Strategies for the Conservation of Plant Genetic Resources for Food and Agriculture

The conservation of plant genetic diversity is critical for the survival of the human species.

By Paula Westmoreland
April 1999

Throughout history mankind has cultivated or collected 7,000 plants for food out of 30,000 edible plants. Today only 30 crops provide 95% of our daily caloric intake.

A catastrophic loss of biodiversity is occurring worldwide. Species, gene combinations and alleles are being lost forever. Some biologists estimate that 15-20% of all plant species will become extinct by the year 2000 (Lugo, 1988, 60). The loss of plant genetic diversity, individual genes or gene combinations within a species, is estimated at 25-30% (Lugo, 1988, 60). It is the loss of genetic diversity that is particularly critical for mankind since genetic variability gives us a treasure chest of gene combinations for adaptation to varied environments, resistance to disease and food security.

Genetic erosion is the result of a number of factors, including habitat fragmentation, over-exploitation (overgrazing and excessive harvesting), competition from exotics (accidental and planned introductions), changes in land use (deforestation and land clearance), population growth, and climate change. The main cause of genetic erosion in the last 40 years has been the spread of modern, commercial agriculture and the replacement of diverse farmer plant varieties with modern, hybrid varieties. In Mexico, only 20% of the maize varieties reported in 1930 now exist. 10,000 wheat varieties were present in China in 1949, by 1970 only 1000 varieties remained (UN FAO, 1996, 22). In the Philippines several thousand rice cultivars existed before the introduction of high-yield varieties. Currently, a few hundred upland traditional cultivars are left in the fields (Salazar, 1992, 18).

Increased attention has been focused on conserving the diversity of our agricultural seed base. Conservation biologists now recognize that the single most important way to conserve a plant species is through the protection of the habitat in which it lives (Prance, 1997, 7). For cultivated crops the habitat is the farm itself. The farmer is ultimately responsible for conservation of plant genetic resources for food and agriculture (PGRFA). Any successful approach must involve the maintenance and promotion of traditional cultural systems and the continued conservation of plant genetic diversity within the farming environment.

Two Agricultural Systems

To understand the loss of plant genetic resources it helps to examine the history of agriculture. Two distinct systems of agriculture have been practiced, one based on diversity the other based on uniformity. Traditional agriculture was prevalent until about forty years ago when industrial agriculture was marketed globally.

Traditional agricultural systems have evolved over thousands of years. A combination of varied topographies, climates and traditional cultures created very diverse farming systems, almost all of which maintained genetic diversity. These systems developed all the major food crops in the world today. PGRFA can be grouped into three categories - traditional and modern cultivars, crop wild relatives and other wild plant species. Traditional agriculture incorporated all these categories into complex farming systems. In Mexico, farmers allow teosinte (wild relative) to grow close in their maize fields so that when the wind pollinates the maize natural crosses will occur, producing new varieties and increasing crop yields (Montecinos, 1992, 108). In Kenya, women harvest wild plants growing within the maize and use them for medicinal purposes, flavorings or biological pest control (UN FAO, 1996, 16).

Intercropping, the mixing of species with complementary requirements, is practiced to control pests and disease. Over 90 different local bean varieties have been intercropped in Burundi (UN FAO, 1996, 188). Intercropping is the norm for maize, millet, cowpea, and many bean varieties in small farming systems. In Malawi, farmers grow a large number of varieties (an average of 12 seed types) some in pure stands, some in mixtures and some interplanted with hybrid maize (UN FAO, 1996, 16).

Traditional agriculture was controlled by the farmer. Breeding occurred through a combination of natural and artificial selection by the farmer in the habitat. Traditional methods promoted heterogenous populations of seed stock and created landraces, the most variable population of cultivated plants. Landraces are crop populations which have not been bred as cultivars, but have adapted through years of selection to the conditions under which they are cultivated.

Traditional agricultural systems prospered because of diversity. Diversity provides communities with varied diets, stability of production, minimization of risk, and reduction in pests and disease. In highly variable environments, higher total production was achieved by planting a wide variety of crops specifically adapted to the micro-environments in which they evolved. Farmers attached importance not only to crop yield, but to other attributes such as taste, cooking ability, marketability, early maturity, the ability to utilize residual soil moisture, and storability.

Diversity is the antithesis of industrial agriculture. Uniform crops are grown from uniform seed in a uniform environment. Success means minimizing ecosystem differences and controlling pests and pollination through the use of chemicals and hybrid varieties. Crop wild relatives and other wild species are regarded as weeds or breeding material for improved seed, not as integral components of an agricultural system.

Industrial agriculture is capital-intensive because habitats are not uniform. Different amounts of fertility, different amounts of rainfall, different pests and different pollinators exist in the world's agricultural areas. Farmers must purchase fertilizers, pesticides and other inputs from the marketplace to produce high-yield varieties.

Industrial agriculture expanded globally with the Green Revolution of the 1960s and 1970s and the Biotechnology Revolution of the 1990s. The World Bank and national governments pushed farmers to adopt the new methods in an effort to achieve food self-sufficiency. In Thailand, the government offered crop loans and insurance to farmers to plant high-yield varieties (Salazar, 1992, 17). In 1963, 1967 and 1969 the Indonesian government launched a series of campaigns to move farmers to high-yield varieties by providing credit for seed, pesticides, chemical fertilizers, and cost of living supports (Salazar, 1992, 31). Within the span of ten years, traditional agricultural systems and traditional varieties disappeared from entire areas.

Productivity of individual crops increased initially with the introduction of high-yield varieties, but the system of monoculture, planting large areas in one crop variety, created significant problems for farmers. In 1991, farmers in the Mekong Delta of Vietnam, Southeast Asia's former center for rice genetic diversity, faced a massive invasion of brown hoppers and tungro infestations that could not be controlled by application of chemical pesticides (Salazar, 1992, 18). In Pakistan, the use of fertilizers, pesticides and irrigation increased soil salinity in 3.2 million hectares of fertile land which reduced yields (Shahid, 1998, 7). In the Red River Valley of Minnesota, one of the finest "bread basket" areas of the world, reduced crop rotations and lack of crop diversity allowed Fusarium Head Blight to flourish destroying wheat crops throughout the 1990s. The Minnesota River is now rated the worst agriculturally polluted river in the United States due to runoff caused by continual corn-soybean crop rotations. (Stuthman, 1998, 5).

Industrial agriculture moved technology from the village to the laboratory, effectively eliminating the farmer's control over production systems. Plant breeding of modern varieties is done by refining "elite" germplasm which has been created from years of research. Breeders try and find new genetic material within their own breeding lines since the "elite" germplasm is easily disrupted by crosses with germplasm from landraces. As a result, plant breeding is done from an increasingly rigid and narrowly defined research base (US FAO, 1996, 99). Research priority is given to inbred lines or hybrids even though heterogeneous cultivars are, on the average, more stable performers.

Conservation Methods

Conservation scientists became alarmed at the reduction in biodiversity in agriculture and began to collect seeds of displaced and endangered varieties. During the 1920s and 1930s N. I. Vavilov directed several expeditions throughout the world to collect seeds of wheat, rye, potato, barley, and other grains. His studies led him to formulate a hypothesis on the 'centres of origin' for crop plants. The theory states "for each crop species there are one or more centres of origin where the crop was domesticated. This is usually the primary centre for in situ diversity for that crop. Continued geneflow between crops and wild relatives underlie their importance as sources for variability" (UN FAO, 1996, 10).

Vavilov was followed in the 1960s and 1970s by a generation of scientists who developed methods for storing seeds ex situ. Ex situ conservation is the conservation of components of biological diversity outside their natural habitats (Maxted, 1997, 25). Ex situ collections are stored in seed gene banks, field gene banks and in vitro. In 1974, the International Board for Plant Genetic Resources (IBPGR) was established with a mandate to coordinate plant genetic resource programs. Collecting missions were accelerated, seeds were removed from their habitat and placed in frozen storage. By 1996 over 6 million accessions were collected worldwide (UN FAO, 1996, 55). The majority of orthodox seeds, which can be stored in seed banks, are either from temperate regions, where dormancy is enforced by cold winters, or from arid regions, where dormancy is enforced by long dry spells (Prance, 1997, 8). Utilization of the stored seeds for breeding purposes has been limited. Many of the world's ex situ collections are poorly documented (UN FAO, 1996, 79). Removed from their place of origin and cut off from use in production, little knowledge exists on the potential uses for some of the seeds.

Conservation science has developed in the past twenty years with new philosophies and conservation methods. These philosophies have pointed plant genetic resource conservation in new directions. Conservation biologists now recognize that a species must compete and evolve to have a viable future. Species do not exist in isolation, but are part of a community. The community includes climate, soil, pollinators, dispersal agents, pests, competitors, and pathogens. Species preservation efforts are now directed towards preservation of communities and habitats. In situ conservation is being given higher priority and the conservation focus is shifting back to the farm.

The Convention on Biological Diversity, adopted in 1992, defines in situ conservation as "the conservation of ecosystems and natural habitats and the maintenance and recovery of viable populations of species in their natural surroundings. In the case of domesticates or cultivated species, in the surrounding where they have developed their distinctive properties." In situ conservation allows the continued evolution of plant characteristics. This is particularly important in regions susceptible to drought. It is under the conditions of environmental extremes that adaptation to stress occurs (Worede, 1992, 85). Ex situ conservation efforts have also been redirected. Local seed banks have been organized to store ex situ collections of seeds grown in the local area. This was particularly valuable in Ethiopia when severe drought threatened the community. Seeds stored in the local seed bank were saved and reintroduced into farmer's fields when the drought passed (Worede, 1993, 396).

Ideological Obstacles to Conservation

Forty years of industrial agriculture has left us a legacy of stereotypical attitudes and beliefs that undermine conservation of plant genetic resources. To move forward we must acknowledge, examine and confront these ideas.

"Farmers can't be trusted to innovate. They are ignorant of science." The reality is that for 10,000 years, thousands of farmers innovated in thousands of field laboratories struggling to sustain their families and their lands. These creative minds are responsible for developing the wide range of food products that we benefit from today. These farmer-scientists developed plant taxonomies to describe and classify plants. The Andean potato farmers used a four-level classification system with an average of 35 potato types and as many as 50-70 names identified in a single community. Some Southeast Asian communities have a five-level taxonomy for rice involving 78 varieties in a single district (Mooney, 1992, 127).

Many traditional farmers possess a detailed knowledge of their crops and preserve their diversity from year to year, identifying and conserving forms, mutations and natural hybrids which occur from time to time. Even crosses with related or ancestral wild species which occur naturally are conserved (Ortega, 1997, 311). A single Amazonian community near Iquitos, Peru cultivates 168 different species in 21 gardens. Chiapas farmers cultivate five races and a dozen local varieties of maize. Jivaro farmers, in one Amazon community, grow up to 100 varieties of manioc. Andean farmers, in a single valley, may grow between 70 and 100 distinct potato varieties with a typical household keeping 10-12 varieties (Mooney, 1992, 127).

"Traditional agriculture is a hindrance to productivity. It will not feed the world." The Green Revolution aimed at increasing the marketable output of individual crops. This is, however, only a partial measure of productivity, especially in developing countries where crops have traditionally been bred to produce fodder for animals and fertilizer for the soil, in addition to food for man (Shiva, 1998, 7). Many traditional societies have developed polycultures that are capable of providing a higher yield from a given area than from an equivalent area sown in separate patches of monoculture, for example, one hectare of sorghum pigeon pea mixture produces the equivalent of 1.62 hectares of sorghum and pigeon pea monoculture. Increased land use efficiency has been reported for the following polycultures: millet/groundnut (1.26), maize/bean (1.38), millet/sorghum (1.53), maize pigeon pea (1.85), maize/cocoyam/sweet potato (2.08), cassava/maize/groundnut (2.51). Green Revolution methods actually reduced food yields in these cases (Shiva, 1998, 8).

In marginal environments, many traditional varieties out-perform modern varieties in drought resistance, field adaptation, flood resistance, or resistance to weeds, disease, and insects. In highly productive environments, landraces have also been shown to outperform high-yield varieties. In the village of Klaten, Central Java, Indonesia, farmers collected 26 traditional rice cultivars. They compared their performance with high-yield varieties provided by the government and discovered that, absent of chemical inputs, seven of the traditional cultivars outperformed three high-yield varieties on total yield per hectare (Salazar, 1992, 25). Since production costs for Rojolele, one of the traditional cultivars, was well below those of the IR-64 high-yield variety, farmers were better off switching back to the traditional variety.

Productivity is different depending on whether it is measured in a framework of diversity or uniformity (Shiva, 1998, 8). To properly evaluate the productivity of traditional agriculture a number of measures need to be taken into account, not just marketable yields.

Guiding Principles for Conservation

The following set of principles can be used to guide our efforts in maximizing the diversity of our plant genetic resources.

Preserve cultural diversity. Cultural diversity is one of the foundations for biodiversity. In the Andean agricultural systems diversity is a part of the cultural heritage. Diversity is related to the particular use to which each potato variety is put - for example, sancochado (boiled), huatia (oven-baked, roasted), chuno (freeze-dried) or moraya (freeze-dried and washed in a stream), while others are used in specific rituals of individual communities (Ortega, 1997, 312). The cultural identity of many groups is tied to essential ingredients of their local cuisine. Fifteen different dishes in Mexican cuisine have been identified that require fifteen different types of maize (Brush, 1991, 76). Even in today's multicultural societies, food and diet remain a critical part of one's cultural heritage.

Base food security on biodiversity. Over the long term, diversity contributes to the efficient and sustainable production of food. It provides resilience and security against adverse conditions and allows mankind to exploit many environments for food. Diversity enhances our diet and provides increased choice. To insure food security we need to maintain diversity in our agricultural systems.

Keep small farmers on the land. Diversity cannot thrive without the community and the circumstances that give rise to it. Traditional farmers know their land, their soil and the agricultural methods required to maintain genetic diversity in their environment. Their selection criteria for planting varieties is complex. Varieties may be maintained because of their storage properties, ease of cooking, nutritional and processing qualities, for historical or cultural reasons, or for use in traditional foods and religious ceremonies (Qualset, 1997, 167).

Conserve diverse environments. The genetic diversity we know today evolved in varied and heterogeneous environments. In order to conserve genotypes we need to conserve a range of environmental conditions.

Integrate conservation with use. Agricultural diversity will not be saved unless it is used. It is only through use that diversity is appreciated (Mooney, 1992, 132). In order to conserve landraces in the 'centres or origin' priority must be given to understanding and increasing their utilization. Conservation activities should build upon and strengthen local systems of knowledge and local institutions.

Strategies to Promote Agricultural Biodiversity

A comprehensive strategy is needed to promote diversity of our agricultural resources and reverse forty years of national and international agricultural policy which has favored industrial agriculture. A successful strategy needs to take into account market development, seed production and distribution networks, research priorities, community conservation, farmers' rights, and government incentives.

Market development
Markets for traditional crops, products made from traditional crops and markets for traditional crop seed need to be expanded. Traditional crops need to be evaluated for special characteristics such as flavor, shape and color which may have sales potential in niche markets. In Peru, certain native potatoes command a higher price because they taste better and are more prestigious as gifts (Brush, 1991, 78). In the United States, alternative markets, such as farmer's markets, which create direct connections between farmers and consumers, have expanded the demand for and the variety of locally-grown produce.

In Kenya, KENGO, a coalition of women's groups, farmer's organizations and local non-governmental organizations (NGOs), has been working with farmers to develop products from traditional fruits and vegetables which contain high nutritional value. Fruits are used for juices, jams, chutneys and food flavorings; vegetables can be dried, powdered, or precooked for infant foods. KENGO's goal is to have food companies incorporate indigenous fruits and vegetables into their products. The government has supported these efforts by creating low-interest loans to develop the market infrastructure for specialty crops (Kiambi, 1992, 61). In the United States, natural food coops have helped expand the market for specialty grains such as quinoa and blue corn. Food processors have incorporated these grains into cereals, chips and tacos.

Organic farming, a $4 billion dollar a year industry that is experiencing a 20 percent annual growth rate, may be a market for traditional seed. Landrace varieties have adapted to specific environments and evolved without reliance on applications of pesticide and herbicide (UN FAO, 1996, 116).

Recognition of the value of local and traditional crops is important for marketing. Labeling products as "diversity rich," promoting model gardens on farms, creating agricultural fairs to acknowledge farmers who maintain the widest crop diversity, exhibitions to display local produce, seed saver networks, and seed exchanges are all methods to promote traditional products (Brush, 1991, 161).

Seed production and distribution networks
Local seed enterprises are an important component of rural farming systems. Control over seed is vital to meet the needs of local markets, protect the farmer's knowledge of indigenous varieties and help strengthen farmer control over genetic resources. Collection, reproduction and distribution of crop varieties on a local level makes minor species available which are adapted to specific locations. The Indigenous Seeds Project in Zimbabwe is geared to strengthening farmer-based seed supply for indigenous crops in drought-prone areas of the country. Farmers, scientists and NGOs participate in seed collecting expeditions. Selected seeds are then planted on farms representative of the area's soil types. Crops are evaluated throughout the growing season. The best seeds are bulked to form an improved population and redistributed to other farmers through local networks (Mushita, 1992, 72).

Research priorities
An expert panel from the Consultative Group on International Agricultural Research (CGIAR) concluded that "while the Green Revolution took as its starting point the biological challenge inherent in producing new high-yielding food crops and then looked to determine how the benefits could reach the poor, a new revolution has to reverse the chain of logic, starting with the socioeconomic demands of poor households and then seeking to identify appropriate research priorities" (FAO, 1996, 112). Research priorities need to shift from a focus on individual crops to complex farming systems. Plant breeding efforts should expand their focus to include ecology, weed science, soil erosion potential, and nutrient use efficiency. (Stuthman, 1998, 6)

Participatory breeding projects involving both scientists and farmers offer the potential to enhance the productivity of traditional agriculture and maintain a broader genetic diversity in our seed stock. In the ICRISAT pigeon pea breeding program in Andhra Pradesh (India), entomologists worked closely with women farmers in on-farm trials. Farmers evaluated the improved pest-resistant pea varieties with their local varieties using their own evaluation criteria. The parameters considered by the women farmers went well beyond the conventional yield and pest resistance measurements used by most scientists (FAO, 1996, 112).

Community conservation
Community seed banks and home gardens play an important role in conserving seed resources for locally-adapted material. Seed bank conservation at the local level helps insure that knowledge of the use and purpose of saved seed exists. The security of genetic resource conservation is strengthened if farmers are actually using plant varieties and restocking the seed bank instead of storing seeds at distant locations. In Indonesia, community seed banks involve 10-20 farmers. Each seed bank has income-generating schemes and training programs on how to cultivate traditional varieties. The seed banks are focusing on rice and other crops which are threatened by displacement from hybrid varieties (Soetomo, 1992, 36).

Home gardens and orchards are living gene banks where indigenous germplasm thrive. The Huastics in Mexico manage agricultural and fallow lands, complex home gardens and forest plots which total over 300 species. Areas near their dwellings are known to contain 80-125 useful plant species, mostly native medicinal plants (Altieri, 1987, 88). In Central Java, 45 species were cultivated in an orchard garden with 25 wild species of medicinal value growing nearby (Qualset, 1997, 170).

Farmers' rights laws
In 1989 the Food and Agriculture Conference defined Farmers' Rights as "rights arising from the past, present and future contributions of farmers in conserving, improving and making available plant genetic resources, particularly those in the centres of origin/diversity" (UN FAO, 1996, 183). Farmers' Rights laws need to be implemented nationally to ensure equitable sharing of the benefits derived from the use of plant genetic resources. With the advent of biotechnology, ownership of genetic resources has become a global issue of contention. The Trade-Related Aspects of Intellectual Property Rights (TRIPs) part of the General Agreement on Tariffs and Trade (GATT) requires all members of the World Trade Organization (WTO) to provide for the protection of plant varieties either by patents or by a sui generis system by the year 2000. TRIPs guarantees Plant Breeders' Rights. Farmers' Rights laws need to recognize the rights of farmer's to save seed and of traditional people to regulate outsider access to their knowledge of plants (Dawkins, 1999, 3). Farmers and farm communities need to be equitably compensated for their contribution to plant genetic diversity if we want that contribution to continue.

Government policies
Government policies which discourage planting of traditional crops need to be eliminated. Programs which offer access to credit, crop loans and insurance are often linked to adoption of modern cultivars. Commodity programs may subsidize specific crops, imported foods and non-local commodities. International agreements may require import quotas on food. All these mechanisms promote export agriculture and discourage production of local cultivars.

Government seed regulations on variety release, seed certification and plant breeder's rights may hamper traditional seed exchanges. Indonesian policy discouraged community seed bank programs by declaring that conservation should not be managed by farmers, but was the responsibility of the government (Soetomo, 1992, 36).

In conclusion, the diversity of our plant genetic resources is rapidly disappearing. Conservation of PGRFA is crucial for the future of world food security. For conservation to be successful, we must reverse forty years of agricultural policy which has promoted industrial agriculture and moved plant breeding off the farm. Instead we need to strengthen traditional institutions and cultures and support farmers in their efforts to conserve our genetic heritage. The diversity that we treasure is more than just unique combinations of genes, it is a community of life.

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