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Hymowitz, T. 1990. Grain legumes. p. 54-57. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR.

Grain Legumes

Theodore Hymowitz


  1. INTRODUCTION
  2. PRIMARY GRAIN LEGUMES
  3. SECONDARY GRAIN-LEGUMES
  4. TERTIARY GRAIN LEGUMES
  5. REMARKS
  6. REFERENCES
  7. Table 1
  8. Table 2
  9. Table 3
  10. Table 4
  11. Table 5
  12. Table 6
  13. Table 7
  14. Table 8
  15. Fig. 1

INTRODUCTION

The two plant families of greatest importance to world agriculture are the 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 (Table 1). On the other hand, 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 (Table 2).

In this paper, I will present 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 (Table 3).

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 (Table 4).

For convenience 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.

PRIMARY GRAIN LEGUMES

Today, twelve crops constitute the primary grain legumes (Table 5). They are characterized by the following:

SECONDARY GRAIN-LEGUMES

Fourteen crops constitute the secondary grain legumes (Table 7). They are characterized by the following:

TERTIARY GRAIN LEGUMES

The tertiary grain legumes (Table 8) 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.

REMARKS

Grain legumes form a major component of the human diet. They are easily stored and transported. Several grain legumes play major roles in world commerce. However, there are a number of constraints concerning grain legumes that should be addressed at this point.

An ubiquitous complaint about grain legumes concerns their low yield level when compared to the cereals. Unfortunately, the internal plumbing of grain legume plants is not well understood. In all grain legumes three processes operate against high grain yields, that is, photorespiration, nitrogen fixation and photosynthetic energy relationships. Photorespiration occurs in the light and consumes about 30% of the products of photosynthesis in all grain legumes. At present, there is no known benefit of photorespiration. For example, maize functions without photorespiration. Secondly, the symbiotic relationship between the legume plant and the Rhizobium bacterial organism does not come free of charge. The diversion of carbohydrates by the plant for use by the bacterial organism to fix nitrogen reduces potential grain production by about 10%. Lastly, it takes more energy by a plant to produce a given amount of oil and protein than starch. This energy intensive process ultimately manifests itself in lower yields in grain legumes.

Another complaint about grain legumes is that they are susceptible to many pests and pathogens. Unfortunately, the relationship between the impact of germplasm collections and the funding of scientific personnel is not well understood. The germplasm collections of the major cereals are from 2 to 8 times larger than the primary legume collections. Secondly, in the U.S. there are at a minimum 10 times as many maize breeders than soybean breeders. Most probably these comparisons are quite similar for plant pathologists and entomologists. Thus, it is not that cereals are less susceptible to pests and pathogens than grain legumes but rather, that the genetic resources (i.e. germplasm collections) are available to an enormous pool of scientific personnel to solve specific problems.

In summation. the grain legumes exhibit an enormous amount of variation and this variation is silently awaiting commercial exploitation. Funds lacking in the past for extensive and intensive research on grain legumes are becoming increasingly available. Lastly, recent advances in yield increase of wheat, rice, and maize has raised hopes that similar results may be possible with the grain legumes by classical plant breeding techniques or by newer genetic engineering approaches.

REFERENCES


Table 1. World production of major crops. Source:FAO Production Yearbook 1986

Crops Million t
Wheat 536
Maize 481
Rice 476
Potato 308
Barley 180
Cassava 137
Sweet potato 110
Soybean 96
Cane sugar 93
Sorghum 71


Table 2. Uses of legumes.

Use Example
Chemical:
laxative senna pods (Cassia)
insecticide, fish poison rotenone (Tephrosia), (Derris, Lonchocarpus)
resin for paints, lacquers (Hymenaea, Copaifera)
gum gum arabic (Acacia), guar gum (Cyamopsis)
tannin bark of Acacia
dye indigo (Indigofera)
steroids seed of Glycine "the pill"
Esthetic value wisteria (Wisteria), flamboyant (Delonix)
Timber rosewood (Dalbergia)
Pasture clovers (Trifolium), alfalfa (Medicago)
Browse trees and shrubs koa haole (Leucaena), honey locust (Gleditsia)
Green manure or soil cover sunn hemp (Crotalaria), kudzu (Pueraria)
Green and conserved forage vetches (Vicia), sweet clovers (Melilotus)
Ornamental jewelry rosary pea (Abrus)
Charcoal mesquite (Prosopis)
Food:
spice fenugreek (Trigonella)
extract licorice (Glycyrrhiza)
seasoning tamarind (Tamarindus)
tubers yam beans (Pachyrhizus, Sphenostylis)
flowers, leaves, shoots winged bean (Psophocarpus)
chocolate substitute carob (Ceratonia)
starch tubers of kudzu (Pueraria)
beverage alfalfa tea (Medicago)
honey nectar of Trifolium, Medicago, Prosopis
grain legumes peas (Pisum), beans (Phaseolus), lentils (Lens)


Table 3. World production of grain legumes. Source: FAO Production Yearbook 1986.

Crop Million t
Soybean 96
Peanut 17
Beans 15
Pea 14
Chickpea 8
Faba bean 4
Lentil 2


Table 4. World vegetable oil production. Source: Soya Bluebook, 1986 American Soybean Association.

Commodity Million t
Soybean 13.5
Palm 7.7
Sunflower seed 6.5
Rape seed 6.0
Cottonseed 3.6
Peanut 3.2
Coconut 3.1
Olive 1.2
Palm kernel 1.1
Linseed 0.7


Table 5. Scientific name, common name and regions of diversity of primary grain legumes.

Scientific name Common name Regions of diversity
Arachis hypogaea L. Peanut South America
Cajanus cajan (L.) Millsp. Pigeon pea India
Cicer arietinum L. Chickpea SW Asia, Ethiopia, India
Glycine max (L.) Merr. Soybean East Asia
Lens culinaris Medic. Lentil SW Asia, Mediterranean
Phaseolus lunatus L. Lima bean Peru
Phaseolus vulgaris L. Common bean Mexico, Guatemala
Pisum sativum L. Pea SW Asia, Mediterranean
Vicia faba L. Faba bean Asia, Mediterranean
Vigna angularis (Willd.) Ohwi & Ohashi Adzuki bean Japan, China
Vigna radiate (L.) Wilczek Mung bean India, SE Asia
Vigna unguiculata (L.) Walp. Cowpea W. Africa, India


Table 6. The species in the genus Glycine, chromosome number, genome designation and distribution.

Species 2n Genome Distribution
Subgenus Glycine
1. G. arenaria Tind. 40 Australia
2. G. argyrea Tind. 40 A2A2 Australia
3. G. canescens F.J. Herm. 40 AA Australia
4. G. clandestina Wendl. 40 A1A1 Australia
5. G. curvata Tind. 40 Australia
6. G. cyrtoloba Tind. 40 CC Australia
7. G. falcata Benth. 40 FF Australia
8. G. latifolia (Benth.) Newell & Hymowitz 40 B1B1 Australia
9. G. latrobeana (Meissn.) Benth. 40 Australia
10. G. microphylla (Benth.) Tind. 40 BB Australia
11. G. tabacina (Labill.) Benth. 40 B2B2 Australia
80 AAB2B2,BBB2B2 Australia, West Central & South Pacific Is., Taiwan, ?South China
12. G. tomentella Hayata 38 EE Australia
40 DD Australia, Papua New Guinea
78 DDEE Australia Papua New Guinea
80 AADD Australia, Papua New Guinea, Philippines, Taiwan, ?South China
Subgenus soja (Moench) F.J. Herm.
13. G. soja Sieb. & Zucc. 40 GG China, Taiwan, Japan, Korea, USSR
14. G. max (L.) Merr. 40 GG Cultigen


Table 7. Scientific name, common name and regions of diversity of secondary grain legumes.

Scientific name Common name Regions of diversity
Canavalia ensiformis (L.) DC. Jackbean Mexico, Southwest US
Canavalia gladiata (Jacq.) DC. Swordbean India, Humid Africa
Cyamopsis tetragonoloba (L.) Taub. Guar India, Pakistan
Lablab purpureus (L.) Sweet Hyacinth bean India
Lathyrus sativus L. Chickling vetch India
Lupinus ssp. Lupins Europe, Andean Highlands
Macrotyloma geocarpum (Harms) Marachel & Baudet Kersting's groundnut Africa
Phaseolus acutifolius A. Gray Tepary bean Mexico, Southwest US
Phaseolus coccineus L. Scarlet runner bean Central American Highlands
Psophocar-pus tetragonloba (L.) DC. Winged bean Papua New Guinea, Southeast Asia
Vigna aconitifolia (Jacq.) Marechal Moth bean India
Vigna mungo (L.) Hepper Black gram Indo-Pakistan subcont.
Vigna subterranea (L.) Verdc. Bambara groundnut Sub-Sahara Africa
Vigna umbellata (Thumb.) Ohwi & Ohashi Rice bean South and Southeast Asia


Table 8. Scientific name, common name and regions of diversity of some tertiary grain legumes.

Scientific name Common name Regions of diversity
Amphicarpa bracteata (L.) Fem. Hog peanut North America
Apios americana Medic. Potato bean North America
Cordeauxia edulis Hemsl. Ye-eb Somalia, Ethiopia
Macrotyloma uniflorum (Lam.) Verdc. Horse gram Southern India, Trop. Africa
Strophostyles helvola (L.) Ell. Wild bean North America
Tylosema esculentum (Burchell) Schreiber Marama bean South Africa


Fig. 1. Proposed idiogram of the pachytene chromosomes of the soybean. Arrow indicates centromere location (2400x).


Last update October 2, 1997 by aw