Considerable Economic Potential Research Articles

First Report of Stem Canker of English Walnut Caused by Fusarium solani in South Africa.

Cultivation of English walnut (Juglans regia L.) has considerable economic potential in South Africa. In February 1999, die-back of walnut trees was observed on ≈30% of trees in an orchard in Gauteng Province, South Africa. Die-back was associated with characteristic cankers and discoloration of the cambial tissue of twigs and young branches. Fifty pieces of discolored tissue from the margins of cankers of five trees were transferred to potato dextrose agar (PDA) after surface-sterilization with 0.5% NaOCl. Fungal colonies emerged from all 50 pieces of diseased tissue. Fungi recovered included Fusarium solani (74.5%), Alternaria tenuissima (17.3%), and a Phoma sp. (6.2%). Small pieces of sterile cheesecloth (10 × 5 mm) were cultured on PDA with an isolate of F. solani from infected walnut trees. Colonized pieces of cheesecloth were applied to stems (≈5-mm diameter) of nine potted J. regia plants in a glasshouse. Each stem was wounded by lightly scraping off a length of bark (5 × 5 mm). Colonized cheesecloth was wrapped around the wound and covered with Parafilm to prevent desiccation of mycelia in the cheesecloth. Nine walnut stems were similarly treated with sterile cheesecloth pieces to serve as control treatments. After 4 weeks, die-back of foliage was observed in all plants artificially inoculated with F. solani. Cheesecloth pieces and surrounding bark were removed, and the length and width of each cambial lesion was measured. The mean area of cambial lesions (length by width) resulting from artificial inoculations was 27.3 × 8.5 mm. None of the control plants developed any symptoms. Koch's postulates were confirmed by consistently reisolating F. solani from inoculated plants. A similar disease of black walnut (J. nigra) was reported by Carlson et al. (1) from five central states in the United States. Our findings represent the first report of F. solani as a causal agent of stem canker of English walnut in South Africa. Reference: (1) J. C. Carlson et al. N. J. Appl. For. 10:1, 1993.

Viabilidade e superação da dormência em sementes de Araçá-boi (Eugenia stipitata ssp. sororia)

O araçá-boi (Eugenia stipitata ssp. sororia McVaugh - Myrtaceae) é uma frutífera amazônica com potencial agroindustrial. O presente trabalho verificou os efeitos da desidratação sobre a viabilidade de sementes e avaliou métodos de escarificação mecânica (por descascamento e lixamento) na superação da dormência de sementes dessa espécie. A qualidade fisiológica das sementes é afetada pela redução do teor de água. As sementes apresentam comportamento recalcitrante, sendo que o nível crítico de umidade pode estar situado entre 58,8 e 47,1%. A desidratação a níveis iguais ou inferiores a 25,76% de água provocou a morte em 100% das sementes. As sementes devem ser semeadas, preferencialmente, logo após a extração e limpeza. O tegumento das sementes apresenta resistência mecânica à expansão do embrião. A remoção total do tegumento foi o método mais eficiente na superação da dormência, pois elimina a resistência na região onde ocorrerá a ruptura pelo embrião, com tempo médio de emergência de 66 dias e percentagem final de emergência de 96%. Os lixamentos provocaram injúrias mecânicas nas sementes, tendo consequências diretas na emergência e vigor.

Growing Shiitake Mushroom on Hardwood Sawdust in the Greenhouse

Seven strains of shiitake mushroom [Lentinula edodes (Berk.) Pegler] produced spawn in culture vessels containing hardwood sawdust amended with YVMBS (yeast extract, multigrain oatmeal, brown sugar) broth within 35 to 45 days after mycelia inoculations. Under greenhouse conditions, shiitake basidiocarps (mushroom fruit) appeared from 1 to 3 months after spawn inoculations of the hardwood sawdust amended with YVMBS broth. The shiitake mushroom strains LE2, LE1, LE6, and LE5 had 10.4, 7.3, 2.5, and 1.6 times more fresh harvested basidiocarps, respectively, on the amended hardwood sawdust compared to the controls. The amount of basidiocarps produced by the shiitake strains LE3, LE4, and LE7 was the same on both hardwood sawdust treatments. The basidiocarps of LE1, LE2, LE3, LE4, and LE5 were averaged 5 inches (12.7 cm) in diameter, however, the basidiocarps of LE6 and LE7 were averaging only 2 inches (5.1 cm) in diameter. The only pests of the shiitake basidiocarps in the greenhouse were slugs, but they were easily controlled by applying table salt. The start up cost of inoculating 100 shiitake spawn blocks on hardwood sawdust on one bench in the greenhouse was $77. The start up cost of inoculating shiitake spawn on 100 logs was $1,329.75. In 1 year, shiitake strains LE1, LE2, LE5, and LE6 produced 19.5, 20.2, 7.9, and 4.5 lb (8.8, 9.2, 3.6, and 2.0 kg), respectively, of harvested fresh basidiocarps on amended hardwood sawdust in the greenhouse. The mushrooms retail for $3.20 to $4.20/lb ($7.05 to $9.26/kg). The use of the hardwood sawdust amended with YVMBS broth for shiitake production in the greenhouse has considerable economic potential for shiitake mushroom growers.

Paraná Basin: Mineral Resource Potentials in Brazil, Uruguay, and Paraguay

The Paraná Basin is a Western Gondwanan cratonic basin that is better defined as the Paraná depositional site, since it has a diverse history as a basin. Sedimentation started in the Ordovician-Silurian, followed by extensive marine Devonian deposition. A Late Paleozoic/ Triassic facies cycle wedge was clearly built during Pangean time. The Early Cretaceous was characterized by extensive basaltic lava flows immediately before the break-up of Pangea. Following these rifting and drifting processes, the basin's structural framework was totally rebuilt, generating new depositional sites in the Late Cretaceous to Tertiary. Based on more recent data, at least two different basins may be defined during the evolution of what was once considered a unique basin. Nevertheless, even if considered as a single basin, the sedimentary pile of the Paraná Basin has considerable economic potential, until now exploited only rudimentarily, except for its groundwater resources. Aggregates, limestones, clays, industrial sands, gems, dimension stones, hydrocarbons, coal, peat, and uranium are some of the potential mineral resources of this basin.

Determinants of the composition and distribution of wildlife communities in Southern Africa : J. T. Du Toit, Ambio, 24(1), 1995, pp 2–6

Sustainable utilization has become widely accepted in southern Africa as the most pragmatic approach to conserving the region's biodiversity. The rich wildlife resources of southern Africa hold considerable economic potential, but the options for maximizing and sustaining this potential are constrained by the ecological and human determinants of the wildlife communities in each particular ecosystem. This paper aims to provide a general overview of these determinants in an attempt to stimulate the transfer of information from ecologists to managers, investors and development agencies. The primary ecological determinants of large mammal communities in African savannas are rainfall and soil nutrients, since these determine the quantity and quality of food available to large herbivores. These ecological determinants are, however, becoming increasingly masked by the effects of land transformation, veterinary controls and wildlife economics.

Flotation of fine-size barite from gravity separation tailings

The concentration of barite by gravity separation generates substantial quantities of fine-particle wastes, and it is estimated that ≈40% of the contained barite is lost to these waste streams. In this study, froth flotation was examined as a potential method for the recovery of fine-barite particles. The study included the use of kinetic equations to estimate the variables effecting flotation, batch-scale rougher flotation tests to study the flotation variables and an examination of alternatives for the cleaning of the rougher concentrate. Results indicated that a concentrate grade of 96.5% could be achieved with a recovery of 77.5%. Although barite flotation from industrial wastes is more difficult than direct barite flotation, the process has considerable economic potential.

Economic Reform in Arab Countries: A Review of Structural Issues for the Remainder of the 1990s

The paper reviews the main structural reform issues facing Arab countries in the remainder of the 1990s. While the nature, extent, and implications of the policy challenges differ among individual countries in the Arab region, several aspects are common to a large number of them. Accordingly, the paper identifies a framework consisting of a core of key reforms that would address these countries` structural weaknesses and assist them in exploiting their considerable economic potential.

Economic Reform in Arab Countries: A Review of Structural Issues for the Remainder of the 1990's

The paper reviews the main structural reform issues facing Arab countries in the remainder of the 1990s. While the nature, extent, and implications of the policy challenges differ among individual countries in the Arab region, several aspects are common to a large number of them. Accordingly, the paper identifies a framework consisting of a core of key reforms that would address these countries’ structural weaknesses and assist them in exploiting their considerable economic potential.

Variação fenotípica em frutos de doze introduções de Cubiu (Solanum sessiliflorum Dunal) avaliadas em Manaus, AM, Brasil

RESUMOO cubiu foi domesticado pelos ameríndios e tem potencial econômico considerável para a agroindústria moderna. Frutos de doze introduções de cubiu foram avaliados em Manaus para determinar as diferenças entre estas: formato, dimensões e carateres de importância econômica (espessura de polpa, volume do suco, grau Brix). Existe considerável variação entre as introduções para todos os carateres avaliados, especialmente tamanho e número de frutos. A concentração de sólidos solúveis totais variou de 4 a 6 e o volume de suco de 10 a 30 ml em frutos de 40 a 190 g. Conclui-se que estas 12 introduções possuem variação ampla que permite progresso genético rápido no melhoramento para qualquer finalidade agroindustrial.

Petroleum Geology and Exploration of Scotts Bluff Trend, Northeastern Denver Basin, Nebraska: ABSTRACT

Ten J Sandstone oil fields form a long, narrow, northeast-southwest trend in western Nebraska. Except for these fields, this area is nonproductive End_Page 527------------------------------ of oil and gas. It is proposed that this group of related fields be termed the Scotts Bluff trend. Subsurface mapping indicates that recurrent movement along Precambrian basement faults has enhanced reservoir quality and localized oil migration, favoring oil accumulation along the trend. The J Sandstone dips gently southwest across the northeastern Denver basin. Low-relief closures and structural noses are critical elements in several structural-stratigraphic traps. However, most of the traps are controlled primarily by an updip facies change from porous, permeable sandstone to siltstone and shale. Most oil production is from the J1 member, whose commercial production limits coincide with porous sandstone bodies at least 5 ft (1.5 m) thick. Three fields each have produced over 1,000,000 bbl of oil. The J1 was deposited in elongate, elliptical, northwest-trending marine bars that are rhythmically separated by laterally equivalent shales. The central-bar facies, which includes most of the reservoir rock, grades into bioturbated bar-margin siltstones which, in turn, grade into interbar shales. Long-distance lateral migration into the shallow reservoirs of the trend from thermally mature shales of the Dakota and Benton Groups near the basin's axis is indicated. Recognition of the trend's characteristics will reduce exploration risk and help realize the area's considerable economic potential. End_of_Article - Last_Page 528------------

THE PROBLEMS, ECONOMIC POTENTIALS AND SYSTEM DESIGN OF LARGE FUTURE TROPICAL MARINE FISH CAGE SYSTEMS

ABSTRACTFuture tropical commercial marine cage culturing systems, for use in exposed coastal sites, are evaluated through a case study approach. Preliminary design options, based on an optimistic extrapolation of present knowledge and capabilities, are developed for projected Hawaiian systems. The effects of different scales of operation on the choices of technical approaches, support activities, and system economics are considered. The resulting designs are also evaluated with respect to economic and bioengineering risks. The problems that must be resolved are indicated in the context of their scientific, technical and economic impacts on such culture systems. It is clear that tropical sea cage culturing of high value food fish has considerable economic potential, even at modest scales of operation.

HYBRIDS AND INDUCED AMPHIPLOIDS OF ELYMUS CANADENSIS X AGROPYRON LIBANOTICUM

North American Elymus canadensis L., 2n = 28, and Asian Agropyron libanoticum Hack., 2n = 14, crossed with ease and yielded vigorous but sterile F1 hybrids, 2n = 21. Chromosome pairing in the hybrids averaged 9.47I, 5.38II, and 0.26III in 150 metaphase‐I cells. One genome of E. canadensis is more or less homologous with the A. libanoticum genome. Treatment of the F1 hybrids with colchicine produced 42‐chromosome amphiploids, C0, which were advanced through two seed generations, C1 and C2. More than half of the metaphase‐I cells in the C0 amphiploids contained 21II; and average associations were 1.09I, 20.16II, 0.07III, and 0.09IV in 116 cells. Meiosis became increasingly irregular beyond metaphase‐I; nevertheless, the C0 amphiploids produced 68% stainable pollen and averaged 0.75 seed per spikelet. Multivalent frequencies increased in advanced generations, and the C2 amphiploids averaged 1.11I, 19.00II, 0.23III, and 0.55IV in 100 metaphase‐I cells. Meiosis was essentially regular in the C1 and C2 amphiploids beyond metaphase I, and the C2 amphiploids averaged 73% stainable pollen and 2.28 seeds per spikelet. The amphiploids have an excellent chance of developing into a meiotically stable, fertile, new species. Forage characteristics of the amphiploids indicate that they have considerable economic potential as a forage grass.

OBSERVATIONS ON THE FIRST SCOLYTID, POECILIPS PTERIDOPHYTAE (COLEOPTERA: SCOLYTIDAE), TO BE FOUND IN ASSOCIATION WITH A FERN (PTERIDOPHYTA)

AbstractPoecilips pteridophytae Schedl is the first species of Scolytidae to be found on a fern. It appears to be fairly widely distributed in New Guinea on the tropical bracken fern, Pteridium aquilnum (L.). The association is most probably of recent evolutionary origin. The immature stages are described in the text. Its life history is relatively short, the life cycle raking 2 to 4 mouths, and takes place wholly width the stem of the fern, except for emigrating adults. P. pteridophytae may have considerable economic potential as a biological control agent of bracken fern in countries where it is a pest.

East African Seaports: An Application of the Concept of 'Anyport'

first century A.D., when the writer of the Periplus of the Erythraean Sea1 visited Mombasa and described trading stations along the coast to which Arab traders from the northern shores of the Indian Ocean brought wheat, sugar, cotton and china in exchange for slaves and ivory, rhinoceros horn, tortoiseshell and cinnamon. Early trading activity was based upon the seasonal reversal of winds in the Indian Ocean and upon the use of Arab sailing dhows; and because only the most rudimentary port facilities were needed, there existed a large degree of flexibility in terms of port sites. No fundamental change took place in this trade pattern until the nineteenth century when several factors combined to produce an acceleration and a reorientation of trade. In the earlier years of the century, African traders were moving increasingly to the coast, and Arabs penetrating farther inland from their base at Zanzibar; later European exploration and administration presented new necessities and opportunities for trade. Thus, the coastlands which for centuries past had been, in trading terms, nothing more than the western shore of the Indian Ocean,2 on the outer fringes of maritime circulations, became the maritime faqade of a developing region of considerable economic potential. This new orientation involved a crystallization of the formerly fluid pattern of port sites, as rail links were built inland and investment in port facilities grew, and the coming of the age of steam navigation also made possible the utilization of harbours hitherto neglected by the dhows. Five ports handling ocean-going vessels have emerged during the past 75 years to serve the needs of East Africa today: Mombasa, Tanga, Zanzibar, Dar es Salaam and Mtwara (Fig. I). Although there are important variations between the five seaports in terms of situation and site conditions, and in terms of facilities and traffic levels, they have shared many common features during their modem growth. This paper is concerned with the analysis of the development of these terminals within the framework of the 'Anyport' technique. The situation of the East African port group as a whole is generally advantageous, and site conditions at individual terminals do not present any insuperable obstacles to physical expansion, in the context of the functional framework within which each port now operates and is likely to continue to operate in the foreseeable future. The conditions of land and water situation which now favour the growth of the seaports have largely arisen during the last Ioo years; developments on both the landward and seaward sides, in transport and in economic and political geography, have now intensified and enormously widened the significance and relationships of the seaports, so that they no longer lie in a backwater but maintain links with major seaports in all the inhabited continents. The East African coast is equipped with several good natural harbours, where adequate shelter and deep water close inshore remove that dependence upon tidal fluctuations which so rigidly restricts shipping manceuvres in many

Economic geology of a part of the Hillsboro, New Mexico, mining district

Recent mining of high-grade Au, Ag, and Cu ore has focused attention on the old Hillsboro, New Mexico, mining district. The examination of old mines and geological study of present operations shows that older development concentrated mainly on oxidized ore with its free-milling Au. Present operations, apparently in the oxidized-primary contact zone, show the mining of primary ore to be now economically feasible, especially with the sporadic occurrence of supergene ore pockets. Geology of the district plus the nature of mineralization is indicative of considerable future economic potential.