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Cassava is
an important urban and rural staple, as well as food security crop
in Tanzania. Recent developments also point to its becoming an
important cash crop in the near future. The improvement of
productivity and yield stability is therefore an important
objective of the Cassava Research Programme of the Department for
Research and Development (DRD) of the Ministry of Agriculture and
Food Security. Cassava in Tanzania is grown in diverse
agro-ecologies. Varieties grown by farmers are often susceptible
to pests and diseases but are preferred for certain
characteristics such as flavour, cooking quality, storability of
processed flour, etc. that are often features of their land races.
In terms of adoption, it is important that these characteristics
are maintained during the process of crop improvement for pest and
disease problems in breeding programs. New tools in the form of
molecular markers have recently become available to accelerate
breeding for disease and pest resistance. A farmer participatory,
marker-assisted, decentralized, breeding scheme has therefore been
put forward as a way of speeding up the process of improving the
productivity and yield stability of cassava germplasm in
Tanzania. The proposed breeding project will take farmer
preferred germplasm by agro-ecology and cross them to improved
introductions that have resistance to Cassava Mosaic Disease (CMD),
Cassava Green Mite (CGM), and Cassava Bacterial Blight (CBB).
Given the fairly large number of parents that will be used,
molecular markers associated with pest and disease resistance will
be employed to reduce, in a logical manner, the number of progeny
to a manageable number. The progeny selected by MAS will be
evaluated in a single season in the corresponding agro-ecology and
then evaluated over two cycles in collaboration with end-users
(rural communities and other cassava producers). The project will
be carried out in a total of six years divided into two three-year
phases. A principal objective of the project is also the
development of capacity for participatory plant breeding and
marker-assisted breeding. This will be achieved by training two
national program breeders at the MSc. and PhD level, and through
two training workshops on participatory plant breeding and
marker-assisted breeding. Activities, including molecular marker
analysis, are being conducted at national program facilities,
while the two International Agricultural Research Centers (IITA
and CIAT) that work on cassava provide back-stopping in
conventional and modern methods of cassava breeding. A second
aspect to the project is the genetic mapping of tolerance to brown
streak virus, a virus that is currently devastating cassava in
predominantly coastal regions from Kenya to Mozambique. This will
be mapped through bulk segregant analysis in the F1.
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