Uganda: New Cassava Varieties Give Farmers Hope
Posted by Unknown in Cassava, New Variety, Uganda on Sunday, 12 May 2013
BY CHRISTOPHER BENDANA
Vangi
Ekirapa, a farmer in Tororo, has for long been struggling to increase
yields in her cassava garden. But with the introduction of NASE 14, a
hybrid cassava variety, Ekirapa has a reason to smile because she is
able to harvest about 12kg of cassava from each stem. NASE 14 was
developed at the National Crop Resources Research Institute (NaCRRT),
Namulonge.
Cassava
production in Uganda is largely affected by Cassava Mosaic and the
Cassava Brown Streak Disease (CBSD). Cassava mosaic affects mainly the
leaves, which turn yellow consequently affecting the photosynthesis of
the plant. This leads to poor yields. CBSD affects the roots turning
them brown.
Experts breed varieties:
Currently,
geneticists and plant breeders are breeding new cassava varieties. The
new variety is a cross between a breeder's two desired varieties each
with traits a breeder is looking for. The traits include drought and
water resistance, pests and diseases resistance and high yielding
traits.
For pollination
to take place the female part of the cassava is covered to stop
fertilization by its male counterpart of the same variety. The female is
monitored before it opens up for pollination. The breeder then
introduces a desired male cassava variety, which he pollinates manually
in a process called controlled pollination.
Controlled
pollination has been going on for many years at the National Crop
Resources Research Institute (NaCRRT), Namulonge. So far, 19 new
varieties from NASE have been breed.
Why is breeding vital?
According to
William Esuma, a research assistant at NaCRRT, cassava breeding is aimed
at solving the problem of low yields, pests and diseases by introducing
improved varieties, especially those from the International Centre for
Tropical Agriculture (IITA).
"We aim at
increasing cassava yields, varieties that are resistant to pests and
diseases and are high in nutrient composition, especially proteins and
vitamin A," Esuma explains.
According to
the World Health Organisation, lack of vitamin A, especially in children
is the major cause of blindness across the globe.
"We also want
to get cassava varieties that mature early and have a long life span.
This will increase market opportunities for farmers," he adds.
How it is done:
The breeding
process involves selection of a desired cassava variety that has one or
more of the desired traits like resistance to drought, pests and
diseases and high yields. It is then pollinated with another that has
other desired traits.
Anthony Pariyo, a breeder at NaCRRT, says the local landraces, which they have been improving include Kakwele and Bamunanika.
They are
crossed with varieties like TME14 from IITA to create the desired breeds
that are high yielding and resistant to pests and diseases.
Cassava
breeders say the local breeds are famous for their root quality, while
the TME 14 is well-known for its high yields, disease and pests
resistance.
The breeding
process involves four stages, which include: evaluation of the seed
produced between landraces and an imported variety. Cloning, where the
stem of the new variety is cut into 10 pieces, planted and evaluated for
uniformity in the plants.
Then there are preliminary field trials and on farm evaluations in different locations in the country.
During the
trials, breeders look for strong and weak points caused by the
difference in environment and the role of heterozygous in the breeding
of cassava. It is common for one cassava clone to produce 10 different
offsprings/varieties.
Pariyo says the institute has so far released 19 varieties, which are tolerant to Cassava Mosaic, but susceptible to CBSD.
"Our focus now
is on CBS D. We are carrying out field trails and the results are
promising. In the next three years, we are likely to get a resistant
variety," he notes.
Commenting on
concerns that the landraces face extinction, Pariyo says all landraces
have been kept in the germplasm. A germplasm is a seed bank where seeds
are kept for future use.
"A breeder's biggest asset is having a diverse germplasm," he says.
Farmers tipped:
Experts say
there are a number of interventions that farmers can put in practice.
First, planting clean seedlings would increase yields by 13% and
improving soil fertility would push it by 17%.
Others are
control of pests and diseases, which improves yields by 16%, control of
soil erosion by 11% and weeding by 9%. They also say intrinsic yield
potential where the role of the breeder is paramount accounts for 19%.
Pariyo says
with good management practices, farmers can harvest between 30-40 tons
per hectare against the current national average of 14 tons as reported
by the Food and Agricultural Organisation.
He says about 60% of farmers are now planting improved cassava varieties.
Pariyo recommends planting seedlings one metre apart for optimum performance.
Cassava takes between 10-12 months to mature.
According to
ASARECA, an agricultural research association in Eastern and Central
Africa, about 80% of Ugandans depend on cassava for their livelihood.
Cassava is the second staple food after maize in Africa.
