Department of Botany

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    Growth and Yield Performance of Selected Upland and Lowland Rainfed Rice Grown in Farmers and Researchers Managed Fields at Ifakara, Tanzania.
    (Academic journal, 2019-01-24) Kitilu, M. J. F.; Nyomora, Agnes M. S.; Charles, J.
    Bridging the yield gaps is of major concern to rice breeders and agronomists under rainfed rice cultivation. The yield performance of lowland and upland rainfed rice varieties was investigated in farmers’ and researchers’ field conditions at four locations in Ifakara. Selected agronomic practices namely; recommended fertilizer (80 kgN/ha), spacing of 20 cm × 20 cm, weed free fields and high yielding varieties of TXD306, Komboka and Tai for lowland rainfed, and NERICA1, NERICA2 and NERICA4 for upland rainfed rice. Moreover, farmer selected varieties Supa India and WahiPesa were used as the local control in this research. The study revealed that yield performance of lowland rainfed rice varieties and in farmers’ fields ranged between 2.9 and 6.9 t ha-1, while in the upland rainfed rice the yield ranged between 2.5 and 5.4 t ha-1. This was similar to yield that was obtained from the researchers’ fields which ranged between 2.4 and 8.5 t ha-1 in lowland and between 1.8 and 4.8 t ha-1 in upland fields. The yield gap analysis revealed that the gap of between 35 and 60% previously reported in lowland rice was narrowed to 0 to 12.1%, while in the upland rice from 24.5 to 28.6% previously reported to 0% and excess yield over the potential yields and yields previously reported by farmers. The performance of all improved rice varieties at farmers and researchers’ field were significantly higher compared to the local check varieties Supa India and WahiPesa. It was concluded that, providing farmers with selected good agronomic practices and supervision of farmers in field management activities enhanced rice productivity under farmers’ conditions and narrowed or bridged the yield gaps that existed.
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    Food security: The role of urban and peri-urban agriculture. A case of Dar es Salaam City, Tanzania
    (INNSPUB, 2018-08-04) Malekela, Asnath. A; Nyomora, Agnes M.S.
    This study examined the contribution of urban and peri-urban agriculture (UPA) on food security in Dar es Salaam city. With the massive population increase in most cities in the world, food insecurity has become a challenge. One of the responses to this is promotion of urban and peri-urban agriculture (UPA). Primary and secondary data were collected using structured questionnaires, in-depth interviews, direct observations, focus group discussions and literature survey. About 201 respondents engaging in urban and peri-urban agriculture were interviewed. Also, 100 local market traders from 10 local markets, and 7 supermarket managers from 7 representatives supermarkets in Dar es Salaam city were interviewed. The Statistical Package for Social Sciences (SPSS) version 20 was used to analyze the data. The findings revealed that UPA had a positive contribution to food security as it was observed that the main aim of 84% of the farmers who engaged in crop production was to get food and income. In the surveyed local markets about 47% of food products were sourced from UPA, also, 6080% of vegetables and 57.1% of the eggs sold in the surveyed supermarkets were sourced from UPA. The study recommends adoption of modern technology for better output with use of limited land and water resources. Also available policies supporting UPA should be reviewed for its sustainable development.
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    Optimal Weeding Period for Groundnuts (Arachis Hypogea L.)
    (1988) Rulangaranga, Z. K.; Banyikwa, Feetham F.
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    Determinants of Woody Cover in African Savannas
    (2005) Sankaran, Mahesh; Hanan, Niall P.; Scholes, Robert J.; Ratnam, Jayashree; Augustine, David J.; Cade, Brian S.; Gignoux, Jacques; Higgins, Steven I.; Le Roux, Xavier; Ludwig, Fulco; Ardo, Jonas; Banyikwa, Feetham F.; Bronn, Andries; Bucini, Gabriela; Caylor, Kelly K.; Coughenour, Michael B.; Diouf, Alioune; Ekaya, Wellington; Feral, Christie J.; February, Edmund C.; Frost, Peter G. H.; Hiernaux, Pierre; Hrabar, Halszka; Metzger, Kristine L.; Prins, Herbert H. T.; Ringrose, Susan; Sea, William; Tews, Jörg; Worden, Jeff; Zambatis, Nick
    Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties1, 2, 3. The availability of resources (water, nutrients) and disturbance regimes (fire, herbivory) are thought to be important in regulating woody cover1, 2, 4, 5, but perceptions differ on which of these are the primary drivers of savanna structure. Here we show, using data from 854 sites across Africa, that maximum woody cover in savannas receiving a mean annual precipitation (MAP) of less than ~650 mm is constrained by, and increases linearly with, MAP. These arid and semi-arid savannas may be considered ‘stable’ systems in which water constrains woody cover and permits grasses to coexist, while fire, herbivory and soil properties interact to reduce woody cover below the MAP-controlled upper bound. Above a MAP of ~650 mm, savannas are ‘unstable’ systems in which MAP is sufficient for woody canopy closure, and disturbances (fire, herbivory) are required for the coexistence of trees and grass. These results provide insights into the nature of African savannas and suggest that future changes in precipitation6 may considerably affect their distribution and dynamics.
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    Semi-viviparous Embryo Development and Dehydrin Expression in the Mangrove Rhizophora Mucronata Lam.
    (2010) Tibazarwa, Flora I.; Nitsch, L. M. C.; Wolters-Arts, M. M. C.; Mariani, Celestina; Derksen, J. W. M.
    Rhizophora mucronata Lam. is a tropical mangrove with semi-viviparous (cotyledon body protrusion before shedding), non-quiescent and non-desiccating (recalcitrant) seeds. As recalcitrance has been thought to relate to the absence of desiccation-related proteins such as dehydrins, we for the first time systematically described and classified embryogenesis in R. mucronata and assessed the presence of dehydrin-like proteins. Embryogenesis largely follows the classic pattern till stage eight, the torpedo stage, with the formation of a cotyledonary body. Ovule and embryo express radical adaptations to semi-vivipary in the saline environment: (1) A large, highly vacuolated and persistent endosperm without noticeable food reserves that envelopes the developing embryo. (2) Absence of vascular tissue connections between embryo and maternal tissue, but, instead, transfer layers in between endosperm and integument and endosperm and embryo. Dehydrin-like proteins (55–65 kDa) were detected by the Western analysis, in the ovules till stage 10 when the integuments are dehisced. An additional 50 kDa band was detected at stages 6–8. Together these results suggest a continuous flow of water with nutrients from the integument via the endosperm to the embryo, circumventing the vascular route and probably suppressing the initially induced dehydrin expression.
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    Shades of Green: Conservation in the Developing Environment of Tanzania
    (2013) Tibazarwa, Flora I.; Gereau, Roy E.; Raven, Peter H.; Sodhi, Navjot S.; Gibson, Luke
    In this chapter, two conservation areas, Lake Natron and Kitulo Plateau, are used to exemplify the challenges and delineate best practices, with Kitulo presenting a notable example of conservation to be emulated. The chapter demonstrates the challenges to and opportunities for achieving sustainable development in Tanzania, based on two development projects. One is a soda ash extraction project and the other a dairy farm converted to a national park. In particular, the chapter focuses on the gray areas where benefits are considered losses and vice versa and the realities of striving towards a balance between development and conservation. Lake Natron and Kitulo National Park are protected for their biodiversity and conservation value under Tanzanian policies and legislation for natural resource management.
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    Cross Compatibility of Cultivars of Gossypium Hirsutum L. and Feral Gossypium Barbadense L. in the Southern Highlands of Tanzania
    (2012-12) Shilla, O.; Hauser, T. P.; Tibazarwa, Flora I.
    Cotton is the second most important cash crop contributing about 15% to the annual foreign earning in Tanzania and is purely from Gossypium hirsutum L. cultivars. Gossypium barbadense L., a textile source in other parts of the world occurs as a feral perennial of ornamental and medicinal value in home gardens. G. barbadense L. is a natural host of the red bollworm, a destructive pest to cotton. The Southern Highlands (SH) of Tanzania have been quarantined from cotton production to control spread of the red bollworm to other growing areas. Transgenic cotton expressing the delta-endotoxin genes from Bacillus thuringiensis (Bt) offers an alternative control to the pest and reduced dependence on insecticide. Gene flow between wild or valued feral relatives and transgenic crops is a biosafety concern should transgene escape result in resistance development and contamination of germplasm. Potential gene flow between feral G. barbadense (including accessions Gb1 and Gb2) from the SH and G. hirsutum cultivars was assessed using controlled hybridization. The crosses produced fertile F1 but intraspecific seeds from G. barbadense did not germinate. G. barbadense is more likely to receive than donate genes implying development of pest resistance if introgressed filial generations express the Bt product.
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    The Growth Response of Two East African Perennial Grasses to Defoliation, Nitrogen Fertilizer and Competition
    (1988) Banyikwa, Feetham F.
    Two East African perennial grasses, Digitaria macroblephara (Hack) Stapf. and Sporobolus ioclados (Trin.) Nees, were grown in pure and mixed culture in a factorial treatment design of defoliation, nitrogen fertilizer and plant density for a period of 90 d. With regard to controls, defoliation reduced total yield of both species per plant by 81%; higher density decreased total yield per plant by 56%; and intraspecific competition decreased total yield per plant 24% more than interspecific competition. High nitrogen promoted total yield per plant by 168%. Total yield per plant of D. macroblephara was 3.2 times greater than that of S. ioclados. With defoliation, density dependent competition decreased total yield per plant by 42% while, without defoliation, density dependent competition decreased total yield per plant by 601%. With defoliation, high nitrogen increased yield per plant by 9% while without defoliation high nitrogen increased yield per plant by 315%. The results suggest that the magnitude of the negative aspects of density dependent competition may be lessened by defoliation and growing plants in mixed culture. It is concluded that in grazing ecosystems it may be advantageous to grow plants in mixed culture since the negative effects of interspecific competition are less than those arising from intraspecific competition.
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    The Physical and Chemical Characteristics of a Phycocolloid from the Red Alga Sarcodia Montagneana j. Agardh of Tanzania
    (1987) Semesi, A. K.; Banyikwa, Feetham F.
    A phycocolloid from Sarcodia montagneana has been evaluated by chemical and physical analyses. The study has revealed that the phycocolloid has a yield of 39.6 per cent (percentage dry weight of alga), an IR spectrum similar to that reported for .lambda.-type carrageenan, an SO4-2 content of 22.5 per cent, a 3, 6-anhydrogalactose content of 5.1 per cent, a galactose content of 51.5 per cent (percentage dry weight of phycocolloid) and a negative optical rotation. The polysaccharide does not form a gel and cannot be modified by alkaline borohydride. It may be used in the food industry as an emulsifying agent.
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    Species-Habitat Relationships in The Serengeti Short Grasslands, Tanzania
    (1989) Banyikwa, Feetham F.
    An improved principal components analysis ordination is used to study grass-habitat relationships in the Serengeti short grasslands. Species distribution is found to be influenced by soil factors along a topographic gradient.
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    Temporally Variable Rainfall Does not Limit Yields of Serengeti Grasses
    (1998) Williams, Kevin J.; Wilsey, Brian J.; McNaughton, Samuel J.; Banyikwa, Feetham F.
    Temporally variable rainfall, on scales ranging from intraseasonal to decadal, is characteristic of the climate of dry grassland ecosystems. A growth chamber experiment indicated that the Serengeti ecosystem's most abundant and widespread grass, red oat grass (Themeda triandra), collected at locations with different rainfalls, growing seasons, and grazing intensities, is insensitive to an ecologically realistic range of rainfall events if the total amount of rain is constant. The result was confirmed under field conditions since plots did not respond to different temporal variances in water supply, although they did respond to levels of water supply. The results suggest that these grasses are water "spenders", using it as fast as they can when it is abundant, and then being semi-dormant in intervals between downpours. This characteristic could provide a competitive advantage in environments characterized by infrequent thundershowers. The ability to tolerate intervals between showers without losing living tissues, or dying, can contribute to the success of grasses in highly variable climates, and will tend to quench potentially drastic fluctuations of energy flow through the food web.
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    Promotion of the Cycling of Diet-Enhancing Nutrients by African Grazers
    (1997) McNaughton, S. J.; Banyikwa, Feetham F.; McNaughton, M. M.
    Experiments in Serengeti National Park, Tanzania, provide direct evidence that large, free-ranging mammalian grazers accelerate nutrient cycling in a natural ecosystem in a way that enhances their own carrying capacity. Both nitrogen and sodium were at considerably higher plant-available levels in soils of highly grazed sites than in soils of nearby areas where animal density is sparse. Fencing that uncoupled grazers and soils indicated that the animals promote nitrogen availability on soils of inherently similar fertility and select sites of higher sodium availability as well as enhancing that availability.
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    Levels of ABA, its Precursors and Dehydrin-like Proteins During Mangrove Leaf Development and Senescence
    (2009) Tibazarwa, Flora I.; Masoud, M; Derksen, J. W. M.; Mariani, C.
    Abstract—Abscisic acid (ABA) and dehydrin proteins are thought to confer tolerance to plant tissue under physiological stress and drought. Rhizophora mucronata, a true mangrove species, is subjected to physiological drought from fluctuating high saline conditions where leaf loss or senescence is considered a possible regulation mechanism to combat stress. Levels of ABA and proteins that cross reacted with an anti – dehydrin antibody were assessed through development with the aim of correlating these factors to physiological water stress or salinity stress in R. mucronata leaves. Younger leaves showed lower levels of ABA than mature and senescing leaves. In situ production and translocation from mature to younger leaves may contribute to these observations. The presence of ABA in senescing leaves is thought to be due to the presence of low levels of physiological activity. Proteins detected by anti–dehydrin antibody require cDNA confirmation, but the visibly increasing intensity of a band at ~64kDa through development suggests potential correlation to drought or salinity stress which is expected to be maximal in maturing leaves. The absence of the dehydrin–like proteins in senescing leaves is postulated to be due to the lack of energy investment to synthesise these proteins in dying leaves.
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    Uterine Contraction Induced by Tanzanian Plants Used to Induce Abortion
    (2011-05) Nikolajsen, Tine; Nielsen, Frank; Rasch, Vibeke; Sørensen, Pernille H.; Tibazarwa, Flora I.; Kristiansen, Uffe; Jägera, Anna K.
    Ethnopharmacological relevance Women in Tanzania use plants to induce abortion. It is not known whether the plants have an effect. Aims of study Collect data on plant use in relation to induced abortion and test the effect of plant extracts on uterine contraction. Materials and methods During interviews with traditional birth attendants and nurses, plants were identified. Cumulative doses of plant extracts were added to rat uterine tissue in an organ bath, and the force and frequency of contractions recorded. Acetylcholine was used as positive control.
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    Distribution and Potential Impact of Feral Cotton on the Reintroduction of Cotton in the Southern Highlands, Tanzania
    (2012) Shilla, O.; Hauser, T. P.; Tibazarwa, Flora I.
    Cotton (Gossypium hirsutum) production is limited by bollworms that cause declining yields and poor lint quality. Generally, farmers manage pests by employing Integrated Pest Management (IPM) strategies, which include biological, cultural, physical and chemical approaches. Pest management by quarantine and pesticide sprays reduce production area and lead to resistance build-up. The Red bollworm, Dipsaropsis castanea is an important cotton pest of significant economical importance to Tanzania. The pest invaded the Southern Highlands (SH) of Tanzania in 1960’s from southern neighbour countries causing the Government to quarantine cotton production from 1968 as measure to limit the spread of the red bollworm. Transgenic Bt cotton with insecticidal properties presents a potential solution to the bollworm infestation in Tanzania. However, concerns associated with transgenic crops viz.; transgene flow to wild and feral relatives, increased potential for resistance evolution, need to be addressed prior to adoption of any transgenic crop. Information from national herbaria, research stations and a field survey established sparse distribution and diversity of feral cotton species G. barbadense, an exotic ornamental from Brazil though as isolated garden plants. Informal interviews revealed medicinal and fibre value of the ornamental. Diploid wild cotton relatives such as G. longicalyx and Gossypoides kirkii were also recorded but are incompatible to G. hirsutum. Field observations indicate continued red bollworm presence in the SH on feral cotton, but low in number as plants are few and isolated. Cluster analysis indicates presence of hybrid remnants of G. hirsutum and G. barbadense suggesting potential for gene flow.
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    Ecosystem Catalysis: Soil Urease Activity and Grazing in the Serengeti Ecosystem
    (1997) McNaughton, S. J.; Zuniga, Gina; McNaughton, M. M.; Banyikwa, Feetham F.
    The activity of soil ureases was evaluated in the laboratory in soils from three locations in the Serengeti National Park, Tanzania, differing in the grazing intensities that the grasslands there support. Urease activity was assayed by the instantaneous release of NH4 as soon as soils drained to field capacity after application of an aqueous urea solution approximating N concentrations in ungulate urine. The appearance of NO3 and SO4 in extracts was used as an index of biological activity and pH changes; neither responded to urea addition. Ammonium appearance in extracts of soils to which water but not urea was applied was low and identical; appearance in extracts where urea had been added was high and differed between sites, increasing with the level of grazer activity at a site. The data document ecologically meaningful levels of soil urease in Serengeti soils and a positive association of those levels with grazing intensity.
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    Root Biomass and Productivity in a Grazing Ecosystem: The Serengeti
    (1998-03) McNaughton, S. J.; Banyikwa, Feetham F.; McNaughton, M. M.
    Does grazing by large wild mammals, an intense form of aboveground herbivory, influence belowground productivity? The vast majority of literature data concentrate on short-term pot studies and indicate that clipping consistently retards root growth. Field studies are few and contradictory, but tend to indicate that grazing has little effect on grassland belowground production. We sampled root-soil cores at 0–10 and 10–20 cm increments, at 11 locations across the Serengeti ecosystem, on 10 dates over an annual cycle, sampling monthly during the rainy and early dry seasons and every 2 mo during peak dry season. Fenced and unfenced plots were replicated (n = 2 or 3) at each location. Live roots, identified visually by brightness and texture, were sorted, washed, dried, and weighed. In addition, profiles were sampled at 10-cm increments to 50 cm in fenced and unfenced plots in short, mid-height, and tall grasslands, representing a gradient of grazing, during the month of peak root biomass. Exclosures erected 22–25 yr previously were similarly sampled in short and tall grasslands to a 30-cm depth. Root biomass reached a pronounced minimum in mid-wet season (February) and a decided maximum at the beginning of the dry season (June). Net productivity, based on maximum–minimum biomass, ranged from 100 to 600 g·m−2·yr−1 to a 20-cm depth, with minima ranging from 40 to 150 g/m2 and maxima from 230 to 700 g/m2, according to location. There was no evidence that grazing reduced root productivity over the annual cycle. Vertical biomass profiles at peak standing crop were similar for short, mid-height, and tall grasslands, with root biomass dropping sharply with depth, except for short grasslands on soils that, atypically, lack a hardpan. In those grasslands, shallow root biomass was lower than in other grasslands, but biomass at depth was distinctly greater. For long-term protected grasslands, root biomasses at peak were identical in short grasslands, whether fenced or unfenced, but fenced tall grasslands had a lower root biomass than grazed plots. We conclude that intense herbivory does not inhibit root biomass or belowground productivity of Serengeti grasslands over either the short or the long term.