川滇高山栎灌丛萌生过程中的营养元素供应动态

萌生更新是森林更新的重要方式, 是硬叶栎林受到干扰后植被恢复的主要机制。以位于青藏高原东南缘的川西折多山东坡川滇高山栎(Quercus aquifoliodes)灌丛为研究对象, 调查分析了砍伐后灌丛萌生过程中基株根系和萌株生物量动态、营养元素含量, 以及基株根系和土壤对萌株生长过程中的营养元素供应动态。结果表明, 川滇高山栎灌丛平均地上和地下生物量分别为(11.25 ± 0.92) t·hm^-2和(34.85 ± 2.02) t·hm^-2, 具有较大的根冠比(3.10:1); 萌生过程中, 萌株生物量呈线性增加趋势, 以灌丛活细根生物量变化为最大, 其次是活中根和活粗根, 树桩和根蔸生物量变化最小; 萌生过程中, 灌丛细根和中根N、P含量表现为先增加、后降低的变化趋势, 萌生初期树桩、粗根和根蔸中N和K的含量明显下降, 根蔸中Ca含量略有下降, 而P没有明显下降, 根系Mg含量变化幅度较大, 灌丛地下根系储存了较多的营养元素; 土壤、树桩、粗根和根蔸是川滇高山栎灌丛砍伐后0-120天萌生生长的主要营养来源, 砍伐后60天, 萌株生长所需的营养除K元素主要来源于根系外, 其余营养元素主要来源于土壤; 在砍伐后60-120天, 基株根系对萌株生长所需的N、K和Ca贡献较大, 而对P和Mg的贡献较小; 在砍伐后120-180天, 根系除K元素对萌生生长还保持较大的贡献外, 对其余营养元素的贡献均较小。高山栎林管理要注重加强地下根系的保护。     

香果树根萌苗生长特性及影响因子分析

香果树(Emmenopterys henryi)为我国Ⅱ级野生保护植物,由于生境遭到破坏、过度开发利用以及种群自然更新能力差等原因,导致自然环境下香果树种群数量迅速衰减。运用方差分析、多重比较、主成分分析等方法,对自然环境下香果树种群的根萌苗生长状况及其主要影响因子进行了研究。结果表明:香果树根萌苗的数量随着苗龄的增长逐渐减少,1a根萌苗的死亡率最高;苗高和基径均随苗龄的增大呈指数增长;香果树根萌苗主要生长在母树东南方120°~150°(以正北方为0°按顺时针方向旋转,下同)位置、距母树树干2 m以内及直径2 cm、长度30 cm的露根上;根萌苗苗高受母树方位影响较小,受露根直径、露根长度以及与母树间距离的影响稍大;母树南向(168.75°)根萌苗的基径显著大于其它方向的根萌苗基径;与北向和南向相比,母树东向和西向根萌苗的冠幅较大;根萌苗苗高、基径和冠幅等形态指标均随着与母树树干间距离的增加而降低,但随着露根直径的增加各形态指标均呈先升高后降低的趋势(露根直径6.5 cm时苗高和基径达到最大值),随着露根长度的增加各形态指标呈先降低后升高的趋势;与树冠内根萌苗相比,香果树母树树冠外根萌苗的死亡率较高。主成分分析结果表明,随着林内光照条件的改善、土壤中有机质含量的增加、砾石覆盖率的增加以及适度的人为干扰均有利于香果树根萌苗的生长。因此,减小林冠郁闭度、增加人工抚育措施对维持香果树的种群发展、实现其种群自然更新具有重要作用。     

SPATIAL DISTRIBUTION AND DEVELOPMENT OF ROOT SPROUTS IN FAGUS GRANDIFOLIA (FAGACEAE)

Root sprouts around 31 Fagus grandifolia parent trees, some declining due to beech bark disease, were studied to describe the pattern of sprout distribution, the ecological importance of this pattern, and the relationship between sprout patterns and parent vigor. Microtome sections of roots were studied to determine the histological origin of sprouts. Sprout distribution was circular and usually centered on the parent tree. Most sprouts were within 8 m of the parent and remained attached to the parent root system even after the sprouts reached 10 yrs of age. Root sprouting in F. grandifolia may be effective in replacing dead parent trees, but the potential for clones to spread is limited. Spatial distribution of sprouts was mostly unaffected by tree vigor. Root sprouts originated from callus tissues associated with wounds on superficial woody roots.     

Characteristics of low frequency magnetic field effect on swelling of wheat seeds at various stages]

Low-frequency magnetic field treatment (50 Hz, 30 mT, 15 min) of wheat seeds with a 50% germination efficiency during imbibition at the stage of root formation leads to a statistically significant increase in the number of seeds having sprouts, a still greater increase in the number of seeds having roots, and to an increase in the length of sprouts compared with the control and the seeds treated several hours later. In the last case, an increase in the germinating capacity with a considerably lesser effect on the number of seeds with roots was also observed. Prolonged treatment with the field during the second day of imbibition decreased reliably the length of sprouts with a weaker influence on the number of seeds with sprouts and roots. These data suggest the principal possibility of the effect of electromagnetic fields on the realization of the genetic program during the germination of wheat seeds.     

Root growth dynamics of Brussels sprouts (Brassica olearacea var.gemmifera) and leeks (Allium porrum L.) as reflected by root length,root colour and UV fluorescence

Minirhizotron observations of roots of leeks and Brussels sprouts grown in the Wageningen Rhizolab were used to study the dynamics of root length. Day of appearance and the time of decay were assessed for individual root segments visible on the minirhizotron surface.A Brussels sprouts crop produced much more root length than leeks, but the average longevity of these roots was about half that of leek roots.To investigate whether root colour or UV fluorescence could be used as a quantitative index of root functionality or root age, changes in root colour (on a scale of greys) over time were measured with interactive image analysis. In both crops a gradual change towards black was found with ageing. Measurements of the intensity of the UV fluorescence showed that leek roots fluoresced more than Brussels sprouts roots. Over time, UV fluorescence decreased in Brussels sprouts roots but increased in leek roots. It is concluded that UV fluorescence cannot be used as a universal indicator of root age or root functionality, but in some plant species it may be used to separate (transparent) roots from the background with image analysis techniques.     

Sprouting in temperate trees: A morphological and ecological review

Sprouting in trees, which results in the production of secondary trunks, is an induced response to injury or to a dramatic change in surrounding environmental conditions. This article reviews the forestry and ecology literature to produce an integrated view of the role of sprouting in both disturbed habitats and closed-canopy forests. Sprouting is a universal attribute of temperate angiosperm trees through the sapling stage of development but is much less common among gymnosperms. Four basic types of sprout morphologies are described: collar sprouts from the base of the trunk, sprouts from specialized underground stems (lignotubers and rhizomes), sprouts from roots, and opportunistic sprouts from layered branches. In a survey of 68 species of trees native to northeastern North America, 41% were found to retain the ability to sprout from the collar into adulthood; 26% sprout from branch layers under natural conditions; and 25% have the capacity to form root suckers. Sprouting in seedlings promotes their survival under a variety of stressful conditions, including suppression by canopy trees, herbivory, site exposure, and desiccation. In contrast, sprouting in mature trees extends the life span of the individual following damage and, in the case of root-suckering species, promotes the colonization of new ground. Although the sprouting of mature trees is more conspicuous than the sprouting of seedlings, its ecological significance is not as great. As a broad generalization, species that grow in stressful sites or sites with frequent disturbances are likely to sprout more vigorously and to retain the sprouting ability longer than are species that grow in less stressful sites or sites with less frequent disturbance. Near the limits of a species’ altitudinal or latitudinal range, the production of basal sprouts, root suckers, rhizomes, and/or branch layers allows trees to spread into adjacent areas, thereby circumventing the difficulties associated with seedling establishment.     

Comparison between clonal and sexual plantlets of Detarium microcarpum Guill. & Perr., a savanna tree species in Burkina Faso

An understanding of the proportion of true seedlings, seedling sprouts and root suckers in the forest is essential for directing the genetic composition of the future crop. We conducted a study to determine the difference between these plantlets of Detarium microcarpum based on morphological characters and carbohydrate contents in leaves and roots. For individuals ≤50 cm in height, root suckers had the highest values for height, stem length, internode number, root diameter, rachis length and leaflet number. The concentrations of starch and total nonstructural carbohydrates in the roots of seedling sprouts were superior. Plantlets did not differ in the concentration of leaf carbohydrates. For individuals >50 cm in height, root suckers had larger values for stem length, root diameter, leaflet length and width. Roots of seedling sprouts showed higher concentrations of soluble sugars and total soluble sugars. True seedlings were distinguished from seedling sprouts and root suckers using all morphological traits except collar diameter and leaflet number. Root suckers and seedling sprouts showed a closer morphological resemblance; thus resulted in slightly more than 50% discrimination success. In conclusion, discrimination between seedling sprouts and root suckers appeared to be more difficult than between true seedlings and clonal plantlets.     

UV-C照射对苦荞芽生长及品质的影响

以苦荞为材料,研究了不同时间UV.C照射对苦荞芽生长及品质的影响,结果表明：UV-C照射对苦荞芽株高有一定的抑制作用;UV-C照射可以增加苦荞芽的茎粗,平均增粗4.25%;UV-C照射对苦荞芽根长的抑制作用不明显;短时间UV-C照射抑制苦荞芽鲜重的效应不明显;短时间UV-C照射可以提高苦荞芽叶绿素的含量,平均比对照提高24.58%;UV-C照射可以提高苦荞芽总黄酮和Vc的含量,平均分别提高11.42%和23.38%;短时间UV-C照射可以促进苦养芽氨基酸含量的提高,平均挺高22.52%,长时间照射降低苦养芽氨基酸的含量.     

狐尾藻与黑藻断枝的不定根和新芽的形成

比较狐尾藻和黑藻2种沉水植物不同节位和不同长度断枝的不定根和新芽形成时间的结果表明,随着断枝节位的下降或断枝长度的增加,狐尾藻不定根的形成时间分别呈延长和缩短的趋势,其新芽均呈缩短趋势;而黑藻不定根的形成时间均呈缩短趋势,其新芽受节位与长度的影响不明显。     

Chlorflurenol: Its effect on photomorphogenesis in potato sprout growth

Two typical dark-responses namely the excessive elongation of sprouts and the formation of sprout hook, are adversely affected by chloroflurenol. It also affects the polarity of sprouts and the formation of roots on tubers, the effect varying with the concentration and the light condition. The significance of these effects of chloroflurenol used in potato production has been discussed.     

The mode of origin of root buds and root sprouts in the clonal tree Sassafras albidum (Lauraceae)

The developmental anatomy of root buds and root sprouts was examined in the clonal tree Sassafras albidum. Root samples from 13 clones that varied widely in age and vigor were sectioned and two types of buds were found, "additional" buds and "reparative" buds. Additional buds form during the early growth of uninjured roots and they perennate by growing outwards in concert with the vascular cambium such that bud traces are produced in the secondary xylem. Reparative buds form de novo in response to senescence, injuries, or other types of disturbance. Reparative buds were found on the roots of seven of the clones, whereas additional buds were found on the roots of all 13 clones. The reparative buds had originated in the proliferated pericycle, where they were subtended by sphaeroblasts, or spherical nodules of wood. Few of the reparative buds were vascularized and none were connected with the vasculature of their parent roots. In contrast, most of the additional buds were vascularized, and the leaf traces of several of the additional buds appeared to be contiguous with the conducting xylem of their parent roots. To determine whether both bud types were functional, 82 field-collected root sprouts and 44 incubation-induced sprouts were sectioned at the root-sprout junction and examined for evidence relating to their mode of origin. None of the sprouts were subtended by sphaeroblasts, but 98% were subtended by bud traces, which indicated that they had originated from additional buds. Although reparative buds were more common than additional buds on some of the root samples, they appear to be dysfunctional at sprouting. Additional buds, on the other hand, are able to sprout both as a normal part of clonal spread and from root cuttings.     

外源赤霉素、6-苄基腺嘌呤及矿物质对水培绿豆芽生长的影响

以‘中绿一号’绿豆为原料用水培法制作豆芽,研究赤霉素、6-苄基腺嘌呤和矿物质对其生长的影响,优化绿豆芽营养液的配方。结果表明,使用由100mg·L-1赤霉素、5mg·L-16-苄基腺嘌呤、0.810g·L-1硝酸钾、0.950g·L-1硝酸钙、0.500g·L-1硫酸镁复配而成的营养液可以缩短豆芽生长周期,且培养出的绿豆芽芽长适宜（4.25cm±0.44cm）、根长较短（1.15cm±0.23cm）、轴径较粗（2.78cm±0.16mm）,芽体洁白而脆嫩。     

Emergence, Growth and Nutrient Composition of Sugarcane Sprouts Under NaCl Salinity

The changes induced by 80 and 120 mM NaCl during emergence and growth of sprouts in salt-tolerant (CPF-213) and sensitive (L-116) genotypes of sugarcane were determined. The rate and percentage of emergence of sprouts, length and dry mass of shoot and root, and number of nodal roots decreased under salinity. Concentrations of Na and Cl increased and those of K, Ca, N and P decreased with a rise in substrate salinity. A greater salinity tolerance ability of CPF-213 than L-116 was attributable to greater root mass and higher nutrient concentrations in the sprouts of the former genotype.     

秧宝灵防止早稻烂秧的生理基础

秧宝灵浸渍早稻种子,可有效地防止其烂秧发生和提高秧苗素质。这主要是由于秧宝灵处理后能加快幼叶的转绿速度,增加芽和幼叶的束缚水含量,提高芽的可溶性蛋白质含量,增强幼苗根系的活力,从而使秧苗具有较强的抗低温胁迫的能力。     

Calystegine distribution in potato (Solanum tuberosum) tubers and plants

Potato plants contain calystegines in leaves, stems, flowers, fruits and roots. Calystegines A₃ and B₂ are the main constituents. Highest concentrations were measured in sprouts emerging from the tubers. In 3 mm long sprouts, 3.3 mg total calystegines per g fresh mass were detected. Dormant tubers directly after harvest contain less calystegines in all parts than sprouting tubers. Flowers and young leaves are the aerial plant tissues with the highest calystegine concentration, i.e. 150 μg total calystegines per g fresh mass. Calystegine levels did not rise when sprouts were wounded. Tropinone application to sprouts and aerial tissues lead to an accumulation of pseudotropine and not to tropine. That indicates that stereospecific tropinone reduction is active in potato.     

Glucoraphasatin: Chemistry, occurrence, and biological properties

Glucoraphasatin is an atypical glucosinolate mainly found in Raphanus sativus roots and sprouts. This review focuses on the chemistry, the occurrence, and the biological properties of glucoraphasatin.     

Differences in attachment of Salmonella enterica serovars and Escherichia coli O157:H7 to alfalfa sprouts

Numerous Salmonella enterica and Escherichia coli O157:H7 outbreaks have been associated with contaminated sprouts. We examined how S. enterica serovars, E. coli serotypes, and nonpathogenic bacteria isolated from alfalfa sprouts grow on and adhere to alfalfa sprouts. Growth on and adherence to sprouts were not significantly different among different serovars of S. enterica, but all S. enterica serovars grew on and adhered to alfalfa sprouts significantly better than E. coli O157:H7. E. coli O157:H7 was essentially rinsed from alfalfa sprouts with repeated washing steps, while 1 to 2 log CFU of S. enterica remained attached per sprout. S. enterica Newport adhered to 3-day-old sprouts as well as Pantoea agglomerans and 10-fold more than Pseudomonas putida and Rahnella aquatilis, whereas the growth rates of all four strains throughout seed sprouting were similar. S. enterica Newport and plant-associated bacteria adhered 10- to 1,000-fold more than E. coli O157:H7; however, three of four other E. coli serotypes, isolated from cabbage roots exposed to sewage water following a spill, adhered to sprouts better than E. coli O157:H7 and as well as the Pseudomonas and Rahnella strains. Therefore, attachment to alfalfa sprouts among E. coli serotypes is variable, and nonpathogenic strains of E. coli to be used as surrogates for the study of pathogenic E. coli may be difficult to identify and should be selected carefully, with knowledge of the biology being examined.     

A scanning electron microscope study of the development of free axonal sprouts at the cut ends of dorsal spinal nerve roots in the rat

Summary Rat dorsal spinal nerve roots were cut and the tip on the ganglionic side of the cut was examined by scanning electron microscopy at 0, 7, 20 and 48 h after operation. Seven hours after cutting, free axonal sprouts had started to protrude from the cut end of the nerve. After 20 h the free sprouts were more profuse than at 7 h but were smaller and had a rougher surface. At both 7 and 20 h many of the sprouts consisted of a stalk 2–7 m in diameter with a bulbous end 5–20 m in diameter. A few branching sprouts were seen. At 48 h the sprouts were shrunken with a deeply furrowed surface. The significance of the surface structure of the sprouts is discussed.I.R.D. is supported by the Medical Research Council; P.K. thanks the Mental Health Trust for a project grant     

Internalization of bioluminescent Escherichia coli and Salmonella Montevideo in growing bean sprouts

AIMS: Investigate the interaction of bioluminescent Escherichia coli and Salmonella Montevideo with germinating mung bean sprouts. METHODS AND RESULTS: E. coli or Salm. Montevideo introduced on mung beans became established both internally and externally on sprouts after the initial 24 h germinating period. In both cases the inoculated bacterium formed the predominant microflora on the sprouted beans throughout. From the bioluminescent profile of inoculated sprouting beans, bacterial growth was found to be in close proximity to the roots but not on the hypocotyls. Clumps (biofilms) of cells with low viability were observed within the grooves between epidermal cells on hypocotyls. Treatment with 20,000 ppm sodium hypochlorite removed the majority of bacteria from the surface of hypocotyls although nonviable single cells were occasionally observed. However, viable bacteria were recovered from the apoplastic fluid, and extracts of surface-sterilized sprouts indicating that the internal bacterial populations had been protected. This was confirmed using in situ beta-glucuronidase staining of surface-sterilized sprouts where cleaved enzyme substrate (by the action of internalized E. coli) was visualized within the plant vascular system. CONCLUSIONS: E. coli or Salmonella present on seeds become internalized within the subsequent sprouts and cannot be removed by postharvest biocidal washing. SIGNIFICANCE AND IMPACT OF THE STUDY: Mung bean production should be carefully controlled to prevent contamination occurring in order to minimize the health risk associated with raw bean sprouts.     

The formation of free axonal sprouts from a dorsal root ganglion-nerve preparation maintained in organotypic culture,and the effects of demecolcine

Summary Nerve-ganglion preparations from rat dorsal spinal nerve roots were maintained in organotypic culture for 20 h. Free axonal sprouts formed at the cut tips. Clear and dense-core vesicles, mitochondria and smooth endoplasmic reticulum accumulated in the axons for a distance of 500 m behind the cut, as has previously been described in dorsal roots sectioned in vivo. Sprouting did not occur in dorsal roots maintained in culture without their ganglia attached. Sprouting was also prevented by demecolcine (3 × 10^-7 M) which reduced the number of microtubules in non-myelinated, small myelinated and large myelinated axons to respectively 45, 30 and 20% of control values. The sprouts contained several types of vesicle including small clear vesicles, large and small dense-core vesicles and flattened vesicles. The possible relevance of the vesicles to transmitter mechanisms in these neurones is discussed.I.R.D. is supported by the Medical Research Council; P.K. thanks the Mental Health Trust for a project grant