Research Highlights of the CIMMYT Wheat Program 1999-2000

of improved crop management practices on these
specific cultivars.
• Pendimethalin plus bromoxynil plus MCPA offer
effective control of the major grass (Sorghum
arundinaceum and Echinochloa colona) and broadleaf
weeds (Zelya pentandra, Portulaca oleraceae and
Corchurus olitorius) in irrigated wheat in the Awash
Valley of Ethiopia. A combination of these three
chemicals effectively controlled both grass and
broadleaf weeds and significantly increased grain
yield.
• Economic optimum rates of N and P fertilizer for
the high-yielding semidwarf bread wheat
HAR1685 (“Kubsa”) were determined under the
improved drainage technology known as broad
bed and furrow (BBF) in Ethiopia. Under two
contrasting cost/price scenarios, partial budget
analysis indicated that 138-46 kg N-P 2
O 5
ha -1 was
the most profitable of the nutrient combinations
tested.
• In Ethiopia, faba bean was recommended for a
three-year crop rotation with wheat. The rotation
improves wheat grain yield by as much as 65% in
year 1 and 35% in year 2, enhances wheat response
to phosphorus fertilizer, fixes as much as 210 kg
ha -1 of nitrogen, and improves soil nitrogen
balances by almost 65 kg ha -1 of nitrogen. The
research service has established demonstration
plots for the technology, which is also being
promoted by the national extension program.
• Higher N application rates recommended for bread
wheat in Ethiopia provide a return on the
investment in fertilizer in excess of 300% and an
additional 12 kg grain for each kg of N applied.
Interestingly, in Vertisol zones in Ethiopia, the N
application exhibited a residual benefit in year 2
equivalent to 40% of the response seen in year 1.
The new N recommendations have been
disseminated by the national bread wheat
extension effort and through Sasakawa Global
2000. Urea use on wheat rose sevenfold between
1994 and 1998, and national wheat production rose
by over 40% during the same period.
Technologies in the pipeline include:
• Economic analysis of long-term crop management
trials, essential to the interpretation of the
agronomic results, is being targeted for analysis
and summarization.
• Competition effects of three broadleaf weed species
(Guizotia scabra, Amaranthus retroflexus and Galium
spurium) on the grain yield of bread wheat have
been studied in Ethiopia; economic thresholds for
herbicidal intervention in relation to weed seedling
density have been determined.
• Twenty genotypes of bread wheat, previously
selected for high grain yield potential under weedfree
conditions, are being tested for yield potential
under competition with Avena sativum (as a proxy
for grass weeds).
Technology Dissemination
Within the ECSA region, the Kulumsa research
center of EARO, Ethiopia is widely recognized as a
center of excellence for bread wheat research. This
center actively collaborates in the regional
networks; thus, a study was initiated in
collaboration with CIMMYT’s Natural Resources
Group to identify the specific areas within ECSA for
which the transfer of materials, technologies, or
information to and from Kulumsa would be
appropriate. Climate similarity maps contained
within the Africa Maize Research Atlas were used
to address this question at the regional level.
The results highlighted the climatic similarity of
Kulumsa to most of the major wheat producing
regions in Eastern Africa (Figure 1), and supported
Kulumsa
Climate similarity zone for Kulumsa
5 month optimum season
+/– 20% precipitation & evapo.
+/– 10% max & min temperature
Figure 1. Climate similarity map for the Kulumsa Research
Center, Ethiopia.
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