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The African Journal of Plant Science and Biotechnology

Abbreviation: African J. Plant Sci. Biotech. Print: ISSN 1752-3931 Frequency and Peer status: Biannual, Peer reviewed

Scope and target readership: The African Journal of Plant Science and Biotechnology accepts reviews and original papers that focus on any aspect of plant science, fundamental or applied. The African Journal of Plant Science and Biotechnology forms part of the Global Science Series that focuses on plant science research originating from any part of Africa, reflecting cultural and/or geographical influence from countries on this continent. In general the author(s) should be from a country inside Africa, or if a foreign team of researchers is involved, then at least one of the authors should be African. Editor-in-Chief Jaime A. Teixeira da Silva, Kagawa University, Japan Technical Editor Kasumi Shima, Japan Statistics Advisor Marcin Kozak, Warsaw University of Life Sciences, Poland Editorial Board and Advisory Panels (Listed alphabetically)

Khalid Ali Khalid Ahmed, National Research Centre, Egypt Thomas Dubois, International Institute of Tropical Agriculture, Uganda Riad El-Mohamedy, National Research Center, Egypt Nehal S. El-Mougy, National Research Center, Egypt Harzallah-Skhiri Fethia, Higher Biotechnology Institute of Monastir, University of Monastir, Tunisia Chakali Gahdab, National Institute of Agronomy, Algeria Mazuru Gundidza, University of Zimbabwe/University of Fort Hare, Zimbabwe/South Africa Faouzi Haouala, Institut Supérieur Agronomique de Chott Mariem, Tunisia Hashem Hussein, Cairo University, Egypt PR Jeyaramraja, Hamelmalo College of Agriculture, The State of Eritrea P. Lava Kumar, International Institute of Tropical Agriculture, Nigeria Reda Moghaieb, Cairo University, Egypt Christopher Ochieng Ojiewo, The World Vegetable Centre, Tanzania Ahmed Oukabli, National Research Institute, Morocco Gamal Hassan Rabie, Zagazig University, Egypt Dharini Sivakumar, University of Pretoria, South Africa Leena Tripathi, International Institute of Tropical Agriculture, Uganda Teferi Yeshitela, OMNIA FERTILIZER Pty., LTD, South Africa

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Guest Editor Dr. Tabo Mubyana-John Department of Biological Sciences, University of Botswana, Gaborone, Botswana

Cover photos/figures: Top plate: Photographs of some of the herbal medicines in Btotswana (from top to bottom, left to right): Hirpicium bechuanense, Cassia abbreviata subsp beareana, Cadaba aphylla, Capparis tomentosa, Helichrysum paronychioides, Jatropha erythropoda, Myrothamnus flabellifolius, Urginea sanguinea, Dicoma anomala (Setshogo and Mbereki, pp 69-74). Bottom graph: CCA ordination and environmental variables overlaid to classify communities of herbaceous and woody plant species in abandoned traditional kraals (Sarah Kizza, pp 8-15). Disclaimers: All comments, conclusions, opinions, and recommendations are those of the author(s), and do not necessarily reflect the views of the publisher, or the Editor(s). GSB does not specifically endorse any product mentioned in any manuscript, and accepts product descriptions and details to be an integral part of the scientific content. Printed in Japan on acid-free paper. Published: July, 2011.

The Guest Editor

Dr. Tabo Mubyana-John Contact e-mail: [email protected] Dr. Tabo Mubyana-John has a B.Sc. from the University of Zambia, an M.Sc. in Soil Science (major microbiology and biochemistry) from the University of Ghent, Belgium and a PhD in Soil Microbiology from the University of Saskatchewan, Canada. She has taught soil microbiology and soil fertility at several universities such as the University of Swaziland, University of Papua New Guinea. Currently, she is lecturing at the University of Botswana where she teaches environmental microbiology to undergraduate and microbial ecology and soil microbiology to post graduate students. Her areas of research focus on microbial-plant interactions and microbial nutrient cycling. Most of her publications are on microbial-plant interactions in the Okavango Delta of Botswana. She has supervised more than 14 postgraduate students on diverse projects related to microbial-plant interactions and soil nutrient cycling in many unique environments.

Foreword

Botswana, located in southern Africa, consists mostly of the Kalahari Desert in the west, the semi arid southeast and central districts, the saltpans scattered around the arid and semi arid landscape. is brought to life by the Okavango Delta. The Okavango Delta is bordered by the Mopane woodlands on one side, saltpans on the other and desert sands. The Okavango is an inland delta sustained mainly by rainfall from the Angolan highlands that converges to form major tributaries, which merge into the Okavango River and eventually spreads into numerous channels, temporary and seasonal swamps. These support a highly diversified pristine ecosystem harbouring an abundance of fauna and flora which characterize the Okavango. The Okavango soils classified as fluvisols by FAO/UNESCO and are highly sandy with a minimum of 85% sand with CEC of 5 meq/100g soil with a low nutrient, low water holding capacity and low organic matter content. Typical habitats consist of floodplains, woodlands and islands. An abundance of grasses and sedges characterize the floodplains. Unique riparian vegetation and palm trees characterize the woodland around the delta. This setup in the middle of a desert climate makes the Okavango a major haven for wildlife ranging from Africa's big five (elephants, lions, hippos, crocodiles, buffaloes) to the small unique lizards which only occur there. Most of the large wildlife in the entire southern Africa are migratory and rely heavily on the Okavango Delta waters in the dry season. Monitoring of the water and plant species and factors that affect plant life in this area would not just help conserve the regional wildlife but also give an indication on the safety of ecological practices in Angola where the flood waters arise from. Apart from the Okavango Delta and the immediate vicinity with a very high plant diversity and density due to flood waters, the Mopane woodlands which are further from the Delta, are very rarely if at all influenced by the delta water. They give rise to a vegetation type of low plant diversity consisting mostly of Mopane (Colophospermum mopane) trees and shrubs (Ximenia caffra). Although very dry (3% soil moisture during dry season) and with little plant diversity they are of great environmental significance. They have a food value to both the people who utilize the Mopane worm which grow on the tree leaves and to the livestock and wildlife which consume the leaves and pods and finally as fuel for the surrounding population. The Mopane worm harvested off the trees is exported throughout southern Africa where they are used as both human and animal feed. From a scientific point of view, the Mopane woodland is an important soil cover in a very hot area (maximum day temperature 52oC) and also plays a major role in the carbon cycling budget of the region. The surrounding semi arid regions are also home to many unique plants such as the baobab (Adansonia digitata) which has both a medicinal and economic value. The saltpans of Botswana found in the desert, are flat expanses of land covered with salt and other minerals. The Makgadikgadi saltpans that cover 12,000 km2 located in north central Botswana are believed to be the largest of their kind in the world. The pan system is made up of two major saltpans being the Sua and Ntwetwe pans, and some small scattered natural saltpans such as Nxai pans Morwamosu, Kang, Tshane and Sekoma located elsewhere in the Kalahari. Among the most extreme habitats in Botswana are the man-made saltern ponds adjacent to Sua Pan located to the east of Makgadikgagdi complex. Although no plants grow on the saltpans themselves, they contain unique microorganisms such as rare algae and fungi which may be of economic important in medical and other industries. The rest of the Kalahari has some of the very unique and rare plants such as the resurrection plant (Selaginella spp.), Devil's claw (Harpagophytum spp.) and cacti including Hoodia gordonii. Many of which have an economic importance, that has yet to be revealed. Amidst all this, microorganisms play major roles in interactions with the plants and other flora, biotic and abiotic aspects, such as soil and the salts in the saltpans and also between themselves, thus influencing the delicate environment. The soil fertility of the region is highly dependent on microbial nutrient cycling such as mineralization and fixation of different elements directly into plants and soil. Due to extreme temperatures in the desert climatic region, soil microorganisms in the region may possess unique adaptation measures and properties whose understanding could help in drought agricultural systems and in the control of some plant pathogens of economic importance. Botswana has a very high density and diversity of both livestock and wildlife both of which rely on the plant life and sometimes compete for the resources. The major portion of the income of of Batswana people is from the rearing of livestock. Thus practices such as fire management and overgrazing could have a negative impact unless an understanding of plant cycles is utilized. The interactions arising from the human pastoralist, the wildlife and the urban dwelling community result in a complex delicate environmental interaction, which if not well understood and managed could result in the catastrophic breakdown of this unique but highly delicate ecosystem which could in turn affect the entire wildlife in the region. The Botswana government having been aware of the delicacy and value of plant science research in the region has established research institutions such as the University of Botswana, Okavango Research Institute and other research organization in the Ministry of Science and Technology to work on some of these aspects in order to conserve the highly valuable ecosystem. This special issue of African Plant Science and Biotechnology highlights research that has been done in Botswana the past few years on some of these aspects.

Dr. Tabo Mubyana-John, June 2011

Foreword Profesor Isaac N. Mazonde

Associate Professor of Geography, Director, Office of Research and Development University of Botswana, Botswanana E-mail: [email protected] This foreword differs from that of Dr. Tabo Mubyana-John in that it synthesizes the papers and then provides a framework in which to view them. The quality of the science that is reported throughout this volume is underpinned by a number of factors acting collectively. These are the diversity of the investigators in terms of their places of origin, their different specializations, and the interdisciplinary approach that they give to their research. All of these factors ensure the cross pollination of ideas, something that is conspicuously evident in the rigour of the methodologies that they employ in their investigations and the rich and diverse experiences that they bring to the treatment of the issues being investigated and their scholarship and manner of communication of research findings. The papers report on work that is done throughout Botswana, stretching from the Okavango Delta, a wetland ecosystem in northwestern Botswana that is known for its rich biodiversity and the innovative use of its plant products by the different population groups that inhabit it. The papers apply a range of analyses, from hard core natural sciences to high level social analysis. Consequently, while some of them analyse toxicity of chemical compounds in plants, others focus on the more palatable social sciences such as food security. This is a measure of strength for the volume because it provides the reader with a comprehensive or at least a varied collection of research findings which are useful to natural and social scientists, and of course, to policy makers as well. All who read these papers will find it a pleasure to do that because they do bring up new knowledge into the fields that they cover. All of them are results of researches carried out with a lot of methodological rigour, and as already indicate above, with the needs of the different types of readers in mind. The first paper presents the research results by a group of five scholars who report on Screening for Anti-infective Properties of Selected Medicinal Plants from Botswana. The findings, based on work done on 39 ethanol extracts from a total of 26 plants distributed throughout Botswana, confirm some anti-infective and wound healing ethnomedical uses in Botswana and show the potential to develop antimicrobial preparations from community natural resources. The title of the second paper is Herbaceous and Woody Plant Properties in Abandoned Kraal Areas in a Hardveld Botswana. It is authored by a scholar from Uganda, whose key interest is to investigate herbaceous and woody plant species in abandoned traditional kraals. The investigator analyses the nutrient status of soil in addition to vegetation composition and communities from the kraal sites, and then proceeds to compare the findings with those from control sites. The author applies three multivariate techniques to establish the classification of the plant communities. These techniques are a twoway indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). The major findings of the study show a whole range of things; differences in soil physio-chemical properties, in patterns and in the composition of vegetation communities between kraals and their surrounding areas. Furthermore, it is established that kraal areas play an important role in influencing systematic distribution of nutrients, these in turn influencing the modification of vegetation patterns. The author uses the findings to explain the emergence of herbaceous and woody species community patterns. The Okavango Delta reed is the focus of the third paper, which is a product of extensive and intensive research by two scientists based at the Okavango Research Institute. These scholars report on some of the properties of Phragmites australis, a reed that has a lot of economic value because of its multipurpose use. Its usages range from cladding house walls to providing perimeter fencing for homesteads. The research findings reveal that the value of the reed in the Okavango Delta could be around US$ 45,000 per hectare, using current market prices. The researchers then make a comparison in land use between this reed and normal agriculture. Their assertion is that the value of the reed can be as high as 90 times that of flood recession agriculture in the same area. The Makgadikgadi Salt Pans outside the Okavango form the bedrock of brine, the natural substance from which salt is made. The forth paper is a chemical study by three scholars who isolate Halophilic bacteria in these salt pans using culturedependent methods. The method involved the use of Polymerase chain reaction (PCR) amplification of the 16S rRNA gene and phylogenetic analysis to identify the strains. And culturing was done aerobically in six different complex salt media, resulting in the discovery of microorganisms that are are regarded as previously un-described and therefore novel species of halophilic bacteria. The fifth paper addresses the fungal contamination of food grains. Fungal contamination of food grain is a real problem that afflicts sorghum and maize, the staple food of Batswana. Three researchers from Botswana, the United Kingdom and Canada research fungal contamination in these two food grains in a paper titled `Fungi and Fusarium Mycotoxins Associated with Maize (Zea mays) and Sorghum (Sorghum bicolor) in Botswana'. The research established that Fungal contamination was greatest on sorghum grains and least on white maize grains. A number of fungi were identified and their presence in food commodities has the potential to lead to food deterioration, and mycotoxin contamination. The research concluded that the presence of mycotoxins in these food grains indicates a need to set up standards that regulate their levels in maize and sorghum which is sold in Botswana.

The discussion on fungi changes course and direction in the sixth paper, entitled `Fungi and their Use in the Possible Control of Nematodes in Botswana Soils'. Here, the authors look at the positive side of what constitutes contamination in the previous paper. The study assesses fungi isolated from three climatic regions of Botswana as a possible control for root knot nematodes affecting the tomato. In greenhouse studies using tomato plants the fungi alleviated the effect of nematodes by increasing plant, shoot height and root weight as compared to the reference controls. The results indicated that Trichoderma sp., Penicillium sp., Dendriphiopsis sp., Fusarium chlamydosporium, Cochliobolus sativus, and Aspergillus fumigatus are nematode antagonistic fungi indigenous to Botswana that can be used to control nematodes as they are better adapted in comparison to introduced fungi. Re-use of waste water is a common feature of dry countries such as Botswana. This matter is taken up in the seventh paper, where three scientists compare soil quality parameters, and salinity and heavy metal levels in soils cultivated with different crops under secondary treated wastewater irrigation in the Glen Valley, near Gaborone City, Botswana. The hypothesis being tested is that the impact of the wastewater on soil quality varies with soils and crop types. The study covers 4 selected crops, maize (Zea mays L.), spinach (Spinacia oleracea), olive (Olea europaea), and tomato (Solanum lycopersicum), most widely cultivated by the farmers. The secondary treated wastewater being used in the Glen Valley is biologically clean, but one recorded case of E. coli emphasizes the importance of avoiding sprinkler irrigation at all costs to protect human health. Range fires are another characteristic of Botswana veld. Some of those who cause wild fires perceive that there is relationship between fire and vegetation regeneration linked to soil fertility. Three scholars look into this issue as they assess the influence of burning on soil microbial dehydrogenase activity, nitrogen content and fungal population along the Boro route in the Okavango Delta in the flood and dry seasons. In the eighth paper titled `The Influence of Range Fire on Soil Fungi, Microbial Activity and Soil Properties along the Boro Route of the Okavango Delta', they cultured soil samples from the burnt plots and the adjacent control un-burnt plots using dilution methods. The results indicate that burning increased fungal diversity and biomass, but reduced overall microbial enzyme activity. The ninth paper reports research work that is carried out in south eastern Botswana, an ecosystem that is different from that of the Okavango Delta which is in the north-western part of the country. In this paper, `Shoot Production by Acacia tortilis under Different Browsing Regimes in South-East Botswana' four researchers investigate shoot production by Acacia tortilis under three distinct land-use types and browsing regimes in south-eastern Botswana: a large mammal exclosure (UB Nature Reserve, UBNR), a conservation area (Gaborone Game Reserve, GGR), and a livestock area (Tlokweng Rangelands, TR). A statistical analysis, one-way ANOVA is applied to determine variation in shoot production within and amongst landuse types, and also across vertical browsing levels ("Low", "Medium" and "Upper"). Mean shoot length varied significantly amongst the three habitats, being highest in GGR, TR, and lowest in UBNR. The results showed that Spinescence (spine number and mass) differed significantly under the three land-use types, being highest in GGR, TR, and UBNR, respectively. Within land-use types, shoot length differed significantly between the three browsing levels. Shoot length declined from the "Upper" to the "Low" browsing levels or zones. Leaf dry-mass differed significantly between the three browsing levels, decreasing from the highest to the lowest levels. The researchers postulate that differential browsing pressure elicited the variable response in shoot production across the three land-use categories, and further discuss the implications for wildlife and rangeland management. Gaborone, the capital of Botswana forms the setting of the tenth paper which is written by two scholars with the title `Floristic Diversity and Uses of Medicinal Plants Sold by Street Vendors in Gaborone, Botswana'. The paper arises from the emergence in growing magnitude, the sale of herbal medicine, either as concoctions or single plant specimens, in the streets and main shopping centres of major towns and cities in Botswana. However, Gaborone is used for convenience as the researchers live in the city. The documented medicinal plants were mostly used to cure skin sores, sexually transmitted diseases (STD) and asthma. In this study, the most dominant families are the Asteraceae and Fabaceae, each with 5 species and roots were most frequently used for the treatment of diseases accounting for 62% of the medicines sold. This study showed that many people in Botswana still continue to depend on medicinal plants for primary healthcare. Bush encroachment, also known as invasive species, is a significant problem in a number of places in Botswana. Identification of the invading plants is crucial for controlling the invasion. The eleventh paper explores some of the difficulties faced by ecologists in trying to control invasive species found in the southern tip of Botswana. The paper, titled `An Assessment of Prosopis L. in the Bokspits Area, South-Western Botswana, Based on Morphology' is the work of a team of four scientists. The researchers suspected extensive introgression and hybridization is suspected in the genus that made the identification of the species very difficult, and this in turn made the control of the invasive species to be equally difficult. Under the circumstances, the objective of the study was to determine the taxonomic structure of Prosopis species found in southern Botswana. A systematic qualitative approach was used to sample the species such that specimen selection was based on observable morphological discontinuities. The morphological characters were subjected to multivariate analysis since the analysis has been reported to be good at identifying hybrids. The study revealed four pure lines of Prosopis and nine hybrid species. The next paper, which is the twelfth, addresses food security from the point of view of dryland arable farming, which is the agricultural practice of the majority of the farmers in Botswana. The three researchers have titled their paper quite simply and in a straight forward manner `Assessing Growing Season Changes in Southern Botswana'. The paper is mainly on the merits of optimal timing in an agricultural season. The researchers argue that information on appropriate planting dates is rarely available from ground sources in a timely manner. Consequently, they propose the use of operational remote

sensing products such as vegetation index to complement ground sources and hence fill missing gaps in planting date forecasting and monitoring. The results from the two approaches showed that the onset and cessation of growing season had shifted backwards in both cases. Onset dates had shifted from the initial mid-September in the early 1960s to early November as of 2009 while cessation dates had shifted from early April to late January. Consequently, the growing season had contracted in length by an average of 14 decadal from the initial value of 22 decadal in the early 1960s. Research on food security extends into the thirteenth paper, which also concludes the volume. This one, titled `Characteristics of Two Sorghum Cultivars Subjected to Water Stress' is a paper by two scholars. Two common sorghum species were used. These were town and segaolane. The objective of the study was to test each of them for response to water stress and photoinhibition. The findings were that town is more prone to photoinhibition that segaolane, and that town was stressed more by water shortage than was segaolane. As indicated at the beginning of this introduction, these papers constitute a minefield in the areas that they address. The variation in the writing styles of the different authors as well as the different ways in which they deal with their research topics add much flavor to the taste of scholarship that they bring with them, and significantly broaden the knowledge base on which they are anchored. Individually and collectively, they extend the frontiers of the understanding that we have had before this volume.

Prof. Isaac N. Mazonde, June 2011

SPECIAL ISSUE: CONTENTS

Stanley Mukanganyama (Zimbabwe), Aku N. Ntumy, Fozia Maher, Mbaki Muzila, Kerstin Andrae-Marobela (Botswana) Screening for Anti-infective Properties of Selected Medicinal Plants from Botswana Sarah Kizza (Uganda) Herbaceous and Woody Plant Properties in Abandoned Kraal Areas in a Hardveld Botswana Michael Murray-Hudson, Gagoitseope Mmopelwa (Botswana) Biomass Production and Economic Value of Phragmites australis Reedbeds in the Southern Okavango Delta, Botswana Bakang Baloi, Maitshwarelo Ignatius Matsheka, Berhanu Abegaz Gashe (Botswana) Isolation of Cultivable Halophilic Bacillus sp. from the Makgadikgadi Salt Pans in Botswana Tuduetso Motlalepula Mokgatlhe (Botswana), Anthony Bupe Siame (Canada), Joanne Elizabeth Taylor (UK) Fungi and Fusarium Mycotoxins Associated with Maize (Zea mays) and Sorghum (Sorghum bicolor) in Botswana Tabo Mubyana-John, Mareledi G. Wright (Botswana) Fungi and their Use in the Possible Control of Nematodes in Botswana Soils Olusegun Areola, Oagile Dikinya, Larona Mosime (Botswana) Comparative Effects of Secondary Treated Waste Water Irrigation on Soil Quality Parameters under Different Crop Types Agripina Banda, Tabo Mubyana-John, Joanne E. Taylor (Botswana) The Influence of Range Fire on Soil Fungi, Microbial Activity and Soil Properties along the Boro Route of the Okavango Delta Samson Kabajan Kenneth Kaunda, Kefilwe Matlhaku, Mmilili Myles Mapolelo, Johannes Mokgosi (Botswana) Shoot Production by Acacia tortilis under Different Browsing Regimes in South-East Botswana Moffat P. Setshogo, Collen M. Mbereki (Botswana) Floristic Diversity and Uses of Medicinal Plants Sold by Street Vendors in Gaborone, Botswana Mbaki Muzila, Moffat P. Setshogo, Baleseng Moseki, Rachel Morapedi (Botswana) An Assessment of Prosopis L. in the Bokspits Area, South-Western Botswana, Based on Morphology Samuel Adelabu, Olusegun Areola, Reuben J. Sebego (Botswana) Assessing Growing Season Changes in Southern Botswana Baleseng Moseki, Kebonyethata Dintwe (Botswana) Characteristics of Two Sorghum Cultivars Subjected to Water Stress

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Stanley Mukanganyama (Zimbabwe), Aku N. Ntumy, Fozia Maher, Mbaki Muzila, Kerstin Andrae-Marobela (Botswana) Screening for Anti-infective Properties of Selected Medicinal Plants from Botswana (pp 1-7) ABSTRACT Original Research Paper: Thirty nine ethanol extracts from 26 plants widely distributed in Botswana were screened for antimicrobial activities against three Gram-positive, two Gram-negative bacterial strains, two Candida species and one Mycobacterium species. Screening was carried out at an initial concentration of 500 µg/disc using the disc agar diffusion method. Most of the plant species gave rise to antifungal activities (20/24), some of them specifically, such as Acrotome inflata, Bridelia mollis, Dichrostachys cinerea, Dicerocaryum eriocarpum, Dicoma capensis, Gomphrena celosioides, Tagetes minuta and Waltheria indica. Minimal inhibitory concentrations (MICs) of extracts with inhibitory activities against Candida albicans, a major opportunistic infective agent in immunocompromised patients, varied between 0.039 and 2.5 mg/ml. Extracts of 10 plant species inhibited the growth of Mycobacterium aurum, a non-pathogenic model organism with similar drug susceptibility as Mycobacterium tuberculosis. MIC values of anti-mycobacterial extracts ranged from 0.039 to 2.5 mg/ml. Interestingly, Ocimum canum leaf extracts and Elephantorrhiza burkei root extracts displayed the lowest MICs against both HIV/AIDS opportunistic pathogens with values of 0.039 mg/ml against Mycobacterium aurum, and MIC values of 0.039 and 0.078 mg/ml against Candida albicans, respectively. Extracts of two plant species, Elephantorrhiza elephantina and Persiceria limbata, exhibited antimicrobial properties against all eight microorganisms tested and only these two extracts were active against the Gram-negative Escherichia coli strain. Antimicrobial ethanol extracts with the lowest MIC values did not show acute in-vitro cytotoxicity up to a concentration of 1000 µg/ml using human embryonic kidney cells (HEK293). The findings confirm some anti-infective and wound healing ethnomedical uses in Botswana and show the potential to develop antimicrobial preparations from community natural resources. Sarah Kizza (Uganda) Herbaceous and Woody Plant Properties in Abandoned Kraal Areas in a Hardveld Botswana (pp 8-15) ABSTRACT Original Research Paper: Herbaceous and woody plant species in abandoned traditional kraals were investigated. To achieve the aim of this study, nutrient status of soil in addition to vegetation composition and communities from the kraal sites were analyzed and results compared with those from control sites. A total of 25 kraals that had been abandoned between 5 and 45 years were sampled. Data were analyzed using multivariate procedures; a two-way indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) to establish classification of the plant communities. The significant environmental variables identified with t-values above 2.1 that determined the composition and patterns of the plant communities were organic matter, plant available nitrogen, calcium and moisture content. The results show major differences in soil physio-chemical properties and also in patterns and composition of vegetation communities between kraals and their surrounding areas. Evidence from the results show that kraal areas play an important role in determining key resource areas by influencing systematic distribution of nutrients. With kraals tending to increase the heterogeneity in the natural distribution of nutrients, it is apparent that animal waste deposited in the kraals modify vegetation patterns as high nutrient tolerant species gain competitive advantage over those that are not. The findings provide some important information that could explain herbaceous and woody species community patterns particularly in semi-arid environments where livestock management by the use of traditional kraals is a common practice. Michael Murray-Hudson, Gagoitseope Mmopelwa (Botswana) Biomass Production and Economic Value of Phragmites australis Reedbeds in the Southern Okavango Delta, Botswana (pp 16-20) ABSTRACT Original Research Paper: Most work globally on Phragmites spp. has been done in temperate northern hemisphere localities, where winter low temperatures and short day lengths cause a seasonal decrease in growth. In this study, we report above-ground stem length-mass relationships, stem densities and daily growth rates in 3 Phragmites australis reedbeds in the flood-pulsed, subtropical Okavango Delta, with the aim of assessing the economic value of this plant, which is widely used throughout north-western Botswana for cladding house walls and fencing yards. Stem density averaged 77 m Length-mass relationships were best represented by a power function y = 8.05x

2 1.85 -2

in 32 plots.

, where y is the dry mass in grams, and x is

-2

the length in metres (r = 0.895). The mean daily growth rate was 0.015 m and did not appear to vary systematically with season. The maximum standing crop calculated from stem length was 2.89 kg m , and occurred in May 2005. Annual above-ground production was conservatively estimated at 20-30 t ha . Assuming that harvesting takes place not more than

-1

once annually, reed beds in the Okavango Delta are worth ~US$ 45,000 ha at market. This land use value is over 90 times that of flood recession agriculture in the same area. Bakang Baloi, Maitshwarelo Ignatius Matsheka, Berhanu Abegaz Gashe (Botswana) Isolation of Cultivable Halophilic Bacillus sp. from the Makgadikgadi Salt Pans in Botswana (pp 21-25) ABSTRACT Original Research Paper: Halophilic bacteria from the Makgadikgadi salt pans in north central Botswana were isolated using culture-dependent methods. Polymerase chain reaction (PCR) amplification of the 16S rRNA gene and phylogenetic analysis were used to identify the strains. Culturing was done aerobically in six different complex salt media. Salt concentrations used were 15, 20, 25 and 30% (2.6, 3.4, 4.3 and 5.1 M, respectively) NaCl, at pH 7.2 to pH 8.0. Four colony morphology types were isolated in axenic cultures comprising Gram-positive cells. Universal bacterial primers were used to amplify 16S rDNA from chromosomal DNA isolated from three of the four distinct colony groups. Restriction enzyme digests analysis of the 16S rDNA revealed seven RFLP types. Five of the RFLP types were subjected to sequencing. Comparison of the 16S rDNA sequence alignment to reference sequence data bases showed samples S2012A3, S2012B2 and S2012B3 to have between 95 and 99% homology to Bacillus sp. BH 164 and Bacillus sp. HS 136 , a novel species recently described as Bacillus persepolensis. Isolate S4102D4 showed 95 to 99% homology to Thalassobacillus sp. JY0201 and Thalassobacillus sp. FIB228 and Halobacillus sp. MO56 species. All five isolates had at least 95% similarity to published sequences implying they could be species within the described genera. A sub-tree drawn to compare the isolates indicated two phyletic lines with S4102D4 being an outlying strain and S2012A3, S2012B2 and S2012B3 being a closely related clonal group all of which branch from Bacillus sp. BH 164. Pending conclusive culture, biochemical and polar lipid composition data these microorganisms are regarded as previously un-described and therefore novel species of halophilic bacteria. Tuduetso Motlalepula Mokgatlhe (Botswana), Anthony Bupe Siame (Canada), Joanne Elizabeth Taylor (UK) Fungi and Fusarium Mycotoxins Associated with Maize (Zea mays) and Sorghum (Sorghum bicolor) in Botswana (pp 26-32) ABSTRACT Original Research Paper: The mycoflora and Fusarium mycotoxins, zearalenone and fumonisin B1, associated with 100 samples of maize and sorghum grains and meals sold in Gaborone (Botswana) were determined. Fungal contamination was greatest on sorghum grains (96%) and least on white maize grains (77%). Maize and sorghum meals had a fungal contamination of 2.5 × 10 CFU/g and 2.3 × 10 CFU/g, respectively. The predominant genera isolated from the grains and meals were Aspergillus, Fusarium, and Penicillium. Other genera included Alternaria, Nigrospora, Acremonium and Phoma. Fusarium verticillioides was the most prevalent Fusarium species, accounting for 76% of all the Fusarium isolates. Other Fusarium species were F. proliferatum, F. semitectum and F. subglutinans. The presence of these fungi in food commodities may lead to food deterioration, and mycotoxin contamination. Nine isolates of Fusarium belonging to the four species were tested for their ability to produce fumonisin B1 on autoclaved maize and sorghum substrates. The amount of fumonisin B1 produced ranged between 1,700-789,000 µg/kg. The collected samples were also analyzed for the presence of zearalenone and fumonisin B1 using thin layer chromatography and high-performance liquid chromatography. Contamination with zearalenone and fumonisin B1 was 97% and 49%, respectively. The amount of zearalenone and fumonisin B1 ranged from 3-980 µg/kg and from 9-2183 µg/kg, respectively. Five samples had concentrations exceeding 1000 µg/kg. The presence of mycotoxins indicates a need to set up standards that regulate their levels in maize and sorghum sold in Botswana. Tabo Mubyana-John, Mareledi G. Wright (Botswana) Fungi and their Use in the Possible Control of Nematodes in Botswana Soils (pp 33-40) ABSTRACT Original Research Paper: A study assessing fungi isolated from three climatic regions of Botswana as a possible control for root knot nematodes (Meloidogyne spp.) affecting the tomato (Lycopersicon esculentum L. var. `Money maker') crops was conducted. Out of 1,250 soil fungal isolates, only 232 soil fungi from the Okavango Delta, Bobirwa district and different saltpans in Botswana could be sub cultured, and screened for antagonism against Meloidogyne sp. Seven of the isolates i.e., Trichoderma sp., Penicillium sp., Dendriphiopsis sp., Fusarium chlamydosporium, Cochliobolus sativus, Aspergillus fumigatus and an unidentified sterile fungus showed potential to immobilize nematode juveniles on agar plates within 2-4 days. C. sativus and Dendriphiopsis sp. showed maximum paralysis on agar plates and eventually death of the Meloidogyne sp. juveniles. In

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greenhouse studies using tomato plants the fungi alleviated the effect of nematodes by increasing plant, shoot height and root weight as compared to the reference controls. Cochliobolus sativus and Trichoderma sp. showed maximum plant protection of tomato plants under greenhouse conditions. Fungi ability to produce cellulase and chitinase were some of the mechanisms studied. The results indicated that Trichoderma sp., Penicillium sp., Dendriphiopsis sp., Fusarium chlamydosporium, Cochliobolus sativus, and Aspergillus fumigatus are nematode antagonistic fungi indigenous to Botswana that can be used to control nematodes as they are better adapted in comparison to introduced fungi. Olusegun Areola, Oagile Dikinya, Larona Mosime (Botswana) Comparative Effects of Secondary Treated Waste Water Irrigation on Soil Quality Parameters under Different Crop Types (pp 41-55) ABSTRACT Original Research Paper: This study compares soil quality parameters, and salinity and heavy metal levels in soils cultivated with different crops under secondary treated wastewater irrigation in the Glen Valley, near Gaborone City, Botswana. The hypothesis being tested is that the impact of the wastewater on soil quality varies with soils and crop types. The study covers 4 selected crops, maize (Zea mays L.), spinach (Spinacia oleracea), olive (Olea europaea), and tomato (Solanum lycopersicum), most widely cultivated by the farmers. Three farm plots per crop type were sampled at 5 sampling points and at two soil depths, 0-15 and 15-30 cm. Samples were also collected at 5 sampling points from two control sites. Irrigation water samples were collected for microbiological analysis from 2 farms per crop type. The most significant differences and relationships are between those crop farms, such as maize and two of the spinach plots, with predominantly sandy soils (loamy sands - sand loams) on the one hand; and the olive, tomato and one of the spinach plots with sandy clay loams on the other. The importance of soil texture was confirmed by the strong correlations between the sand and silt contents, several soil quality parameters, heavy metals and other elements. With the exception of Cd and Hg, most soil heavy metal contents were lower on the irrigated plots than on the control plot. The EC values also show that soil salinity levels were still low on the irrigated fields, but SAR and ESP values were high. The secondary treated wastewater being used in the Glen Valley is biologically clean, but one recorded case of E. coli emphasizes the importance of avoiding sprinkler irrigation at all costs to protect human health. Agripina Banda, Tabo Mubyana-John, Joanne E. Taylor (Botswana) The Influence of Range Fire on Soil Fungi, Microbial Activity and Soil Properties along the Boro Route of the Okavango Delta (pp 56-62) ABSTRACT Original Research Paper: The influence of burning on soil microbial dehydrogenase activity, nitrogen content and fungal population along the Boro route in the Okavango Delta was assessed in the flood and dry seasons. Soil samples from the burnt plots and the adjacent control un-burnt plots were cultured on agar plates using dilution methods. Fusarium spp. were dominant while Aspergillus species were low in burnt plots. The other fungi such as Drechslera sp., Exophiala jeanselmmei, Penicillium compactum and Chrysosporium merdarium were only in the burnt plots as compared to unburnt control plots. However, fungal diversity and soil dehydrogenase activity reduced after 6 months of burning showing significant increase in Chrysosporium merdarium in almost all the burnt plots. The influence of burning on soil nitrogen was insignificant instead flooding had a stronger influence on nitrogen content than burning. The results indicate that burning increased fungal diversity and biomass, however reduces overall microbial enzyme activity after burning without influencing soil nitrogen and pH. Samson Kabajan Kenneth Kaunda, Kefilwe Matlhaku, Mmilili Myles Mapolelo, Johannes Mokgosi (Botswana) Shoot Production by Acacia tortilis under Different Browsing Regimes in South-East Botswana (pp 63-68) ABSTRACT Original Research Paper: We investigated shoot production by Acacia tortilis under three distinct land-use types and browsing regimes in south-eastern Botswana: a large mammal exclosure (UB Nature Reserve, UBNR), a conservation area (Gaborone Game Reserve, GGR), and a livestock area (Tlokweng Rangelands, TR). We applied one-way ANOVA to determine variation in shoot production within and amongst land-use types, and also across vertical browsing levels ("Low", "Medium" and "Upper"). Mean shoot length varied significantly amongst the three habitats, being highest in GGR, TR, and lowest in UBNR. Spinescence (spine number and mass) differed significantly under the three land-use types, being highest in GGR, TR, and UBNR, respectively. Within land-use types, shoot length differed significantly between the three browsing levels. Shoot length declined from the "Upper" to the "Low" browsing levels or zones. Leaf dry-mass differed significantly between the three browsing levels, decreasing from the highest to the lowest levels. The highest number of thorns produced was significantly

higher on the "Upper" browsing zones. Thorn mass did not vary significantly across the browsing zones. We postulate that differential browsing pressure elicited the variable response in shoot production across the three land-use categories, and further discuss the implications for wildlife and rangeland management. Moffat P. Setshogo, Collen M. Mbereki (Botswana) Floristic Diversity and Uses of Medicinal Plants Sold by Street Vendors in Gaborone, Botswana (pp 69-74) ABSTRACT Original Research Paper: The sale of herbal medicine, either as concoctions or single plant specimens, has become common in the streets and main shopping centres of major towns and cities in Botswana. A study was undertaken to collect information on the uses of medicinal plants sold by street vendors in Gaborone, Botswana, during June 2008 to December 2008. The indigenous knowledge of the street vendors and the plants used for medicinal purposes were collected through questionnaire and personal interviews during field trips. The survey showed that the street vendors used 47 species of plants distributed in 45 genera belonging to 29 families to treat various diseases and health conditions. The documented medicinal plants were mostly used to cure skin sores, sexually transmitted diseases (STD) and asthma. In this study, the most dominant families are the Asteraceae and Fabaceae, each with 5 species and roots were most frequently used for the treatment of diseases accounting for 62% of the medicines sold. This study showed that many people in Botswana still continue to depend on medicinal plants for primary healthcare. Mbaki Muzila, Moffat P. Setshogo, Baleseng Moseki, Rachel Morapedi (Botswana) An Assessment of Prosopis L. in the Bokspits Area, South-Western Botswana, Based on Morphology (pp 75-80) ABSTRACT Original Research Paper: The genus Prosopis comprises 44 species. Extensive introgression and hybridization is suspected in the genus, which makes identification of the species very difficult. Accurate identification of the species is crucial in controlling invasive species, within this genus. That is so because the method of control is species specific. The objective of the study was to determine the taxonomic structure of Prosopis species in Southern Botswana. A systematic qualitative approach was used to sample the species such that specimen selection was based on observable morphological discontinuities. The morphological characters were subjected to multivariate analysis since the analysis has been reported to be good at identifying hybrids. The multivariate analysis included anova, cluster analysis, factor analysis and canonical correlation. The study revealed four pure lines of Prosopis and nine hybrid species. The pure lines are Prosopis chilensis, P. juliflora, P. velutina and P. glandulosa and they all belong to one section, ALGAROBIA. The observed hybrids were P. chilensis x P. glandulosa, P. glandulosa x P. chilensis, P. juliflora x P. glandulosa, P. chilensis x P. juliflora, Acacia karroo x P. juliflora, P. glandulosa x P. pallida, P. juliflora x P. pallida, P. chilensis x P. juliflora x P. glandulosa and P. chilensis x P. pallida. It was therefore concluded that the Prosopis species in Southern Botswana have formed a hybrid swam. And for the hybrids P. chilensis x P. glandulosa and P. glandulosa x P. chilensis it was concluded that gene flow between P. chilensis and P. glandulosa is bidirectional. For the hybrid P. juliflora x P. glandulosa it was concluded that gene flow was from P. juliflora to P. glandulosa. Samuel Adelabu, Olusegun Areola, Reuben J. Sebego (Botswana) Assessing Growing Season Changes in Southern Botswana (pp 81-88) ABSTRACT Original Research Paper: Perfect timing of planting date is not only one of the key factors which strongly affect crop production in rain-fed agriculture but it is also a valuable leading indicator for food security monitoring in semi-arid environments like Botswana. This is especially true when, as in many parts of semi-arid regions, the rainy season starts with some light showers followed by dry spells, which can cause poor crop emergence or even desiccate a young crop and lead to poor yields and greater food insecurity and hunger. Unfortunately, such information on appropriate planting dates is rarely available from ground sources in a timely manner. However, operational remote sensing products such as vegetation index can be used to complement ground sources and hence fill missing gaps in planting date forecasting and monitoring. The aim of this study therefore was firstly to derive the growing season metrics for the southern district of Botswana using standard methods of deriving growing season from climatic indices and from satellite imagery and secondly to study the trend of the growing season metrics in the study area. The results from the two approaches showed that the onset and cessation of growing season had shifted backwards in both cases. Onset dates had shifted from the initial mid-September in the early 1960s to early November

as of 2009 while cessation dates had shifted from early April to late January. Consequently, the growing season had contracted in length by an average of 14 decadal from the initial value of 22 decadal in the early 1960s. The study also showed no statistically significant difference between the growing season metrics derived from the two approaches (climatic and NDVI) hence any of the two approaches can be used to determine growing season metrics in the study area. Baleseng Moseki, Kebonyethata Dintwe (Botswana) Characteristics of Two Sorghum Cultivars Subjected to Water Stress (pp 89-91) ABSTRACT Research Note: The effects of water stress on the photosynthetic characteristics of two locally-cultivated sorghum cultivars (`Segaolane' and `Town') were investigated over a period of weeks. Water stress was imposed on 1-week-old plants by withholding water. Measurements of chlorophyll fluorescence were used to determine changes in the efficiency of light utilization for electron transport, the occurrence of photoinhibition of photosystem II photochemistry on the sorghum cultivars. Drought treatment significantly decreased leaf area in all species, an important factor in drought-induced decreases in photosynthetic productivity. Water-stressed `Town' exhibited a decrease in maximum photochemical efficiency of PSII (estimated from dark-adapted Fv/Fm ratio) with increasing period of withholding water. Light-adapted Fv'/Fm' estimated the efficiency of excitation energy transfer to open PSII centres. Water-stressed `Town' displayed a decrease in the efficiency of excitation energy transfer to open PSII reaction centres throughout the entire study period. The quantum yield of PSII electron transport (PSII), which represents electron flow beyond PSII, decreased markedly in water-stressed `Town' compared with that of water-stressed `Segaolane'. These initial findings indicate that `Town' is more prone to photoinhibition than `Segaolane'.

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