Triticum aestivum L.
Common wheat, Bread wheat
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
- Chemical Analysis of Biomass Fuels
Common wheat, best known and most widely cultivated of the wheats, is
cultivated for the grain, used whole or ground. Fine ground, it is the source
of flour for the world's breadmaking. Main use is for flour and bread-stuffs
known by various names throughout the world. Grain also is the source of
alcoholic beverages, beer, industrial alcohol made into synthetic rubber and
explosives. Bran from flour milling also an important livestock feed; germ is
valuable addition to feed concentrate. Grain fed to livestock whole or
coarsely ground. Starch is used for pastes and sizing textiles. Straw made
into mats, carpets, baskets, and used for packing material, cattle bedding, and
paper manufacturing. Some wheat is cut for hay. Wheat grown for grain crop is
also used for pasture before the stems elongate and as a temporary pasturage;
it is nutritious and palatable.
According to Hartwell (19671971), the seeds are used in folk remedies for
cancers, corns, tumors, warts, and whitlow. Reported to be antivinous,
bilious, demulcent, discutient, diuretic, emollient, excipient, intoxicant,
laxative, useful as a poultice, restorative, sedative, used as a shampoo and
vulnerary, common wheat is a folk remedy for burns, cancer, diarrhea,
dysentery, ecchymosis, epistaxis, fertility, fever, flux, gravel, hematuria,
hemoptysis, hemorrhage, incontinence, leprosy, leucorrhea, menorrhagia,
neurasthenia, nightsweat, perspiration, scald, tumor, warts, whitlow, and
wounds (Duke and Wain, 1981).
Per 100 g, the grain is reported to contain 326335 calories, 11.5714.0 g
H2O, 9.414.0 g protein, 1.82.5 g fat, 69.175.4 g total carbohydrate, 1.82.3
g fiber, 1.7 g ash, 3646 mg Ca, 354400 mg P, 3.04.3 mg Fe, 370435 mg K,
0.430.66 mg thiamine, 0.110.12 mg riboflavin, and 4.35.3 mg niacin. The
grain contains allantoin plus uricase; sinapic acid has been isolated from
wheat germ. The grain is said to cause poisoning in stock, though no toxic
principle has been found. Wheat can absorb toxic concentrations of selenium
but "selenium" wheat rarely causes poisoning (Watt and Breyer-Brandwijk, 1962).
One kg of grain contains 0.03 mg As2O3; grain also contains Mg, Mn, Zn, Fe, and
Cu. Amino acid composition is shown in the Table from the Wealth of India.
Essential amino acids in wheat proteins (after Wealth of India)
| ||Inner |
|Bran (%) ||Germ (%) ||Whole |
|Arginine || 2.92 ||4.50 ||7.53 ||6.20 ||3.81|
|Histidine ||1.65 ||1.74 ||1.68 || 3.03 ||1.65|
|Isoleucine || 7.02 ||6.56 ||4.50 ||5.23 ||6.97|
|Leucine ||9.14 || 7.98 || 6.52 ||7.33 ||8.27|
|Lysine ||1.92 ||2.60 ||3.87 ||5.44 || 2.80|
|Methionine ||1.12 ||1.40 ||1.09 ||1.28 ||1.32|
|Phenylalanine ||3.95 || 3.43 ||2.45 ||2.47 ||3.68|
|Threonine ||2.56 ||2.72 ||2.85 ||6.28 ||2.78|
|Tryptophan ||0.93 || 1.12 ||1.83 ||0.90 ||1.03|
|Valine ||3.65 ||4.02 ||4.10 ||4.20 ||4.00|
Wheat germ oil is rich in tocopherols (vit. E) and essential fatty acids.
Sitosterol, ergosterol, and campesterol, phospatidic and
glyceroinositophosphatidic acids, phytoglycolipid, serine, etc., are also
reported. Wheat contains ca 1% pectin. Wheat bran oil is also high in
tocopherols, 68% of which is epsilon-tocopherol. Alpha-tocopherol, which has
the highest vit. E activity of the tocopherols, constitutes only 11% of the
tocopherols in the bran oil. Much more detail on wheat chemistry can be found
in the Wealth of India (C.S.I.R., 19481976). Fresh forage contains 3035% DM,
of which (ZMB) 8.623.3% is CP, 15.121.5% CF, 6.111.6% ash, 1.83.7% EE, and
40.166.0 NFE. Straw, on the other hand, contains 92.0% DM, of which 3.1% is
CP, 45.4% CF, 10.2% ash, 1.1% EE, and 40.2% NFE. Indian hay (ZMB) contained
5.1% CP, 35.1% CF, 7.2% ash, 1.3% EE, and 51.3% NFE; Indian silage 3.5% Cp,
39.4% CF, 14.6% ash, 0.5% EE, and 42.0% NFE (Gohl, 1981). Leaf protein isolate
contains (g/16g N): methionine, 2.39; tryptophane, 1.41; histidine, 1.97;
arginine, 9.16; and total lysine.
Annual grass; culms simple, erect, hollow or pithy, glabrous, up to 1.2 m tall;
leaves flat, narrow, 2038 cm long, about 1.3 cm broad; spikes long, slender,
dorsally compressed, somewhat flattened; rachis tough, not separating from
spikelet at maturity; spikelets 25-flowered, relatively far apart on stem,
slightly overlapping, nearly erect, pressed close to rachis; glumes keeled in
upper half, firm, glabrous, shorter than the lemmas; lemmas awned or awnless,
less than 1.3 cm long; palea as long as the lemma, remaining entire at
maturity; caryopsis free-threshing, soft or hard, red or white. Hexaploid.
Reported from the China-Japan, Hindustani, and Central Asia Centers of
Diversity, wheat, or cvs thereof, is reported to tolerate alkali, bunt,
disease, drought, herbicide, hydrogen flouride, high pH, laterite, low pH,
mildew, salt, nematodes, phage, rust, smog, smut, and virus (Duke, 1978). This
species is the source of most US wheat cvs, there being >200 named cvs
cultivated in the United States. Many other cvs exist elsewhere. Since so
many cvs are available, one should consult the agricultural agent of a
particular region to ascertain which ones are best for, that particular area.
No attempt will be made here to describe these cvs, except to indicate they are
classified in the following manner: Hard red spring wheats yielding high
quality bread flour; Hard red winter wheats producing superior bread flours;
Soft red winter wheats yielding flour for cakes and biscuits; Durum wheat
hybrids yielding hard kernels made into semolina for macaroni products; red
durum hybrids used in mixed wheat flours; white wheats yielding grain for
breakfast foods, flour for cakes, pastries, and crackers, and various mixed
wheats used mostly for feeds for livestock. The spring and winter types
constitute about 95% of the wheat grown in the United States. (2n = 42.)
T. aestivum known only under cultivation; its nativity has been lost.
Briggle (1981) states, "The precise origin of the wheat plant as we know it
today is not known. Wheat evolved from wild grasses, probably somewhere in the
Near East. A very likely place of origin is the area known in early historical
times as the Fertile Crescenta region with rich soils in the upper reaches of
the Tigris-Euphrates drainage basin.
Ranging from Boreal Moist to Rain through Tropical Very Dry to Dry Forest Life
Zones, wheat is reported to tolerate annual precipitation of 1.9 to 25.0 dm
(mean of 162 cases = 7.9), annual temperature of 4.9 to 27.8°C (mean of 162
cases = 13.4), and pH of 4.5 to 8.3 (mean of 141 cases = 6.5) (Duke, 1978).
Adapted to a wide variety of climatic conditions. Principal wheat-growing
areas of the world have similar growing conditions: the Russian prairies, the
fertile pampas of Argentina, the Wheat belt of United States, all have fertile
dark soils rich in nitrogen; rather hot, cloudless summers; rainfall which,
although low, is well-distributed. A good wheat soil has physical structure
which holds together, making good water retention and favorable conditions for
nitrate formation. Hot, humid conditions are unfavorable for wheat-growing.
Propagation by seeds. Use minimum number of tillage operations to help prevent
soil compaction and restriction of root and water penetration. The two
principal purposes for preparing a seedbed are the development of nitrates and
the conservation of moisture. In areas where rainfall is limited, as in
western Kansas, summer fallowing is the most successful method for storing and
conserving soil moisture. Good summer fallow is one in which the soil is kept
free of plant growth and the soil surface is kept open to permit rapid
penetration of moisture, and cloddy to prevent wind and water erosion. Avoid
excessive turning up of new soil because such tillage dries out the soil.
Start first tillage in spring as soon as weeds begin to grow, usually about May
1. After the first tillage, cultivate soil only enough to prevent weed growth
and to maintain a rough surface. In some areas stubble mulch tillage method of
fallowing is practiced, by which enough residue is anchored to soil surface to
protect the crop and soil from wind and water erosion. Contour and stripe
planting may be used. Cultivation of soil well in advance of seeding hastens
the decay of organic matter, thus liberating nitrogen and making it available
to plants as nitrates. Early seedbed preparation is necessary for highest
yields. Crop rotation of fallow, wheat, and sorghum is an excellent practice
in some areas. Date of planting wheat seed depends on the locality, type of
wheat, and the hessian fly problem. Rates of seeding differ with the type of
wheat, size of seed, and locality, varying from 22100 kg/ha, generally 33
kg/ha is recommended. Local agents should be consulted about weed control.
Irrigated wheat averages 86.25 bu/ha instead of 65.5 bu/ha. Wheat uses about
60 cm of water throughout the growing season. The type of fertilizer used
should be determined by a soil test. The three main types being nitrogen,
phosphorus, and potash. However, moisture, rather than plant food nutrients,
is the limiting factor in production in most seasons under dryland farming.
Yield response to nitrogen fertilizer is determined by moisture, soil, type of
seedbed, and crop stand. Nitrogen may be supplied with anhydrous ammonia,
nitrogen solution, or in dry forms as ammonium nitrate, urea or in mixed
fertilizers. Phosphate is best supplied with superphosphate or in a mixed
fertilizer. Potassium is best supplied with muriate of potash or in a mixed
fertilizer. Nitrogen fertilizer and potash may be broadcast and worked into
the seedbed before seeding or applied at time of seeding by using a combination
fertilizer-grain drill, or applied as a top-dressing during the winter just
prior to spring growth. Superphosphates are usually placed in the row with the
seed (Reed, 1976).
Winter wheat is most widely used for temporary pasture crop. It can be grazed
without apparent injury to the grain crop, provided it is not grazed severely
over an extended period of time, or too late in the spring. Pasturing should
not begin in fall until plants have become firmly rooted. Grazing should be
discontinued just before plants begin to grow erect in preparation for
jointing. Harvesting the grain should be delayed until the wheat is
sufficiently mature to store well, with moisture content of 13.5% or less under
ordinary conditions. Wheat is harvested with combine properly adjusted to
minimize grain losses. Storage bins should be cleaned and treated before grain
is placed in them. Seed storage to 3 years in dry storage bins.
In general, yields of wheat vary from 40.4 to 65.1 bu/ha, with higher yields up
to 85 bu/ha obtained with irrigation. Yields depend on climatic conditions,
variety or cultivar of wheat planted, size of kernel, and number of kernels per
head. Production figures presented by Briggle (1981) showed Iran rather low
with 1,100 kg/ha ranging to West Germany with 4,110 kg/ha, cf the US with 2,040
kg/ha. In the US, Ohio was high with 3,162 kg/ha compared with South Dakota at
1,608 kg/ha. In 1979 the world low production yield figure was 160 kg/ha in
Jordan, the international production was 1,782 kg/ha, and the world high
production yield was 7,000 in U.A.E. (FAO, 1980a). Dibb (1983) compares US
yields of 2,100 kg/ha to 1,300 kg/ha in the developing countries and a world
reported record of 14,500 kg/ha. Wheat is one of the most important food
plants of man. It enters into international trade more than any other food.
World production in 1971 was 303 million metric tons. Major producers are, in
order, United States, USSR, China, Canada, France, Italy, Indian Union,
Argentina, Australia, and Pakistan. The economic stability of many nations is
affected by the exchange in wheat and other commodities (Reed, 1976).
According to the phytomass files (Duke, 1981b), annual productivity ranges from
4 to 18 MT/ha. Chaff is estimated to constitute 25% of the grain. Wheat straw
is calculated at 1/22 times grain yield, more frequently, 1 1/2 times.
However, in some countries, wheat biomass averages more than 6 MT/ha, double
this if double cropped. The highest phytomass figure to date in our files is
18 MT/ha/yr. Australians figure that methanol produced from wheat stubble is
about 7 times as expensive per GJ as Kuwaite oil, but half as expensive as
ethanol from wheat grain ($A 1.25 per GJ for oil, 8.8 for methanol from
stubble, 14.115.4 for ethanol from grain) (Boardman, 1980). Research
reiterated by Palz and Chartier (1980) indicated that straw from winter wheat,
summer wheat, winter barley, summer barley, winter rye, and oats all gave
calorific values based on moisture-free dry matter of 17.04 (± 5%) MJ/kg, or
based on air dry matter 15.06 (± 3.5%) MJ/kg. High N fertilization raised
calorific values by ca 425 KJ/kg. Increasing moisture content from 14 to 20%
reduced calorific value by 9%. Since straw available as feedstock is normally
air-dry, a calorific value of 15 MJ/kg is assumed by Palz and Chartier (1980)
for all cereal varieties and species. The assumed grain straw ratio for:
wheat is 1.23
barley is 1.45
oats is 1.16
rye is 0.70
other cereals are 1.10
Elsewhere Palz and Chartier assume 17.5 MJ/kg as the typical energy value for
the dry matter of herbaceous materials. Reducing Kvech's (1979) numbers by 10%
to convert approximately to DM yields for residues, we have the following
figures for Kourim, Czechoslovakia, rounded to the nearest MT: Medicago
sativa, 7; Trifolium pratense, 4; Vicia faba, 4; Avena
sativa, 3; Lolium perenne, 3; Secale cereale, 3; Trifolium
repens, 3; Triticum aestivum, 3; Brassica Tapa, 2; Hordeum
vulgare, 2; Phacelia tanacelifolia, 2; Beta vulgaris, 1;
Sinapis alba, 1; Solanum tuberosum, 1. The harvest index of
cereals in general is ca 0.36, meaning that 64% of total above ground crop
production is residue, at least 1/3 of which should be left in the field.
'Prior' barley has the HI ranging from 0.48 to 0.41 with increasing N
fertilizer levels. Wheat usually runs about 0.30 to 0.35 HI. Rice often has a
high HI, while grain sorghum generally has a low HI. The 'Green Revolution'
cereals with short straw and high grain yields have relatively high HI.
Biomass engineers might prefer a low HI. The estimated cost of ethanol and
methanol from cereal grains is $0.35 per liter, and $0.16 per liter; the
overall energy efficiency, i.e. the ratio of the energy value of the gross
liquid fuel output to the total energy inputs including feedstocks is 0.34 for
ethanol and 0.40 for methanol. For each ton of ethanol produced from cereal
grains, there is another ton of dry distiller's residue, valued in the U.S. as
animal feed (Stewart et al. 1979). Briggle's figures show that fertilizer
constitutes the biggest energy input for spring wheat, 2,102,000 Btu/ha out of
a total energy input of 5,646,000 Btu/ha, compared with 3,401,000 out of 7,478
for winterwheat. Preplanting required 1,025,000 Btu/ha for spring wheat,
994,000 for winterwheat; planting takes 268,000235,000, fertilizer application
10,00057,000, pesticide application 18,00044,000, pesticides 14,00060,000,
irrigation 146,000953,000, harvesting 257,000398,000, truck 271,000368,000,
grain handling 7,00015,000, farm pickup 763,000800,000, farm auto
220,000233,000, electricity and overhead, 42,000, miscellaneous 54,000 to
326,000 Btu/ha (Briggle, 1981). Briggle's earlier work (1980) showed wide
variation in output/input ratios, the highest ratio (4.64) representing hard
red spring wheat yields of ca 4.7 MT/ha (equiv. 15,500,000 kcal/ha) from energy
inputs of only 3,350,000 kcal/ha in Idaho, the lowest ratio being 0.43,
representing Texan winter wheat yields of ca 2.4 MT/ha. Energy inputs ranged
from 218 million kcal/ha and yields from ca 1,000 to 5,000 kg. Briggle (1980)
adds that wheat is an energy frugal crop, produced with the energy equivalent
of less than 5 barrels oil/ha compared to corn at closer to 10 barrels and
potatoes at nearly 25.
Wheats are attacked by many fungi and other organisms. Some cvs are resistant
to the various rusts, smuts, and virus diseases. The most important fungal
diseases of wheats are the following. Extension agents should be consulted
concerning diseases in an area before growing wheat. Also cvs should be
selected for growing which are resistant to such diseases. Fungal diseases of
wheat: Rusts (Stem or Black rust, Puccinia graiminis f. sp.
tritici; Leaf or Brown rust, P. recondita; Stripe or Yellow rust,
P. glumarum); Smuts (Bunt or Covered smut, Tilletia caries and
T. foetida; Dwarf Loose smut, Ustilago tritici); Mildews (Downy
mildew, Sclerospora macrospora; Powdery mildew, Erysiphe graminis
f. sp. tritici); Root rots (Common root rot, Helminthosporium
spp. and Fusarium spp.; Take-all root rot, Ophiobolus graminis;
Browning root rot, Pythium spp.); Foot rots (Eye spot,
Cercosporella herpotrichoides; Snow mold, Fusarium spp.); Blights
and Scabs (Head blight or scab, Fusarium spp.; Rhizoctonia blight,
Rhizoctonia spp.; Typhula blight, Typhula spp.; Anthracose,
Colletotrichum graminicola; Kernel smudge, Helminthosporium spp.,
Alternaria spp.); Blotches (Glume blotch, Septoria nodorum; Leaf
blotch, S. tritici; Speckled leaf disease, Leptosphaeria avenaria
f. sp. triticea; Ergot, Claviceps purpurea. Diseases caused by
bacteria include the following: Pseudomonas atrofaciens (Basal glume rot
or bacterial black-tip) and Xanthomonas transluscens f. sp.
undulosa (Black shaff). Diseases caused by viruses include the
following: Wheat mosaic, Wheat streak mosaic, Wheat striate mosaic, and Yellow
dwarf. Insect pests encountered in various areas include: English grain aphid
is the most common aphid affecting wheat, attacking the heads and being very
damaging when populations become high prior to the late-dough stage. Other
insects and cutworms, darkling beetles, hessian fly, and salt marsh
caterpillars, may cause damage during the seedling stage. A great number of
species of nematodes have been isolated from wheats in various parts of the
world. Where nematodes are a problem, the agricultural agent should be
Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985)
reported a spread of 17.51 to 16.49 MJ/kg, compared to 13.76 for weathered rice
straw to 23.28 MJ/kg for prune pits. On a % DM basis, the straw
contained 71.30% volatiles, 8.90% ash, 19.80% fixed carbon, 43.20% C, 5.00% H,
39.40% O, 0.61% N, 0.11% S, 0.28% Cl, and undetermined residue.
Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985)
reported a spread of 16.20 to 15.16 MJ/kg, compared to 13.76 for weathered rice
straw to 23.28 MJ/kg for prune pits. On a % DM basis, the dust
contained 69.85% volatiles, 13.68% ash, 16.47% fixed carbon, 41.38% C, 5.10% H,
35.19% O, 3.04% N, 0.19% S, and undetermined residue.
Complete list of references for Duke, Handbook of Energy Crops
- Boardman, N.K. 1980. Energy from the biological conversion of solar energy.
Phil. Trans. R. Soc. London A 295:477489.
- Briggle, L.W. 1980. Introduction to energy use in wheat production. p. 109116.
In: Pimenter, D. (ed.), Handbook of energy utilization in agriculture. CRC
Press, Inc. Boca Raton, FL.
- Briggle, L.W. 1981. Wheat. Triticum aestivum. p. 6770. In: McClure,
T.A. and Lipinsky, E.S. (eds.), CRC handbook of biosolar resources. Vol. 11.
Resource materials. CRC Press, Inc. Boca Raton, FL.
- C.S.I.R. (Council of Scientific and Industrial Research). 19481976. The wealth
of India. 11 vols. New Delhi.
- FAO. 1980a. 1979. Production yearbook. vol. 33. FAO, Rome.
- Dibb, D.W. 1983. Agronomic systems to feed the next generation. Crops and Soils
- Duke, J.A. 1978. The quest for tolerant germplasm. p. 161. In: ASA Special
Symposium 32, Crop tolerance to suboptimal land conditions. Am. Soc. Agron.
- Duke, J.A. 1981b. The gene revolution. Paper 1. p. 89150. In: Office of
Technology Assessment, Background papers for innovative biological technologies
for lesser developed countries. USGPO. Washington.
- Duke, J.A. and Wain, K.K. 1981. Medicinal plants of the world. Computer index
with more than 85,000 entries. 3 vols.
- Gohl, B. 1981. Tropical feeds. Feed information summaries and nutritive values.
FAO Animal Production and Health Series 12. FAO, Rome.
- Hartwell, J.L. 19671971. Plants used against cancer. A survey. Lloydia 3034.
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fuels. Calif. Agric. 39(5/6):1416.
- Kvech, O. 1979. The importance of crop residues in rotations of an intense
farming system. Rostlinna Vyroba 25(10):10131022. (abstract only)
- Palz, W. and Chartier, P. (eds.). 1980. Energy from biomass in Europe. Applied
Science Publishers Ltd., London.
- Reed, C.F. 1976. Information summaries on 1000 economic plants. Typescripts
submitted to the USDA.
- Stewart, G.A., Gartside, G., Gifford, R.M., Nix, H.A., Rawlins, W.H.M., and
Siemon, J.R. 1979. The potential for liquid fuels from agriculture and forestry
in Australia. CSIRO. Alexander Bros., Mentone, Victoria, Australia.
- Watt, J.M. and Breyer-Brandwijk, M.G. 1962. The medicinal and poisonous plants
of southern and eastern Africa. 2nd ed. E.&S. Livingstone, Ltd., Edinburgh
Last update Friday, January 9, 1998 by aw