Tree Propagation Research Articles

Ukuran Benih Dan Skarifikasi Dengan Air Panas Terhadap Perkecambahan Benih Pohon Kuku (Pericopsis Mooniana)

Nedun tree (Pericopsis mooniana) is one of commercial trees. The propagation of nedun tree generatively has an obstacle due to it’s dormant character and the variety of seeds weight and the both factors are suspected influence the germanitaion. This research aimed to determine effect of seed weight for nedun seed germination and the best of seeds weight for nedun seed germination; the effect of soaking in hot water at beginning temperature 80˚C by different soaking period on germination, and the best effect of soaking in hot water at beginning temperature of 80˚C by different soaking period on germination. This research was compiled in a randomized complete block design, with 5 treatments and 3 groups. Seeds were catagorized in to three group of weight which were heavy, medium, and light. The treatments consisted of without scarification (as a control), soaking in hot water at beginning temperature of 80ºC during 12 hours, 24 hours, 36 hours, and 48 hours. Every experiment unit consisted of 100 seed. The observed variables were consisted of germination percentage, mean daily germination, germination value, and the ability to germinate. Data analysis methods were used variance homogenity, variance analysis and least of difference test at 5% significant level. Based on the analysis of variance showed that seeds weight significantly affected the mean daily germination, but had no effect on germination percentage, germination value, and the ability to germinate. Seeds weight had a mean daily germination 15.088 days to germinate. The medium seeds were germinated faster than heavy seeds and light seeds. Seed scarification gave effect on germination percentage and germination value significantly, but not significant on mean daily germination and ability to germinate. Seeds scarification with hot water at beginning temperature 80°C for 48 hours had germination percentage 28,000%, germination percentage was better than the scarification for 36 hours, 24 hours, 12 hours, and control.

Electrical Trees in a Composite Insulating System Consisted of Epoxy Resin and Mica: The Case of Multiple Mica Sheets For Machine Insulation

Epoxy resin and mica sheets consist the essential insulation of rotating machine stator bars. Such an insulation, although very resistant to partial discharges, is subjected to considerable electrical stresses and consequently electrical trees may ensue. In this paper, an effort is made to simulate electrical tree propagation in multiple epoxy resin/mica sheets with the aid of Cellular Automata (CA). An attempt to compare the simulation results with experimental results is also made.

Characterization of electrical trees in Bakelite insulator by fractal analysis

SUMMARY Electrical trees are characterized by a technique of fractal characteristics in pattern formation for decades. The geometrical patterns of dielectric breakdown such as lightning discharge, surface discharges, and electrical trees are known to be fractal in nature. It is well known that the electrical trees are frequently occurring in insulating materials. The present investigation deals mainly with the fractal properties of 2D (Dimension) patterns of real electrical tree obtained in insulating materials. The electrical tree patterns are generated experimentally under AC and DC of different voltage levels. The time of voltage application is noted, and the leakage current is measured using digital storage oscilloscope. A charge-coupled device (CCD) camera is used to record the propagation of electrical tree during the experiment. C++ is used to calculate the fractal dimension for experimentally obtained electrical trees by using box counting method. It is found that fractal dimension is a function of magnitude of the voltage, treeing time, and leakage current. Fractal analysis is a good and suitable tool for the analysis of electrical treeing. Copyright © 2014 John Wiley & Sons, Ltd.

An Overview of Electrical Tree Growth in Solid Insulating Material with Emphasis of Influencing Factors, Mathematical Models and Tree Suppression

Nowadays, the most widely used insulating materials in high voltage equipment such as cables are polymeric insulations due to the numerous merits they possess with regards to electrical performance compared to paper insulations. However, electrical treeing, one of the dielectric pre-breakdown phenomena, has been considered as a major contribution to the failure of insulating polymeric materials. Thus, this paper provides an overview on the factors affecting the initiation and propagation of electrical tree. Discussions on parameters that affect the growth of electrical treeing such as applied voltage, electric field enhancement, partial discharge, frequency of applied voltage and temperature are given. Some discussions on the various models are also highlighted. The tree related models being discussed herein include Weibull, Lognormal, Johnson SB, Dielectric Breakdown Model, Discharge-Avalanche Model, and Field-Driven Tree Growth. In addition, discussions on the use of nano-sized fillers in polymeric insulating material to inhibit electric treeing are highlighted.

Nonlinear time series analysis of partial discharges in electrical trees of XLPE cable insulation samples

This paper presents an investigation into the nonlinear dynamics characteristics of the partial discharge (PD) sequence measured during the propagation of typical electrical trees in XLPE cable insulation. Calculation of the correlation dimension and the largest Lyapunov exponent from the PD sequence is used to illustrate the nonlinear characteristics of the PD behavior in the electrical tree growth. The results provide strong evidence for the existence of deterministic chaos in the PD phenomenon of electrical trees, where the correlation dimension and the largest Lyapunov exponent are related with the PD activity of the tree growth, rather than a presence of random stochastic process. The fluctuating correlation dimension of the PD sequence during the branch-pine tree growth is associated with the transition of PD patterns and the change of the channel conductivity of the tree structure. It is also found that the nonlinear dynamics characteristics of the PD sequence are influenced by the applied voltage, the channel conductivity and the electrical tree shape. A possible mechanism is presented for the formation of different chaotic extents of typical electrical trees in XLPE cable insulation.

Investigation on insulation material morphological structure of 110 and 220 kV XLPE retired cables for reusing

Most of the 110 and 220 kV cables are in service till the end of life, but part of them would be out of service by refurbishment. This research is focused on evaluating the cable insulation and determining whether the cable can be reused. All the cables used in this research satisfactorily passed the AC voltage and partial discharge tests. Then the fourier transform infrared spectroscopy, thermogravimetry analysis, differential scanning calorimetry, dynamic mechanical analysis, and tensile machine were used to analyze the insulation morphological structure and performance of 20 retired 110 and 220 kV crosslinked polyethylene cables obtained from the Beijing and Zhuhai districts. The results show that the structure parameters which can represent the physical change and the irreversible chemical change of cables have obvious time dependence characteristic. DSC result shows that crystallinity, melting range, and crystallization rate increase slightly with service years. DMA experiment illustrates that the temperature of mechanical loss peak, Tγ, shifts to a higher temperature while the mechanical loss increases slightly and temperature dependency of storage modulus increases with service years. The electrical treeing experiment utilized cable operated for 17 years, which is the longest operation year for the samples. Compared with new cable, the cable operated for 17 years has a slight decrease in tree initiation time and an obvious increase in tree propagation time. These experiment data show that the insulation material morphological structure is mainly stable, and the test results are also a contribution to the lifetime expectancy evaluation of the 110 and 220 kV XLPE cable.

In Vitro Propagation of the Important Tasar Oak (Quercus serrata Thunb.) by Casein Hydrolysate Promoted High Frequency Shoot Proliferation

An efficient micropropagation protocol has been developed for tasar oak. Nodal segments from in vitro grown seedling were used for shoot multiplication. Best shoot multiplication response, in terms of number of shoots per explant as well as shoot length, was obtained in woody plant (WP) medium supplemented with 6-benzyladenine and indole-3-acetic acid (8.88 μM BA + 1.43 μM IAA); but the establishment of cultures was difficult due to basal callus formation and necrosis in due course of time. Out of the two used growth adjuvants, casein hydrolysate (CH, 500 mg L−1) promoted shoot multiplication rate significantly in comparison to silver nitrate and also eliminated the basal callus formation problem and necrosis faced during the later stage of shoot proliferation. In vitro rooting on WP medium supplemented with 100 μM indole-3-butyric acid (IBA) when applied for 48 hr gave the best results in comparison to prolonged exposure. Well-acclimatized plantlets were transferred to the field with 80% survival rate. This protocol could be useful not only to propagate and conserve this oak but can also uplift the socioeconomic status of the Himalayan people as its leaves are used to feed the tasar silk worm during rearing period. This method will also be helpful for propagation of high value trees for a reforestation program.

EFFECT OF WATERMELON PROPAGATION BY CUTTINGS ON VEGETATIVE GROWTH, YIELD AND FRUIT QUALITY

Watermelon (Citrullus lanatus) is an important vegetable crop grown in Egypt. Seedless watermelon hybrids are preferred by most consumers because of their sweet taste and lack of hard seeds. The seedless watermelon (triploid hybrid watermelon) seeds are very expensive, do not germinate well and show least homogenous germination and growth. For these reasons, the present study aims to propagate seedless watermelon by cuttings to minimize the amounts of imported watermelon hybrid seeds in general and seedless watermelon in particular and reducing the cost of production and producing homogenous plants. Cutting is a method of asexual plant propagation widely used in horticulture. It is most commonly used for the propagation of trees and shrubs grown commercially. In vegetable crops cuttings are used on sweet potato and cassava as a commercial propagation method and cuttings can be used as a commercial propagation method in tomato, potato, eggplant, cucumber, melon and watermelon. The seedless watermelon cv. Yellow Buttercup QV 766 F1 (yellow flesh) and SSX 7402 F1 hybrid (red flesh)) and seeded watermelon cv. Aswan F1 hybrid were grown in plastic house for use as a source of cuttings (mother plants). Two types of cuttings were use, the first type was cuttings from terminal growing point of the main stem and lateral branches 10-15cm in length 0.45and 0.6 cm in diameter and the second type was cuttings including one node, bud and leaf. The study was conducted in three different experiments using randomized complete blocks design with three replicates during the seasons of 2010/2011 and 2011/2012 at a private farm in El-Badrashein City. Each hybrid was conducted in a single experiment. Each experiment included two types of cuttings treated with three concentrations (0, 100, 200 ppm) of IBA and planted in seedling trays or pots No.8cm. Twelve cutting treatments beside the control which was produced from true seeds were used in each experiment. The obtained results showed that shoot tip cuttings with any concentrations of IBA and planted in seedling trays or in pots treatments gave a lower survival percentage than cuttings including one node and treated with any concentration of IBA and planted in seedling trays or in pots. This may be due to the significant increment in number of roots in cutting treatments have one node compared with both cutting include shoot tip and control plants. All cutting treatments which included one node gave a higher survival percentage than the seeds germination in both seedless cv. Yellow Buttercup (QV 766) F1 and SSX 7402 F1 hybrid while, the highest seed germination were recorded in Aswan F1 in both seasons. All cutting treatments gave a significant increment in all vegetative characteristics after 45 days from transplanting and early yield compared with control. The number of days from transplanting to flowering showed significant decrease than the control. The plants from cuttings reached harvesting 15 days earlier than the control. No significant differences were recorded between all cutting treatments and the control plants in all vegetative growth, yield components and fruit characteristics. All cutting treatments gave a significant increase in early yield when compared with control plants.

Inhibiting Effect of Nonlinear Shielding Layer on Electrical Tree Propagation inside Insulation Layer of High-Voltage Cable

Nonlinear insulated materials can uniform electric field distribution in non-uniform electric field. In order to inhibit the electric tree initiation and propagation inside high-voltage cross-linked polyethylene (XLPE) insulated cable, a kind of 220kV high-voltage XLPE insulated cable with new structure is designed by embedding nonlinear shielding layer into XLPE insulation layer of high-voltage cable with traditional structure in this study. Experimental and simulation results indicate that the nonlinear shielding layer can effectively inhibit electrical tree propagation inside the XLPE specimens, and obviously extend the breakdown time caused by electric tree propagation. When the electrical tree propagates into the nonlinear shielding layer sandwiched between insulation layers of cable, the electric field distribution near the tip of electrical tree is obviously improved. These findings prove the feasibility and the effectivity of inhibiting electrical tree propagation inside high-voltage cable by adding nonlinear shielding layer into the insulation layer.

Electrical Trees in a Composite Insulating System Consisted of Epoxy Resin and Mica: The Case of Multiple Mica Sheets For Machine Insulation

Epoxy resin and mica sheets consist the essential insulation of rotating machine stator bars. Such an insulation, although very resistant to partial discharges, is subjected to considerable electrical stresses and consequently electrical trees may ensue. In this paper, an effort is made to simulate electrical tree propagation in multiple epoxy resin/mica sheets with the aid of Cellular Automata (CA). An attempt to compare the simulation results with experimental results is also made.

Germination of stored seeds of four tree species from the tropical dry forest of Morelos, Mexico

Los estudios sobre la propagación de árboles de los bosques tropicales secos son escasos en México; además, la procedencia de las semillas usadas en los programas de reforestación generalmente no se conoce o recibe poca atención. El conocimiento de los patrones de germinación de semillas de distintas procedencias, y cómo cambian a través del tiempo, es útil para identificar fuentes de semillas adecuadas para los programas de reforestación y para desarrollar programas de recolecta y almacenamiento en las condiciones de baja tecnología que prevalecen en los viveros rurales. Se evaluó la variación en el tamaño y la germinación de semillas almacenadas de tres diferentes procedencias por especie en Acacia bilimekii, Haematoxylum brasiletto, Lysiloma acapulcense y L. divaricatum . Las semillas se recolectaron en cuatro sitios del Bosque Tropical Seco de Morelos, México, y se almacenaron a temperatura ambiente. El tamaño de las semillas se estimó mediante el volumen de 75 semillas por procedencia/especie. Se realizaron periódicamente pruebas de germinación entre los seis y 24 meses; el efecto de la procedencia y el tiempo de almacenamiento se analizaron mediante análisis de varianza. Se presentaron diferencias significativas en el tamaño de las semillas entre procedencias en todas las especies, mientras que el efecto de la procedencia en la tasa de germinación fue significativo en tres de ellas. La capacidad de germinación cambió con el tiempo de almacenamiento entre especies y procedencias; después de 24 meses, era aún ≥ 50% en todas las procedencias de las dos especies de Lysiloma , pero en A. bilimekii hubo grandes diferencias entre procedencias. La capacidad germinativa promedio fue baja en H. brasiletto después de seis meses. Es necesario realizar más investigaciones sobre germinación y almacenamiento de semillas de un grupo más amplio de especies y sus procedencias para poder restaurar los bosques tropicales secos de México.

Effect of Reactive Diluents on the AC Electrical Treeing in Epoxy/Nanosilicate Systems

The effect of reactive diluents on the ac electrical treeing in epoxy/nanosilicate systems was studied, in a needle-plate electrode geometry. Diglycidyl ether of bisphenol A (DGEBA) type epoxy was used as a base resin, and layered silicate was used as a nano-sized filler. Polyglycol (PG) or 1,4-butanediol diglycidyl ether (BDGE) was introduced as a reactive diluent to the DGEBA/nanosilicate system, in order to decrease the viscosity of the nanocomposite system. PG acted as a flexibilizer, and BDGE acted as a chain extender, after the curing reaction. To measure the treeing propagation rate, a constant alternating current (ac) of 10 kV/4.2 mm (60 Hz) was applied to the specimen, in a needle-plate electrode arrangement, at <TEX>$30^{\circ}C$</TEX> of insulating oil bath. When 10 kV/4.2 mm (60 Hz) was applied, the treeing propagate rate in the DGEBA system was <TEX>$1.10{\times}10^{-3}$</TEX> mm/min, and that in the DGEBA/PG system was <TEX>$1.05{\times}10^{-3}$</TEX> mm/min. As 1.5 wt% of nanosilicate was added to the DGEGA/PG system, the propagation rate was <TEX>$0.33{\times}10^{-3}$</TEX> mm/min. This meant that the nano-sized layered silicates would act as good barriers to treeing propagation. The effect of chlorine content was also studied, and it was found that chlorine had a bad effect on the electrical insulation property of the epoxy system.

Effect of Electric Field Frequency on the AC Electrical Treeing Phenomena in an Epoxy/Reactive Diluent/Layered Silicate Nanocomposite

The effects of electric field frequency on the ac electrical treeing phenomena in an epoxy/reactive diluent/layered silicate (1.5 wt%) were carried out, in needle-plate electrode arrangement. A layered silicate was exfoliated in an epoxy base resin, by using our ac electric field apparatus. To measure the treeing propagation rate, constant alternating current (AC) of 10 kV with three different electric field frequencies (60, 500 and 1,000 Hz) was applied to the specimen, in needle-plate electrode arrangement, at 30℃ of insulating oil bath. As the electric field frequency increased, the treeing propagation rate increased. At 500 Hz, the treeing propagation rate of the epoxy/PG/nanosilicate system was0.41×10-3 mm/min, which was 3.4 times slower than that of the epoxy/PG system. The electrical treeing morphology was dense bush type at 60 Hz; however, as the frequency increased, the bush type was changed to branch type, having few branches, with very slow propagation rate.

Effect of IBA, rooting media and planting date on vegetative propagation of button wood tree (Conocarpus erectus L.)

Effect of IBA, rooting media and planting date on vegetative propagation of button wood tree (Conocarpus erectus L.)

An In Vitro Germination Technique for Some Stone Fruit Species: the Embryo Isolated from Cotyledons Successfully Germinated without Cold Pre-treatment of Seeds

Seeds of temperate fruit species need a long time to germinate as a result of their requirement of stratification or cold treatment. Therefore, fast and uniform germination techniques are desirable and important for fruit tree propagation and especially for breeding studies. The effects of combinations of benzylaminopurine (BAP) and gibberellic acid (GA3) on in vitro embryo germination of apricot, peach, and wild cherry were determined without seed cold pretreatment. The results showed that no germination was recorded in all the seeds with testa. In the seeds without testa, no germination (wild cherry) or limited germination (less than 10%) was recorded. When the embryos separated from cotyledons were cultured, successful germination was obtained for all species. In general, the addition of different combinations of BAP and GA3 into the Murashige and Skoog (MS) medium significantly increased the germination ratios of embryos without cotyledons in all species. For wild cherry, the best treatment (66.7% germination) was MS media containing 0.5 mg·L−1 BAP + 2.0 mg·L−1 GA3 or 0.5 mg·L−1 BAP + 4.0 mg·L−1 GA3. For peach, the best treatment (86.7% germination) was MS medium supplemented with 0.5 mg·L−1 BAP + 3.0 mg·L−1 GA3. For apricot, the best treatment (93.3%) was MS media containing 0.5 mg·L−1 BAP + 3.0 mg·L−1 GA3, 1.0 mg·L−1 BAP + 1.0 mg·L−1 GA3, or 1.0 mg·L−1 BAP + 2.0 mg·L−1 GA3.

Influence of impedance contrast on field distribution and tree growth in laminate dielectrics

The effect of the impedance characteristics of an imbedded barrier and inclusions on tree growth and field distribution characteristics was explored through Monte Carlo and finite element method based simulations. A stochastic tree propagation computer model was developed for the laminate composites that were comprised of a high-permittivity barrier layer imbedded in the low permittivity matrix. The impedance of the high-permittivity barrier was altered by systematically changing the permittivity (εr) of the barrier, resulting in a permittivity contrast ranging from 1 to 100. The model showed that there is a significant change in the various breakdown tree propagation characteristics such as number of breakdown steps, speed and shape with impedance contrast. A compilation of several simulation runs was statistically analyzed for each barrier and the number of breakdown steps increased significantly as the barrier permittivity approached 100. The results of this model can be generalized to impedance contrast between dielectric layers that include complex permittivity.

Vegetative propagation of mature dragon trees through epicormic shoots

cEmbrapa, Centro Nacional de Pesquisa de Florestas, Colombo-PR, Brazil. SUMMARY Epicormic shoots were induced in stumps and detached branches of adult Paulownia fortunei var. mikado plants to evaluate rooting potential. Stem cuttings obtained from shoots of stump were prepared with 12 cm in length and two leaves reduced to 78.5 cm² (10 cm diameter). Cuttings from shoots of branches were prepared with 8-10 cm in length, and two leaves reduced to 50 % of the original size. Anatomical analysis was performed to evaluate possible barriers to rhizogenesis. After disinfestation, indolebutyric acid (IBA) was applied (0, 500, 1,000, 1,500 and 2,000 mg L -1 ). Installation was made in plastic pots with a volume of 170 cm³ and 53 cm³, respectively for each type of cuttings, with fine vermiculite and carbonized rice hulls (1:1 v/v) as substrate. After 60 days in a greenhouse, cuttings from epicormic shoots of branches presented rooting (58.12 %) and the average length of the three longest roots/ cutting (4.76 cm) was higher than in cuttings from stumps. The highest number of roots/cutting (7.66) and percentage of cuttings with callus (27.50) was observed in cuttings from stumps. There were no anatomical barriers observed harming the roots formation in the two types of cuttings. The use of indolebutyric acid is not required to induce rooting.

The mechanism of electrical treeing propagation in polypropylene

Growth property of electrical treeing is an important parameter to evaluate the insulation performance of a polymer. The complex non-uniform state of aggregation structure determines the electrical treeing growth in polypropylene (PP), a typical semi-crystalline polymer. In this paper, the electric treeing resistance property experiments for PP as well as the PP sample with nucleating agents are carried out. Effects of crystal shape, crystallinity, and crystalline structure on the electrical treeing growth characteristics in PP and PP with nucleating agents have been analyzed using polarized light microscopy (PLM) and differential scanning calorimetry (DSC). Thermodynamic and dynamic mechanisms of electrical treeing propagation are represented respectively by the thermodynamically driven action of phase interfacial free energy and the discharge-avalanche theory, demonstrating the essential role of electric field distribution in electrical treeing growth. According to physical properties of crystalline phase and amorphous phase in semi-crystalline materials, a computational model of interior electric field distribution has been established to simulate local electric field distribution in the polymer material under needle-plate electrode configuration, and used to analyze the characteristics of electrical treeing channel growing along the grain boundary in semi-crystalline materials. Inhibition effects of crystalline structure changed due to the nucleating agents on electrical treeing growth along the electric field direction are investigated.

Factors Influencing Development of Farm Forestry in Lugari District, Kakamega County, Western Kenya

This study was conducted to establish the factors influencing the development of farm forestry in Lugari Division, Western Kenya. Data was collected between December 2007 to January 2008. Structured questionnaires/schedules, key informant interviewing, and secondary sources of data were used to collect data. All collected data were entered in SPSS 13.5 to facilitate statistical analysis using descriptive statistics such as frequency distributions and cross tabulations. Significant differences between expected and observed attributes were analyzed by non-parametric Chi-square tests. Farm sizes, species preferences, end use of tree products, access to and availability of preferred germplasm and planting materials, availability of resources for raising seedlings, access to extension services, and marketing constraints as well as biological and technical factors such as diseases, pests and planting methodologies were established as important factors influencing farm forestry and tree planting in general, in the division. This study has also demonstrated that farm forestry can be a useful tool for enhancing the livelihoods of many people and contributing to rural development in Lugari, and can be readily adopted if identified challenges can be comprehensively addressed. It is recommended that tree propagation techniques and distribution networks should be developed to enable affordable access to a wide range of appropriate germplasm. Small scale farmers should be assisted, through extension services, to manage and enhance the value of their tree crops. Institutional support through incentives such as credits, subsidies, technical support and creation of market opportunities including forest policy and legislation sensitization and implementation would boost farm forestry

Rapid multiplication of Dalbergia sissoo Roxb.: a timber yielding tree legume through axillary shoot proliferation and ex vitro rooting.

An efficient and improved method for in vitro propagation of mature tree of Dalbergia sissoo, an ecologically and commercially important timber yielding species, has been developed through axillary shoot proliferation. Bud breaking occurred from nodal shoot segments derived from rejuvenated shoots produced during early spring from a 20-25-year-old lopped tree, on MS medium containing 8.88μM benzylaminopurine (BAP). Multiple shoots differentiated (20-21shoots/node) on re-culture of explants on half-strength agar gelled amended MS medium with a combination of 2.22μM of BAP and 0.002μM of thidiazuron (TDZ) with 1.0mM each of Ca(NO3)2, K2SO4, KCl, and NH4(SO4)2. The maximum shoot multiplication (29-30 shoots/node) was achieved on subculturing in the above mentioned but liquid medium. Furthermore, the problem of shoot tip necrosis and defoliation observed on solid medium were overcome by the use of liquid medium. Ex vitro rooting was achieved on soilrite after basal treatment of microshoots with 984μM of indole-3-butyric acid (IBA) for 2min. About 90% microshoots were rooted on soilrite within 2-3weeks under the greenhouse conditions. From 20 nodal shoot segments, about 435 hardened plants were acclimatized and transplanted. This is the first report for rapid in vitro propagation of mature trees of D. sissoo on liquid medium followed by ex vitro rooting.