PHD-Department of Plant and Microbial Sciences

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Browsing PHD-Department of Plant and Microbial Sciences by Subject "Introgressing Genes"

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    Introgressing Genes for Maize Lethal Necrosis Disease Tolerance to Maize Inbred Lines and Awareness Evaluation in Selected Counties in Kenya
    (Kenyatta University, 2023) Peterson, Muchemi Kariuki; Joseph Wainaina Kamau; Mathew Piero Ngugi
    Maize lethal necrotic disease remain a major biotic challenge facing maize production in Kenya and the entire Sub-Saharan region. The disease is caused by the synergistic co-infections of any member of potyviridae family and maize chlorotic mottle virus (MCMV). Improving maize cultivars through hybridization of single crosses and screening in a multiple agro ecological locations, is a fundamental stage in understanding projeny performance and disease reaction across the varying ecologies/locations.The identifications of the best parental combinations are important stages towards identification of MLND resistance maize cultivars in Kenya. The current study aimed at introgressing genes for maize lethal necrosis disease that is tolerance to maize inbred lines and determination of the level of awareness at Bomet and Nyandarua counties. Bomet County is the hot spot area for Maize lethal Necrotic Disease in Kenya, while Nyandarua county have a variation of agroecological zones imprptant for maize breeding. Structured questionnaire were used to collect data on farmers awareness and MLND managements among Bomet and Nyandarua Subcounties. A total of twenty-four inbred maize lines were collected at Kenya Agriculture Research and Livestock Organization Muguga Centre. In addition four commercial checks were also collected as positive and negative control for Maize Letahl Necrotic Diseases evaluation. The selected inbreds lines and control maize lines were evaluated in a green house environment at Kenyatta University. Field evaluation for MLND was also done at Bomet County. Ten inbred lines, six susceptible and four tolerant, were selected for hybridization. This was followed by identification of inbred lines and their hybrids with high combining ability for MLND resistance, yield, and other morpho-agronomic traits under natural MLND hotspot conditions. Twenty-four single cross hybrids were evaluated in MLND hotspot areas (Longisa and Itembe) Bomet county. The varieties of maize grown by the farmers differed significantly (P < 0.05) across all the five Sub counties in Bomet County. Majority of the farmers in Bomet County preferred genotype DK777 (23.91 %), SC DUMA 43 (8.26 %). Genotype DK777 was mostly prereferred by farmers due to MLND tolearant ability compared to other commercial hybrid. On the contrary, maize farmers in Nyandarua County preffered genotypes H614, H629 and H628 (26.27 %, 18.63 %, 16.87 % and 13.28 %), across all the Sub-counties (P < 0.05). The preference of H614 was due to high yielding compared to other maize varieties. Farmer’s knowledge, awareness and management varied significantly among sub counties evaluated. The screened inbred lines both at controlled environment and natural field, indicated several symptoms like mottling, dwarf maize plants, sterile tassels, short cob, and development of silk on ear position. Maize genotypes KUBT 2, KUBT 6 and KUBT 7 recorded tolerance in both green house and natural environment at Bomet County. Inbred lines KUBT6, KUBT7 and KUBT2 recorded the lowest severity levels after screening using natural conditions at Bomet County. Maize Hybrids KUBT2×KUBT9, KUBT6×KUBT9 and KUBT7×KUBT17 recorded negative Specific Combining Ability effect for severity scores which is an indicator of desirable genes tolerance to MLND. These single crosses hybrids are therefore, recommended for further evaluations to validate the stability for resistance to MLND in Kenya and Sub-saharan region towards food sustainability. The awareness evaluation of MLND among maize farmer, should be given first priorities toward management of MLND in Kenya.