ABSTRACT The seaweeds of the Namibian coast have received little attention from researchers despite the fact that there is a successful industry based on seaweed exploitation. Beach cast Graci/aria verrucosa (Hudson) Papenfuss is collected (9000-15000 t (wet) y-1) in the Luderitz area for the production of agar, Laminaria schinzii Foslie was harvested for a short period from April 1987 to March 1989 and there is an increasing interest in utilizing other seaweed species on the coast. The natu...
ABSTRACT The poor response of some plant species, e.g. wheat, to ammonium nutrition has been attributed to a diversion of carbon allocation from structural material for root extension to functions associated with the assimilation and translocation of ammonium in the root. The aim of this research was to investigate carbon allocation in response to ammonium or nitrate nutrition in wheat, an ammonium intolerant species, and maize, which exhibits ammonium tolerance. Experiments were · carried ...
Abstract The seed that eventually gave birth to this thesis was planted in August, 1975 when, during a cruise of the Research Vessel Meiring Naude the existence of deep-sea cyclonic vortices in the South Western Indian Ocean was discovered. Little was it realised during that small, fortuitous beginning in 1975 that the study would develop into the first detailed physical oceanographic investigation of the Mozambique Ridge and adjacent Mozambique Basin areas. It could also not be foreseen tha...
Abstract. A brief review of the literature on the effects of nitrate and ammonium nitrogen sources on plant growth, and the assimilation of those nitrogen sources, has been presented. A water culture technique for the growth of maize was developed. The use of a gravel rooting medium with nutrients recycling through the rooting medium, and an iron supplement in the form of ferric citrate, resulted in superior growth of nitrate-fed plants in comparison to that observed with a hydroponic growth...
Abstract One of the central goals of plant ecology is to understand the factors that control the local distribution of plant species and thus the composition of communities. The aim of this study is to determine plant functional traits that can be associated with drought tolerance/avoidance and to test whether wood density is a good indicator of drought tolerance. The study was carried out in Kruger National Park in the month of June. A number of plant traits including wood density, leaf thic...
Abstract Seagrass meadows have important ecological roles in coastal ecosystems and provide high-value ecosystems services compared to other marine and terrestrial habitats. Despite this, there is growing evidence that this key ecosystems is declining on a global scale. Much of these declines have been attributed to the effects of human alterations of marine habitats. Continued destructive activities, in both South Africa and elsewhere, if not managed properly will result in the demise of sea...
ABSTRACT Production of potato (Solanum tuberosum L.) in Kenya is constrained by many biotic, abiotic and socio-economic factors. Among the biotic constraints, bacterial wilt, caused by Ralstonia solanacearum (Yabuuchi et al., 1995) presents major management difficulties. Attempts to combat the disease have been difficult due to the complex heterogeneous genetic make-up of the pathogen, comprising different races and biovars, its survival mechanisms and its large number of hosts, including wee...
ABSTRACT: Activities of the distilled water, ethanolic and chloroform extracts of Daldina concentrica an ascomycetous fungus was investigated on Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus) using agar well diffusion method. Ethanolic extract of Daldina concentrica showed significantly antibacterial activity against all the test microorganisms except Bacilllus cereus (P ≤0.05). Staphylococcus aureus was the most sensitive organism t...
ABSTRACT The quest to boost dietary protein production from readily available and affordable sources is ever increasing in developing countries. The indigenous edible Pleurotus species (oyster mushrooms), which grow naturally on wood wastes, are potential protein supplements. However, little information is available on the usage of selected tropical trees for optimum mushroom cultivation. Therefore, this research was designed to investigate the growth and yield of oyster mushrooms on sawdust...
ABSTRACT Mushrooms such as Pleurotus, Vovariella and Auricularia species are cultivated for food and medicinal purposes in the world. However, cultivation of Auricularia in Nigeria is limited due to inadequate information on its characteristics, nutritional contents and cultivation requirements. Hence, this study was designed to characterise Auricularia species in Southwestern Nigeria and determine suitable substrates for their cultivation. Fifty-four samples of Auricularia species were ran...
Abstract Lippia javanica (Burm. F.) Spreng occurs naturally in eastern, central and southern Africa. It has widely been used as herbal tea, for ethnomedicinal applications and as a botanical pesticide. Lippia javanica species exhibit great morphological and chemical variations which are notable across a number of natural populations. Differences in morphological taxonomy on important characters such as peduncle length and number of inflorescence per axil have been reported which has led to th...
ABSTRACT The demand for agricultural land is driving the conversion of moist Kenyan savannah into agroecosystems (grazing fields and croplands) and together with altered rainfall patterns, is likely modifying soil moisture, soil respiration and carbon store in the ecosystem. Nevertheless, the carbon dynamics of moist savannas plus of the converted ecosystems are poorly understood yet planning for sustainable use of the ecosystem need to be based on scientific knowledge. While previous studie...
ABSTRACT Of all the uses of African plants, the aspect of medical use has probably attracted the most attention and has also been the most complex and varied. Nearly 70,000 species of higher plants have been used for medical purposes world wide. Medicinal plants form the key component to traditional medicine which remains the major source of health care for over 70% of the Kenyan population. Over 90% of the population use medicinal plants at one time or another. The increasing need to develop...
ABSTRACT Taro (Colocasiae esculenta L. Schott) popularly known as ‘nduma’ is an aquatic plant grown for its edible leaves and corms. It is mainly cultivated in Western and Central Kenya but its production is constrained majorly by Phytophthora colocasiae, a taro leaf blight (TLB) disease. The disease causes destruction of leaf and corm. Knowledge pertaining to taro association with the disease incidence, severity, index, Rainfall, R.H, temperature, interrelationship between agronomic trai...
ABSTRACT The Petroleum Industry has a huge potential for the pollution of the environment at every stage of its operation, hence the need to constantly fashion out new strategies for maintaining the sanctity of our environment. Fungi associated with diseased Irvingia gabonensis (Baill) seeds found in the open markets were suspected to possess the ability to degrade the hydrocarbon substances contained in these seeds. These fungi were isolated bimonthly from the diseased seeds of I.gabonensis...