Tuesday, August 9, 2011


Grain and Legumes are important in human and animal life as source of foods for decades. The two plant families of greatest importance to world agriculture are the family of Poaceae (cereals and grasses) and the Fabaceae. The legume family contains about 650 genera and 18,000 species. In terms of production volume, the cereals are the most important as they furnish the carbohydrates that constitute the major portion of human and animal diets. During my university lecture on this topic, my lecturer did mention that in terms of sheer numbers of genera and species used by humans, the legumes are by far the most utilized plant family Legumes are used for their chemicals, esthetic value, timber, as cooking fuel, browse trees and shrubs, forage crops, pasture crops, cover crops, green manures, for feed and food. This article discuss about the importance and basic knowledge of grain and legumes based on my reference to few books and website.

I will discuss an overview of the Fabaceae grown for food focusing upon those plants used as grain legumes. The grain legumes are those plants used as food in the form of unripe pods, immature seed or mature dry seed, directly or indirectly. Not only do the grain legumes provide variety to the human diet but they also supply dietary protein for many populations lacking animal or fish protein. In general, the grain legumes are rich in lysine but poor in methionine content, thereby complementing the reverse amino acid pattern found in cereals. Additionally, virtually all of the grain legumes fix their own nitrogen, thereby reducing, in many situations, the cost of nitrogen inputs by farmers. The grain legumes, especially soybeans and peanuts, are excellent sources of vegetable oils used in the production of cooking oil, margarine, mayonnaise, and salad dressings.

In this discussion I have divided the grain legumes into three categories-primary, secondary and tertiary grain legumes. The legumes in each category will be discussed in the following sections.

As for today, twelve crops constitute the primary grain legumes. They are characterized by the following:

The crops primarily belong to two tribes of the subfamily Papilionoideae that is, the Vicieae (Lens, Pisum, Vicia) and Phaseoleae (Cajanus, Phaseolus, Vigna). Exceptions include Arachis which is placed in the Aeschynomeneae and Cicer which is now placed in its own tribe the Cicereae. The Phaseoleae are distributed in the tropics or subtropics while the Vicieae are distributed in the Sino-India region or the Fertile Crescent.
• During the domestication process, the primary grain legumes coevolved with the major cereal crops. Thus, the soybean is paired with rice in China; peas, lentils and chickpeas with wheat and barley in the Fertile Crescent; beans with maize in the New World; and cowpeas with sorghum in Africa.
• The crops are grown over wide geographical areas and traded in world commerce. Major comprehensive germplasm collections are maintained for each crop. They all have at least one full time curator.
• Cultivars have been developed through modern plant breeding procedures. Land races of these crops are rapidly disappearing.
• Except for Vicia faba, the conspecific wild relative of each cultigen has been identified.
• For each crop, there is at least one major national or international center of research excellence. A critical mass of plant breeders, pathologists, entomologists, soil scientists, etc. are available to solve production problems. In addition, fundamental research has been conducted on the crops. For example, at the University of Illinois the genomic relationships of species in the genus Glycine and the idiogram of soybean chromosomes have been elucidated.

Fourteen crops constitute the secondary grain legumes. They are characterized by the following:

The crops primarily belong to the tribe Phaseoleae (Canavalia, Lablab, Macrotyloma, Phaseolus, Psophocarpus, Vigna). Exceptions include Cyamopsis which is placed in the Indigofereae, Lathyrus is a member of the Viceae and Lupinus which is placed in the Genisteae. Cyamopsis, Lathyrus and all of the species in the genera assigned to the Phaseoleae, except for Phaseolus coccineus, are distributed in the tropics and subtropics. Phaseolus coccineus comes from the Central American highlands. At present, the Lupinus species utilized in the temperate zones originate from the Andean highlands or temperate Europe.
• Guar and the lupins are unusual members of the secondary grain legumes. Several million acres of guar are cultivated in India, Pakistan, the U.S. and elsewhere for use as a source of gum. The gum is extracted from the seed for utilization in the paper, oil well drilling, explosive, and mining industries as well as in many processed food and beverage products. The use of guar as a grain legume is limited to certain regions of India and Pakistan.
The lupins, Lupinus albus, L. angustifolia, L. cosentinii, L. luteus and L. mutabilis primarily are used as green manures, fodder crops or forage for livestock. In the past, the lupins rarely were used as grain legumes because the seeds were rich in alkaloids. Only in the past 20-30 years, have cultivars been developed with reduced alkaloid content in seed and non-dehiscent fruits. These are the so-called "sweet" lupins. Lupins and winged beans are next to soybeans among the grain legumes with regard to protein content in seed (28-48% depending on species). The use of sweet lupins as a food for humans remains to be fully explored.
• As grain legumes, the crops are not grown over wide geographical areas and overall are not important in world trade.
• National germplasm collections of each crop are available, however, the curators usually have several crops to maintain or curate a specific collection on a part-time basis. Funds to maintain the collections usually come from short term grants.
• Except for guar and lupins, simple selection is the main plant breeding technique used for cultivar development. Thus, the distinction between cultigens and wild forms are often blurred. A high proportion of the total production is derived from land races.
• Instead of centers of research excellence, the research conducted on these crops is usually based upon the interests of one or two vigorous scientists employed at a specific location. These scientists usually enlist the assistance of a professional colleague working in another discipline on another crop to help them solve a particular problem.

The tertiary grain legumes are those legume species rarely grown outside their native habitat. They are not true domesticated plants but rather cared for or protected plants whose seed is harvested by the indigenous population primarily during times of environmental stress. Most of the information about these plants comes from social scientists, missionaries or perhaps taxonomists conducting floristic investigations. Initiation of germplasm collections would be the first logical step in evaluating the potential of these grain legumes.


M Anem


(Adapted from a book " An introduction to the botany of tropical crops'

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