Germplasm: Farmers Try the New but Trust the Old

The tantalizing benefits of modern improved crop varieties are their ticket onto the subsistance farm. But farmers closely observe these newfangled high-tech varieties, while continuing to foster the crops that fed their ancestors. Given this situation, who could possibly be better situated to compare the two? And who but the subsistence farmer could better appreciate the value of conserving traditional plant varieties, or be better placed to do so?

The introduction of modern improved crop varieties has made conservation of traditional varieties increasingly important. At present, the major international research stations are the guardians of plant genetic material in so-called ex situ gene banks. In situ conservation, the maintenance of plant genetic material in its natural setting, has been proposed as an alternative to augment existing germplasm collections, and to complement ex situ conservation.

For in situ conservation to be successful farmers and conservationists must work together and have a common understanding of a given system. If this goal can be achieved then in situ resources can be used to replenish ex situ research, to provide insight into the ecosystem and species-ecosystem interaction, to produce larger quantities more economically than ex situ, and to serve as a supplement or backup to ex situ conservation.

Germplasm Stereotypes

There are four categories of plant germplasm, each requiring a different conservation method: wild crop relatives such as teosinte (Zea diploperennis); semi-domesticated (weedy) crops such as Fonio (Digitaria exilis); perennial species (especially tree species); and landraces. Landraces are ancient crops associated with centers of crop origin, and depend on traditional, subsistence farming systems. The obstacle to landrace conservation has been lack of effective farmer involvement.

Conservation of wild relatives can be achieved with protected biological reserves to maintain species in their ecological niche. Weedy relatives depend on habitat disturbances such as tilling or clearing to survive. Commercial management of perennials, such as tree species, is not usually intended to preserve germplasm, but it does have that effect.

The diffusion of improved crop varieties into areas of the crop's origin is thought to result in genetic erosion. But three case studies in which improved germplasm is introduced into tropical farming systems support the argument that genetic erosion is not inevitable.

Potatoes in Peru

Peru is home to the potato, and an area where tremendous potato diversity can be found. The farming systems that support this diversity are under pressure from demographic, technological, and economic change.

A 1952 survey of potato varieties compared to a 1980 survey from the same location revealed virtually all of the same plant varieties.

A cross section study was conducted between 1984 and 1986 to evaluate how potato diversity was affected over time. The study area focused on two valleys on the Eastern slope of the Andes, the Tulumayo in central Peru and the Paucartambo in southern Peru. Farmers in both sites have adopted modern varieties but continue to cultivate landraces.

The Tulumayo Valley is characterized by intensive commercial production and a high rate of adoption of improved potato varieties. These farmers are Spanish speaking and many have off-farm jobs.

Paucartambo farms are less intensive, less commercial, and, on average, twice the size of farms in Tulumayo. A smaller percentage of land is planted to modern varieties in Paucartambo. Farmers speak Quechua, and few seek off-farm work. The Tulumayo farms reveal on average 10.3 potato varieties per household while Paucartambo farms average 9.6.

This comparison shows that technological, economic, and social change are not necessarily equated with germplasm loss. Farmers in both systems consciously maintain traditional varieties because they recognize beneficial traits that are not captured in improved varieties, such as taste and a better market price.

Maize in Mexico

Maize originated in Mexico. Maize diversity there is high, particularly because this plant is by nature genetically diverse and varieties are easily cross pollinated.

Two technologies that might reduce genetic diversity in Mexican maize are sterile hybrids and new seed purchased by farmers at frequent intervals. The purchase of seed is thought to have a particularly major impact on maize genetic diversity.

The Mexican state of Chiapas is characterized by two farming systems, traditional Mayan agriculture in the highlands and a modern commercial sector along the Pacific coast. The traditional system is mostly devoid of purchased seed while the coastal area is dominated by modern varieties.

Between 1946 and 1988 there was reportedly no decrease in maize varieties in the strategy. The objective is to encourage activities that are already occurring in the farming system.

Continuity. Existing incentives to conserve landraces should be reinforced.

Development goal. Agricultural development policies that will enhance incentives to maintain existing germplasm resources are needed.

Internationalism. Crop germplasm is considered by many as an international public good. Horizontal and vertical collaboration is therefore needed on a global scale in situ conservation programs to succeed.

S. Brush. 1991. A Farmer Based Approach to Conserving Crop Germplasm. Economic Botany. 45(2) pp. 153-165.