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May 6, 2009
Source:
Bioversity
International
It is often claimed that the
introduction of high-yielding crop varieties threatens
agricultural biodiversity. Farmers who adopt the modern
varieties abandon their traditional varieties and overall
genetic diversity falls as a result. Generally this is true, but
a new paper published online in Field Crops Research shows that
it need not be the case, especially if the modern varieties
count farmer varieties among their parents.
In the early 1990s, while a PhD student at Bangor University in
the UK, Bhuwon Sthapit, now a senior scientist at
Bioversity
International, was instrumental in breeding three new
varieties of rice suitable for upland rice farms in Nepal. This
was no ordinary breeding programme, however. Sthapit worked
closely with farmers in a client-oriented approach that involved
the farmers in both setting the goals of the breeding programme
and participating in the selection of the final varieties from
the many crosses. The varieties were selected from crosses of
Chhomrong Dhan, a local landrace well adapted to the cold
conditions of high-altitude rice farms in Nepal, with Fuji 102
and IR36, more productive material from international breeding
programmes.
Farmers selected three lines: Machhapuchhre-3 (M3),
Machhapuchhre-9 (M9, which is similar to M3 but with lower cold
tolerance) and Lumle-2 (L2, like M3 with better grain quality
and easier threshing). Only M3 was officially released, but M9
and L2 have been adopted widely thanks to informal seed
exchanges among farmers. By 2004 about 60% of the land in the
study villages was sown to one of the three COB (client-oriented
breeding) varieties, while traditional varieties occupied the
remaining 40%. In adopting the COB varieties, many farmers had
dropped traditional landraces, but there was no clear pattern to
which landraces were dropped in which villages. The variety
dropped most commonly was Chhomrong Dhan, one parent of all
three COB varieties.
To assess genetic diversity an international team of researchers
from Bangor and Nepal analyzed DNA from the three COB varieties,
a random selection of landraces and a control group of modern
varieties. Overall, genetic diversity was greatest in the
landraces, and least in the COB varieties. However, there was no
loss of genetic diversity across the district as a whole, at
least as long as the three COB varieties were adopted on less
than about 65% of the land. Indeed there is an increase in
diversity as the COB varieties are adopted because the
high-yielding parental varieties contribute alleles not
previously encountered in the area.
Another crucial result is that although some farmers grow COB
varieties on 100% of their land, nevertheless, at least 11
diverse landraces survived on some 40% of the land. These
landraces clearly meet needs not fulfilled by the COB varieties.
For example, although the most commonly dropped variety was
Chhomrong Dhan, farmers in the Gurung community continued to
grow that variety.
“It is the preferred rice for preparation of the dish Madeko
Bhat used during funerals and other ritual and social
ceremonies,” Sthapit explained.
The client-oriented breeding programme was clearly a success; it
resulted in farmers adopting modern varieties adapted to high
altitudes, whose cultivation improved the livelihoods of the
farm families. The adoption of the new varieties reduced the
number of households and the area for some landraces, but
overall genetic diversity increased because the modern varieties
contained alleles not seen before in the district. They also
contained alleles from the landraces, so preserving that genetic
diversity too.
“The conclusion is clear,” said Sthapit. “Participatory breeding
and client-oriented breeding programmes should choose locally
adapted varieties as parents for breeding. It ensures that
landrace genes are conserved and increases the likelihood that
the breeding programme will succeed.”
Related News:
-
Nepal's farmer breeders in the news (04/07)
-
Farmer rice variety gets official approval (10/07) |
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