|
CASSAVA
PROGRAMME
Introduction
Cassava is among the high priority commodity
crops on NARO's research agenda. The crop was introduced
to Uganda through what is Tanzania by Arab traders between
1862 and 1875. Its cultivation greatly increased between
1931 and 1933 and subsequently became a cheap source
of food. It ranks second among the major food crops,
regarded as the most important cheap source of staple
food and cash crop. Its flexibility in the farming and
food systems, ability to do well in marginally stressed
environments and apparent resistance/tolerance to pests
and diseases, particularly locusts encouraged its rapid
spread and adoption. It is presently grown throughout
the country. A total of 3.5 million metric tonnes of
the crop were produced from 450,000 hectares of land
grown until 1990 when mosaic epidemic devastated the
crop.
The major constraints that affect cassava production
include (a) the use of inferior low yielding varieties;
(b) lack of good quality planting material; (c) pests
such as cassava mealybug (CM), green spider mite (CGM),
(d) diseases, including the current pandemic of cassava
mosaic viruses (CMV), cassava bacterial blight (CBB)
and anthracnose (CAD), (e) labour bottlenecks and poor
cultural practices (f) cyanogenic glucosides which hinder
cassava utilisation (g) bulkiness and perishability
affecting commercialisation of the crop, (h) poor methods
of utilisation.
Goal and Objectives of the Cassava
Programme
The Uganda Cassava Development Programme (UCDP)
is mandated to carry out research and development activities
on cassava improvement in the country. It conducts multidisciplinary
research at Namulonge Agricultural and Animal Production
Research Institute (NAARI) and other experimental substations
located in different ecological regions of the country
where the crop is important. The overall goal of the
programme is to supply adequate food and raw materials,
stimulate production for export in order to raise income
and improve quality of rural life while conserving the
natural resource base.
Specifically, research objectives
are to:-
a) Understand farmer's cassava production and
utilisation practices, identify constraints/needs and
adjust research priorities and objectives appropriately,
b) Collect and preserve local cassava germplasm and
use them in breeding more
adapted, farmer/consumers acceptable varieties resistant
to major pests and
diseases.
c) Develop appropriate, integrated and ecologically
sustainable methods for the control of major pests and
diseases
d) Develop improved agronomic and post harvest practices
acceptable to resource poor farmers and continuously
provide in-service and higher degree training facilitate
attendance at conferences and workshops by programme
staff respectively, in order to form a well co-ordinated
inter-disciplinary team which ensures sustainable national
capacity.
The specific development objectives
are to
a) Carry out accelerated on-farm trials, collaboratively
identify improved, appropriate varieties and other technologies
acceptable to farmers.
b) Assist extension staff, NGOs etc to multiply and
distribute suitable sufficient planting material of
varieties to many farmers over the shortest possible
time.
c) Continuously to understand the socio-economics, adoption
and impacts of root crop technologies
d) Train extension staff, opinion leaders and farmers
on improved production/utilization practices.
Support by various stakeholders
Financial support for the programme comes from the
Uganda Government and, the International Development
Research Centre (IDRC), Canada, USAID - PL 480 (food
Security, Washington, International Department for Agriculture
Development (DFID), U.K.
The Programme recognised the strategic important role
of collaborators in agricultural technology development
and transfer and accordingly, strengthened collaboration
with many national research systems, international organizations,
and, overseas institutions. The programme has developed
close linkages with IITA and its Regional Centre for
Eastern and Southern Africa (ESARC) by deriving technical
and material backstopping.
The Programme is a member of the Eastern Africa Root
Crops Research Network
(EARRNET), Cassava Biotechnology Network (CBN), International
Bemisia Working Group (IBG) and the Intercenter Whitefly
Initiative and many other relevant organisations. The
team collaborates very effectively with the post-harvest
and soils research team at Kawanda Agricultural Research
Institute, (KARI), the Food Research Institute (FORSI),
Makerere University and Agricultural University, Wageningen.
Similarly, the programme has solicited support and
co-operation from non-governmental organizations, notably
CARE (U) International, Lutheran World Federation, ACORD,
Agricultural Development Programme (ADP), Farming Systems
Support Programme (FSSP), Eastern and Southern African
Root Crops Research Network (ESSARN) to mention but
a few.
The close linkage between the Programme, policy makers,
extension staff, NGOs and farmers has made enormous
contribution in development and dissemination of
improved and sustainable cassava technologies. This
approach will continue to be
employed in introducing, identifying, evaluating, disseminating
and validating improved cassava technologies within
the medium to high altitudes and semi-arid areas in
Uganda where the potential of cassava in bridging the
food gap is immense.
ACHIEVEMENTS
(1) Technology development , (2) Technology
transfer
Technology development
A range of both hard and soft technologies have
been developed through a concerted interdisciplinary
and inter-institutional approach. Todate, 9 varieties
have been officially released; TMS 60142, TMS 30337,
TMS 30572, SS4, SS5, TMS 4(2)1425, CE 85, CE 98, 30557
code-named Nase 1, Nase 2, Nase 3, Nase 4, Nase 5, Nase
6, Nase 7, Nase 8, Nase 9 respectively. Further, several
clones are in advanced stages of evaluation and wait
release. Besides other recommendations have been made
across disciplines ranging from phytosanitary control
measures to improved production husbandry practices.
For example, rouging and selection of clean planting
materials, planting in isolation, restricted movement
of diseased materials, use of varietal mixtures, spacing
1 m x 1 m, stakelength (25-40 cm), intercropping, rapid
multiplication techniques, ratooning and safe use of
bitter cassava varieties.
Technology transfer
(1)Multiplication of mosaic resistant varieties, (2)
On-farm trials, (3) Capacity building, (4) Contribution
of knowledge to science, (5) Global spill-overs, (6)
Conferences, workshops and courses.
Multiplication of mosaic resistant
varieties
Inorder to accelerate the technology transfer process,
a machinery, National Network of cassava workers (NANEC)
was put in place in 1991. Through this network, research
on cassava has been able to register greater successes
including development of new mosaic cassava varieties.
An integrated strategy for multiplication and distribution
of virus-free stocks of improved varieties was developed
and used by NANEC. Todate, more than 250,000 ha of improved
resistant varieties have been established. By and large,
NANEC through its participatory research approaches
in the development and transfer of cassava technologies
has been overwhelming successful. This is explicitly
illustrated by high yields of new cassava varieties
that bridged the yield-gap caused by the devastating
CMD epidemic, the rapid adoption and uptake of new cassava
varieties, and the large and positive internal rates
of return (IRR) derived from the overall cassava project
and from separate projects. The IRR has been estimated
to be between 100 and 200%
On-farm trials
A number of on-farm trials have been conducted
throughout the country. The trials enabled identification
of cassava genotypes suitable fort he diverse local
and farmers' conditions and strengthened the partnership
amongst researchers, extensionists and farmers since
each had a role to play in the trials. To-date, more
than 580 on-farm trials have been conducted.
Capacity building
Nearly all the programme staff has been trained
at Masters' and Ph.D. level. The training of farmers
and other stakeholders increased farmers' knowledge
on mosaic and its control. Currently, there is greater
awareness on CMD spread and control than before. Not
only did creation of awareness stop at farm level, it
went even to other members of the public. The programme
has documented some of its activities on video and this
has been put for public viewing over Uganda Television
at least four times a year since 1996.
Contribution of knowledge to
science
The classical study of molecular biology of UgV, particularly
DNA-A, has shown that the virus arose through hybridization
between torelated viruses, EACMV and ACMV. This is the
first report to show that when two related geminiviruses
co infect a host, a recombination is possible. This
is of great significance because it suggests that geminiviruses
could become even more important as more than one species
adapt to similar hosts.
The studies has also shown that ACMV and EACMV co-infected
cassava. Plants infected in this way showed more severe
symptoms that those infected singly. This is important
because it suggests that two related geminiviruses can
co-infect one host and cause synagestic effects on symptom
severity. It demonstrates that mild strain protection
is less likely in geminiviruses unlike in other viruses
where cross-protection is the order.
Global spill-overs
The knowledge, technologies and experiences
generated in Uganda, puts the programme at a unique
position to assist neighboring countries experiencing
similar problems. The mosaic epidemic has already destroyed
much cassava in western Kenya, entered Tanzania and
is spreading rapidly in DRC and Southern Sudan. The
programme has already been approached to assist in Kenya.
A substantial amount of planting material was mobilized
and planted as nucleus multiplication at Alupe Research
Station and Kakamega Regional Research Station (Fig.
15). The first series of harvests of these stems have
been moved to initiate multiplication of mother gardens
in a few districts in western Kenya. Plans are underway
to expand these to cover multiplication in all districts
and sub-counties within districts. Requests have been
received from Tanzania. Discussions have been held with
the scientists there and plans to initiate multiplication
has been drawn up. A similar thing could be extended
to DRC and Southern Sudan once insecurity in those countries
stops.
Conferences, workshops and courses
The program successfully organised and conducted
a number of conferences, workshops and courses such
as the International workshop on cassava mosaic disease
in Africa organised jointly with NRI; International
seminar on integrated management of pests, weeds and
diseases of cassava in Africa-organised jointly with
CTA, NRI, NARO; the third international scientific conference
of the cassava biotechnology network-organised jointly
with CBN, CIAT; national workshop on post-harvest technologies
for root crops-organised jointly with IITA; Advanced
statistical data analysis course (twice)-organised jointly
with EARRNET.
ON-GOING RESEARCH ACTIVITIES
Intercropping and cultural management, (2)Cassava
varietal Improvement, (3) Integrated pest management,
(4) Cyanide Studies, (5) Socio-Economic Studies
Intercropping and cultural management
1) The effect of ratooning and age on cyanogenic
potential in cassava
2) Source-link relationship in dry matter partitioning
among cassava genotypes in different agro-ecologies
3) Farmer participatory review of cassava agronomic
recommendations
4) Farmer participatory development of soil fertility
management strategies in cassava production
5) Integrated solutions to weed managemnet in cassava
production
Cassava varietal Improvement
1) Evaluation of germplasm for cyanogenic association
2) Collection, evaluation, characterisation and maintenance
of germplasm
3) Regional variety trial
4) Yield trials with advanced selections
5) Studies on genotype x environment interaction and
yield stability
6) Introgression of ACMV resistance genes into local
elite cassava
Integrated pest management
1) Studies on alternative host plants of B.tabaci
and CMVs
2) Studies on CMV transmission by B.tabaci using resistant
and susceptible varieties as a sources of virus
3) Studies on immigration and emigration of B.tabaci
in cassava fields in relation to epidemic progress
4) Comparative study on whitefly infestation in CMV-infected
and CMV free cassava
5) Studies on the resistance of cassava to cassava mosaic
disease
6) Effect of varietal diversity on the spread of CMD
7) Equilibrium in cassava and the CMD pathosystem
8) Serological and molecular variability of CMGs
9) Nature and dynamics of CMD epidemic
10) Variability and virulence of CMGs in Uganda
11) Evaluation of local cassava clones for susceptibility
virus content and type, reversion/recovery and yield
12) Potency of resistant cassava varieties as sources
of cassava
geminiviruses
13) Progress of cassava mosaic in different forms of
varietal mixtures
14) Effect of stage of infection, virus type and content
on reversion
15) The impact of use of CMD resistant varieties on
variability of CMG
16) Significance of reversion and recovery in the epidemiology
of CMD and sustainability of cassava varieties
17) The effect of ratooning cassava on 'reflux' of CMGs
18)Influence of selection and roguing CMD resistant
varieties on the incidence of CMD
19) Screening cassava genotypes for resistance to cassava
green spider mite (CGM) and cassava mealybug
19) The Interaction between strains of cassava mosaic
geminiviruses and effects on growth and yield
20) Studies on replacement series between susceptible
and resistant varieties and compensation for virus damages
in a CMD-pathosystem.
Cyanide Studies
1) The effect of ratooning and age cyanogenic
potential in cassava
2) Evaluation of the cyanogenic potential of cassava-based
food products across selected locations
3) Screening of cassava varieties for preferred post-harvest
quality parameters (including low cyanide content)
4) Effect of soil chemical factors and soil types on
cyanogenic potential
5) Impact of age and season of harvesting; handling
methods on cyanogenic potential
6) Quantification of glucosides and linamarase enzyme
in different cassava genotypes
Socio-Economic Studies
1) Adoption study of technologies developed
on cassava
2) Cassava variety On-farm testing
3) The economics of technologies developed on cassava
4) Farmer coping strategies with CMD at different CMD
epidemic stages
5) Issues on participatory research on cassava in Uganda
6) Cassava stem production and quality materials in
the major cassava growing areas of Uganda
7) Sensitization of the farming community on improved
methods of cassava production
8) Understanding farmers' practices for utilising cassava
technologies in CMD post-epidemic areas in Uganda
9) The role of participatory Integrated pest management
(IPM) and community-based technology transfer centres
(COBTTEC) in development, and adoption of cassava technologies
10) Assessment of the efficiency and impact of different
approaches adopted in the testing and transfer of cassava
technologies in Uganda
STAFF
RESEARCH PUBLICATIONS
|
