Browsing by Author "Nyaga, Justin"

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    Effect of Institutional and Farmer Based Climate Change Adaptation Measures on Crop Production in Mavuria Ward, Mbeere South Sub-county, Embu County, Kenya
    (Original Research Article, 2020-12) Nyaga, Samuel K.; Gathungu, Geofrey K.; Nyaga, Justin; Njeru, Jafford R.
    Africa is under pressure from climate stresses and is highly vulnerable to the impacts of climate change. In Kenya, agriculture is the backbone of the economy making it an important contributor to food security of rural households. Currently crop productivity is being affected by continued climate variations and decline in soil fertility. Adaptation to climate change requires to be given high and urgent priority for sustainable crop production. A study was conducted in Mavuria ward, Mbeere South Sub-County, Embu County to evaluate the effects of climate change adaptation on crop production. The study used both descriptive and experimental research designs. The primary data on adaptation measures was collected from farmers and institutions using questionnaires. In the data analysis, descriptive statistics were used to organize the climate data and that of the respondents into frequencies. Further, a Pearson correlation test was done to determine the relationship between farmer and institutional based mechanisms on adaptation to climate change at α=0.05. The main adaptation mechanisms identified were soil fertility improvement, soil and water conservation, early planting, pest and disease control, provision of certified seeds, and awareness creation. In view of these findings, the study recommends continuous implementation of these measures that can help strengthen farmers and institutional adaptation mechanisms towards climate change for improved crop production.
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    Response of Selected Kenyan Rice Cultivars to Infection by Root Knot Nematode (Meloidogyne incognita)
    (2019-03) Namu, John; Alakonya, Amos; Karuri, Hannah W.; Nyaga, Justin; Masanga, Joel; Njeri, Editah
    Meloidogyne incognita causes huge yield losses in rice which is the third most important cereal crop in Kenya. The aim of this study was to identify M. incognita-resistant rice cultivars from Kenya and relate the responses to known resistance pathways with OsPR1a, OsPAL1, and OsJAMYB as marker genes in rice. Five rice cultivars BW 196, Basmati 217 (Pishori), Sindano, IR 2793-80-1 (grown in lowland irrigated fields), and NERICA 4 (grown in upland rainfed fields) were evaluated for resistance to M. incognita under greenhouse conditions in two separate trials. The number of nematode eggs, reproduction factor (RF), and the level of galling were determined. The RF was used to select resistant cultivars. There was a significant difference (P < 0.001) in the number of eggs, galling index, and RF among the cultivars. NERICA 4, BW 196, and Sindano were classified as resistant with an RF <1. There was differential expression of the three marker genes between susceptible and resistant cultivars. OsJAMYB gene was up-regulated in leaves of all rice cultivars after 1 and 3 days post inoculation (dpi). OsPAL1 was up-regulated in leaves of all varieties at 3 dpi while OsPR1a was down-regulated in leaves of resistant plants at 1 dpi and 3 dpi. These results provide an insight on sources of M. incognita resistance in Kenyan rice and it also forms an interesting starting point for further studies on defense responses of common rice varieties to root knot nematode infection.
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    Staff Profile - Dr. Justin Nyaga
    (University of Embu, 2015-07) Nyaga, Justin