Major production areas for processing peas are the north central states of Wisconsin, Minnesota, Michigan, and the western states of Washington and Oregon. The Palouse region of eastern Washington and northern Idaho is the primary domestic production area for dry peas, lentils, and chickpeas; while the coastal region of south-central California is of equal importance for chickpeas. Faba beans are of minor importance in the United States and are most often used for livestock feeding either as grain or as green forage. Faba beans have not gained any popularity in the United States as food and overseas market outlets have not been developed. Scattered areas of faba beans can be found in western Washington, irrigated areas of Montana and Wyoming, and several northeastern states. Prospects for expanded production of the cool season food legumes depend on overseas market outlets for these crops and prospects for increased domestic usage. Large areas of the arid western states could successfully produce cool season pulses, especially chickpea, lentil, and grasspea, if uses and outlets were developed. There has been some interest in grasspea as a specialty crop for the United States; however, at the present time, low yields and neuro-toxins in the seeds are major limitations. A description of the cool season food legumes, including production methods, disease and insect pests, and their potential as alternative crops for the United States is discussed in this review.
Chickpea. The genus Cicer contains 9 annual and 31 perennial species. Only one annual species, C. arietinum is cultivated. Cicer arietinum and C. reticulatum Lad., its presumed progenitor, have 2n = 16 chromosomes as do the other annual species. Chickpea plants are usually branched and have strong woody stems that can be strongly erect or semiprostrate. Flowers are borne on racemes that originate from stem axes. Flowers of desi types are typically violet; whereas flowers of kabuli types are white. Pods are usually borne singly and contain one, two and sometimes three seeds. Seeds of desi types are small, sharply angular and are variously pigmented. Kabuli type seeds lack pigmentation and are generally larger but can vary widely in size and have a "ramshead" shape.
Lentil. The genus Lens contains two biological species L. culinaris and L. nigricans (Bieb.) Godron both with 2n = 14 chromosomes (Muehlbauer 1991a). Lens culinaris contains three subspecies including ssp. culinaris Medic. the cultivated type, ssp. orientalis (Boiss.) Handel-Mazzeti, the presumed progenitor of the cultivated lentil, and ssp. odemensis Lad. Lens nigricans, the other biological species, containing ssp. nigricans and ssp. ervoides (Brign.) Grande, is not cultivated. Lentil plants, with their thin stems and small leaflets are very weakly upright. Flowers of lentil plants can range from nearly white to violet, often with blue or violet stripes on the standard, and are borne on racemes that originate from the stem axes. Pods typically have one or two and occasionally three seeds. Seeds are lens shaped and can vary in size from 2 to about 9 mm in diameter. Cotyledons can be red, yellow or green. Seeds can be variously pigmented but uniformly tan or beige seedcoats, sometimes mottled, are most common.
Faba bean. Vicia is a very large genus and contains over 130 species (Smartt 1990). Vicia faba, the cultivated species, has 2n = 12 chromosomes. Faba beans vary greatly in seed size, seed shape, seed color, growth period, and yield. Recognized types of faba bean include two subspecies; paucijuga L. and faba L. The latter subspecies has been further divided into (i) var. minor, which has small rounded seeds that are about 1 cm long; (ii) var. equina, with medium-sized seeds that are about 1.5 cm long and are typical of the so called "horse bean" and (iii) var. major, the horticultural type with large, broad, flat seeds that are about 2 to 3 cm long (Kay 1979). Faba bean plants are strongly upright with stiff main stems. Flowers are borne on the stem axes and are typically white and partly deep purple. Seeds are contained in large fleshy pods that vary considerably in length from less than 5 to over 30 cm. The smaller seeded types of faba beans, vars. minor and equina, are often referred to as field beans, while the larger seeded types, var. major, are referred to as "broadbeans" (Bond et al. 1985). The smaller seeded minor and equina types are commonly used for animal feeding while the larger seeded major types are most often used as a green vegetable or as a dry pulse. A common food use for faba beans in the Middle East is Foul Medanes a common breakfast dish in Egypt. The pods are often picked green and the seeds used directly as a green vegetable. Also, in some Mediterranean countries, small amounts of faba bean flour are used in bread making (Bond et al. 1985).
Grasspea. The grasspea, Lathyrus sativus, is a member of a large genus which contains over 150 species (Smartt 1990). Grasspea has 2n = 14 chromosomes. Grasspea plants are viny with flattened stems and are weakly upright. Flower morphology is similar to that of Pisum spp. Flowers are usually borne singly on racemes that originate from the stem axes. Pods usually contain 4 to 7 seeds that are small, usually round and heavily pigmented. Grasspea is very drought tolerant and produces some grain yield where other pulse crops are likely to fail completely. It is surprising therefore that this particular crop plant has not received much attention. Consequently, most of what is grown throughout the world are local landraces; although Kay (1979) lists several cultivars. These landraces all have a high content of ß-N-oxalyl-L-alpha, ß diaminopropionic acid (ODAP), the compound considered to incite the condition known as "lathyrism," an irreversible paralysis, if the seeds are consumed in excessive amounts (Smartt 1990). Progress is being made in reducing this compound in breeding lines of grasspea (A.E. Slinkard pers. commun.); a development which could lead to increased production of the crop for food in dry areas. Grasspea production, though very minor in the United States, is mostly from local landraces.
There is minimal cross pollination in peas (Gritton 1980), lentils (Wilson and Law 1972), and chickpeas (Niknejad and Khosh-Khui 1972); however, cross-pollination can be over 50% in faba beans (Poulsen 1975; Hanna and Lawes 1967). Cross-pollination is thought to be high in grasspea, but actual data have not been reported.
'Alaska' peas are used extensively by the dry pea industry in the United States. Numerous strains are available typically with large, smooth round green seeds. 'Alaska' peas are spring sown as soon as the land can be prepared and they bloom in about the 10th node; usually about 45 days after planting. The vine type is tall and weakly upright, indeterminate, and usually nonbranching. 'Alaska' typically reaches maturity approximately 95 days after sowing. The strain locally designated as 'Columbian' in the Palouse region of Washington and Idaho is popular with producers and processors because of its consistent high yields, good seed size, and good seed color qualities. 'Alaska 81', released to producers in 1984 (Muehlbauer 1987a), has produced comparable yields and seed quality and has virus resistance.
Cultivars of the small-sieve 'Alaska' type are used less extensively and are characterized by slightly smaller seed size, earlier maturity when compared with regular Alaska types, and they tend to be slightly dimpled and more susceptible to seed bleaching. Seed bleaching is a condition in which peas that are normally green at dry seed maturity lose their color, and take on a yellow-white appearance. Bleaching is brought about by moisture imbibition following rain or heavy dews.
'Latah' is a large yellow spring sown dry pea cultivar that has a long vine habit, blooms in about the 14th node, and is relatively high yielding. The cultivar was recently replaced by 'Umatilla' (Muehlbauer 1987a).
'Umatilla' is about 16 cm shorter and 13% higher yielding when compared with 'Latah'. 'Umatilla' sets double pods compared to the single podding habit for Latah and is resistant to seed shattering. The seeds of 'Umatilla' are larger and have averaged 18.7 per 100 seeds compared to 17.1 for 'Latah'. Seeds of 'Umatilla' are bright yellow; representing a significant improvement in seed quality when compared to 'Latah' in which the seeds often have an undesirable green cast. 'Umatilla' is very well adapted to splitting, a major use for yellow peas.
Several cultivars of fall sown peas (P. sativum ssp. arvense) (referred to locally as "Austrian Winter" peas) are currently available for commercial production. Yields of common Austrian Winter peas have been extremely variable because of disease and insect problems but they tend to be tolerant of fusarium root rot (Auld et al. 1979; Murray and Slinkard 1973). In Idaho, Austrian Winter peas are seeded in the fall (late September or early October) into roughly tilled soil. Winter survival is enhanced by the rough tillage, previous crop residues and snow cover during the colder winter months. Austrian Winter peas are often used for green manure to improve organic matter and nitrogen status of soils.
'Fenn' has purple flowers, an average vine length of nearly 2 m, triple flowers per peduncle, yellow cotyledons, and speckled seedcoats (Murray and Slinkard 1973). Yield potential of 'Fenn' is slightly larger than common Austrian Winter (Auld et al. 1979).
'Melrose' is similar to 'Fenn' and has purple flowers and an indeterminate flowering habit. 'Melrose' has a vine length of about 2 m and higher yield potential than 'common Austrian Winter' or 'Fenn' (Auld et al. 1979).
'Glacier' has shorter vines and improved seed yields when compared to 'Melrose' (Auld 1982). 'Glacier', with its shorter growth habit, is not as suitable for green manuring as are other Austrian Winter cultivars.
A number of commercial dry pea cultivars are available that are representative of types grown extensively either in Canada, Europe, New Zealand, or the United Kingdom. 'Marrowfats' is a popular dry pea type grown in England and used in the canning industry. 'Marrowfats' is also used extensively in the Orient as a snack item. 'Marrowfats' tends to be late maturing and often are severely attacked by infestations of powdery mildew. The seeds of 'Marrowfats' are typically large (30 to 35 g/100 seeds), slightly flattened, dimpled, and have green cotyledons. 'Marrowfats' often bleach and are of poor quality when wet conditions coincide with crop maturity. 'Marrowfats' of acceptable color can be grown if they are swathed at about 18 to 23% seed moisture content, threshed as soon as possible, and dried artificially.
'Chilean 78' is a yellow cotyledon type that requires a growth period of 95 to 110 days, depending on weather, to complete its growth cycle. 'Chilean 78' produces seeds which are about 6.5 mm in diameter and have varying degrees of seedcoat mottling.
'Brewer' (Muehlbauer 1987b) has yellow cotyledons and is earlier to flower and produces yields which average 20% greater than 'Chilean 78'. About 95 days are required for the growth period for 'Brewer'. 'Brewer' has seeds which are slightly larger and more uniform when compared to 'Chilean 78'.
'Laird' is a large yellow-seeded cultivar developed by A.E. Slinkard in Canada (Slinkard and Bhatty 1979). 'Laird' has excellent seed quality traits (large, thick seeds free of mottle and of good color); however, the major disadvantage of 'Laird' in the United States is late blooming and maturity (about 2 weeks later than 'Chilean').
'Eston' is a small-seeded yellow cotyledon cultivar developed by A.E. Slinkard in Canada (Slinkard 1981). Seeds of 'Eston' are about 40% smaller than 'Chilean 78', however, the cultivar has provided exceptionally high yields.
'Redchief' is a red cotyledon cultivar that consistently outyields 'Chilean 78'. 'Redchief' has about the same plant habit as 'Chilean 78' and requires about 95 to 105 days to mature, depending on the weather. 'Redchief' produces seeds that are about 6.0 mm in diameter, free of seedcoat mottling. Markets for large seeded red cotyledon lentils are limited; however, efforts are underway in the United States to develop suitable outlets (A.E. Slinkard pers. commun.).
'Indianhead' is a small black seeded cultivar developed in Canada also by A.E. Slinkard. 'Indianhead' is primarily used as a green manure cover crop on the Canadian prairies. The cultivar is characterized by rapid and vigorous vegetative growth.
'Emerald' is a green cotyledon cultivar recently released (Muehlbauer 1987b). The cultivar blooms several days later than 'Brewer' or 'Chilean 78'. Yields are equivalent to or slightly less than 'Brewer' in most years. The acceptability of a green cotyledon type in domestic and international markets is yet to be determined.
'Crimson' has small brown seeds with red cotyledons (Muehlbauer 1991b). The cultivar is typical of the lentils grown in the near east and northern Africa. The cultivar is well adapted to intermediate rainfall zones (350 to 400 mm annually) and therefore could become an alternative crop in rotation with wheat in those areas. Marketing of small red lentils will depend upon availability of equipment for decortication and splitting; the major process used for small red lentils.
'UC-5' is a pureline selection from 'White Spanish', a common cultivar grown in California for over 100 years. 'UC-5' is similar to both 'White Spanish' and 'Mission' but seems to have more resistance to early season root rot in California.
'Surutato 77' is a Mexican cultivar that has shown excellent resistance to fusarium wilt in California and Mexico. 'Surutato 77' blooms and matures about 7 days earlier compared to 'UC-5' and 'Mission' in California. Because of its disease resistance and excellent quality, 'Surutato 77' has become the predominant cultivar in Mexico, and appears to have replaced 'UC-5' in California. Production of 'Surutato 77' is also expanding in the Pacific Northwest.
'Tammany' is a unifoliate cultivar recently released (Muehlbauer and Kaiser 1987) for production in the Pacific Northwest. The cultivar is similar to 'Surutato 77', but is several days earlier to mature.
'Garnet' is a desi type cultivar (Muehlbauer and Kaiser 1987) with small brown angular seeds. Desi types are grown on a limited but steadily increasing area in the Pacific Northwest. Desi type cultivars have potential as an alternative crop to cereals in dry areas and can often replace summer fallowing.
'Sarah' originated from 'C235', an Ascochyta blight-resistant desi type, developed in India. 'Sarah' has shown excellent resistance to Ascochyta blight in the Palouse region of eastern Washington and northern Idaho (Muehlbauer and Kaiser 1990). Yields and quality are also very good. 'Sarah' is also adapted to dry areas and could become a significant rotational crop with the cereals if markets can be developed.
The adaptation of lentil, chickpea, and grasspea to dry conditions make these crops suitable for production in the semi-arid regions of the western United States. In those areas, grain legumes could be ideal rotational crops with cereals or possibly can be used as fallow replacement crops in regions that receive sufficient rainfall to permit annual cropping.
Inoculation with the appropriate strain of Rhizobia is essential when these food legumes are seeded into fields for the first time. Fields should be reinoculated if there has been a lapse of several years between crops. Rhizobium leguminosarum is the appropriate inoculant for peas, lentils, grasspeas, and faba beans; whereas, chickpeas require a strain specific for Cicer species. Inoculants can be purchased in either the peat or the granular form. The peat form is often applied to the seeds with a sticker to improve adherence. Application of the peat inoculant over the seed in the drill hopper is not advised because it tends to settle to the bottom of the hopper and not be uniformly distributed throughout the field.
The sulfur containing amino acids, methionine, and cystine, are limiting in the proteins of these grain legumes. However, a favorable amino acid profile is easily obtained with the combined use of cereal grains in the diet.
The cool season food legumes usually do not respond to nitrogen fertilization; but low rates, applied in bands next to but not in contact with the seeds, at planting can be beneficial to early stand establishment. There is a high requirement for phosphorous and soils should be fertilized to adequate levels. These crops seem to respond to additions of potassium and sulfur where soil tests indicate deficiencies. For additional information on mineral nutrient requirements, see Muehlbauer and Summerfield (1989).
Seed treatments. Seeds of peas, lentils, chickpeas, and faba beans should be treated with an appropriate fungicide to prevent seed decay and pre- and post-emergence damping-off. Pythium spp. and Rhizoctonia spp. can cause extensive damage to stands if not controlled. To prevent damage from wireworms and seedcorn maggots, seeds should be treated with an appropriate insecticide.
Seeding rates and depths. Optimum plant populations vary for the cool season food legumes. The optimum density is about 880,000 plants/ha for lentils and 310,000 plants/ha for chickpeas. Plant densities from 130,000 to 550,000/ha are used in faba bean production and densities of 200,000 to 250,000/ha are common for grasspea. The smaller seeded cultivars are usually seeded at slightly higher densities.
Seeding depths for peas and faba beans can be up to 7.5 cm. Deep seeding is often used to prevent phytotoxicity from shallow incorporated herbicides. Lentils and chickpeas have difficulties in emergence from deep planting and are sown no deeper than 5 cm depending on moisture conditions.
Weed problems. Weeds can compete with the food legumes and significantly lower seed yields. In addition, exudates from weeds can cause staining of the seeds and reduce crop quality. Annual grass weeds such as wild oat are a particularly serious weed problem in the food legumes. Control is most often accomplished through the use of soil incorporated herbicides. Post-emergent applications of herbicides can be effective for broadleaf weed control in peas and faba beans. Herbicides registered for use on this group of crops varies between states. In all cases, however, rates and the timing of herbicide applications are extremely important for effective weed control and to minimize crop injury.
Lentils and chickpeas are less competitive with weeds when compared to peas or faba beans. Because of their less competitive nature, careful attention must be paid to obtain optimum weed control. The best broadleaf weed control methods in these two crops have involved preemergence surface applications of herbicides.
Weed infestations can be troublesome at the time of harvest through staining of the seeds during the threshing operation. Nightshade (Solanum spp.) can be particularly damaging to the appearance of kabuli chickpeas and staining can be so severe as to make the crop unacceptable to processors. Seeds of the other cool season food legumes can also be badly stained by weed exudates.
Of the food legumes, chickpea, lentil, and grasspea seem to have the greatest potential for expanded production. These grain legumes are tolerant of dry conditions and can be used as fallow replacements in many areas of the arid western states. Development of grasspea as a viable drought tolerant crop will depend on the incorporation and use of low neuro-toxin germplasm.
| Scientific name | Common name | Region of adaptation |
| Arachis hypogaea L. | Peanut | Humid to semi-arid |
| Cajanus cajan (L.) Millsp. | Pigeon pea | Humid to semi-arid |
| Cicer arietinum L. | Chickpea | Cool season,sub-tropical semi-arid |
| Glycine max (L.) Merr. | Soybean | Humid to sub-humid cool season or sub-tropical |
| Lablab purpureus (L.) Sweet | Hyacinth bean | Sub-humid to semi-arid |
| Lathyrus sativus L. | Grasspea | Semi-arid |
| Lens culinaris Medic. | Lentil | Cool season to semi-arid |
| Lupinus spp. | Lupin | Humid to sub-humid |
| Macrotyloma uniflorum (Lam.) Verdc. | Horse gram | Sub-humid to semi-arid |
| Parkia spp. | Locust bean | Sub-humid to semi-arid |
| Phaseolus lunatus L. | Lima bean | Humid to sub-humid |
| Phaseolus vulgaris L. | Common bean | Humid to sub-humid |
| Phosphocarpus tetragonologa (L.) DC | Winged bean | Humid tropics |
| Pisum sativum L. | Field pea | Temperate to sub-tropical |
| Vica faba L. | Faba bean | Sub-tropical to temperate |
| Vigna aureus (Roxb.) Hepper | Green gram | Humid to semi-arid |
| Vigna radiata (L.) Wilczek | Mung bean | Humid to semi-arid |
| Vigna unguiculata (L.) Walp. | Cowpea | Humid to semi-arid |
| Area (1000 ha) | Yield (kg/ha) | Total production (1000t) | ||||
| Common name | 1979-81 | 1987-89 | 1979-81 | 1987-89 | 1979-81 | 1987-89 |
| Chickpea | 9601 | 9593 | 625 | 713 | 6028 | 6850 |
| Faba bean | 3685 | 3186 | 1162 | 1309 | 4284 | 4171 |
| Field pea | 7501 | 9899 | 1140 | 1605 | 8494 | 15885 |
| Lentil | 2201 | 3217 | 596 | 795 | 1312 | 2562 |
| World production (all pulses)z | 61074 | 68886 | 674 | 815 | 41153 | 56092 |
| Area (1000 ha) | Yield (kg/ha) | Total production (1000t) | ||||
| Common name | 1979-81 | 1987-89 | 1979-81 | 1987-89 | 1979-81 | 1987-89 |
| Chickpeaz | 4 | 6 | 1200 | 1200 | 4.8 | 7.2 |
| Lentily | 78 | 43 | 1073 | 1314 | 84 | 60 |
| Faba beanz | --- | <1 | --- | 1600 | --- | 1.6 |
| Field peay | 70 | 76 | 2310 | 2696 | 163 | 204 |