Mexico
March, 2007
Source:
CIMMYT E-News, vol 4 no. 3, March 2007
Solving a major disease problem
in durum wheat was not enough to satisfy farmers. They need and
will get quality too.
Karim Ammar, a durum wheat breeder with CIMMYT, is proud of his
new wheat lines growing green and disease-free this season in
the Yaqui valley of northern Mexico. Even with the efficiency of
a shuttle system between the Yaqui valley and the highland
research station at Toluca, Mexico which allows wheat breeders
to plant and select wheat twice a year, it still takes six years
to get to where Karim is now.
(Access to CIMMYT video:
http://www.cimmyt.org/english/wps/news/2007/mar/yieldBack.htm)
“Between preliminary yield trials and elite yield trials we’ve
got about 2500 lines and they are all resistant to leaf rust,”
he says.
This is good news for the durum wheat farmers of the world.
Durum wheat is the kind used for pasta, couscous and semolina.
Today, 85% of spring durum wheat grown in developing countries
traces its origins to the durum wheat program at
CIMMYT in Mexico. The Center
regularly sends out seed samples to national breeding programs
around the developing world, and the most suitable in each
region are used to breed local varieties. When mutations in the
leaf rust fungus allowed it to bypass the resistance mechanisms
in durum wheats, the breeding team at CIMMYT was faced with a
serious problem.
“We had to rebuild the program, because you can no longer use
something that becomes susceptible to a disease. That’s no
service to the national programs or farmers in developing
countries,” says Ammar, who comes from Tunisia. He is acutely
aware that the work he is doing will have a major impact in
developing countries where durum wheat is grown.
It might have been easy to look this as a single
problem—producing disease-resistant plants or plants that can
produce more grain—but the team realized the challenge was much
more complicated. Farmers in developing countries need more than
grain if their livelihoods are to improve. They need grain that
is high in quality and for which there is a market.
Breeding itself is a process of combination and then
elimination—selecting potentially good parent seeds with
desirable characteristics and crossing them, then eliminating
the offspring plants that don’t measure up. The process is
cyclical and repeated until the breeder is satisfied that all
required characteristics have been incorporated into the new
wheat plants.
Leaf rust reduces yields enough to make growing susceptible
varieties a losing proposition for farmers. Their needs were at
the heart of the breeding strategy devised by the breeding team.
“So their priority becomes ours and once objectives are defined
with our clients and their respective markets in mind, then I
start thinking about the plants—how would a plant or a certain
cross or combination of genes achieve that objective in the most
efficient, fastest way possible,” Ammar says.
The breeders knew that disease resistance was vital but quality
that was acceptable to farmers and their markets was equally
essential. At the same time they thought they could enhance the
performance of the wheats under drought stress and incorporate
resistance to other diseases. In the beginning they had to
sacrifice yield and other key characteristics to be sure they
had resistance to the leaf rust, the biggest problem durum wheat
growers were facing. But once that was done, the team focused on
making the best possible wheats from all other perspectives.
“Now we’re back to the point where we can address yield, drought
tolerance and quality very effectively because we know we have
enough variability for rust resistance. It’s no longer the
critical trait,” says Ammar.
The most critical trait now might well be the color or the
quality of the gluten in durum wheat grains. Last year farmers
in the Yaqui Valley of Mexico grew close to 150 000 ha of a
durum wheat variety that yielded well and stood up to leaf rust.
Unfortunately, because its grain did not have enough yellow
pigment, desired by the export market, there was little market
for the wheat except as pig feed. Many of the 2500 new lines
that Ammar is testing outperform that variety in yield and in
the most important quality traits
The best of the lines at the CIMMYT breeding station will be
sent to national programs for evaluation. Mexico has already
begun to evaluate in parallel so it will be ready as soon as
possible to release new varieties based on the CIMMYT lines to
the national production system .
For more information Karim Ammar, Wheat Breeder (k.ammar@cgiar.org)
Source:
http://www.cimmyt.org/english/wps/news/2007/mar/yieldBack.htm
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