File:
<majcerea.htm> <Economic Plants
Index> <Main Botany Menu> <Home>
Major
Cereals
(Contacts)
Please CLICK on
Underlined Categories to view:
[ to search for Subject Matter, depress Ctrl/F ]:
=======================================================================
|
Introduction Cereals have been throughout
history and are unquestionably the most important sources of plant food for
humans and livestock All of the
original ancestors of cereals have been lost over the millennia that they
have been cultivated. The development
of all the major cereals occurred long before recorded history for all the
oldest civilizations were already familiar with several kinds of barley,
wheat and other grains. Also the
actual origin of these cereals had been so long forgotten that they were
given supernatural powers and played a part in the religious ceremonies of
the various nations of antiquity (Hill 1952). In ancient Rome they held
festivals at seeding time and harvest in honor of the goddess of Ceres, whom
they worshipped as the giver of grain.
They brought offerings of wheat and barley to these festivals, the
“cerealia munera” or gifts of Ceres, from which the name “cereals” was
derived. In ancient Greece similar
religious ceremonies were observed.
In America the natives of Mexico worshipped an agricultural deity to
whom they brought the first fruits of their harvest. All cereals are members of the
grass family, Gramineae, and are similar in possessing the characteristic
fruit of that family, the karyopsis.
In this fruit the wall of the seed is fused with the ripening ovary
wall to form the husk. The term
“grain” is given either to this type of fruit or to the plant that produces
it. There are six true cereals in the
world today, which are Wheat, Rye, Rice, Oats and maize. Of these wheat, maize and rice are the most
important, and each has played roles in the development of
civilizations. The millets, sorghums
and even buckwheat are often referred to as cereals, but they belong to a
different classification. There are many reasons why cereals
are such important crops. One of more
of these grasses is available in each of the different world climates. The northern regions have barley and rye,
the temperate regions wheat and the tropics and warmer temperate areas rice
and maize. Cereals also have a wide
range of soil and moisture requirements.
They can be cultivated with a small amount of effort and give a high
yield. The grains are relatively easy
to handle and store because of their low water content, and they are very
high in food value. Cereals contain a
higher percentage of carbohydrates than any other food plants as well as a
considerable amount of protein and some fats. There are even vitamins present. In modern times the quest for greater yields has sometimes
sacrificed flavor, and low yielding varieties that may possess
characteristics of quality are gradually being ignored or even lost. This is especially noticeable in the cold
cereal industry that produces an array of products few of which match up in
flavor or texture to those of the earlier 20th Century. Some high latitude areas of South America
have managed to continue production of superior cold cereal products for
local consumption. - - - - - - - - - - - - - - - - - - - - - - - - - - This is the most widely grown
cereal of temperate regions. Its
native home is not definitely known because it is so ancient. There are some indications that highlands
in Syria and Palestine might be the place of origin, but the Central Asian
plateau and the Tigris and Euphrates valleys might be included. Of course Vavilov considered wheat to have
had multiple origins, the soft wheats originating in the mountains of
Afghanistan and the southwestern Himalayas, while the durum or hard wheats
may be from Abyssinia, Algeria and Greece and the einkorn variety from Asia
Minor. Archeological evidence
indicates that wheat had already been cultivated by earlier than 4,000 B.C. Wheat was at the core of Babylonian
civilization and it was cultivated by all the other Old World nations of
antiquity. Aristotle, Pliny and
Theophrastus all mentioned numerous varieties of wheat. In China it was grown by 2,700 B.C. and
was used by the lake Dwellers of Switzerland and Hungary, civilizations that
go back to the Stone Age. Wheat was
first introduced into America at Mexico in 1529. Wheat was sowed in New England in 1602 and it reached Virginia
by 1611, California by 1769 and Minnesota by 1845 (Hill 1952). Wheat is an annual grass in the
genus Triticum that comprises a large number of wild as well as
cultivated species. The wild species
are often weeds. Cultivated wheat, Triticum
aesticum, reaches a height of 2-4 ft.
The flower is a terminal spike or head consisting of 15-20 spikelets
that are borne on a zigzag axis.
Individual spikelets are sessile and solitary, consisting of 1-5
flowers each. The mature grain
consists of the embryo (6 %), a starchy endosperm (82-86 %), the nitrogenous
aleurone layer (3-4 %), and the husk or bran (8-9 %). The husk is made up of the remains of the
nucellus, the integuments of the seed coat and the ovary walls or pericarp. Innumerable species and varieties
of wheat have arisen over its long period of cultivation. This was the result of intentional or
unintentional selection on the part of humans of forms that had some
particularly desirable qualities.
Eight principal kinds of wheat were were differentiated as species by
Hackel: einkorn, Polish wheat, emmer,
spelt common wheat club wheat durum wheat and poulard wheat (Hill 1952). Modern classification has been on the
basis of chromosome number with the most important species falling into three
groups: Diploid (7 pairs) = Triticum
monococcum; Tetraploid (14 pairs) = T. dicoccum, T. durum, T.
polonicum, T. timopheevi and T. turgidum; Hexaploid (21 pairs) = T.
compactum, T. aesticum and T. spelta. Various varieties of these species have
been produced at different times. Einkorn, emmer and spelt are the
most primitive. They resemble the
wild species of Triticum with fragile jointed heads that break during
threshing and the grain does not separate easily from its enclosing envelopes.
Triticum monococcum
has
been called “One-grained Wheat” because it has only
one fruit in each spikelet. It is one
of the oldest species, dating back to the Stone Age. It is a plant that can be grown in very poor
soil and will therefore is useful in regions where other types cannot
survive. Einkorn is a small plant,
rarely 2 ft. in height with a very low yield. It is still cultivated to some extent in mountainous regions of
Southern Europe, especially in Spain.
It is not used much for baking but primarily for animal feed. In other places it continues to be grown
for experimental purposes.
Emmer, Triticum dicoccum, is also known as “Starch
Wheat,” “Rice
Wheat,”
or “Two-grained Spelt.” It has a flattened
head with bristles or awns. It is
another very old type that was grown in Babylonia and by all the early
Mediterranean civilizations and the lake Dwellers of Europe. It is still cultivated in the mountainous
areas of Italy, Spain, Germany, Switzerland and Russia. It thrives in dry soil. After being introduced into the United
States from Russia it was used for livestock and breakfast foods and in
experimental breeding efforts. Triticum spelta is another primitive
wheat of antiquity, spelt is hardy and can be grown in the poorest
soils. It has been cultivated in the
Mediterranean region for centuries and is still grown in Spain. In North America is has been used as
livestock feed. Polish wheat, Triticum
polonicum,
or “Giant
Rye”
has a very characteristic appearance due to the long papery bracts
surrounding each spikelet. The stems
are solid and the bluish-green ears are flattened. The species is of comparatively recent origin. Despite its name it did not originate in
Poland. It has been grown chiefly in
Spain and Italy, Turkestan and Abyssinia.
The plants are large, but have a small yield of little value. Polish wheat has not proven to be well
adapted to North American growing conditions because it gives a low yield.
Also known as “English
Wheat” or “River Wheat”, Poulard Wheat, Triticum
turgidum,
is an old species that probably originated in dry portions of the southern
Mediterranean region. The heads are large
but the yield is small and the plant is only of importance in England. Elsewhere it is grown only in small
quantity. Triticum compactum (tenax), also called “Dwarf Wheat” or “Hedgehog Wheat” is different from all
other species in having short compact heads and small kernels. The plants are small and have a very stiff
and strong straw. Club Wheat is well
adapted to poor soil and is grown chiefly in the mountainous areas of Central
Europe, Abyssinia and Turkestan. It
has been grown in Chile and in the Western United States. The grains are soft and have low protein
content, so the flour is not used for bread but rather for pastry flour. Triticum durum has a thick head with
long stiff beards and large, hard, amber or red grains that are rich in
gluten. This species has been
cultivated for a long time in the arid regions of the Old World. It is the main wheat in Spain and is also
grown in Algeria, India and Russia.
Durum wheats were introduced into North America from Russia and have
been extremely valuable. The low
rainfall and high temperatures typical of the Great Plains renders the region
unsuitable for most other crops without irrigation. These wheats are very hardy and drought tolerant. Their high gluten content makes them
especially suitable for macaroni, semolina and other types of pastas. They are mixed with other flour in bread
baking. Red durum wheats are used for
livestock. Triticum vulgare is the principal source
of bread flour. These wheats occur in innumerable
varieties differing in both external morphological and physiological
characteristics. There are bearded
and beardless varieties, red and white varieties and hard and soft varieties. The hard wheats are richer in proteins and
usually have small grains; the soft wheats produce large grains that are
richer in starch. The physiological
characteristics include such things as yield per acre, late or early
maturing, resistance to drought, cold or disease; behavior in milling and
baking, and the season that they are sown (spring or winter). Spring wheat is sown in the spring and
harvested in late summer. Winter
wheat is planted in the autumn and develops a partial root system before the onset
of cold weather. In the spring it has
a vigorous early growth and can be harvested in early summer. Winter wheat has a higher yield, is more
resistant to disease and matures earlier. Triticum timopheevi from Russia is especially resistant
to disease and thus has been used in breeding programs with standard
varieties. Seven grades or classes of wheat
are recognized by the United States Department of Agriculture. The five most important are Hard Red
Spring Wheat, Durum Wheat, Hard Red Winter Wheat, Soft Red Winter Wheat and
White Wheat. About 20 percent of the wheat
grown in the United States has been Hard Red Spring Wheat. They are grown primarily in Minnesota,
North & South Dakota and Canada where the winters are too severe for
winter wheat. They are used for bread
flour. Marquis Wheat has been one of
the chief varieties.
Amber durum wheats are all spring wheats and include at least 10
varieties. Kubanka is a well-known
variety. They make up about 6 percent
of the wheat crop and are grown mainly in North & South Dakota and
Minnesota. Their use is almost
entirely for macaroni and other pastas. This grade of wheat is grown
primarily in the central and southern Great Plains where hot summers and
severe dry winters are common.
Kansas, Nebraska, Texas and Oklahoma lead the production, and this
wheat makes up about 47 percent of the total crop. Turkey is a common variety.
The flour is of high bread making quality. This group constitutes about 30
percent of the United States wheat crop.
It is the principal wheat grown east of the Mississippi River and is
centered in Ohio, Indiana and Illinois.
It is also cultivated inn the Pacific Northwest. It is adapted to a more humid climate than
the other wheats. The grains are
starchier and the flour is used for pastry, cake, breakfast foods and home
baking. This group also includes the
red club wheats.
This group makes up about 5 percent of the United States wheat crop
and it comprises all of the white-grained forms, whether common wheat or club
wheat, and includes both hard and soft and spring and winter wheats. They are grown in the Pacific Northwest
and in the northeastern United States.
The flour is used for pastry and breakfast foods and is blended with
hard-wheat flour for bread making.
Wheat is best adapted to moderately dry temperate climates, and is not
grown in warm humid regions. Climates
with a growing season of at least 90 days and an annual rainfall of not less
than 9 inches are essential. Over 30
in. of rain is detrimental. Generally
regions with a cool moist spring merging into warm, bright, dry harvest
periods are the best, but the various kinds of wheat differ in their
requirements. Good climatic
conditions for wheat are found in nine different areas in the world and these
are the principal wheat-producing regions.
They include the plains of southern Russia and the Danube, the
Mediterranean countries, Northwestern Europe, the central plains of the
United States and Canada, the Columbia River basin in the Pacific Northwest,
Norwest India, north central China, Argentina and Southeast Australia.
Clays and loams are the best soils for wheat although a light sandy
soil may be used. If the ground is
too wet the plants lack vigor and produce a small yield. But a porous soil does not hold sufficient
moisture. Lime is an essential
element and must be added if the calcium content of the soil is low. Nitrogen, Phosphorous and potassium are
also required. The best fertilizer is
barnyard manure.
The land must be thoroughly cleared for wheat is easily choked out by
weeds. Crop rotation is generally
practiced and wheat is planted after a crop of beets, turnips or tobacco that
kill out weeds. The methods of
cultivation naturally vary depending on the kind of wheat and the character
of the soil and climate. The time of
sowing depends on whether the plant is a winter or summer crop. For a good harvest the seed must be heavy,
well developed and fully ripe. Only
the finest ears are used for seed.
The grains are winnowed to remove dust and light grains. They are then sifted and bolted and are
treated with chemicals to kill any fungus spores. Wheat may be sown broadcast, either by hand or by machine, the
former method being confined to small farms.
Two kinds of machines are used on large farms. One sows the wheat broadcast and the other
drills furrows and buries the seed all in one operation. Germination begins immediately and the
first leaves appear within two weeks.
Inn the case of spring wheat growth continues unchecked until
maturity, but in winter wheat it is halted with the advent of frost. If the cold is too severe or if the roots
are exposed, winter wheat may die.
Weeding is constantly required.
On the largest farms machines are used which plow 24 furrows at one
time. The various stages of the
ripening grain are known as milk-ripe, yellow-ripe or dough, full ripe, and
dead ripe. Wheat is not always
allowed to mature fully for it is then more valuable for livestock feed. Several insect and fungus pests attack
wheat. The latter include bunt, smut
and rust. Wheat rust causes colossal
losses, often wiping out a whole crop.
Many attempts have been made to import rust-resistant varieties, as
well as drought-resistant varieties, and continuing efforts are made to
produce them experimentally. Methods of harvest vary with the
size of the farm. Various kinds of
simple reaping scythes, reaping hooks or machines continue to be used in
underdeveloped areas to cut the culms and binding machines bind them into
sheaves. The wheat is then stored and
must be kept dry. Threshing is the
next process. This involves the
separation of the grain from the spike.
This has long been done by hand, using a flail. It is a long and tiresome process, but is
less damaging to the grain than a threshing machine. The wheat is laid in rows all pointing in
the same way to a depth of 1 in.
These rows are then struck at regular intervals with the flail, and
then the wheat is turned and the process repeated. A cart that traces a spiral course over the stalks has been
widely used in Europe. After
threshing the wheat is winnowed and sifted.
Threshing machines are frequently used. These are either horizontal or vertical and consist of rapidly
revolving drums of hard wood, provided with barbed beaters that struck the
ears with a substantial force and with a frequency up to 800 r.p.m. The most complicated harvesting machines,
the combines, are used for large acreages.
They reap, clean, thresh, winnow and sift the grains, separate the
wheat from the chaff, eliminate foreign seeds, sort into grades and bag the
grain, leaving the bags behind and finally binding the straw. These huge portable factories are more and
more mechanized, but used to be drawn by horses. They can cut a swath over 40 ft. wide. It is possible with the aid of less than
eight people to harvest 120 acres each day. Storage must be in firmly built,
well-ventilated structures to keep out grubs and small pests. Buildings with a concrete wall and floor
are best suited for storage.
Subterranean silos are constructed in tropical areas. The great grain elevators at world ports
are often startling sights. The grains were “brayed” between
two stones in ancient times. Then a
mortar and pestle was used, and later millstones operated by wind or
waterpower. Most of the old mills had
a fixed lower stone upon which a movable upper stone revolved. The grains were dropped into openings in
the upper stone and gradually worked out between the stones that had grinding
surfaces cut in radiating lines. The
whole grain was milled. The roller process of milling was
then perfected. The first step in
this process involves cleaning and scouring.
This consists of screening, to remove all foreign seeds, dust, sticks,
straw and pieces of bran. The grains
are then thoroughly washed and scoured.
The next step is tempering.
This prepares the grain for the best condition for milling. A little water is added that toughens the
bran and prevents it from breaking up so that it will flake out all in one
piece. Finally the conditioned and
tempered wheat is submitted to breaking, grinding and rolling. The grains are first ground between
corrugated iron rollers, the so-called “first break.” This cracks the grain and almost flattens
it. A small quantity of flour, the
“break flour” is separated out by sieves while the main portion goes to the
“second break” for more complete flattening and the partial separation of the
bran and embryo. This process is
repeated until five sets of rollers, each moving at a different speed, have
been used. In each case bolting
separates the ground material from the coarse bran. After a while all the bran is removed and the purified material
is passed to smooth rollers for final granulation. Finally it is bolted with a cloth (originally silk) containing
12,000 meshes per square inch and is then ready for packing. The final product is the best grade of
flour or the “First Patent. Material
that has been separated out is known as middlings and may be processed and
made into inferior grades of flour, or used for other purposes. Granular particles midway in size between
the grain and flour, are known as semolinas.
Durum wheat semolina is used for macaroni and ordinary wheat semolina
for farinas. The above-described process
produces white flour. In the milling
of graham flour the entire grain is used while in whole-wheat flour only a
part of the bran is removed. Wheat Production
& Consumption The world production of wheat
increases steadily with the United States producing over one-quarter the
amount. Kansas and North Dakota are
the leading states. Other large
wheat-producing countries are Russia, China, Canada, India, France, Italy,
Germany, Argentina, Turkey and Australia. France has led in the per capita
consumption of wheat, followed by New Zealand, Australia, the United States,
Great Britain, Germany and Canada.
The United States per capita consumption of wheat was once estimated
at 4.5 bushels.
Wheat products are almost certainly the most widely used articles of
the human diet. In the United States
they furnish about one-fifth of the total food materials of an average
family. The flour is used mainly for
making wheat bread. Where other
cereals are used the produce is called corn bread or rye bread, etc. The hard wheats provide bread flour while
the flour from soft wheats is used for cakes, biscuits, pastry, crackers,
etc. Other edible by-products are
breakfast foods and the various farinas; and the pastas such as macaroni,
spaghetti and noodles. Semolinas are
used for macaroni. These are
separated from the flour and bran and mixed with 30 percent water. The resulting dough is kneaded and put in
a hydraulic press. The dough is
squeezed out through holes in the bottom.
Each hole has a little pin in the center with the result that a hollow
tube of dough is formed. Strings of
dough are cut into 3-ft. lengths and are dried and cured at a temperature of
70 deg. Fahrenheit. Spaghetti and
vermicelli are merely small types of macaroni. Rolling out the dough into thin strips makes noodles. Durum wheat is used for macaroni.
Wheat is also used in the manufacture of beer and other alcoholic
beverages and industrial alcohol. It
is an excellent livestock feed. A
special kind is grown for the preparation of starch for use in the sizing of
textile fibers. Wheat straw excels
all other kinds because of its very great strength. It has been used for seats of chairs, mattress stuffing and the
manufacture of such diverse articles as straw carpets, string, baskets,
beehives and wickerwork. Leghorn hats
are straw hats made from the bearded wheat of Tuscany. Wheat straw is also used for packing and
thatching and as a fodder and manure.
The entire wheat plant is also a valuable source of fodder. - - - -
- - - - - - - - - - - - - - - - - - - - - - Indian corn or maize, Zea mays,
is America’s main contribution to the important group of cereals. Maize had been thought to have originated
in a wild state in the lowlands of southern Mexico and Central America from
which it spread to the Andes where its cultivation goes back to prehistoric
time. The ancestor was probably
teosinte a primitive ancestor that bore a single row of kernels in a
husk. Selection in southern Mexico
resulted in a cob with several rows of kernels. Later development produced the longer cob or ear familiar as
the commercial maize of modern times. Grains of this later variety maize found
in the tombs of the Incas in Peru represent several different varieties, so
that the plant must have been grown for many centuries prior even to the
period of the Inca civilization. From
Peru is has been thought to have moved northward again and played a prominent
role in the civilization of the Mayas and Aztecs. The Amerindians in New Mexico grew it as early as 2,000
B.C. By the time of Columbus maize
was growing all the way from the Great lakes and the lower St. Lawrence
valley to Chile and Argentina. Maize was introduced into Europe
by Columbus, or possibly
earlier, and into Asia by the earlier Portuguese
explorers. It is now grown
worldwide. Large yields are possible
from maize even under primitive conditions of agriculture.
The largest of all cereals, maize is a tall annual grass that can
attain a height of 3-15 ft. The
jointed stem is solid and contains a considerable of sugar when not
mature. The leaves are large and
narrow with wavy margins. There is an
extensive fibrous root system with aerial prop roots at the base of the stem. Two kinds of flowers are the tassel, at
the top of the stem, which bears the staminate flowers and the cob or ear
with pistillate flowers. The ear is
produced lower down on the stalk and thus is protected by the leaves. Each ovary has a long silky style, the
corn silk. The ovaries, that become
the mature grains, are produced in rows on the cob. A husk composed of leafy bracts surrounds the cob. The grains have a hull (6 %), protein or
aleurone layer (8-14 %), endosperm (70 %) and embryo (11 %). Two kinds of endosperm are usually
present: a hard, yellow endosperm and
a soft white starchy endosperm. There are no known wild species of
the genus Zea, but The original ancestor was most likely a pod corn
that gave rise to maize through hybridization between some species of Tripsacum
and Teosinte, Euchlaena mexicana, a wild relative
in Mexico. It is comparatively easy
to perform breeding trials with maize; even the Amerindians had learned how
to select, produce and preserve the best varieties that gave rise to easily
cultivated and rapidly maturing varieties.
No other cereal has so many
different varieties that fall into seven quite distinct classes all of which
breed true to type. These are pod, pop, flint, dent, soft, sweet and waxy. Although they readily hybridize there are
very little intermediate types produced.
The classes differ mainly in the nature of the endosperm and the shape
of the grain and have been considered by some authorities to be species and
others to be varieties. Hill (1952)
believed that they should be considered as agronomic
groups. Each grain is covered with a husk
in Pod Maize. The plant is very leafy
and the tassels heavy. The grains may
resemble those of any of the succeeding types, which suggests that pod maize
might be very close to the primitive form from which the others had been
derived. Pod maize has little if any
commercial value. The grains are usually elongated
and oval. Although small in size they
are exceptionally hard and flinty with a tough hull. The endosperm is mostly of the hard glossy
variety. On exposure to high
temperatures, the grains explode forming a snow-white fluffy, palatable mass
or Popcorn. It
results as a sudden expansion of the soft endosperm that turns the grain
inside out. It is probably due to the
expansion of the moisture content of each individual starch grain after
partial hydrolysis during the heating phase.
For a time the flinty protein layer confines the swelling endosperm,
but eventually this breaks and the sudden release of pressure causes the
endosperm to become everted about the embryo and hull. The presence of too much white endosperm
prevents popping. There are two kinds
of popcorn: rice popcorn, in which
the grains are pointed and tend to be imbricated, and pearl popcorn, in which
the grains are rounded and very compact.
The plants produce a large number of small ears. This type of maize was undoubtedly grown
in prehistoric time. There are over
25 different varieties grown for human consumption.
The embryo and white endosperm are entirely surrounded by the hard
endosperm in Flint Maize leaving an undented grain. Plants attain a height of 5-9 ft, and tend to have two
ears. The ears are long and
cylindrical with hard smooth grains in 8-16 rows that tend toward different
colors. Flint maize matures early and
so is grown in New England and other colder areas of North America. The endosperm extends to the top
of the grain in Dent Maize, with the hard endosperm being present only on the
sided. This causes an indentation of
the mature grain at the top due to the shrinking of the softer material. This is the largest maize, stems sometimes
attaining a height of 15 ft. A single
ear is produced. They are very large,
up to 10 in. long, weighing three-quarter pounds and sometimes having as many
as 48 rows. The deep wedge-shaped
grains are generally yellow or white.
Dent maize is the main type grown in the Corn Belt of the United
States as it gives an enormous yield.
It is the source of most of the commercial grain and also of livestock
fodder and ensilage. Over 330
varieties have been developed.
The endosperm is entirely lacking in Soft Maize. This is a very old type that was extensively
cultivated by the Amerindians because of the ease with which it could be
crushed. The grains resemble flint
maize in shape and appearance, but the size varies from small forms to the
large Cuzco variety of Peru that are 3/4 in. or more in diameter. Over 30 different varieties are
known. Maturity is very late in the
season and it is not grown in any quantity in North America. In Sweet Maize the entire
endosperm is translucent, and the starch has been partially changed to
sugar. The grains are broad and
wedge-shaped with a typical wrinkled surface. The plant is adapted to the cooler areas and is the main type
grown in northern areas of North America for canning purposes. The grain is used in the unripe
state. Over 65 varieties have been
developed. The endosperm is waxy in Waxy
Maize and the carbohydrate material occurs in a different form from that in
other varieties. It is used as a
substitute for tapioca. The starch is
entirely amylopectin, whereas ordinary cornstarch is a mixture of amylopectin
and amylose.
Being summer annual maize requires very definite environmental
conditions for proper development.
The plant does best in a fertile, friable, well-drained alluvium, such
as the deep, warm, black loams along river bottoms and in drained
swamps. These soils must have a high
organic and nitrogen content and must not bake out. Additionally, temperature, sunlight and moisture are limiting
factors. The temperature of both the
air and soil is important, especially during the growing season from May to
September in the Northern Hemisphere (November to March in the Southern
Hemisphere). A mean average summer
temperature of 75 deg. Fahrenheit is optimum, but temperatures below 66 deg. Fahrenheit
are detrimental. Cloudy days hinder
development. Adequate moisture is
essential, with the optimum being a 20-inch annual rainfall occurring mostly
in summer. There is a great
difference in growth habit under different climatic conditions and there are
varieties adapted to each type. A
continental climate is most favorable.
The growing season varies from 90-160 days, depending on the locality. Maize does mature adequately north of 50
deg. of latitude although it can be grown there as livestock fodder. There are relatively few regions
that have the right combination of the necessary environmental conditions and
where maize can be raised as a commercial crop on a large scale. The principal maize growing regions of the
world include the east, central and middle western United States; the Mexican
plateau; the Argentine pampas; the highlands of Brazil; the basins of the
Danube, Dnieper and Po river in Europe; northern India; China and Manchuria;
Vietnam; java; the Nile valley; and South Africa. The most prolific area for maize is the great Corn Belt of the
United States, located in the Mississippi valley in the states of Illinois,
Indiana, Missouri, Iowa, Kansas and Nebraska. To grow maize on a commercial
scale the fields must be well plowed and harrowed. The seed is planted to a depth of 1-3 in. in regularly spaced
rows. Constant weeding and hoeing are
necessary with care necessary not to injure the roots. The use of fertilizers and crop rotation
are advisable. Maize has
comparatively few natural enemies, the corn borer being the worst insect and
corn smut the most serious of the fungus pests. Drought may cause very serious damage. There have been very few changes
in harvesting procedures over the millennia.
On small farms the ears are still husked by hand directly in the
field, and cattle are allowed to graze on the stalks. On larger farms the maize is cut with a
corn knife or a machine. The stalks
are stacked to permit additional ripening of the grain. After a month of this curing process the
ears are husked by machine. Maize
must be stored in well-ventilated bins to allow excess moisture to evaporate
and to properly protect against rodents and small pests. No cereal is used in so many ways as Maize. About one-half the crop is used as a food
for livestock. The grain is very
nutritious with a high percentage of easily digested carbohydrates, fats and
proteins and very few deleterious substances. The pork industry is dependent almost entirely maize in the
United States and has used about 40 percent of the total amount raised. Cattle, horses and other domestic animals
are also fed maize. It has been
estimated that 10-12 lbs. of maize is converted into 1-lb of beef, while 5-6
lbs. yields 1-lb. of pork. Not only
is the grain valuable as a livestock feed but the entire plant is an
important fodder. It can be used
green, dried or as silage. For silage
the leaves and stems are cut into small pieces and placed in silos. Here a slight fermentation occurs and the
resulting produce is more palatable for cattle. Stover, the residue after the ears have been removed, is also
fed to cattle or used for silage. Although Maize is an important
food in Neotropical America, it is not widely used as food in the rest of the
world. Cornmeal is a poor breadstuff,
owing to the absence of gluten, and corn bread is very crumbly and cannot be
baked in loaves. The meal was first
prepared by merely pounding the grain.
Later millstones were used and now a milling process involving the use
of rollers has been substituted. The
whole grain was formerly used in milling, but the fatty oil, present in the
embryo, gave an unpleasant odor and taste to the meal. In modern processes the embryo and hull
are removed. Both white and yellow
meals are milled. Cornmeal has many
uses in other countries and in the southern United States. When boiled with water it becomes mush or
hasty pudding, the Italian polenta.
It is often baked in cakes such as Johnny Cakes, ashcakes, hoecakes,
corn pone, and the Mexican tortillas.
For corn bread the meal is mixed with wheat or rye flour. Scrapple is cornmeal that has been boiled
with scraps of pork, liver and kidney and then seasoned and fried. Hominy or samp and hulled corn are
prepared by soaking the grains in the lye of wood ashes to remove the hull
and them cooking until soft. Small
portions of the hard endosperm obtained during the milling process constitute
hominy grits. The grain is also used
in the preparation of many breakfast foods.
In North America much maize on the cob is eaten, and sweet corn is
extensively canned.
Industrial uses of maize and maize products have steadily increased in
importance. The manufacture of
cornstarch and its derivatives, glucose or corn syrup, corn sugar, dextrins
and industrial alcohol and the production and uses of corn oil obtained from
the embryo are important commodities.
The grain is used for making various alcoholic beverages and the
fibers in the stalks have been sued for making paper and yarn. The pith can be made into explosives or
light packing material. The inner
husks are for cigarette papers and the cobs are for fuel, smoking pork
products, and as a source of charcoal and furfural, the latter a raw material
used in making solvents, explosives, plastics, synthetic rubber and
nylon. Zein, the protein in maize,
can be made into artificial fibers with good tensile strength and wool like
properties. Ethanol is not a common
ingredient in gasoline in North America.
Usually the United States produces nearly one-half of the world’s
supply of maize. Iowa and Illinois
are the leading states, but through irrigation other states have begun to
produce it also and various amounts are grown in every other state as well.
The utilization of hybrid maize has greatly increased the
production. Crossing two carefully
selected superior inbred strains produces hybrid seed. The first generation single crosses are
uniform in size like the parents, but the ears are small. They are especially suited for the
production of sweet-corn seed.
Double-cross hybrids that result from the combination of two single crosses,
are exceptionally vigorous and produce larger uniform ears with from 15-20
percent more kernels. The yield from
hybrid seed is increased from 5-15 bushels per acre. The raising of hybrid corn and the
production of the seeds has become an important enterprise. In order or amount produced the
United States leads the world followed by China, Argentina, Brazil, India,
Mexico, South Africa, Italy and Russia. - - - - - - - - - - - - - - - - - - - - - - - - - - Rice, Oryza sativa,
replaces all other cereals in tropical countries as the staff of life and
dominates the economic and social structure.
Over half the world’s populations find rice as an indispensable
food. Over 95 % of the world crop is
produced in the Orient. Rice cultivation extends back into
the ancient past with no authentic records as to when it started. The plant originated somewhere in
Southeastern Asia, but it has spread to every warm region of the world. The history of rice and the history of
China are closely tied. Rice was
first cultivated in China with records going back further than 2,000
B.C. In classical Chinese the words
for agriculture and rice culture are synonymous. This indicates that rice was the dominant crop at the time the
language was taking form. In other
languages the words for rice and food are identical. Rice was introduced into India before the
time of the Greeks and very early reached Syria and Northern Africa. The first rice was grown in Europe in 1468
in Italy. The first rice grown in
America was in South Carolina in 1694 from seed brought from Madagascar. Rice is a large annual grass that
grows to a height of from 2-4 ft.
Instead of bearing an ear, rice produces a panicle, an inflorescence
composed of a number of fine branches, each terminating in a single grain
surrounded by a husk. The grains are
easily detached together with this brown husk. In this condition it is known as paddy. Innumerable varieties of rice have been
developed. These differ in the color,
shape, size, flavor and other traits of the grain. One of these types contains a sugary substance instead of
starch, which forms a soft, sticky palatable mass on boiling. Other species of Oryza occur as
wild plants in the tropics of both hemispheres.
Rice prefers a climate where the average summer temperature does not
go below 77 deg. Fahrenheit. It grows
best on damp soils underlain with semi-impervious subsoil in places where it
can be flooded. The delta and flood
plains of the monsoon region are especially favorable. One type of rice, the upland or hill rice
may be grown without irrigation. This
kind had been preferred in Central and South America. Elsewhere the lowland rice that requires
flooding during part of its development, is grown almost exclusively. Rice culture in wet areas is similar
worldwide. In many countries
primitive methods of agriculture are used.
In developed countries rice cultivation has had a remarkable
expansion. The fields are plowed or hoed and
the rice is sown broadcast or transplanted from seedbeds when 9-10 in.
high. The young plants are covered
with water, at first only at night, but later continuously, and the water is
kept circulating. Upon ripening the water
is drawn off and the fields are allowed to dry out. Rice is harvested in a manner similar to wheat and the stalks
are stacked up to dry. There may be
two or three crops a year. In the
United States rice production is wholly mechanized. Rice grains are removed by
threshing or by drawing the stalks through narrow slits. When used directly for daily consumption
the rice is left in the “paddy” condition because it stores better that
way. The grains are husked just
before they are to be used, and they are then pounded in a mortar with a
wooden mallet and winnowed. The
resulting grain is very nutritious for it contains considerable protein and
fat as well as starch.
For commercial preparation of rice, the impurities are removed and the
paddy is passed between millstones to break up the husk. Blowers remove the chaff. The grain is then pounded in huge mortars
and a portion of the bran layer and embryo is removed. The waste is known as rice bran. The white rice is then scoured by friction
and polished and a coating of glucose, talk or chalk is added. During these last processes the outer,
more nutritive parts of the grain are removed. The rice polish that is left as a residue is twice as
nutritious as the finished product. Rice is used mainly as a food by
over half the world’s population. It
needs to be supplemented by legumes or some other food rich in proteins. A diet of rice and soybeans constitutes
the food of millions of people in Asia.
The polished rice, which reaches the world markets, is much less
nutritious, but its use is widespread.
Rice hulls and rice polish are valuable as livestock feed. The straw may be plaited and made into
hats, shoes and other articles. Rice
starch is widely used in Europe.
Intoxicating beverages are made from rice in Japan and other areas. China continues to produce most of
the world’s rice, followed by India and Pakistan. Other important countries that produce rice are Japan, Java,
Vietnam, Thailand, Burma, Brazil, Korea and the Philippines. The United States produces a substantial
amount in the southeastern States and California. Rice is also grown in Egypt and Africa while Italy leads the
European production. |