Lecture 2. Grains, beans, pulses and nuts

As an introduction to food, an important plant use category, we present some general facts and definitions. In separate lectures, we will consider five major groups of edible plants – and example plant families for each group – that make an important contribution to the global diet: (1) Grains, legumes and nuts with an overview of Poaceae; (2) Tubers and roots, with an overview of Dioscoraceae; (3) Fruits and vegetables, with an overview of Solanaceae; (4) Salads and leaf vegetables, with an overview of Asteraceae; and (5) Spices, condiments and flavorings, with an overview of Zingiberaceae.

General facts on food plants:

• There is a great diversity of food that comes from domesticated, managed and spontaneous (i.e. "wild") species.
• Some 12,000 of the estimated 270,000 plant species have been used as food, but only 150 of these have ever been widely cultivated.
• Of these domesticated species, only 20 species account for over 90% of the global food supply.

Definitions:

• Nutraceutical is a new term, coined by Stephen DeFelice of the Foundation for Innovation in Medicine, that means "a food or part of a food that has a medical or health benefit, including the prevention and treatment of disease"
• Agricultural biodiversity or agrobiodiversity. Agricultural biodiversity refers to the variety and variability of animals, plants and micro-organisms on earth that are important to food and agriculture which result from the interaction between the environment, genetic resources and the management systems and practices used by people. It takes into account not only genetic, species and agroecosystem diversity and the different ways land and water resources are used for production, but also cultural diversity, which influences human interactions at all levels. It has spatial, temporal and scale dimensions. It comprises the diversity of genetic resources (varieties, breeds, etc.) and species used directly or indirectly for food and agriculture (including, in the FAO definition, crops, livestock, forestry and fisheries) for the production of food, fodder, fibre, fuel and pharmaceuticals, the diversity of species that support production (soil biota, pollinators, predators, etc.) and those in the wider environment that support agro-ecosystems (agricultural, pastoral, forest and aquatic), as well as the diversity of the agro-ecosystems themselves.
• Agricultural ecosystems or agroecosystems. Agroecosystems are those "ecosystems that are used for agriculture" in similar ways, with similar components, interactions and functions. Agroecosystems comprise polycultures, monocultures, and mixed systems, including crop-livestock systems (rice - fish), agroforestry, agro-silvo-pastoral systems, aquaculture as well as rangelands, pastures and fallow lands. Their interactions with human activities, including socio-economic activity and sociocultural diversity, are determinant. Agroecosystems may be identified at different levels or scales, for instance, a field/crop/ herd/pond, a farming system, a land-use system or a watershed. These can be aggregated to form a hierarchy of agro-ecosystems. Ecological processes can also be identified at different levels and scales. Valuable ecological processes that result from the interactions between species and between species and the environment include, inter alia, biochemical recycling, the maintenance of soil fertility and water quality and climate regulation (e.g. micro-climates caused by different types and density of vegetation). Moreover, the interaction between the environment, genetic resources and management practices influence the evolutionary process which may involve, for instance, introgression from wild relatives, hybridization between cultivars, mutations, and natural and human selections. These result in genetic material (landraces or animal breeds) that is well adapted to the local abiotic and biotic environmental variation.

Source: Pimbert, M. 1999. Sustaining the Multiple Functions of Agricultural Biodiversity. FAO background paper series for the Conference on the Multifunctional Character of Agriculture and Land, The Netherlands, September 1999. Citatation: International Technical Workshop organized jointly by the Food and Agriculture Organization of the United Nations and the Secretariat of the Convention on Biological Diversity(SCBD), with the support of the Government of the Netherlands 2-4 December 1998, FAO Headquarters, Rome, Italy. www.fao.org/sd/epdirect/EPre0063.htm

Grain crops – also called cereals – are the most important sources of plant food for people, providing two-thirds of the energy and half the protein of the diet. Grains were among the first plants brought under cultivation, around 8000 BC. Legumes, also called pulses, are second in importance to grains as food crops. They are good sources of protein (20 – 40 per cent), rich in essential amino acids, including lysine (deficient in cereals). The term nut is popularly used for a seed or fruit having an edible kernel inside of a brittle or hard shell. Unlike grains and legumes, nuts come from many different plant families. Nut kernels are very nutritious, containing up to 30 per cent protein and 70 per cent oil. Nut remains have been found in archaeological sites dating back to before 10,000 BC. Many nuts are pressed to produce oil used for cuisine, cosmetics and other purposes.

Examples:

The Poaceae or Graminae, including key genera such as Avena, Hordeum, Oryza, Pennisetum, Secale, Sorghum, Triticum and Zea, is a large plant family, comprising 650 genera and 8700 species. It is cosmopolitan, ranging from the polar circle to the equator, but is especially well represented in tropical and north temperate subarid zones. Estimated to be the principal component in 20% of the global vegetation, grasses are present in all vegetation types, and dominating steppe, prairie and savanna. Considered the ecologically most dominant and economically most important plant family in the world, the Poaceae provides all the cereal crops, most of the world’s sugar, forage for animals and construction and crafts materials such as bamboos, canes and reeds. About 70% of the world’s farmland is planted in cereals, and over 50% of the world intake of calories come from grasses.

Overheads:

• Use of wild plants and animals for food and medicine by farming communities (From: Pimbert, M. 1999. Sustaining the Multiple Functions of Agricultural Biodiversity. FAO background paper series for the Conference on the Multifunctional Character of Agriculture and Land, The Netherlands, September 1999.)
• Examples of species domesticated in centers of origin of food production (From: Pages 126 –127 in Diamond, J. 1998. Guns, Germs and Steel: A Short History of Everybody for the Last 13,000 Years. London, Vintage).
• Examples of early major crop types around the ancient world (From: Page 100 in Diamond, J. 1998. Guns, Germs and Steel: A Short History of Everybody for the Last 13,000 Years. London, Vintage).

Key references on grains:

National Reserch Council. 1996. Lost Crops of Africa. Volume 1. Grains. Washington, D.C., National Academy Press.

Singh, U. and B. Singh. 1992. Tropical grain legumes as important human foods. Economic Botany 46:310-321.

Teshome, A., J.K. Torrance, B. Baum, L. Fahrig, J.D.H. Lambert and J.T. Arnason. Traditional farmer’s knowledge of sorghum (Sorghum bicolor [Poaceae]) landrace storability in Ethiopia. Economic Botany 53:69-78.

Teshome, A., L. Fahrig, J.K. Torrance, J.D.H. Lambert, T.J. Arnason and B.R. Baum, Maintenance of sorghum (Sorghum bicolor [Poaceae]) landrace diversity by farmers’ selection in Ethiopia. Economic Botany 53:79-88.

Perspective (Diamond 1997:136-137): "The wild ancestors of many Fertile Crescent crops were already abundant and highly productive, occurring in large stands whose value must have been obvious to huner-gatherers. Experimental studies in which botanists have collected seeds from such natural stands of wild cereals, much as hunter-gatherers must have been doing over 10,000 years ago, show that annual harvests of up to nearly a ton of seeds per hectare can be obtained, yielding 50 kilocalories of food energy for only one kilocalorie of work expended. By collecting huge quantities of wild cereals in a short time when the seeds were ripe, and storing them for use as food through the rest of the year, some hunting-gathering peoples of the Fertile Crescent had already settled down in permanent villages before they began to cultivate plants.

Since Fertile Crescent cereals were so productive in the wild, few additional changes had to be made in them under cultivation… The principal changes – the breakdown of the natural systems of seed dispersal and germination inhibition – evolved automatically and quickly as soon as humans began to cultivate the seeds in fields. The wild ancestors of our wheat and barley crops look so similar to the crops themselves that the identity of the ancestor has never been in doubt. Because of this ease of domestication, big-seeded annuals were the first, or among the first, crops developed not only in the Fertile Crescent but also in China and the Sahel."

Exercise:

Creating a framework of food use categories and plant families

Taxonomy: creating a classification of grains, legumes and pseudo-cereals

Videos:

Last Plant Standing: Part 1

Developing Stories: Seeds of Plenty, Seeds of Sorrow

Widely acknowledged as one of the most successful development strategies of the Twentieth Century, the Green Revolution is credited with ensuring that India and other developing nations no longer suffer from famine and hunger. But 25 years later, Manjuira Datta’s thoughtful documentary asks, who has been the principal beneficiary of the biotech package? The poor peasant? The big farmer? The multinational corporation? ? And what damage has the Green Revolution done to the social structure and ecologies of Third World countries? The film reveals a darker, more problematical side to the Green Revolution. In India it has helped create a new serf class and the dramatic crop yields of the early years have fallen away in the wake of pesticide poising and short-lived miracle wheat strains. (1992, 52 minutes)

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