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Accueil du site → Doctorat → Afrique du Sud → 2008 → Breeding for Cassava brown streak resistance in coastal Kenya.

University of KwaZulu-Natal (2008)

Breeding for Cassava brown streak resistance in coastal Kenya.

Munga, Theresia Luvuno.

Titre : Breeding for Cassava brown streak resistance in coastal Kenya.

Auteur : Munga, Theresia Luvuno.

Université de soutenance : University of KwaZulu-Natal

Grade : Doctor of Philosophy (PhD) 2008

Résumé partiel
Cassava (Manihot esculenta Crantz ssp. esculenta) is the second most important food crop and a main source of income for the rural communities with potential for industrial use in the coastal region of Kenya. However, its productivity of 5 to 9 t ha-1 is low due to the low yield potential of the local cassava landraces caused by cassava brown streak disease (CBSD) among other biotic and abiotic constraints. Breeding for CBSD resistant varieties with farmer desired characteristics is hampered by limited information on the current status of the disease and farmers’ preferred characteristics of new CBSD resistant genotypes. In addition, there is a lack of an effective inoculation technique for cassava brown streak virus (CBSV) for screening genotypes for CBSD resistance. Information about the general combining ability (GCA) and specific combining ability (SCA) for CBSD above and below ground symptoms, fresh biomass yield (FBY) and fresh storage root yield (FSRY) (kg plant-1), harvest index (HI), dry matter % (DM %) and picrate score (PS) is limited and conflicting especially for the cassava germplasm in Kenya. These studies were carried out to update information on the status of CBSD, farmer’s preferences for cassava genotypes, and identify the most effective CBSV inoculation technique. In addition, the studies aimed to : determine the GCA and SCA for, and gene action controlling, the incidence and severity of above ground CBSD, root necrosis, FBY, FSRY, HI, DM %, and PS ; and identify CBSD resistant progeny with farmers’ desired characteristics. A survey carried out in three major cassava-growing divisions in Kilifi, Kwale and Malindi Districts indicated that there was potential to increase production and productivity by increasing the area under cassava production and developing CBSD resistant genotypes that are early maturing, high yielding and sweet. In addition, CBSD was widely distributed, being present in 98.0% of the farms surveyed at a mean incidence of 61.2%.


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