Ethiopian Journals Online (EJOL)
Not a member yet
4332 research outputs found
Sort by
PERFORMANCE OF PRESERVATIVE TREATMENTS ON 32 TIMBER TREE SPECIES AGAINST TERMITES AND FUNGAL ATTACK AT BAKO, SOUTHWESTERN ETHIOPIA
Get PDFIn Ethiopia, wood damage in construction and furniture sectors caused by biodegradingagents is economically important. Experiments were carried out on 32 timber species to studypreservativetreatabWity (laboratory test) and natural durability of construction timbers, andeffectiveness of preservatives against subterranean termites and fungal deterioration at Bako. Antaristoxicaria (681.14 and 20.43 kg m·3) and Eucalyptus camaldulensis (37.33 and 1.12 kg m·3) indicate thehighest and the lowest chemical absorption and retention properties, respectively. A. toxicaria (25 mm)and Fagaropsis angolensis (1.5 mm) had the highest and lowest chemical penetration, respectively.Significant differences (p < 0.01) were found in the absorption, retention and permeability of CopperChromium Arsenate (CCA) among the timbers. In the damages caused by termites and fungi, significantdifferences (p < 0.01) were also found between stakes treated with CCA and the controls among thestudy species and field exposure times, and in the interactions between preservatives and study speciesas well as preservatives and field exposure times. The extent of attack varied with species,preservatives, application methods and length offield exposure periods. The majority of stakes (> 62%)treated with CCA by pressure method resisted degradation by termite and fungi for more than 11 years,those treated with used motor oil fOl;more than five years and the untreated stakes for one to fouryears. Therefore, timbers from matured trees should be selected and rationally utilized for furnitureand construction purposes with appropriate protection measures taking into accountplace! environment of use, the costs of preservation, the service life of each timber species and theservice life intended
MECHANISMS OF DROUGHT RESISTANCE IN GRAIN II:.STOMATAL REGULATION AND ROOT GROWTH
Get PDFEarlier research works conducted to identify mechanisms of drought resistance in grain legumes under soil water stress of -0.6 MPa showed that drought resistance (maintenace of turgor) in chick pea was due to a significant decrease in osmotic potential (osmotic adjustment) while in common bean it was due to maintenance of high leaf water potential, but not due to osmotic adjustment. Green house experiments were conducted in the University of Hohenheim, Germany to determine whether maintenance of high plant water potential in common bean under stress was the function of stomatal regulation and/or root growth. Seven days mild drought (-0.15 MPa ) decreased the water potential to -0.35 and -0.89 MPa, accompanied by a dry matter decrease of 25 and 15% in common bean and chick pea, respectively. Higher dry matter decrease in common bean was due to reduced CO2-fixation, whereby photosythesis was reduced by 75% in common bean but only by 20% in chickpea. Significant decrease in the rate of photosynthesis decreased the sugar reserve (glucose, fructose and sucrose) of commont bean significantly, which could be responsible for the reduced biomass synthesis. Decrease in the rate of photosythesis was attributed to significant decrease in stomatal conductance. However, water use efficiency was significantly higher in common bean than in chick pea regardless of water regimes. A rhizotrone experiment showed that root length density of common bean was higher than that of chick pea (by a factor of two), accompanied by higher root weight. It was concluded that high plant water potential of common beans under stress was not due to osmotic adjustment but it was the function of effective stomatal regulation and robust root system
APPLICATIONS OF A SINGLE CARBON ELECTRODE
Get PDFA single carbon electrode used with a common arc welder has been successfully used on steel to weld, to surface harden, to spot weld sheet, to pierce holes and to do simple brazin
EFFECT OF PLANT HORMONES ON THE GROWTH AND NUTRIENT UPTAKE OF MAIZE IN ACIDIC SOILS OF THE HUMID TROPICS
Get PDFAn experiment was conducted in a greenhouse to investigate the availability of phosphate fertiliser in acidic soils, and to evaluate the effects of phosphorous and synthetic plant hormones on yield and nutrient uptake of maize (cv. Golda FAO-240). The soil was limed with 1.05 g of Ca(OH)2 and 12.2 g of CaSO4.2H2O 1.7 kg-1 soil according to Jensen Curve. Phosphorus was applied as Mono-ammonium dihydrogen phosphate at the rate of 0, 26 and 52 mg P 1.7 kg-1 soil by placed application using neutral compost as a buffering material. Benzyladenine (BA) and gibberellin (GA) were applied as exogenous plant hormones. Nitrogen, K, Mg, Cu, Mn, Zn, B and Mo were applied uniformly to all pots. In treatments that received P fertiliser without BA the dry matter yield and P uptake by plants were higher by 15.9 and 19.5%, respectively, compared to the results of P with BA. Similarly, in treatments that received P fertiliser without GA the dry matter yield and P uptake by plants were higher by 9 and 15.4%, respectively
RESTORATION OF NATIVE FOREST FLORA IN THE DEGRADED HIGHLANDS OF ETHIOPIA: CONSTRAINTS AND OPPORTUNITIES
No full textWide spread deforestation and subsequent degradation is severely threatening the natural forest resources in Ethiopia. What is imperatively and urgently needed today is ecological restoration. In order for ecological restoration to be successful and cost effective, critical analyses of possible constraints and available opportunities are crucial. Such Knowledge increases our understandings of ecosystem responses and a more reasonable prediction of where and why restoration efforts will be difficult or possible. These understandings will also improve the decision-support systems for the kind of restoration strategies or tools to apply and what kind of management techniques to follow. Available literature indicated that scarcity or complete absence of viable soil seed banks under natural environments and in environments affected by humans, such as abandoned farmlands, poor seed rain/dispersal and site impoverishment would be severe limitations to ecological restoration in the country. On the other hand, land abandonment due to marginalization followed by the establishment of plantation forests as foster crops are opportunities that could be utilized for rapid and productive restoration of the vast degraded ecosystems in the country. Nevertheless, successful utilities of these management options certainly demand conservation of the remnant natural forests to serve as propagule donors. Hence, conservation of the scattered remnant forests in the country is the major prerequisite for successful future restoration ventures
INTERFACES OF REGENERATION, STRUCTURE, DIVERSITY AND USES OF SOME PLANT SPECIES IN BONGA FOREST: A RESERVOIR FOR WILD COFFEE GENE POOL
Get PDFStudies on the diversity, regeneration, structure and uses of some woody species in theBonga Forest, one of the Afromontane forests of Ethiopia were made. A 900 m2 (30 m x 30 m) quadratwas laid following the homogeneity of vegetation in order to collect vegetation data. Investigation ofthe seedling density and regeneration of target species has been carried out using the same quadratsize. In each of these quadrats, the numbers of all seedlings that are up to the height of 150 cm wererecorded. Individuals attaining 150 cm and above in height but less than 10 cm in diameter at breastheight (DBH) were considered as sapling and counted. DBH and height of all woody species that areabove 150 cm high and more than 10 cm thick were also recorded. Interviews were conducted to collectdata on various human pressures exerted on different species. A total of 243 plant species belonging to85 families were recorded from the Bonga Forest. Of these, 66 families were angiosperms, 2gymnosperms and 17 monilophytes (ferns). Studies on the structure and regeneration of some woodyspecies indicated that there are species that require urgent conservation measures. Sound managementand monitoring, as well as maintenance of biodiversity, cultural and economic values of the forestrequire conservation activities that promote sustainable uses of the forest and its product
Additive Main Effects and Multiplicative Interaction Analysis of Coffee Germplasms from Southern Ethiopia
Get PDFAdditive main effects and multiplicative interaction (AMMI) analysis is a recently recommended effective method to study the genotype by environment (GxE) interaction pattern of multi-environment varietal trials. This work deals with modeling and examining the GxE interaction pattern of the multi-environment trials of 43 genotypes and eight environments from Southern Ethiopia coffee (Coffea Arabica L.) collections using a randomized complete block design (RCBD) with four replications. The work further attempts to predict yield based on the ammi model and evaluate and recommend high performing and adaptable varieties. The AMMI model with the first two interaction principal component axes (AMMI2) is found to be appropriate and parsimonious for the data. Environments e5, e6, e7, e8 and e3 are found to be high potential environments, where genotypes having high-yield (greater than 14 qt/ha) and resistant to Coffee Berry Disease (CBD) are associated. Among the 43 genotypes, 1, 9, 2, 3, 32, 12 and 25 are found to have the best performance with 3, 32, 12 and 25 being highly stable. Among the high-yielding genotypes, 33, 4, 23, 34 and 27 are found to be highly unstable and particularly adapted to environments 5, 6, 7 and 3, respectively
SPECIES COMPOSITION, RELATIVE ABUNDANCE AND HABITAT ASSOCIATION OF THE BIRD FAUNA OF THE MONTANE FOREST OF ZEGIE PENINSULA AND NEARBY ISLANDS, LAKE TANA, ETHIOPIA
Get PDFThe present study was carried out in Zegie Peninsula and Kibran Gebriel and Entos Iyesus Islands of Lake Tana from August 2006 to March 2007. Sampling sites were stratified based on the vegetation type and area cover. Point count technique and chi-square test were employed to see the association of birds with the different vegetation strata. A total of 101 bird species were recorded, out of which 91 were residents (three endemics) and 10 were Palaearctic migrants. The Zegie Peninsula had high species diversity and evenness (0.96 and 0.86, respectively). The relative abundance of birds during the wet and dry seasons was variable. A total of 54 and 68 species were recorded during the wet and dry seasons in the Zegie Peninsula, respectively. The islands possessed 24 species each season. Habitat association of birds within the vegetation strata of Zegie Peninsula during the wet season was: highest at the shore (4.50), followed by gardens (4.00), bushes and shrubs (3.33) and trees (2.17). During the dry season, the highest mean number of birds occurred in the garden vegetation (4.86), followed by trees (3.23), fringe type of vegetation (3.22), and bush and shrub vegetation (2.60). During the wet season, the association of birds with the vegetation stratum was not statistically significant (p > 0.05, chi-square =13, df =7, n = 32). However, this was significant during the dry season (p < 0.05, chi-square = 66.238, df =9, n = 84). Conservation action to minimize the anthropogenic effect at Zegie should be the order of the day
Fault control on patterns of Quaternary monogenetic vents in the Ethiopian Rift between Omo and Tendaho
No full textField and remote sensing data are used to examine the distribution of volcanism and fault geometry in the Ethiopian Rift between Omo-Chew Bahir rift and Tendaho graben during the Quaternary and evaluate their influence on the location and shape of individual vents as well as the development of alignments. The results of remote sensing, and field study of the total (2214) cone populations reveal that monogenetic vent alignments and the long axes of elongate cones are parallel to and spatially linked with mapped normal faults. This is consistent with the overall sub- latitudinal extension direction in the Quaternary deduced from fault slip analysis and earthquake focal mechanism solutions. Out of the rift axis, pre-existing faults were apparently reactivated and acted as conduits for magmatism to reach the surface, and hence vent clustering. On regional scales, vent clusters are located in Quaternary volcanic fields along the rift axis and in zones of reactivation of pre-Tertiary structures. Sixty two percent of the vents in the study area are part of nine regional vent alignments that vary in length from 48 to 68 km. On sub-regional scales, twelve clusters ranging in length from 10 to 30 km have been mapped. Locally, field structural data show that individual vents and short vent alignments, up to 10 km in length, occur along and adjacent to faults, particularly along fault segments, intersections, and bifurcations. The long axes of elongate volcanic cones also have trends generally parallel to the local faults