The Other Grasses

1
The Other Grasses Rice and Corn Rice is the 2nd
most important cereal crop. About 11 of arable
land is devoted to rice production. That
production is about 370 million metric
tons/year. Almost 1/3 of the human population
depends on rice as their principal food
source. Rice was domesticated and first
cultivated 11,500 years ago in eastern China and
India virtually simultaneously. In both places
the species domesticated was Oryza sativa. There
is a different congener, O. glabberima, that
originated and is grown in Africa. It is believed
that rice evolved in lowland tropical areas, and
evolved means to survive the periodic flooding
that occurs there.
2
Rice plants live and in drawings from the
Linnean herbarium
3
The adaptations rice evolved to survive flooding
are air chambers that permit air (O2) to reach
continuously from stomates in leaves through
stems to portions of the plant (stems, roots)
below water level. Rice is not dependent on
growing in flooded paddies. In many places (here
Georgia, U.S.) rice is grown without flooding.
Most rice, however, is grown in paddies in water
5 10 cm deep. There are also special varieties
of deep water rice (DWR) that grow in 2 m depth
or more (called floating rice.
4
Rice grown in standing water avoids certain types
of pests, e.g. weeds, but is subject to a variety
of diseases pathogens, rusts, and small insects
(thrips) are at the top of the list. Not all
weeds are problems. There is a mutualistic
association between an aquatic fern, Azolla, and
a photosynthetic cyanobacterium, Anabaena
azollae, that contributes nitrogen and reduces
the need for fertilization in growing rice.
Thats Azolla around the rice plant. This is an
example of multicropping. The ducks feed on
Azolla (and on the rice), but become a second
crop from the same paddy.
5
Rice is a monocarpic (single seed crop), annual
plant. Harvesting and planting must occur
annually. Pollination is by wind. There is a
limited capacity for self-pollination, but mostly
successful pollination comes from
outcrossing. There has been enormous effort to
develop rice varieties for differing environments
and characteristics. It all begins with a wild
progenitor from the foothills of the Himalayas in
Asia, Oryza rufipogon. From it the two major
Asian rice groups were developed Oryza sativa
var. indica on the Indian side of the mountains
and Oryza staiva var. japonica on the Chinese
side. In China, at least, the wild rice was
collected and the domesticated variety produced
by 7,500 (Diamond) to 7,000 (Crawford and Shen)
YBP.
6
In Africa rice cultivation is more recent, going
back 3,500 years. In the Near East rice
cultivation began around 800 BC, and then it
spread to Europe, but was not widely grown until
the 15th century. Rice (Oryza glaberima) came
from Africa to the New World in (a very specific)
1694. It began in the Carolinas, expanded,
collapsed with the end of slavery, then picked up
again further west (Louisiana, Arkansas,
Texas). World production of rice was
approximately 700 million tons in 2005. Leading
producers China 185 million
tons India 129 Indonesia 54 Bangladesh
40 Vietnam 36
7
Rice is commercially prepared by first removing
the chaff (hulling the rice). The result is
brown rice. White rice continues the process,
removing the germ and bran. White rice is then
polished with glucose or talcum powder. Due to
the potential for asbestos contamination, talc
polishing is no longer legal in North
America. White rice is frequently enriched to
restore vitamins and minerals lost in removal of
bran and polishing. Nutrients in 100 g of
white rice brown rice Carbohydrates 79g
Fat 0.6g Protein 5.2 7.6g 8.5
9.5 g Vitamin B6 0.15mg other vitamins
thiamine, B1
8
Relative consumption of rice 3 Kg/person/year in
the U.S. 160 Kg/person/year in
Asia Characteristics of the two main rice
types Oryza sativa var. indica - long-grained,
less sticky due to lower amounts of
amylopectins, grown in tropical and
semi-tropical environments. It can be grown in
3-4 months, and thus produce several crops per
year. Oryza sativa var. japonica short-grained,
more sticky due to larger amounts of
amylopectins, grown in temperate environments,
flowers as a short-day plant, thus likely one
crop per year. Many cultivars long-grained and
aromatic Basmati, medium-grained Patna, a hybrid
of Basmati and long-grained American rice called
Texmati, black and red cultivars from Indonesia.
9
There is a third type (not another cultivar)
called Oryza sativa ssp. Javanum that is not
widely cultivated, but is regarded by rice
geneticists as a rich source of new genes to use
in selecting new varieties. Among the results of
variety selection higher yields, disease
resistance, and a golden rice that synthesizes
ß carotene in the endosperm. Production of golden
rice in developing countries could enormously
reduce vitamin A deficiency diseases (and vitamin
deficiency blindness). How many varieties are
there? IRRI (International Rice Research
Institute in Los Baños, Philippines) houses
67,700 Asian cultivars 26,000 African cultivars
gt1000 wild strains
10
Wild rice varieties in North America are no
relation to Oryza. Zizania aquatica and Zizania
texana, the types of wild rice you could buy in a
store, are still mostly harvested from the wild
by First Nations collectors in small boats.
Attempts to cultivate wild rice have, in general,
been failures.
11
Corn is the 3rd most important cereal crop.
Linneaus gave corn its proper binomial, Zea mays,
and maize is its common name throughout the
Americas. Corn evolved from Zea mexicana or
teosinte. There are apparently three other wild
species of Zea all are native to Mexico and
northern Central America. Races are indigienous
to Columbia, Peru, Chile, Arizona and New
Mexico It is thought that maize actually evolved
from one race of teosinte, Zea mays ssp.
parviglumis whose genetic sequence almost
indistinguishable from modern maize. This race is
from the Balsas River basin in the
Michoacan-Guerrero border region of western
Mexico. After origin, maize seems to have
diversified into a number of different races in
the course of domestication.
12
Maize differs from the other grasses considered
it is monoecious, with male and female flowers
separate on the plant. The male (staminate)
flowers are at the top of the stalk (culm) and
are commonly called the tassel.
The remnants of the pistillate (female)
flowers are the corn silk you clean from the ear
before cooking and eating it.
13

• There are a number of types of corn grown. They
  can be sorted out by intended use, and by the
  nature of the starch stored in the grains. The
  starches are
• Amylose a nearly unbranched chain of glucose
  molecules, hard starch and
• Amylopectin a highly branched chain of glucose,
  soft starch
• The basic types of corn are
• Popcorn (Zea mays everta) - hard starch on the
  outside surrounding a soft starch core. This is
  very old, and may be the most primitive type.
  Popcorn pops because unlike most other grains,
  the outer hull, or pericarp, of the popcorn
  kernel is both strong and impervious to moisture.

14
As the kernel is heated past the boiling
point, water in the kernel turns to superheated,
pressurized steam, contained within the
moisture-proof hull. Under these conditions, the
starch inside the kernel softens and becomes
pliable. The pressure continues to increase until
it reaches the breaking point of the hull a
pressure of about 135 psi, or 9.1 atmospheres.
The hull ruptures rapidly, causing a sudden drop
in pressure inside the kernel and a corresponding
rapid expansion of the steam, which expands the
starch and protein of the endosperm into an airy
foam.
15
2. Dent corn (Zea mays indenata) used in
livestock feed, industrial products, and
processed food. This is commonly called field
corn. The name dent comes from the change in
shape of the kernels as the corn matures.
3. Flint corn (Zea mays indurata) - also known
as Indian corn, is used for similar purposes as
dent corn. Flint corn is distinguished by a hard
outer shell and kernals with a range of colors
from white to red.
16

4. Sweetcorn (Zea mays saccharata) - Sweet corn
is extra sweet because it contains more natural
sugars than other types of corn. (Field corn
contains 4 sugar at the same stage standard
sweet corn contains 10 sugar.) Almost 50 of the
sugar can be converted to starch only 24 hours
after sweet corn is picked, so it is best to eat
it fresh! 5. Flour corn (Zea mays amylacea) -
is used in baked goods. It has a soft kernal
that is easy to grind. Flour corn is primarily
white, although it can be grown in other colors,
for example, blue corn. One of the oldest types
of corn, flour corn was a chief type grown by
native Americans.
17
Products from maize include corn oil
(unsaturated), margarines corn syrup cornstarch
adhesives, sizing, bulkers beer, bourbon,
Canadian (Club) whiskey silage (animal
feed) industrial material (cellulose for rayon
etc.) corn extract nutrients for antibiotic
production organic acid production (acetic,
citric, butyric acids) ethanol additive to
gasoline (now 10 in regular gas)
18
In terms of human consumption and nutrition there
are a large variety of applications succotash
corn boiled beans popcorn was known and used
by Incas (dont need to grind popcorn to get at
the nutritional part), and was likely consumed by
North American colonialists. The text suggests it
was used as a breakfast cereal with milk and
maple sugar. Only later did popcorn become a
snack food. Several major historical changes are
associated with corn cultivation and transport of
corn-based products expansion westward in the
U.S. and Canada an underlying reason for the
Louisiana purchase Canals, Railroads, roads
19

• Maize is low in tryptophan, lysine and other
  essential nutrients (Niacin Vitamin B12),
  therefore
• Diets heavily dependent on corn show evidence of
  Kwashiorkor
• Nutritional problems occur with a corn-only diet
  vitamin deficiency causes pellagra. However,
  native American processing of corn with lime
  frees vitamins, and the disease rarely appears.
  In Europe, without lime processing, pellagra was
  first noticed in 1730 and the nutritional basis
  of the disease was not resolved until 1930s
• 3. There has been a recent emphasis on fortifying
  amino acid content using both GMO (genetically
  modified organisms, controversial) and
  traditional breeding approaches