebl.]、星毛橡(Q.stellata Wangenh)、美洲白橡(Q.alba L.)、沼生白橡(Q.bicolor Willd.)、蒙古栎(Q.mongolica Fisch.ex Ledeb)这8种橡木适合制造橡木桶,其共同特征是有合适的管孔大小,具有一定的透气性,可以与外界空气发生微氧反应;有丰富的侵填体,可以堵塞橡木桶内壁管孔,降低气体和液体在木材中的渗透性,从而保证陈酿过程中酒的口感。10种橡木的木射线和轴向薄壁组织无明显区别。为此,橡木的导管大小和侵填体多少是判定是否适合制造橡木桶的关键要素。  相似文献   
3.
ABSTRACT

The connection between chemical composition and anatomy of wood is poorly studied. Abiotic and biotic growth conditions affect the synthesis of structural compounds and the anatomy of wood at the same time as they affect growth. In this study, the wood chemical composition, and connections between wood chemistry and anatomy were studied in downy birch (Betula pubescens Ehrh.) grown on four growth sites possessing mineral and peat soils. Lignin, holocellulose, extractive and ash contents, and effective heating value were analysed and compared with libriform fibre double wall thickness and lumen diameter, vessel size and number, and ray and axial parenchyma numbers. Measured lignin and extractive contents were exceptionally high and holocellulose content low. Correlations between wood anatomy and effective heating value were partly different on different soils. Correlations between holocellulose and anatomy were the opposite of the correlations between other chemical compounds and anatomy. The significant correlations between chemical composition and anatomy were commonly opposite in trees grown on peat than in trees grown on mineral soil. Particularly, vessel characteristics and fibre wall thickness correlated significantly with wood chemistry in trees grown on mineral soil. The connections between wood anatomy and chemistry proved to be soil-dependent.  相似文献   
4.
Radiata pine sapwood and heartwood were dried using high-temperature, conventional-temperature, and air drying schedules with and without pre-steaming. They were then impregnated by vacuum treatment with double-distilled water, toluidine blue, and fluorescein dye. For sapwood, there were only minor differences in uptake between drying methods and when pre-steaming was used. Using microscopy, the primary flow pathways in sapwood were found to be the resin canal network and ray parenchyma cells, which provided conduction without large resistance. In heartwood, uptake was strongly influenced by pre-steaming the green lumber. After pre-steaming heart-wood, there was an increase in uptake from all surfaces but especially from the radial surfaces. Lower extractive contents, disruption of epithelial and ray parenchyma cells, and alteration of the condition of bordered pits were also associated with pre-steaming. It was therefore possible to classify flow paths in radiata pine heartwood five ways, according to uptake values and wood anatomical features.This research was presented in part at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998.  相似文献   
5.
软枣猕猴桃的解剖学研究   总被引:2,自引:1,他引:1  
软枣猕猴桃为猕猴桃科的一种野生经济植物.本文对其进行了解剖学研究,并对叶片和花粉进行了扫描电镜的观察,并与本属的其他种作了比较分析.研究结果表明,根的初生木质部为二原型,在次生结构中存在特殊的环带状中柱鞘细胞;根、茎的次生结构中木薄壁组织为多种类型;木射线为异形Ⅰ和异形Ⅱ。次生韧皮部的筛管具复筛板,无伴胞,为双子叶木本植物型等补充了前人对猕猴桃科报道的不足,并为其引种、栽培等提供理论根据.  相似文献   
6.
采用紫花芒、桂香芒、红象牙和印度1号芒果的果实,通过扫描电子显微镜观察,发现果实皮孔少,开口小,蜡质密度大的紫花芒果实耐贮藏。分泌腔多的桂香芒和印度1号果实芳香味浓。果肉薄壁细胞中淀粉粒增多,果实愈趋近成热。薄壁细胞中淀粉粒多的桂香芒,果实后熟后含糖量高。  相似文献   
7.
为探明冻害对柑橘、龙眼枝梢内部水分运输功能的影响,以‘福眼’(Dimocarpus longgana L.)和‘玫瑰橙’(Citrus sinesis O.)枝梢(‘福眼’为老熟春梢;‘玫瑰橙’为完成自剪的春梢)为试材,采用常规石蜡切片法和甲醇脱色法,就模拟冻害(T ≤ -5℃)处理对枝梢维管组织结构变化与水分输导功能的影响进行研究。结果表明,冻害处理导致枝梢木薄壁细胞内部结构异常,木质部组织结构完整性丧失,阻断‘玫瑰橙’和‘福眼’茎内木质部导管水分运输。  相似文献   
8.
《Plant Production Science》2013,16(3):184-189
Abstract

Cassava (Manihot esculenta Crantz) can produce a high crop yield even in an environment with irregular rains. This is mainly attributed to its abilities to maintain leaf area under drought conditions and rapidly regrow after rain. In this study, we investigated the mechanism of leaf maintenance under water deficits through measurement of photosynthetic rate and water potential changes in leaves. The cassava plants were grown in pots and exposed to water deficits, and the diurnal changes in water potentials, rates of photosynthesis and transpiration and stomatal conductance were measured. The relationship between leaf water potential (ψW) and photosynthetic rate with decreasing soil water, and osmotic adjustment were also investigated. With respect to water supply in leaves, the movement of water in plants was measured using stem heat balance. Under water deficits, photosynthesis occurred only in the early morning. The water loss was reduced by stomatal closure in the mid-day. This was attributed to the complete closure of the stornata during the decrease in ψW to a range between –1.0 and –1.4 MPa. Furthermore, the firm stomatal closure is caused by the consistency of osmotic potential under decreases in soil water, i.e., to a lack of osmotic adjustment. Water stored in the pith parenchyma of stem flowed into leaves in the morning. From these results, we conclude that cassava can consistently maintain an adequate water level in leaves via water storage and the sensitivity of stornata to water deficits, thereby avoiding leaf dehydration.  相似文献   
9.
In this paper we have examined rubber particle formation in cortical parenchyma cells of guayule (Parthenium argentatum Gray) plants exposed to the low temperature of the fall and winter of the Chihuahuan Desert that stimulates rubber formation.Plants were transplanted to field plots in May in Ft. Stockton, TX. In September most of the cortical parenchyma in cross-sections 3 cm from the stem tips and from the base of the stems were mature, containing a central vacuole, tonoplast and a parietal cytosol with chloroplasts, mitochondria, peroxisomes and a few rubber particles. In 8-month-old plants examined in January many of the cortical parenchyma cells 3 cm from the stem tip were immature and completely filled with cytosol containing a high population of rubber particles. At this stage of development there was a thickened secondary cell wall but no central vacuole, tonoplast or parietal cytosol and all the rubber particles were formed in the central cytosol. In the cortical parenchyma in early stages of central vacuole development, by the coalescing of microvacuoles, the rubber particles were located in the developing central vacuole and in the cytosol being appressed toward the cell wall. In 8-month-old plants in January, the cortical parenchyma at the base of the stems was more mature than cells near the stem tips. These cells showed a later stage of development of a central vacuole from microvacuole fusing and contained a high population of mixed sizes of rubber particles and a thin layer of parietal cytosol containing chloroplasts, mitochondria and rubber particles with a partly developed tonoplast. There was clear evidence of the fusion of small rubber particles with other rubber particles that may represent a mechanism for the growth of rubber particles.  相似文献   
10.
The morphological consequences of anabolic clenbuterol treatment on the testicular parenchyma were investigated in 30 pigs at morphological and ultrastructural levels. Clenbuterol was given with food (1 ppm). In the first group (n=10), treatment was maintained until slaughter (experimental period 3 months). In the second group (n=10), clenbuterol was withdrawn 2 weeks before slaughter (experimental period 2.5 months). A third group (n=10) of pigs not fed with clenbuterol served as controls. Animals were slaughtered at 9 months of age and samples of testicular parenchyma were collected for light and electron microscope studies. In the clenbuterol-treated groups, the interstitial cells showed a considerable increase in the organelles involved in testosterone production, with an increased development of the mitochondria, smooth endoplasmic reticulum, Golgi apparatus and lipid droplets compared to the control group. The seminal epithelium displayed many lipid vacuoles and evident signs of tubular involution, such as degenerating and multinucleate germ cells. Sertoli cells gave evidence of metabolic alterations such as large lipid deposits and cytolysosomes.  相似文献   
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