Browsing by Author "Mapuranga, Rangarirai"

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    Characterisation of upland cotton grown in Zimbabwe using agronomical and morphological markers for Verticillium wilt tolerance
    (Cogent OA, part of Taylor & Francis Group, 2020-05-25) Chapepa, Blessing; Mapuranga, Rangarirai; Manjeru, Pepukayi
    Accurate morphological characterisation of plants is used for selecting the best performing varieties. The morphological markers can be visualised without molecular techniques making it the easiest way of identifying variation within varieties. Characterisation of Verticillium wilt tolerant lines in cotton variety is important in understanding the underlying genetic control of Verticillium wilt tolerance. Five local varieties with varying tolerance to the disease and different yield potentials were crossed in a half diallel mating design in 2013. The ten crosses and five parental lines that were produced by the mating system were subjected to Verticillium wilt by artificial inoculation in 2013/14. These cotton lines were characterised using agronomic and morphological markers to identify Verticillium wilt resistance. Screening for Verticillium wilt resistance was done to identify morphological and agronomical markers which were used to group similar lines through cluster analysis. Three parental lines were identified with good morphological and agronomical performance that could be used in Verticillium wilt resistance breeding. These were CRI-MS-1, SZ9314 and BC853 which produced superior offspring in the diallel mating system. Furthermore, qualitative morphological traits and the agronomical traits were used as markers for selection of Verticillium wilt resistance cotton germplasm.
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    The impact of plant density and spatial arrangement on light interception on cotton crop and seed cotton yield: an overview
    (BMC., 2020-07-27) Chapepa, Blessing; Mudada, Nhamo; Mapuranga, Rangarirai
    Light attenuation within a row of crops such as cotton is influenced by canopy architecture, which is defined by size, shape and orientation of shoot components. Level of light interception causes an array of morpho-anatomical, physiological and biochemical changes. Physiological determinants of growth include light interception, light use efficiency, dry matter accumulation, duration of growth and dry matter partitioning. Maximum light utilization in cotton production can be attained by adopting cultural practices that yields optimum plant populations as they affect canopy arrangement by modifying the plant canopy components. This paper highlights the extent to which spatial arrangement and density affect light interception in cotton crops. The cotton crop branches tend to grow into the inter-row space to avoid shade. The modification of canopy components suggests a shade avoidance and competition for light. Maximum leaf area index is obtained especially at flowering stage with higher populations which depicts better yields in cotton production.
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    Poor maize productivity in Zimbabwe: Can collusion in pricing by seed houses be the cause?
    (Cogent OA, part of Taylor & Francis Group, 2019-11-04) Tibugari, Handsen; Chikasha, Tinei; Manyeruke, Ngonidzaishe; Mathema, Ndabanye; Musara, Joseph P.; Dlamini, Dumisa; Mapuranga, Rangarirai; Mapanje, Olga; Banda, Annabel; Parwada, Cosmas
    High cost of hybrid seed can affect food self-sufficiency. A study was conducted to investigate the structure, conduct and performance of the hybrid maize seed industry in Zimbabwe to determine whether the level of competition in the industry caused high and unstable prices. Primary data on the quantity of hybrid maize produced and/or marketed, pricing strategies and hybrid maize seed prices for the period 2011 to 2015 was collected using questionnaires administered to marketing managers of 10 seed houses involved in hybrid maize seed production and marketing in Zimbabwe as well as key stakeholders. The questionnaires were also used as interview guides for key informant interviews with production managers of respective seed houses. Secondary data were obtained from annual reports and technical bulletins of respective companies. The analysis involved respondent triangulation as well as triangulating the data from responses with secondary data in order to increase the convergent validity of the data. Descriptive statistics, ANOVA and trend analysis were used for data analysis. Results indicated that the hybrid maize seed industry in Zimbabwe is highly concentrated meaning that there is low competition. The study established that there may be tacit collusion in the pricing of hybrid maize seed in the form of dominant firm price leadership. The study showed that prices have not been stable for the period 2011 to 2015. It is recommended that the government should enact policies that; prohibit abuse of a dominant position, prohibit mergers which create or strengthen a dominant position and prohibit state aid that creates monopolies.
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    Worrying cadmium and lead levels in a commonly cultivated vegetable irrigated with river water in Zimbabwe
    (Cogent OA, part of Taylor & Francis Group, 2020-08-10) Tibugari, Handsen; Mafere, Gerald; Dube, Sinikiwe; Chakavarika, Murawu; Mandumbu, Ronald; Musara, Joseph P.; Mapuranga, Rangarirai; Gumbo, Tapiwa; Banda, Annabel; Mathema, Ndabanye; Goche, Tatenda; Zvigumbu, Bernard M.; Mpofu, Nkosentsha
    Vegetable cultivation using river water, which may be polluted with heavy metals, can cause health problems to consumers. A study to establish cadmium and lead levels in water from Msasa, Manyame; Mukuvisi and Nyatsime Rivers was conducted in 2019. A questionnaire survey involving 105 randomly selected urban vegetable growers was conducted to examine farmer knowledge of the potential of polluted water to contaminate produce through heavy metals. Water, soil and vegetable samples were also collected and analysed for heavy metal presence using atomic absorption spectrophotometry. Results showed that some farmers (62%) were aware that wastewater could contain heavy metals. The majority of farmers (67%) applied phosphate-based fertilisers, a potential source of cadmium. Tested at P < 0.05, the results showed that sampled water from the four sites failed to meet the Standards Association of Zimbabwe 5560 (1997) standards. Cadmium tissue concentration from wastewater from Msasa and Manyame rivers was 1.3 and 1.17 mg g−1 respectively, which were 59 and 65 times higher than 0.02 mg g−1 from the control. Water from Manyame and Nyatsime rivers contains levels of heavy metals which exceed the Environmental Management Agency (EMA) safety guidelines. Farmers need to be educated on health hazards from contaminated wastewater. Enforcing regulations on effluent disposal, licencing of vegetable vendors and labelling of vegetables with information on source of water used to irrigate the crop can help reduce exposure of unsuspecting vegetable consumers.