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)

Website: http://www.bioversityinternational.org

Published: May 6, 2009