Stable or even slightly greater diversity
On a national level, the researchers inventoried the common names of the varieties used by farmers between 1996 and 2001. This meant surveying almost 1700 farms in 79 villages. Furthermore, in 2003, samples were collected from six villages in Maritime Guinea and compared, using molecular markers, with samples taken by a survey mission to the same village in 1980 and kept in cold storage in Montpellier ever since. The results obtained ran counter to the alarmist vision of genetic erosion. The number of rice varieties and genetic diversity were stable, or had even increased slightly. Since 1996, when improved varieties were introduced, the number of varieties, which varied from 4 to 40 depending on the village and the region, had increased by 10%. There had thus not been any loss of local varieties in Guinea.
The substantial varietal diversity observed is typical of subsistence agriculture: more than 80% of the varieties grown were local. Each village could thus allow for the range of prevailing agroecological conditions and different uses of rice. However, almost 90% of the varieties inventoried were only grown by a small number of farmers, and despite the observed diversity, these "minor" varieties are now under strong threat of extinction. Moreover, there was not only diversity in terms of the number of varieties, but also within each of those varieties. Each variety was the sum of a large number of pure lines, and the proportion of those lines varied from one farm to another. This "multi-line" structure can be put down to how the farmers manage their rice varieties, ie frequent exchanges and replacement of varieties and seeds, and cropping and seed production practices that favour genetic mixes and recombination.
50% of the genetic wealth of varieties in a village held on a single farm
As regards preserving the diversity within each local variety, in situ conservation on farms, which is compatible with agricultural development, looks like the only feasible option. In fact, it would be impossible to sample all the lines that make up a variety and keep them ex situ, for instance in a cryobank. The researchers working on the study thus characterized the varieties grown in Maritime Guinea, in two villages with contrasting production systems. To this end, they used descriptors combining common names and molecular markers (short DNA sequences). The results showed that a single village may hold the equivalent of 70% of regional diversity. On a more detailed analysis level, a large farm may hold 50% of the genetic wealth of a village. As a result, a small number of villages and farms is therefore sufficient to cover the genetic diversity of a whole region such as Maritime Guinea. This type of structure could eventually be extended to cover the whole of the country.
Helen Burford | alfa
New research recovers nutrients from seafood process water
31.10.2018 | Chalmers University of Technology
Plant Hormone Makes Space Farming a Possibility
17.10.2018 | Universität Zürich
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences