Food from Dryland Gardens - An Ecological, Nutritional, and Social Approach to Small Scale Household Food Production (CPFE, 1991) Part III - Garden harvest (introduction...) 14. Saving seeds for planting (introduction...) 14.1 Summary 14.2 Seeds, gardens, and diversity (introduction...) 14.2.1 Diversity in the Seed 14.2.2 Diversity in the Garden 14.2.3 Conserving and Using Genetic Diversity: How and for Whom? 14.3 Seed saving (introduction...) 14.3.1 Seed Harvest and Processing 14.3.2 Seed Drying 14.4 Saving seed from trees (introduction...) 14.4.1 Cold Stratification 14.5 Seed storage (introduction...) 14.5.1 Moisture and Temperature 14.5.2 Pest Control 14.6 Resources References 15. Processing, storing, and marketing food from the garden (introduction...) 15.1 Summary 15.2 Harvesting garden foods 15.3 Cooking and using garden foods (introduction...) 15.3.1 Fresh Foods 15.3.2 Dried Foods 15.4 Food drying (introduction...) 15.4.1 Materials for Drying 15.4.2 Preventing Contamination 15.4.3 Selecting and Preparing Produce for Drying 15.5 Sprouting and malting (introduction...) 15.5.1 Sprouting 15.5.2 Malting 15.6 Fermentation (introduction...) 15.6.1 Pickling 15.7 Storing garden foods (introduction...) 15.7.1 Preharvest Storage 15.7.2 Postharvest Storage of Fresh Produce 15.7.3 Storing Dried Produce 15.7.4 Storing Other Processed Garden Foods 15.8 Marketing garden produce (introduction...) 15.8.1 Harvesting for Market 15.5.2 Transport from Garden to Market 15.8.3 Protecting Produce Quality at the Market 15.9 Resources References 16. Weaning foods from the garden (introduction...) 16.1 Summary 16.2 The role of weaning foods 16.3 Nutrient density (introduction...) 16.3.1 Energy 16.3.2 Protein 16.3.3 Vitamins and Minerals 16.3.4 Weaning Food Consistency 16.4 Hygiene 16.5 Weaning as a part of daily life 16.6 Resources References 17. Glossary (introduction...) 17.1 Abbreviations used in measurements 17.2 Equivalencies in units of measurement 17.3 Atomic symbols and molecular formulas 17.4 Other abbreviations and acronyms 18. Some crops for dryland gardens (introduction...) 18.1 Common English and scientific names for some crops and crop groups 18.2 Important dryland garden plant families 19. Resource organizations 20. References

Food from Dryland Gardens - An Ecological, Nutritional, and Social Approach to Small Scale Household Food Production (CPFE, 1991)

Part III - Garden harvest

In the Chapters of Part I we discussed the nutritional, economic, environmental, and social contributions of gardens to sustainable development. Part II presented the principles of plant, soil, and water management to meet these goals and ideas for applying these principles in ways consistant with the criteria for sustainable development. But the story does not end with the harvest. Many of the benefits of gardens depend on what happens to seeds and food after they are harvested. The goals of local self-reliance and control, and an approach to gardens that builds on local resources and knowledge, will help insure that the garden harvest promotes equity as well as social and environmental sustainability, and that the benefits will endure well beyond the life of the project.

14. Saving seeds for planting

Gardeners and farmers all over the world have been selecting and saving seeds and other plant propagation materials since the beginning of agriculture and plant domestication over 10,000 years ago. Almost all of the crops grown today are products of this selection and new varieties created by scientists are based on the work of these past generations. Plant selection by gardeners and farmers continues to be vital for conserving genetic resources and for producing crop varieties best suited to local needs. Years of experience and observation give people an understanding of desirable crop characteristics. This long and successful history is the reason why existing seed selection and saving techniques must be understood before suggestions for improvement are made.

Even when appropriate seeds are available for purchase, the advantages of saving her own seeds often make it worthwhile for the gardener. Saving seeds reduces the costs of gardening and takes advantage of locally adapted varieties. If the gardener does not save her own seeds, a good alternative is some other source of locally selected and grown seeds, such as other gardeners, local seed co-ops, or regional seed houses. (Suggestions for selecting materials for vegetative propagation are given in Chapter 7).

Introducing new crops and crop varieties has a long history and many now “traditional” or indigenous local crops or crop varieties, such as watermelon in southwestern North America and chilis in West Africa, were introduced from other continents or regions. (See section 1.1 for a definition of the word “indigenous” as it is used in this book). However, the most common obstacles to productive gardens for improving household nutrition or economic conditions - such as lack of control over resources, poor water quality, or marketplace competition from agri-business - will not be resolved by introducing a new crop. For this reason we believe that nonlocal, new crops should not be the focus of garden projects, and if used, should only be introduced as part of an experiment, and never as a replacement for local garden crops.

The implications of saving seeds, especially of local varieties, go far beyond the effects on the gardener and her garden. Genetic resources for the future world food supply are becoming scarcer with the loss of indigenous varieties and the diverse local agricultural systems that produce and maintain them. At the same time, new and expensive plant-breeding technologies are being used by commercial, multinational seed companies. These changes raise new issues about the control and economics of seed production, and the genetic diversity upon which all food systems rely. These are issues that affect the gardener and that she addresses when saving her own seeds.

In this book the terms folk variety or indigenous variety refer to crop varieties that have been selected and managed by local people and the local growing environment. In the past these varieties have been called “land races” or “primitive varieties.” We use the term folk varieties in support of the efforts of Third World countries and the United Nations Education, Scientific and Cultural Organization (UNESCO) to have these varieties recognized as a part of the “folk” heritage of indigenous communities, and thus give them control over and compensation for the use of these genetic resources.¹

14.1 Summary

Saving garden seeds for planting is important because it reduces investments and risks while promoting self-reliance. When local seeds are saved, genetically diverse folk varieties are conserved on-site for future generations.

Diversity in indigenous gardens results from planting genetically diverse varieties, several varieties of some crops, and many different crops, with combinations changing over the seasons and years. Commercial or industrial crop varieties are usually bred for industrial agriculture, have more genetic uniformity among individual plants of the same variety, and fewer varieties are grown in the cropping system. Bred for production under optimal conditions, industrial varieties generally require more purchased inputs and are a greater risk for the gardener in marginal lands. Although they may be appropriate in some situations, such as intensely managed gardens with abundant water and nutrients, they should not be promoted as a replacement for folk varieties.

Saving seeds can be done easily along with other work in the garden. Seeds should be harvested after they are mature, or they may not grow. Techniques for cleaning, drying, and storing seeds are easy to learn and are vital for maintaining seed stocks for next season’s garden and for future generations. If not properly cared for, stored seeds can spoil or be damaged by pests. However, simple methods, many of them locally developed, can prevent or greatly reduce these problems.

14.2 Seeds, gardens, and diversity

The indigenous crops, gardens, and fields of the world contain great biological diversity. This diversity occurs on several levels:

· Folk crop varieties contain a diversity of genetic information.
· Often there are many different varieties of each crop.
· Gardens and fields frequently contain mixtures of many different crops and varieties.
· Gardens and fields in different ecological or cultural settings have different crops and crop mixtures.

The biological and ecological diversity of indigenous systems is good for gardens and other small-scale food production because it increases yield stability and local self-reliance. Yield stability is a measure of the variation in the amount of usable harvest from year to year. When exposed to stresses such as drought, flooding, pests, diseases, and high temperatures, total crop yields will decrease relatively little in mixed plantings of diverse indigenous varieties compared to monocultures of genetically uniform industrial varieties.² In other words, diversity reduces the risk of having nothing to harvest from the garden. Indigenous agriculture also reduces the risk of going into debt and losing land, because it is more self-reliant, and does not depend on obtaining credit to purchase expensive seeds, fertilizer, pesticides, and irrigation pumps.

Industrial agriculture is characterized by varieties that respond to favorable growing conditions created by increased inputs of irrigation water, chemical fertilizers and pesticides, and often mechanization. Compared with traditional agriculture, industrial agriculture often increases yields per unit of land and labor, and has contributed a great deal to increasing the world food supply, not only through production in industrialized countries, but as the green revolution in the Third World. This industrial approach has also been applied to gardens.³

In contrast to indigenous varieties, very few varieties of industrial crops are bred and released to the public. Within each industrial crop variety there is less diversity than in folk varieties, and the industrial varieties are developed for, and planted over, much larger areas. Table 14.1 is a simplified comparison of the differences in diversity at several levels between industrial and indigenous agriculture.

Choosing between indigenous and industrial varieties and gardens involves a trade-off. Even though the individual plants lack diversity, industrial varieties can sometimes be desirable for dryland gardeners. Also, not all new varieties are genetically uniform or dependent on expensive inputs. To minimize risk to the gardener, some diversity should be maintained at all levels (individual plants, crop varieties, and crops in the garden). This can be done by encouraging gardeners to continue growing their local folk varieties even when they are also trying new, industrial varieties, and to plant their gardens with a mixture of different indigenous and new crops and crop varieties.

There is some evidence that small farmers who do grow industrial varieties often continue to grow folk varieties for a number of reasons.⁴ For example, Hopi Native American farmers in dryland southwestern United States continue to maintain their own Hopi sweet corn variety even when cultivating an industrial sweet corn variety.⁵ A common reason given by farmers for doing this is that the industrial varieties produce large sweet ears, but the Hopi variety is better adapted to the local environment. If the growing conditions are especially dry the Hopi variety will produce a harvest but the industrial varieties will fail.

Table 14.1 The Diversity Continuum at Different Levels in Agriculture^a

More	DIVERSITY	Less
In the Crop
	Variety
Heterogeneous folk varieties		Homogeneous industrial varieties
	Individual Plants
Heterozygous		Homozygous
In the Garden or Field
	Number of varieties
Many		Few
Number of crops
Many (polyculture)		Few (monoculture)
	Number of types of gardens or crops
Many		Few

^a From Cleveland and Soleri n.d.c.

14.2.1 Diversity in the Seed

Folk varieties have been selected for their adaptation to local growing conditions and local people’s needs. Along with related wild species, they are the world’s major store of genetic diversity for crop plants (Box 14.1). The number and genetic diversity of folk varieties is maintained, or even increased, by gardeners and farmers over generations in the following ways:

· Domestication of new wild plants.

· Introduction of new genetic information by crossing between folk varieties, and between crops and their wild and weedy relatives.

· Introduction of new crops and varieties from other villages or regions

· Selection of advantageous spontaneous mutations.⁶

In these ways genetic diversity is conserved even though some folk varieties are always being lost, either abruptly through replacement by other varieties, or slowly through selection by gardeners, farmers, and the environment.

While indigenous crop selection has not been well documented, some examples do exist, such as Richard’s description of rice variety selection be Mende farmers in West Africa.⁷ The farmers keep not only their existing 70 rice varieties pure, but are constantly searching for and experimenting with new varieties, a process they enjoy greatly. When potential new varieties appear in their fields as a result of mutations, cross pollination, or accidental mixing, the farmers carefully remove plants with undesirable variations and save those with desirable traits. Farmers test these new varieties, or ones aquired from neighbors or markets, in fertile, moist patches of soil near their houses. If the tests appear successful they will multiply the seed for full-scale planting. Farmers also sort a variety into separate lines when it becomes highly variable, harvesting seeds with different characteristics separately.

Many crops grown in both indigenous and industrial gardens are introductions from other regions. For example, in southwestern North America beans, maize, chili peppers, and other crops came from Central America, while watermelon, wheat, fava beans, garbanzos, and peaches were introduced from the Mediterranean and Africa by Spanish colonialists only a few centuries ago. Over time both native and introduced crops have diversified into many folk varieties which are important in local food systems today.

Folk varieties are constantly evolving in response to changes in the environment and in gardeners’ needs. The gardener who selects and saves her own seeds may be particularly interested in a few characteristics, such as timing of production or flavor. But at the same time, the plants she chooses are being selected for their ability to grow and produce in the garden environment. In choosing the most vigorous and desirable plants, the gardener is selecting for a complex combination of characteristics particularly suited to her resources and needs as well as the garden environment.

The increasing production and promotion of industrial seeds, many of which are hybrids (Box 14.2), is radically changing this traditional system of conserving genetic diversity in folk varieties.⁸ When folk varieties with their adaptive characteristics selected for by generations of gardeners and farmers are replaced by industrial varieties, the result is usually a reduction in diversity, both within the variety and often in the cropping system itself. When this happens, gardeners and farmers must rely on seeds that they may not be able to produce themselves and that may not meet their needs as well as the abandoned folk varieties. The result may be to increase the risk of survival for the food system as well as the social and cultural foundation of the community.

Box 14.1 Genetic Diversity in the Seed Genetic structures and processes are complex, but the following simplified explanation will help readers understand how the issue of diversity is affected by the kind of seeds used in the garden. A plant’s genotype is the genetic information that it inherited. A genotype is composed of all the genes located on the chromosomes in the nucleus of a cell (Figure 14.1). Each cell in that plant contains this same genotype (except the gametes, as explained below). The genes contain all of the information the plant needs to grow and reproduce. In all plant cells except gametes, chromosomes come in pairs. Onions, for example, have 16 pairs, and tomatoes 12 pairs of chromosomes. However, there is only one of each chromosome in sex cells or gametes, the pollen from the male parent and the ovule in the female parent. That is, 16 single chromosomes in onion gametes and 12 single chromosomes in tomato gametes. When the male and female gametes are united at fertilization, they form an embryo which again has two of each chromosome. In each chromosome pair in the embryo one chromosome is from the male parent and the other from the female parent. This embryo will grow into a seed. Alleles are the two or more alternative forms of one gene and are used as a gauge of diversity in individual plants and varieties. Because chromosomes usually occur in pairs there are two locations for each gene in each cell. Therefore an individual plant can have a maximum of two different alleles for each gene. However, within all the plants of a crop variety there can be many alleles for one gene, with different combinations of these alleles being expressed in individual plants in the population. That is, a single plant or a crop variety can be either genetically diverse or uniform (Figure 14.1). Homozygous plants are those with only one allele for a gene. A homogeneous variety is one with many plants which are homozygous for one or more genes, that is they all contain the same allele for that gene. Individual heterozygous plants contain two different alleles for a gene and heterogeneous varieties include plants heterozygous for many genes, having two or more alleles for those genes.

Many industrial seeds have been selected for high production under conditions where there is pest protection with chemicals, plant nutrients supplied with chemical fertilizers, good soil, plenty of water, a single large harvest, and no competition from other crops or weeds. Maximum yield/disease and pest resistance, adaptedness to mechanized cultivation and harvesting, and fruit size and appearance are frequently the kinds of traits selected for. Other characteristics like drought hardiness, tolerance of marginal soils, continuous harvesting, adaptation to mixed cropping, taste, grinding texture, and “by-products” like bean leaves as a green vegetable, have not been considered relevant. This means that industrial varieties will often not be adapted to the low-input, and less-than-optimal conditions of most dryland gardens and fields.⁹ Seed produced this way, frequently far from the environment where it will be grown and the people who will grow it, fails to take advantage of local expertise and the genetic resources available from folk varieties. Industrial varieties usually cannot fulfill the combination of gardener’s needs and demands of the local growing conditions.

It is now recognized that the costs of controlled, optimum-environment agriculture are prohibitive for gardeners and farmers in many parts of the world. This is especially true for low-resource gardeners and farmers in the Third World. As a result, some breeding programs at international agricultural research centers have been changing. For example, the International Institute for Tropical Agriculture (IITA) is working to develop cowpea varieties that are drought-resistant and others that can be grown for both food and fodder, and the International Crop Research Institute for the Semi-Arid Tropic’s (ICRISAT’s) recent work with sorghum and millet focuses on drought adaptation.¹⁰ ICRISAT is also working on mixed cropping of cereals and legumes such as millet and cowpeas. The dominance of production as a breeding criteria has lessened somewhat, and some crop breeders are focusing their work on developing varieties adapted to local growing conditions, sometimes using local folk varieties as raw breeding material.¹¹ However, there is still a long way to go in terms of breeding programs recognizing the value of folk varieties, the expertise of local gardeners and farmers, and the adaptive complexity of the varietal selection that occurs in indigenous gardening and farming.¹³

The major influence on crop breeding in the decades to come will be the new agricultural biotechnologies, especially genetic engineering, which makes possible the direct transfer of genes even from distantly related organisms to crop plants. While this technology has the potential to help gardeners and small-scale farmers, this help is not inevitable. Agricultural biotechnology is dominated by private industry, and their profit making goals will undoubtedly have an influence on the varieties produced.¹⁴ For example, many of the world’s largest seed companies are now owned by private, multinational corporations which specialize in chemical manufacturing.¹⁵ A major objective of this new corporate strategy is developing varieties that will increase sales of the company’s other products. Worldwide, over 27 corporations have begun research on creating crops that are tolerant to herbicides, thus encouraging increased herbicide use.¹⁶ An example is Monsanto’s new soybean (Glycine max) which was bred to tolerate large quantities of that company’s herbicide glyphosate, known commercially as Roundup.

Figure 14.1 Chromosomes, Genes, Alleles, and Their Role in Genetic Diversity

Box 14.2 Hybrid Seeds A hybrid is the product of the cross between any two genetically different individuals. However, in popular usage the word has come to refer to a particular kind of hybrid developed for propagating agricultural crops.12 This more common definition is the one we use here. Hybrid seeds are the product of a cross between homogeneous inbred lines. To help understand the process we give a simplified description of how single-cross hybrid maize seeds are produced (Figure 14.2). First, different plants from the same species (Zea mays in this case) are inbred, or self-pollinated, for many generations, with offspring selected for particular desirable traits. Eventually this inbreeding results in very homogeneous populations of plants whose offspring therefore, always have the desired characteristics. These breeding populations are referred to as inbred lines, for example, lines A and B. While inbreeding fixes desirable traits, it also fixes undesirable traits and can produce weak, unhealthy plants. However, these undesirable characteristics are unimportant to the breeder as long as they do not interfere with the characteristics being selected for. In the second step, selected inbred lines are paired. To ensure that all of the seed saved is the result of cross-pollination, one line is identified as the female parent and the other as the male. The female line is rendered incapable of self-pollinating either by cutting off the male flowers (tassels) of these plants in the field, or through introducing male sterility genes when creating that line. Thus, all of the seeds borne by the plants of the female parent line are a cross of lines A and B (A × B). Because all A plants are genetically identical to each other, and all B plants are genetically identical to each other, the result of the A × B cross is predictable. The seeds produced by this cross are F1 generation hybrids, which are sold to farmers. These seeds produce strong, healthy F1 plants because of the mixing of genetic material. The cross-pollination of these identical F1 plants (F1 × F1) or [(A × B) × (A × B)], produces seed meant for consumption. However, if this seed is saved and planted it grows into F2 plants, different both from their parents and from each other. Some of these plants are weak and lack vigor and many of them will show the undesirable traits of the original inbred parent lines, A and B. They may have some desirable traits but overall are unpredictable, unhealthy, and inadequate for food production. Therefore new hybrid seed must be purchased by the gardener or farmer every year. Commercial seed production of some other crop hybrids also depends on male sterility in one parent. For example, if seeds saved from fruit of most hybrid watermelon varieties are planted, there will be a complete crop failure, because there will be no pollen to fertilize female flowers. In the 1970s the genetic material widely used to create male sterility in maize in the United States resulted in widespread genetic uniformity and vulnerability to disease (Box 14.3). Today many varieties of commercially produced garden vegetable seeds are hybrids. This includes tomatoes, peppers, squash, melons, cabbage, lettuce, onions, and other popular garden crops.

Figure 14.2 An Example of Hybrid Seed Production in Maize (1)

Figure 14.2 An Example of Hybrid Seed Production in Maize (2)

Box 14.3 The Southern Corn Leaf Blight A well-known recent example of the risks of genetic uniformity is the southern leaf blight epidemic which swept maize (corn) plantings in the United States in 1970.17 At the time, approximately 75% of the maize grown in that country shared identical genetic material for male sterility used in hybrid seed production. However, this was linked genetically to susceptibility to a fungus causing leaf blight. The blight spread rapidly through the country and losses were estimated at 710,000,000 bushels of maize, worth US $1 billion in 1970. New genetic material was essential in subsequent breeding programs seeking resistance to the fungus and other problems. This disaster drew attention to the trend in industrial agriculture away from biological diversity, and the risks of this trend.

14.2.2 Diversity in the Garden

Indigenously based mixed gardens are living gene banks that conserve genetic diversity while serving gardeners’ needs. Gardens change through time as the household changes in size and needs, as perennial crops grow bigger, or die and are cut down, and as new crops and varieties are introduced or old ones are abandoned. In addition, gardens differ from household to household, community to community, and region to region, with changing climate, soils, diets, and history.

Gardens often contain many crops that serve different purposes. Some may provide fruits or vegetables, some medicine or craft materials, others may be grown for the beauty of their flowers, and all may also be grown for market. An irrigated garden in arid northern Pakistan may include vegetables such as egg-plants, tomatoes, bitter gourds, amaranth, portulaca, and chilis; perennial fruit producers like grapes and mulberries; chinaberry trees (Melia azedarach), whose wood is used for construction; and a species of jute for making rope.¹⁸ In northern Mexico, household gardens produce fruits, vegetables, flowers, and chicken eggs for sale and household consumption, and medicinal herbs for home use.¹⁹ A survey of 145 gardens of Tswana agropastoralists in Botswana revealed 45 domestic species and 8 wild species which had been transplanted or were sprouting spontaneously.²⁰

Different varieties of the same crop may be grown in gardens for several reasons,²¹ such as their adapted-ness to environmental conditions at a specific growing time. Data on different varieties is scarce for gardens, but there are examples for field crops. For example, Mende farmers in Sierra Leone (section 14.2.1), recognize 70 different rice (Orriza spp) varieties by name and sight, and each household grows an average of 4 to 8 varieties.²² These varieties are suited to different growing conditions and have diverse growing characteristics, especially time from sowing to harvest. In one short-season variety, some farmers are selecting for tough outer glumes (the papery coat or bract around the seed) and long awns (the hair-like bristle growing out from the glume) which help protect the grains from birds, a major pest of early rice.

In the small country of Malawi in southern Africa there are many varieties of common bean. Even though only 4 varieties make up the majority of area planted, farmers grow an average of 13 varieties per household.²³ Local farmers, primarily women, explain that they grow so many varieties because of differences in flavor, cooking quality, market demand, time to maturity, digestibility, and ability to cope with pests, disease, and environmental stress like drought. For example, most farmers plant early-, middle- and late-maturing varieties to maintain a constant food supply. Other varieties are planted for good leaf and pod production or fast cooking time. Similarly, in Rwanda 18 bean varieties are grown.²⁴ One of these varieties is almost completely destroyed by pests under normal conditions. However, when drought occurs every 5 to 15 years, this variety produces a harvest when the others do not, and it is for this reason that farmers continue to grow it.

Another advantage of diversity in the garden is that it can provide a number of crops that meet the same needs. This adds variety to the diet, increasing production stability and diminishing the risk of reduced food or income should one crop fail. For example, a West African garden can provide dark green leaves from amaranths, jute, baobab, or cowpea, and oil-rich nuts and seeds from groundnuts, sesame, or egusi melon seeds. An Egyptian oasis garden produces many popular tree fruits such as guavas, pomegranates, apricots, and oranges which can be sold in local markets or consumed at home as delicious, high-vitamin treats.

In southern Mexico new housing projects do not provide as much garden area as local people are accustomed to having. A nutritionist working with children in the area found that these new gardens contained significantly less crop diversity than more traditional village gardens in the same area.²⁵ She also found that as garden crop diversity decreased, so did household vitamin C intake. Research on homegardens in Java found that the greater the cropping diversity the higher the overall nutrient production/m², and the higher the production of vitamins and minerals, in particular.²⁶

14.2.3 Conserving and Using Genetic Diversity: How and for Whom?

Whether the goal of feeding the world population in the future is pursued primarily through industrializing world agriculture or improving on indigenous agriculture, genetic diversity will be essential.²⁷ By contributing resistance to pests, disease, drought, and poor soil, and to improved processing, cooking, and nutritional quality, the genetic diversity contained in folk varieties and wild crop relatives is a valuable resource both for gardeners and farmers, as well as for government and private commercial plant breeders.

Folk varieties and wild crop relatives are essential as sources of resistance when industrial varieties succumb to diseases and pests. This happens regularly and leads to what is called the “breeding treadmill” or “varietal relay race” as breeders rush to replace varieties that have “broken down” with new ones containing a new source of resistance.²⁸

But the need for crop genetic diversity is even more critical for low resource gardeners and small-scale farmers in marginal areas. Diversity is one of their most important resources, giving them the flexibility to adapt and survive, minimizing the risk of working in an unpredictable, harsh environment. When gardeners and farmers are less vulnerable to environmental stress and input shortages, they can be more self-reliant and have more control over their own food system.

One of the most important sources of genetic material is the crop’s center of diversity. The center of diversity is the area in which the species has its greatest genetic variety, in number of varieties of both that species and of related ones. The center of diversity can be, but is not necessarily, the area where the species originated or was domesticated, and where diversity is maintained and increased by crossing with related wild and weedy species. Varieties from areas outside the center of diversity may also possess valuable characteristics because they have adapted to different conditions.²⁹

The growing destruction of both the natural environment and indigenous farms and gardens means that genetic diversity is rapidly disappearing. Loss of genetic diversity is also occurring for most major commercial vegetables in the industrial world, where diverse, open-pollinated local varieties are being replaced by a few hybrids marketed by multinational corporations.³⁰ Once all plants of a species or crop variety are gone, the information they carried in their genes can never be recovered.

There are two major ways of saving crop genetic diversity. In situ (or on-site) conservation is maintaining genetic diversity in gardens and fields, or in wild natural areas. Ex situ conservation is collecting and preserving plant genes in seed or gene banks, away from the environment where they are growing. More and more of our genetic diversity is being stored in freezers in gene banks for plant breeders creating industrial varieties. For those who assume that progress means eliminating indigenous agriculture, there is little need for alternative approaches to crop genetic conservation.

However, along with an increasing number of people, we believe that indigenous gardening and farming have important cultural and biological value and in many situations offer advantages over industrial food production (Part II).³¹ According to this perspective, in situ conservation of crop genetic diversity is essential and offers some of the following advantages:

· Genetic diversity is widespread and available to local gardeners and farmers; it is not controlled by a distant bureaucracy unfamiliar with local needs whose main purpose is to serve the needs of plant breeders.

· Genetic diversity is not isolated from its growing environment and subject to deterioration and accidental loss.

· In situ conservation is not dependent on expensive equipment which may break down, or on government or international financing which can fail.

· At the same time that in situ conservation maintains crop genetic diversity, it maintains local knowledge of plants and their uses, and diversity in the food system; it also helps support the communities that depend on it.

· Growing folk varieties and encouraging wild and weedy crop relatives not only conserves genetic diversity, but supports socially and environmentally sustainable food production.

This is not to say there is no use for ex situ conservation. Ex situ conservation can still play an important role as a complement to in situ efforts. Small-scale, low-technology, locally controlled community or regional seed banks can avoid many of the shortcomings of larger, more expensive ones, and provide a valuable back-up in cases of emergency. For example, in Ethiopia researchers from that country’s Plant Genetics Resources Centre are working with farmers to identify important folk varieties. They are establishing regional seed banks to maintain reserves of these varieties and make them available to people who have lost their own seed stocks due to war and famine.³²

No matter where genetic diversity is preserved, very controversial questions remain about the control and use of this diversity. In the capitalist world economic system, genetic resources have become a commodity; they are being turned into property with a monetary value which can be owned and sold. There is now a heated debate about new laws created in the industrialized countries enabling plant breeders to patent crop varieties.³³ A patent is a legal contract which, for a designated time, gives an individual or organization the sole right to produce and sell a particular commodity such as seeds for a new crop variety.

Such laws favor the industrialized nations and their commercial plant breeders over the Third World which has few commercial breeders or the facilities they require. The cost of large-scale commercial breeding programs is prohibitive for Third World countries, therefore most of the patents and profits go to industrialized nations.

Another reason for the current controversy is that much of the genetic material used in modern breeding programs for the world’s major food crops comes from centers of crop genetic diversity in the Third World. For example, although the United States and Canada make up one of the world’s major food-producing regions, all of their 20 major food crops (measured in quantity produced) originated in other areas, mostly in the Third World.³⁴ Over 40% came from Latin America (e.g., maize, tomatoes, and potatoes), 36% from the Middle East (e.g., wheat, grapes, and apples), and 4% from Africa (e.g., sorghum and millet). Of the remaining 20%, 16% are from China and Japan (e.g., rice, soybeans, and oranges).

As the center of diversity of most major food crops, the Third World would be the source of the so-called raw materials used to develop many patented crops. Until now these materials have been seen as the common heritage of all people and collected free of charge. However, when genetic material is used in the breeding program of a commercial seed company it is that company, not the Third World, that will earn the profits from it. There is even a chance the product may end up being sold to the Third World. Third World gardeners and farmers would then purchase a new crop variety created with genetic material from folk varieties which they and their families have been developing for generations.

This aspect of the debate is an excellent example of how values and assumptions have a major effect on scientific activity and national and international policy. Current laws and procedures for control of plant genetic resources and compensation for them is based on the assumption that the work of a few individual breeders in laboratories and test plots over several years is more worthy of recognition and compensation than the work of a farming community over many generations. Factors contributing to this value-based assumption include the disregard of the skills and knowledge of indigenous farmers and gardeners, and a world economic system that favors the rich and powerful.

Since 1975, coordinating the collection and seed banking of crop genetic diversity worldwide has been the responsibility of the International Board for Plant Genetic Resources (IBPGR), a part of the Consultative Group on International Agricultural Research (CGIAR). CGIAR is controlled by private donors, primarily from the industrial nations, causing many Third World countries to fear that they may lose control over their own genetic resources.³⁵ In fact, most major collections of genetic material are in seed banks in industrial nations or at CGIAR member organizations.³⁶ Exceptions to this are the growing number of small, independent seed banks being established by regional conservation groups.

Concern about the pattern of genetic resource control and use resulted in demands by some members of the FAO that the world community recognize the contributions of Third World ecosystems, gardeners, and farmers to the world’s genetic resources. Two suggestions of how to do this have been: 1) extending the principle of free exchange to include not only gardeners’ and farmers’ folk varieties and wild plants in Third World countries, but also the plant breeders’ varieties and elite breeding lines which are currently considered private property, or 2) recognizing “farmers’ rights” and offering compensation to Third World countries for their plant genetic resources, as is now given to commercial plant breeders and seed companies.³⁷ More recently discussion of this last idea was continued at an international conference on plant genetic resources in Madras, India.³⁸ The consensus statement issued by the group of participants from both industrial and Third World countries calls for a US $500 million fund to compensate Third World countries for the use of their genetic resources and to assist their efforts to conserve them. The fund, representing only 3% of the global seed industry’s annual sales, would be maintained through subscription fees paid by industrial countries based on the size of their commercial seed industry and their use of Third World genetic resources. Many questions, including how and to whom such a fund would be distributed remain to be resolved. Meanwhile the larger debate about control and ownership of genetic resources continues.

14.3 Seed saving

Saving of seeds by gardeners and farmers is the only way to preserve the full diversity of locally adapted folk varietes. Seeds from many garden crops can simply be collected in the garden and stored, while others need to be processed and dried for best results.

Seed saving is selection in action. Gardeners look for seed produced by plants with desirable characteristics such as drought and heat adaptation or pest and disease resistance. In addition to characteristics affecting production, the flavor, texture, size, color, and cooking and storage qualities of the food the plants produce are also important. For example, in Togo, local maize varieties are preferred over high-yielding new hybrids because the tight husks of the local ones significantly reduce damage by grain beetles during storage.³⁹

Still other characteristics are sought in garden plants used for medicine, crafts, and other purposes. By selecting seeds of devil’s claw plants (Proboscidea parviflora) with dark, long fibers, the most desirable characteristics for their craft, Tohono O’Odham Native American basket weavers in the southwestern United States and northern Mexico have created several new folk varieties.⁴⁰

14.3.1 Seed Harvest and Processing

Saving seed from several of the best and healthiest plants in the garden maintains genetic diversity and reduces the risk of having poor seeds. Seeds that are saved for planting must be viable, that is, capable of growing into a healthy plant (section 6.2.4). If seeds are harvested before they are mature, development of the embryo and seed coat will be interrupted and the seed will not be viable. Seeds that are an abnormal shape, very small, or damaged in some way should not be saved. Larger seeds are best because they contain more food to support the seed embryo before and during germination.

The length of time seed can be stored depends on the type of seed, its quality, and the storage conditions. As seeds get older they become less viable, because the embryos weaken and die. Therefore the longer they are stored, the lower their germination percentage becomes (section 6.6.1). If stored for a long time, some seeds such as beans become so hard and dry that water cannot penetrate them to swell and break the seed coat. Growing out saved seed after 2 to 3 years helps avoid this problem and ensures fresh, viable seed stock. To allow for losses during storage, germination, and early growth, about 50% more seed than needed for planting should be saved.

Harvesting and processing seeds from different types of plants is described below and summarized in Table 14.2. (Section 14.4 discusses tree seeds.)

POD-BEARING Seeds of plants like fenugreek, sesame, beans/peas, and arugola are mature when the pods have dried to a light brown color and are starting to become brittle. At this time the pods are ready to dehisce, or pop open to distribute the seeds. Pods of some crops such as peas, do not easily dehisce, but others, such as arugola, do so at the slightest touch, throwing seeds quite a distance (Figure 14.3). If dehiscing is a problem, seed stalks can be harvested while the pods are turning brown but are not brittle, and left to finish drying, out of the sun in a bag or on a piece of cloth, where the seeds can be easily collected.

Figure 14.3 Arugola Pods Dehisce Readily

Table 14.2 Seed Harvest and Processing

Crop	When to harvest seeds	Processing
Pod-bearing: e.g., pulses, okra, crucifers, sesame, peas	Just before pod dries, while it is turning brown but still pliable	Dry pods on cloth, paper, mat, so that seeds can be collected when pods open
Cucurbits: e.g., squash, gourds watermelons, melons	Squash and gourds: at least 6 weeks after fruit is considered ripe; watermelon: when fruit is eaten; other melons: when fruit is overripe	Wash seeds and dry slowly in shade
Peppers	When fruit is ripe; remove seeds as fruit is eaten, either fresh or dried	Dry seeds
Soft, small-seeded fruit: e.g., tomatoes, tomatillos, eggplant	When fruit is ripe to overripe	Fermentation (see description in text); for eggplant no fermentation, wash seeds and dry
Seed-bearing flower heads: e.g., cilantro, Niger seed, sunflowers, amaranth	Just before seed head becomes completely dry and brittle	Cut seed heads, lay on cloth or in bag, when dry remove seeds by rubbing
Maize	Past milk stage, when color has developed, may be left on plant until dry if no pest or mold problems	Dry seeds on cob, husk may be left on or removed
Fruit trees: e.g., mango, cashew dates, citrus, papaya, jujube, stone fruits	When fruit is completely ripe	Remove fruit flesh and clean seed; plant fresh, dry, and/or stratify, depending on crop

Figure 14.4 Squash Seeds can be Dried in a Basket

CUCURBITS The seeds of most squashes, pumpkins, and gourds continue to mature even after the fruit has reached its full size and is ripe for eating. Keeping mature fruit from which seed is to be saved in cool, dry storage for 6 weeks or longer, known as after-ripening, ensures time for seed development.⁴² When slightly immature fruit is picked, for example after an early frost, viable seeds can sometimes be saved if the fruit is allowed to after-ripen. When the seeds are removed from the fruit they should be rinsed and separated from the pulp. Any small, flat seeds that float while being washed can be composted, as they are hollow and not viable. Seeds should be dried in a well-ventilated place like a basket (Figure 14.4).

Watermelon seeds are mature when the ripe fruit is eaten, and they can be rinsed and dried immediately. Leaving other melons to continue ripening for a few days after they are first ready to eat allows the pulp and seeds to separate more easily. After cutting the melon open, the seeds are rinsed, and all remaining pulp is removed before they are laid out to dry.

PEPPERS Seeds from sweet peppers and hot chilis are obtained from fruit that has matured on the plant to a red, orange, or black color, depending on the variety. The fruit can be either fresh or dried (Figure 14.5). Seeds taken from fresh fruit may need rinsing before drying.

SOFT SMALL-SEEDED FRUIT Tomatoes and tomatillos contain many small seeds, so only a spoonful of pulp provides more than enough seeds for most gardens. The mashed pulp of mature fruits from several selected plants is placed in an uncovered container such as a bowl or jar. The pulp is left to ferment (section 15.6) with occasional stirring. Fermentation takes 3 to 7 days depending upon the air temperature:⁴¹ the warmer the air temperature, the less time required. A sour smell and bubbles on the pulp’s surface are signs that fermentation is occurring.

Fermentation destroys microorganisms on the seeds which can cause some diseases, and it thins out the pulp, allowing the heavier seeds to separate and sink to the bottom (Figure 14.6). Fermentation also removes the gelatinous coating on these seeds, changing their texture from slippery, to rough and nonslippery. This can be felt by rubbing them between two fingers. This stage of seed processing is complete when the seeds and pulp have separated. Any seeds floating near the surface are hollow and not viable. These and the pulp can be skimmed off the surface and composted. The viable seeds are rinsed with water and laid on a cloth, piece of screen, or similar material, to dry in a place protected from the wind and direct sun.

Figure 14.5 It is Easy to Collect Seeds from Chilis

Eggplant or garden egg seeds do not need to be fermented. The pulp of soft, overripe fruits from several selected plants is mashed. The seeds are separated by rinsing them with water, after which they are laid out to dry.

Figure 14.6 Fermentation and Separation of Tomato Pulp and Viable Seeds

SEED-BEARING FLOWER HEADS Cutting off the seed heads of plants like sunflower, onion, carrot, amaranth, cilantro, and chia just before they have completely dried is a great help in collecting their many seeds. The seed heads are placed in bags or on cloth in the shade to finish drying. When brittle and dry, seeds are easy to remove by rubbing or shaking the seed heads (Figure 14.7).

Figure 14.7 Gently Rubbing Dried Cilantro Seed Heads on a Firm Surface Easily Removes the Seeds

MAIZE A good indicator of seed maturity in maize is the browning of the husk or leaves around the ear. If birds and other pests are not a problem the ears do not need to be harvested until the whole plant has died. However, in very hot areas the sugars in the kernels may start to ferment inside tight husks, especially in the sweet varieties. The fermentation causes the kernels to explode, destroying them as seeds. To avoid this the husks can be opened slightly although this may allow pests inside. If the kernels have passed the stage when the juice inside is “milky,” and have developed their mature markings or color, they can be harvested and allowed to dry in the shade with their husks open or removed.

Maize is frequently stored on the cob which may reduce some pest damage to the softer part of the seed where it was attached to the cob. There are many traditional ways to store maize seed, either with or without the cob or husks: in containers, hung in bunches, or strung up in hanging racks as is done in parts of northern Mexico (Figure 14.8).

Figure 14.8 Maize Hung to Dry for Planting Seed in Northern Mexico

14.3.2 Seed Drying

All seeds must be dry before storage. Small hard seeds harvested in the dry season can be stored immediately with no further drying. Larger, moister seeds usually require extra drying after harvest. When seeds are spread out to dry, turning or mixing them several times a day speeds drying and helps prevent mold. In dryland areas with high daytime temperatures (greater than 35°C or 95°F), it is best to dry seeds in the shade to avoid the danger of overheating and overdrying, which can damage the seed coat and embryo. Sometimes if drying is too rapid, case hardening can occur in larger, moist seeds such as those of squash and melons. Case hardening is the drying of the outside surface while the inside is still moist. The moisture trapped inside the seed encourages the growth of fungi and bacteria,⁴³ and can also attract insects. However, some people such as the Tohono O’Odham of the southwestern United States and northern Mexico have a long tradition of drying seed in the sun with good results.⁴⁴ The exposure to sun and heat may also help rid the seeds of some insect pests. If a successful tradition like this does exist, understanding how it works and supporting its continuation is the best approach.

Baskets, pieces of cloth or mats, calabashes, and pots can all be used for drying seed. Seeds may need protection to prevent birds and insects from eating them and to keep insects from laying eggs which may later hatch in storage. An upside-down basket (Figure 14.9), or a piece of cloth stretched over the container, protects the seeds while still allowing air circulation.

Figure 14.9 An Upside-Down Basket can be Set on Top of Drying Seeds to Protect Them from Birds, Insects, and Wind

Rubbing dry seeds between hands or on a piece of cloth will separate seeds that may be stuck together. This is easy if the seeds are clean and dry. Only gentle rubbing is needed; hard pressure can scratch the seed coat and result in disease problems or drying of the embryo. Seeds from moist fruits such as squash, melons, tomatoes, chilis, and eggplants are brittle when dry, and will break if bent in half.

Seeds with some sort of pod or casing such as pulses are easier to store and plant if separated from this casing. There may be exceptions to this when pods offer some protection in storage. To remove pods after drying, any mature pods that have not opened can be threshed or rubbed to break them open, then winnowed in a light breeze as is done with grain. When dropped from shoulder or waist height the heavier seeds will fall straight down into an awaiting container while the pods and other debris will be blown away. Before storing, large pod-borne seeds should be dried for several days after removing their pods.

After drying, it is a good idea to keep seeds for several days at the same temperature at which they will be stored. If the seeds do not feel damp and do not stick to each other during this time they are probably dry enough for storage. The length of time to dry seeds varies greatly depending on the air humidity, drying conditions, seed size, and how clean the seeds are.

14.4 Saving seed from trees

Although many trees are propagated vegetatively (Chapter 7), some are grown from seeds with good results. Seedlings are also grown as root stock for later grafting. Seedlings have a stronger root structure than plants started from cuttings, especially during the first few years, and therefore are hardier under stress. However, if the tree is dioecious the sex of the seedling will not be known until it flowers, which could take many years. This is an important reason why some trees are not propagated from seeds.

To ensure that the seed collected is fully developed, only healthy, mature fruits, including those that have just fallen from the tree, should be gathered. The seed of some dryland garden trees such as olive, date, cashew, carob, and baobob can be easily stored for later planting. First, any fleshy part of the fruit or sweet pod which could attract pests or host seed-damaging bacteria and fungi should be removed. The seed is then dried in the shade for a few days, depending upon its size. Finally, seeds are stored in a cool, dry, ventilated place, in a breathable container such as a basket or bag.

Cashew seed can be stored for 7 to 12 months.⁴⁵ Olive, date, carob, and baobob remain viable for several years, although germination percentages may drop (section 6.6.1). We have planted baobob seed stored for over 15 years with excellent germination.

The hard outer coat of olive and stone fruit seed provides good protection during storage and can be cracked when it is time to plant. Seeds for planting pistachios are picked when the hard outer hulls turn blue green. These hulls are also useful for storage, but are thought to inhibit germination, and so they should be carefully cracked or removed before planting.⁴⁶

Seeds of mangoes, avocados, and citrus, should be planted when fresh, although limited storage may be possible. In eastern Senegal, cleaned mango seed is briefly air dried in the shade and then stored for up to 100 days packed in ceramic containers with moist charcoal.⁴⁷ The charcoal acts as an evaporative cooling system keeping the seeds cool and moist but not wet. Similarly, clean, partially dried citrus seed can also be stored for short periods in ground charcoal.⁴⁸

14.4.1 Cold Stratification

Cold stratification is the process of chilling seeds, which is required for good germination of some seeds and the production of healthy seedlings. Even if these seeds do germinate without stratification, the seedling is frequently dwarfed and growth is abnormal. Dryland tree seeds that require cold stratification are those of species or varieties that grow in high altitude or latitude drylands with a marked cold season, such as the stone fruits, olive, jujube, and pistachio. The seeds of these and other trees whose fruits ripen in these areas during the late summer and fall often need cold stratification.

Good temperatures for cold stratification are 2°C to 7°C (36°F to 45°F), but they can be lower.⁴⁹ The best way for dryland gardeners to stratify their tree seeds is to leave them exposed to the cold winter weather of their area. Selected seeds should not be stored in the house or other places where they would be protected from low winter temperatures. They can be buried in the ground, or in a container filled with moist sand or soil and left outdoors for the cold season, and then removed and planted when the cold weather has passed. Seeds can also be planted directly in the ground approximately 15-20 cm (6-8 in) deep at the beginning of the cold season.

The Navajo Native Americans living in the southwestern United States grow peaches, a crop introduced to the area by the Spanish several centuries ago. At the end of the hot season, fruits are cut up and dried for storage, and their seeds discarded nearby.⁵⁰ The seeds are stratified by exposure to the winter temperatures. The following spring the viable seeds produce seedlings, the best of which are selected and transplanted to permanent growing sites.

14.5 Seed storage

Good seed storage conditions include low moisture and temperature, and protection against rodents and insects. High temperatures and moisture encourage seed-damaging fungi and bacteria and increase respiration, shortening the seed’s life. Extremely high temperatures can kill the seed. Locally available storage containers and additives can prevent or minimize pest damage to stored seeds.

A sealed, airtight container can keep out moisture, rodents, and insects. A calabash or clay pot, for example, can be plugged and sealed with clay or wax. A piece of cloth dipped in hot wax can be draped over the container opening to seal it. The Tohono O’Odham of the Sonoran Desert traditionally stored seeds in small ceramic vessels called hahawa.⁵¹ A piece of broken pottery was trimmed to fit the vessel’s mouth where it was sealed in place using the heated sap of a local tree. Lidded jars and wooden or metal boxes also work well. On the other hand, a container that is closed but not sealed allows the gardener to check periodically on the condition of the seeds. However, this may lead to problems with moisture if the outside air is humid. Leather pouches, pots, cans, boxes, or jars can all be used. Table 14.3 summarizes dryland seed storage problems and responses.

14.5.1 Moisture and Temperature

In some dryland areas moisture may not be a problem and periodically opening containers or storing seed in closed but breathable containers like unglazed clay pots, baskets, cloth, or leather pouches is fine. However, even in very arid areas the increased humidity during a short rainy season can lead to damage of the stored seeds, greatly reducing their viability. Sealed containers of glass, metal, or glazed clay are non-breathable or airtight and will keep out moisture (Figure 14.10).

Toasted grains or pulses can be added to absorb excess moisture in an airtight storage container.⁵² The grains or pulses are toasted by slow heating without burning, which dries them out completely so they readily absorb water. As soon as the toasted materials have cooled to room temperature, they are mixed with the seeds and put into an airtight container which is then sealed. The stored mixture should contain twice as much toasted material as seed. Each time the container is opened, the old toasted grain or pulses must be replaced with some that are freshly toasted. Fresh ashes absorb moisture given off by stored seeds and are a good additive for this purpose, as well as for pest control as discussed in section 14.5.2. If available and inexpensive, corn starch, salt, and baking powder can also be used to absorb any moisture seeds give off. However, unlike ashes or toasted grains, these additives should not be mixed in directly with the seeds but kept in a cloth or paper bag inside the seed storage container. These additives, especially salt, draw so much moisture out of the seeds that seeds can become desicated and die if they are surrounded, for example, with salt. When using any additive it is a good idea to check the condition of the seeds regularly.

Table 14.3 Summary of Dryland Seed Storage Problems and Responses

Storage problem	Response
High temperatures	Shade, insulate, keep away from source of heat, take precautions for moisture
Moisture (encouraging fungi and bacteria)	Dry seeds thoroughly, add toasted grain and/or ashes to container, avoid heat
Rodents	Keep storage area clean, use sealed containers, “guards” on container legs, or stone-based container
Insects	Keep storage area clean, use sealed container, use additives; e.g., sand, ashes, smoke, herbs, oil

Figure 14.10 Breathable and Nonbreathable Storage Containers (1)

Figure 14.10 Breathable and Nonbreathable Storage Containers (2)

Figure 14.10 Breathable and Nonbreathable Storage Containers (3)

Figure 14.10 Breathable and Nonbreathable Storage Containers (4)

Closed seed storage containers should be shaded from the sun and kept away from cooking fires or walls heated by the sun or fire. Even well-dried seeds contain some moisture, and will produce water vapor if they get hot. Containers with thick walls offer some insulation from rapid temperature changes.

14.5.2 Pest Control

There are two ways to deal with pest problems in stored seed. One is to repel pests by making the seeds or the storage environment undesirable. The second method is to kill the pests. Indigenous methods of pest control in stored seed and foods operate by repelling or killing pests while manufactured pesticides act by killing them.

As discussed in Chapter 13, manufactured synthetic pesticides pose a number of problems: they must be purchased; their availability may not be reliable; directions for correct and safe use may not be available or accessible; and they are poisonous not only to pests but to humans and other animals as well (section 13.2.4). Pesticides can not only poison those handling them or seeds treated with them, but can affect others now and in the future through contamination of rooms, containers, soil, and water.

Some indigenous, as well as recently developed methods for controlling pests in stored seed using inexpensive, locally available materials have been found to be just as effective as manufactured pesticides.⁵³ These methods are practical and much safer, and there is growing interest in them worldwide.

Just like people, insects and rodents living in a dry environment are attracted to moisture, so storage containers and areas should be kept dry. Keeping the storage area clean is also important because an unclean storage area attracts pests, offering them not only food but also places to hide or nest (Figure 14.11).

Some insects like weevils (Apionidae family) and bruchids (Bruchidae family) can lay their eggs on seeds such as beans while they are still in the garden. If conditions are right, the eggs will hatch later and the larvae will eat the seeds. Holes in the seeds and powder at the bottom of the container from the damaged seeds are signs of these pests and their small white larvae can probably be found inside or around the seeds. These and other pests in stored seeds will die if they cannot obtain enough oxygen. Therefore, storing seeds in sealed, airtight containers with as little extra air space as possible will help to reduce pest damage. This does not limit the amount of oxygen enough to harm the seeds themselves.⁵⁴

Rats, mice, or other rodents can also be kept out by sealing the containers, or by storing seeds in containers with leg guards that prevent rodents from reaching the seeds. Indigenous storage bins for grains frequently include these leg guards (Figure 14.12). Another method used in some parts of Sahelian West Africa is to build the storage bin on a stone base which rodents cannot climb up or chew through.⁵⁵ Similar smaller containers may be appropriate for seeds, or a container of garden seeds can be placed inside such a bin.

In addition to the condition and care of the storage area, another way to reduce pests is by using a repelling substance, such as a local plant. For example, the compound azadirachtin contained in the leaves and seeds of neem trees (Azadirachta indica), which grow in the drylands of Africa and Asia, has been found to be an effective insect repellent.⁵⁶ One method used by farmers in western India and Pakistan is to grind the leaves into a paste which is mixed with clay and formed into seed storage containers.⁵⁷ In West Africa dried, powdered neem leaves are also used as an insect repellent.⁵⁸ Spicey, strong-smelling dried chili peppers and onion leaves, used in southern Nigeria in stored cowpea seed, may also repel weevils to some extent.⁵⁹ Some Native Americans used wild tobacco leaves (Nicotiana rustica) to repel insects from stored seeds.

Figure 14.11 A Clean Storage Area with Sealed Ceramic Seed Jars in Burkina Faso (After Dupriez and De Leener 1983:157)

Certain additives operate primarily by killing pests but may also repel them. Fine sand can be added to seeds in a ratio of one or more volumes of sand to one volume of seed.⁶⁰ Because it fills the spaces between seeds and because of its weight the sand prevents insects from moving around easily. Adult bruchid beetles, common pests in stored beans, are unable to move around enough to mate and reproduce in beans mixed with sand, and so the population dies out. The sand also scratches the thin wax coating of the insect’s outer cuticle and its delicate limb joints, causing it to dry out and eventually die.

Dust additives operate the same way as sand although some may scratch while others absorb the insect’s protective waxy layer, exposing it to dehydration. Ashes and finely ground limestone are other common additives that fill spaces between seeds and absorb insect’s waxy protective layer.⁶¹

In the West African country of Togo, one volume of bean seeds is thoroughly mixed with between one and two volumes of cooking fire ashes.⁶² The ashes should also completely cover the surface of the stored seeds. Some people feel that the ashes from burnt goat and cattle dung or from burning certain local trees are particularly effective.⁶³ Sand mixed with the seed coats of Polygala butracea or with the leaves and husks of Cassia nigricans provided good protection of cowpeas stored in locally made clay jars in northern Togo.⁶⁴

Figure 14.12 A Traditional Storage Bin in Iran with Wooden Disks as Leg Guards Against Rodents (After NAS 1978:73)

Another additive used to protect stored seeds from insect damage is oil. In Nigeria, weevil infestations in dried cowpeas are minimized by coating the seeds with a layer of groundnut or palm oil, (approximately 5-8 ml of oil/kg of seed, 0.1 fl oz of oil/lb of seed).⁶⁵ The oil is believed to act both chemically as an insect repellent, and mechanically by sealing air out of the peas and preventing growth of any weevil larvae they contain. In rural India, castor bean (Ricinus communis) oil is used to protect stored seed.⁶⁶ Similarly, neem oil was found to be very effective for controlling pests in stored cowpeas in northern Togo.⁶⁷ Hulled, ground neem seed powder was kneaded by hand to squeeze out the oil. These cowpeas had a germination rate of 27% after 8 months of storage, compared with only 2% for untreated seeds. Those stored in sand, however, had a better germination rate of 47%.

In many areas smoke is traditionally used to protect stored food, seed, and even houses from pests.⁶⁸ Seed or food can be stored over the cooking fire or in a raised container under which a fire is periodically built (Figure 14.13). The important points to remember about this method of pest control are not to overheat the seeds or food by placing them too close to the fire, and to only use containers such as loosely woven baskets that allow ventilation so that any moisture released due to increased temperatures will not be trapped inside. Bundles of unthreshed grains or pulses can be treated with smoke, but care must be taken that they do not dehisce while in storage.

14.6 Resources

Control of crop genetic resources has become an important issue of international debate, in part because it reflects larger questions about the relationship between the industrial and Third Worlds, the “north” and the “south.” This debate is represented by a rapidly growing number of publications on genetic resources including Shattering (Fowler and Mooney 1990), The Gene Hunters (Juma 1989), First the Seed (Kloppenburg 1988) and Altered Harvest (Doyle 1985). For Spanish speakers and readers there is Daniel Querol’s Recursos Genticos, Nuestro Tesoro Olvidado (1988). In addition, this issue is being discussed now in both popular and academic periodicals all over the world.

Botany books can be good sources of information on plant genetics. For example. The Biology of Plants (Raven, et al. 1981:115-166) has a section on genetics and evolution. Cox and Atkins (1979:513-536) look at plant and animal genetics in agriculture.

Figure 14.13 Using Smoke to Protect Stored Seeds and Grain from Pests (After FAO 1970:161)

Resources with simple practical information about seed saving and storage for the low-resource gardener are GTZ (1980) and Stoll (1987). The new On Farm Seed Project was started by the private US organization Winrock International Institute for Agricultural Development (see Chapter 19 for the address). The project is conducting experiments and workshops on on-farm seed storage methods in Senegal and The Gambia. They also publish a bilingual (French and English) newsletter Seed Sowers/Les Semeurs.

References

¹ African Diversity 1990.

² Cleveland and Soleri 1989.

³ Cleveland and Soleri 1987.

⁴ Brush 1986; Brush, et al. 1988.

⁵ Soleri and Cleveland 1989.

⁶ Oldfield 1984:27-32.

⁷ Richards 1986:131-146.

⁸ Plucknett, et al. 1987:3.

⁹ Atlin and Frey 1989.

¹⁰ IITA 1986:52-55; ICRISAT 1986:15, 33,54.

¹¹ Andrews 1989.

¹² Cox and Atkins 1979:553.

¹³ Cleveland and Soleri 1989.

¹⁴ Could 1988.

¹⁵ Buttel, et al. 1985; Doyle 1985:94-113,167-172.

¹⁶ Goldburg, et al. 1990.

¹⁷ Cox and Atkins 1979:520-521; Doyle 1985:1-17; NAS 1972; Oldfield 1984:22-23.

¹⁸ Cleveland and Soleri n.d.b.

¹⁹ Cleveland 1986.

²⁰ Grivetti 1978.

²¹ Clawson 1985.

²² Richards 1985:98-99; Richards 1986:133-138,142,149.

²³ Ferguson and Sprecher 1987.

²⁴ Dupriez and De Leener 1987:199-200.

²⁵ Dewey 1981:35.

²⁶ Marten and Abdoellah 1988.

²⁷ Harlan 1976; Plucknett, et al. 1987.

²⁸ Crisp and Astley 1985; Plucknett et al 1987:3-4,17-26.

²⁹ Oldfield 1984:27-32.

³⁰ Crisp and Astley 1985.

³¹ Oldfield and Alcorn 1987.

³² Fowler and Mooney 1990:206-207.

³³ Kloppenburg and Kleinman 1987.

³⁴ Kloppenburg and Kleinman 1987.

³⁵ Kloppenburg and Kleinman 1987.

³⁶ IBPGR 1987.

³⁷ Kloppenburg and Kleinman 1987.

³⁸ African Diversity 1990; Keystone Center 1990.

³⁹ Zehrer 1980:52.

⁴⁰ Nabhan and Rea 1988.

⁴¹ Leon and Withers 1986:70.

⁴² Leon and Withers 1986:72.

⁴³ NAS 1978:50-53.

⁴⁴ Nabhan, et al. 1981.

⁴⁵ Garner, et al. 1976:193.

⁴⁶ Hartmann and Kester 1983:628.

⁴⁷ Bittenbender 1984:81; Tuck 1985.

⁴⁸ Purseglove 1974:512.

⁴⁹ Hartmann and Kester 1983:135.

⁵⁰ Jett 1979.

⁵¹ Nabhan, et al. 1981:6.

⁵² DCFRN #8-1.

⁵³ Zehrer, et al. 1980.

⁵⁴ Zehrer 1980:115.

⁵⁵ Zehrer 1980:48.

⁵⁶ Ahmed and Grainge 1986; NAS 1980:114.

⁵⁷ Ahmed and Grainge 1986:204.

⁵⁸ Zehrer 1980:120.

⁵⁹ Ofuya 1986.

⁶⁰ Zehrer 1980:110.

⁶¹ NAS 1978:55.

⁶² Zehrer 1980:114.

⁶³ DCFRN #4-2.

⁶⁴ Zehrer 1984:453-460.

⁶⁵ King, et al. 1985:218.

⁶⁶ Zehrer 1980:121.

⁶⁷ Zehrer 1984:459.

⁶⁸ FAO 1970:158-160; Dupriez and De Leener 1983:156; NAS 1978:55; Zehrer 1980.

15. Processing, storing, and marketing food from the garden

The majority of fruits and vegetables are most nutritious when eaten fresh from the garden without processing or storage of any kind. Yet year-round harvests may be limited by the climate, garden space, or lack of time. Also, some garden crops like mangoes or peaches can produce a larger harvest at one time than can be used. For example, market gardeners in southern Senegal say that at least 50% of their abundant, peak-season mango harvest rots each year.¹ In these situations processing and storing some of the produce is a way to save it for use later in the year.

In many areas there is a long tradition of food processing and storage which is important economically, nutritionally, and socially (Figure 15.1). However, in some cases the time and resources required for processing and storing garden produce just do not make sense under local conditions. This will be decided by the gardener or whoever else is doing the work.

The goals of processing garden produce are to:

· Maintain the best possible nutritional value.
· Require as little time and as few resources as possible.
· Use inexpensive, locally available inputs.
· Produce foods that appeal to local tastes and do not cause illness.

Marketing is another way gardeners or their households can use the garden harvest, and income is a strong incentive, especially for poor households. Marketing a small amount from a household garden is often an easy way to earn a little money, but marketing a large amount of produce, is far more complicated and risky. Reducing the gardener’s dependence on factors beyond his control is the best way to cope with this.

15.1 Summary

Fresh garden crops harvested when ripe should be eaten or processed quickly for the greatest nutritional benefit. Most fruits are best when harvested ripe and handled gently to avoid bruising, although some may be harvested while still unripe.

Preservation and processing of garden foods affects different nutrients in different ways. Vitamins are the most sensitive: the longer the time from harvest to consumption, and the longer and hotter they are cooked, the greater the loss.

Drying is one of the easiest and most effective ways to preserve dryland garden produce if a few simple guidelines are followed. Sprouting, making, drying, and fermenting of some foods increases the nutritional value per unit weight. Many popular indigenous foods are prepared these ways. Some foods, like olives, African locust beans, and cassava, can only be eaten after processing to remove toxins and anti-nutrients. Processing also produces foods that taste good.

Garden produce can be stored fresh or processed. Fresh produce has a relatively short storage life. Dried garden foods can be stored much longer using simple techniques to eliminate pests and microorganisms that cause spoilage.

Special considerations when harvesting garden produce for market include finding reliable and affordable transportation, picking fruits before they are fully ripe, and packing produce to protect it during transportation. Once at the market, simple measures such as shading and sprinkling fresh garden produce with water protects its quality and appearance.

15.2 Harvesting garden foods

Most garden foods have the highest nutrient content and best flavor when they are harvested as close as possible to the time they will be eaten or processed. The exceptions are pulses, cereals, sunflower and sesame seeds, and other crops that are allowed to ripen and dry on the plant before harvesting.

Figure 15.1 In Many Areas there is a Successful Tradition of Food Drying

Harvesting fruit or leaves from perennials or young annuals can affect the plant’s future production. For example, when harvesting apricots, care should be taken not to damage the fruiting spurs which will continue to produce fruit for 3 to 4 years. When harvesting leaves, enough must be left on the plant for adequate photosynthesis for future growth.

In some parts of Nigeria both the leaves and pods of okra are eaten. Studies there found that if only leaves on the lower half of the plant are harvested, pod production will not be reduced.² In Zambia, researchers working with Ethiopian mustard greens found that harvesting up to half of the total leaf area every 1 or 2 weeks increases leaf production.³ However, harvesting three-quarters of the leaf area causes yields to drop. Research on the effects of harvesting cowpea leaves concluded that moderate leaf harvesting reduced pod production but the combined edible yield of pods and leaves (in dry weight) was greater for most varieties than the yield when only pods were harvested.⁴

As fruits ripen, there is an increase in the amount of vitamins they contain, especially vitamin C. Sugar content also increases, making them more flavorful. A color change from green to yellow, orange, or red is a sign of ripening in many fruits like tomatoes, peppers, stone fruits, papayas, mangoes, and bananas. Other fruits are green when ripe, but become softer, like avocados, or softer and sweet smelling, like some melons and guavas.

Many fruits bruise and spoil easily and should be carefully harvested and handled. Including a little of the stem, or pedicel, directly above the fruit when harvesting it helps reduce spoiling (Figure 15.2). Removing the place at the top of the fruit where it is attached to the plant often exposes some of the moist flesh under the fruit’s skin, which easily rots. With dates, removing the attachment, or cap, allows dirt and insects to get deep inside the fruit. However, no matter how carefully harvested, the stem may drop off of very ripe fruit and this fruit should be eaten or processed as soon as possible.

Some fruits can be eaten before they are fully ripe. Unripe fruits add new flavors and textures to the diet and can be used differently than ripe ones. For example, both sweet peppers and chilis can be used when green. Green papayas and tomatoes can be cooked to reduce their bitterness. Green mangoes are used to make relishes, and in some areas such as southern Sudan we have seen them eaten fresh, sprinkled with lime juice, salt, and chili powder. Bananas and plantains are higher in starch and lower in sugar before they ripen, and unripe ones are cooked and eaten.

Figure 15.2 Harvesting Garden Fruits with the Stem still Attached (1)

Figure 15.2 Harvesting Garden Fruits with the Stem still Attached (2)

Figure 15.2 Harvesting Garden Fruits with the Stem still Attached (3)

Figure 15.2 Harvesting Garden Fruits with the Stem still Attached (4)

Unripe fruits may also be eaten when other food is scarce. In southern Pakistan, for example, people whose food supplies are running low before the dates ripen, process and eat unripe dates.⁵ The bright green, unripe dates called kimri are mashed in a basket, releasing some of their tannin-loaded juices. These kimri are then put in a ceramic jar which is wrapped in a blanket and left overnight. By the next day the kimri have turned a mud color and lost much of their bitterness.

15.3 Cooking and using garden foods

Cooking can improve the nutritional value of food and helps soften or break down the cellulose in plant cell walls, making the nutrients inside available for digestion. It destroys toxins present in some uncooked pulses such as lima beans, cowpeas, and lentils. Cooking can also destroy some nutrients. However, great efforts need not be made to retain high levels of a nutrient in one food when the nutrient is abundant and readily available in the diet. For example, if a child is eating fresh guavas every day, the loss of vitamin C from cooking malted beans should not be a concern. Table 15.1 summarizes suggestions for minimizing nutrient losses in cooking.

15.3.1 Fresh Foods

The greatest concentration of nutrients is usually in the outer layers of fruits and vegetables, so trimming and peeling should be kept to a minimum. Gardening without toxic chemicals means that lots of peeling and trimming is not necessary. In urban areas, garden produce grown above ground, like leaves and fruits, often has toxic lead residues from the lead in gasoline (petrol) used in vehicles. This is especially true of gardens grown near busy city streets. Washing this produce in a mixture of vinegar and water can remove most of these residues.⁶ If this is not possible it is a good idea to peel city-grown fruits, especially for children.

The hotter and longer most fresh fruits and vegetables are cooked, the more vitamins will be destroyed. Even though boiling and steaming does not raise the temperature much above 100°C (212°F), the boiling point of water, it can still destroy vitamins. Vitamin C is the most sensitive to heat, although vitamin A is also affected. A study of eight vegetable leaves commonly eaten in Ghana showed vitamin C losses of 44-78% when boiled for 10 minutes in a covered container with just enough water to cover the leaves.⁷ Frying in oil can be much hotter than boiling or steaming, and therefore destroys more of these heat-sensitive vitamins.

Water-soluble vitamins, like vitamin C, niacin, riboflavin, and thiamin, are dissolved out of foods by water. To minimize these losses:

· Avoid cutting food into small pieces, exposing more surface area to air and water.

· Avoid soaking fresh fruits and vegetables before cooking (exceptions include some root crops like cassava).

· Cook for the shortest possible time with a minimal amount of water.

· Drink vitamin-rich cooking water, or use it in other dishes.

· Do not salt raw fruits and vegetables because this draws out water containing dissolved nutrients.

Both cutting and cooking will cause losses in nutrients due to oxidation. Vitamins A, C, E, and folacin oxidize, meaning that their chemical structure is altered, and their nutritional value reduced. Exposure to the air (which contains 20% oxygen) and to heat both increase oxidation. For example, an orange cut open long before it is eaten loses vitamin C by oxidation.

Raising the pH of cooking solutions by adding bicarbonate of soda, ashes, or other alkaline substances can shorten the cooking time and improve the color of some vegetables. However, it destroys vitamin C and thiamin in foods. Similarly, acids contribute to the destruction of carotenoids, an important source of vitamin A in fruits and vegetables.⁸

Table 15.1 Cooking and Nutrient Content of Foods

Nutrient sensitivity	Garden examples	Suggested cooking method
Heat sensitive (vitamins A, C, and thiamin)	Many fruits and vegetables	Where appropriate, eat produce fresh, soon after harvest; keep cooking time brief and temperatures low; avoid frying
Water soluble (vitamin C, niacin riboflavin, thiamin)	Tomatoes, peppers, squash, greens	If cooking with water, try steaming with minimal amount of water; use this cooking water in other foods
Alkaline sensitive (vitamin C, thiamin)	Greens, pulses	Do not add bicarbonate of soda or ashes while cooking

15.3.2 Dried Foods

Dried fruits are a flavorful treat and can be eaten with or without first cooking them in water. Other dried foods such as green leaves, onions, okra, or tomatoes, are cooked before being eaten and are often used for making sauces or soups. Unlike fresh fruits and vegetables, presoaking most dried foods is recommended because it shortens cooking time and saves precious fuel, and the soaking water can be used for cooking. Dried leaves and small fruits only need presoaking for an hour or less. Pulses and tubers, which are bigger than leaves, have a greater volume and need to be soaked longer, often overnight. One volume of dried food can absorb two volumes or more of water (Figure 15.3).

Soaking dried pulses such as pigeon peas or chick-peas dissolves anti-nutrients like tannins and phytates into the water (section 2.10).⁹ In these cases the soaking water should be poured on the garden, and fresh water used for cooking.

The seed coats of pulses are high in fiber which is fine for most adults but should be removed when making weaning foods or food for someone with a stomach or intestinal infection or diarrhea. Seed coats can be removed by soaking beans or seeds and rubbing the coats off while they are still wet, or by parching.¹⁰ Parching is soaking pulses in oil or water and then drying them so that their seed coats crack and can be easily rubbed off. Lightly roasting groundnuts (which are not soaked) makes it easy to remove their papery coats.

15.4 Food drying

Drying is one of the oldest and most widely used methods of processing food for storage. In Egypt, for example, a popular green called mulukhiyah (jute) is grown or purchased in large quantities during the warm season. The washed leaves are stripped from the stalks and dried on palm-fiber mats. Some people partially dry the mulukhiyah in the sun, then move it indoors to complete the drying, while others dry it entirely in the shade.

In central Mali the Dogon grow bunching onions in dry-season gardens.¹¹ The onions are harvested in two stages so that they may be dried for sale or household use. First, the green onion tops or leaves are removed. These are then pounded into a pulp which is formed into balls, with any extra liquid being squeezed out. These balls ferment and are left to dry in the sun for about 10 days. The day after removing their tops the onion bulbs are dug up. If possible they are eaten or sold immediately. Otherwise they are also pounded and formed into balls which are fermented and sun-dried for later sale or home use.

Figure 15.3 One Volume of Dried Garden Produce can Absorb Two or More Volumes of Water

Drying preserves foods by removing the water which spoiling microorganisms need to grow. Since fresh fruits and vegetables contain about 80% water,¹² drying reduces their volume and weight substantially. It also concentrates their nutrients and preserves them for times when these nutrients may not be available in fresh foods. For example, an experiment in Senegal found that on average, after drying and storage for 6 months a 100-gm (3.5-oz) piece of mango contained 100% of the RDAs for vitamins A and C for children.¹³

Drying is a quick and easy method for preserving many garden foods, including leafy greens, okra, onions, tomatoes, eggplants, squash, roots, and tubers. Sweet fruits such as dates, cashew apples, figs, peaches, apricots, mangoes, bananas, papayas, and loquats do not need to be dried as completely as vegetables because their high sugar content also acts as a preservative (section 15.4.3).

High temperatures make drying go faster by increasing the rate of evaporation. However, sunlight destroys vitamins A and riboflavin, and high temperatures destroy vitamins A, C, folacin and thiamin¹⁴ by increasing oxidation. One study showed that cowpea leaves dried in the open sun kept only 11% of their vitamin C and 42% of their vitamin A compared with 24% and 57% for leaves dried in the cooler shade.¹⁵ Flavor and color are also lost by exposure