and Biological Importance of Rice
the cereals, rice and wheat share equal importance as leading
food sources for humankind. Rice is a staple food for nearly one-half
of the worlds population. In 1990, the crop was grown on
145.8 million hectares of land, and production amounted to 518.8
million metric tons of grain (paddy, rough rice). Although rice
is grown in 112 countries, spanning an area from 53° latitude
north to 35° south, about 95 percent of the crop is grown
and consumed in Asia. Rice provides fully 60 percent of the food
intake in Southeast Asia and about 35 percent in East Asia and
South Asia. The highest level of per capita rice consumption (130
to 180 kilograms [kg] per year, 55 to 80 percent of total caloric
source) takes place in Bangladesh, Cambodia, Indonesia, Laos,
Myanmar (Burma), Thailand, and Vietnam.
rice commands a higher price than wheat on the international market,
less than five percent of the worlds rice enters that market,
contrasted with about 16 percent of the wheat. Low-income countries,
China and Pakistan, for example, often import wheat at a cheaper
price and export their rice.
Value in Human Nutrition
rice has a relatively low protein content (about 8 percent in
brown rice and 7 percent in milled rice versus 10 percent in wheat),
brown rice (caryopsis) ranks higher than wheat in available carbohydrates,
digestible energy (kilojoules [kJ] per 100 grams), and net protein
utilization. Rice protein is superior in lysine content to wheat,
corn, and sorghum. Milled rice has a lower crude fiber content
than any other cereal, making rice powder in the boiled form suitable
as infant food. For laboring adults, milled rice alone could meet
the daily carbohydrate and protein needs for sustenance although
it is low in riboflavin and thiamine content. For growing children,
rice needs to be supplemented by other protein sources (Hegsted
1969; Juliano 1985b).
Importance of Rice
the basis of mean grain yield, rice crops produce more food energy
and protein supply per hectare than wheat and maize. Hence, rice
can support more people per unit of land than the two other staples
(Lu and Chang 1980). It is, therefore, not surprising to find
a close relationship in human history between an expansion in
rice cultivation and a rapid rise in population growth (Chang
a human food, rice continues to gain popularity in many parts
of the world where other coarse cereals, such as maize, sorghum
and millet, or tubers and roots like potatoes, yams, and cassava
have traditionally dominated. For example, of all the worlds
regions, Africa has had the sharpest rise in rice consumption
during the last few decades.
for table use is easy to prepare. Its soft texture pleases the
palate and the stomach. The ranking order of food preference in
Asia is rice, followed by wheat, maize, and the sweet potato;
in Africa it is rice or wheat, followed by maize, yams, and cassava
(authors personal observation).
industrial usage, rice is also gaining importance in the making
of infant foods, snack foods, breakfast cereals, beer, fermented
products, and rice bran oil, and rice wine remains a major alcoholic
beverage in East Asia. The coarse and silica-rich rice hull is
finding new use in construction materials. Rice straw is used
less in rope and paper making than before, but except for modern
varieties, it still serves as an important cattle feed throughout
Asia. Because rice flour is nearly pure starch and free from allergens,
it is the main component of face powders and infant formulas.
Its low fiber content has led to an increased use of rice powder
in polishing camera lenses and expensive jewelry.
Origin, and Evolution
is a member of the grass family (Gramineae) and belongs to the
genus Oryza under tribe Oryzeae. The genus Oryza
includes 20 wild species and 2 cultivated species (cultigens).
The wild species are widely distributed in the humid tropics and
subtropics of Africa, Asia, Central and South America, and Australia
(Chang 1985). Of the two cultivated species, African rice (O.
glaberrima Steud.) is confined to West Africa, whereas common
or Asian rice (O. sativa L.) is now commercially grown
in 112 countries, covering all continents (Bertin et al. 1971).
wild species have both diploid (2n = 2x = 24) and tetraploid (2n
= 4x = 48) forms, while the two cultigens are diploid and share
a common genome (chromosome group). Incompatibility exists among
species having different genomes. Partial sterility also shows
up in hybrids when different ecogeographic races of O. sativa
are hybridized. The cultivated species of Oryza may be
classified as semiaquatic plants, although extreme variants are
grown not only in deep water (up to 5 meters) but also on dry
land (Chang 1985).
the cereals, rice has the lowest water use efficiency. Therefore,
rice cannot compete with dryland cereals in areas of low rainfall
unless irrigation water is readily available from reservoirs,
bunds, and the like. On the other hand, the highest yields of
traditional varieties have been obtained in regions of cloudless
skies, such as in Spain, California, and northern Japan (Lu and
"wild rice" of North America is Zizania palustris
(formerly Z. aquatica L. [2n = 30]), which belongs to one
of the 11 related genera in the same tribe. Traditionally, this
species was self-propagating and harvested only by Native Americans
in the Great Lakes area. Now it is commercially grown in Minnesota
and northern California.
origin of rice was long shrouded by disparate postulates because
of the pantropical but disjunct distribution of the 20 wild species
across four continents, the variations in characterizing and naming
plant specimens, and the traditional feud concerning the relative
antiquity of rice in India versus China. Among the botanists,
R. J. Roschevicz (1931) first postulated that the center of origin
of the section Sativa Roschev., to which O. glaberrima
and O. sativa belong, was in Africa and that O. sativa
had originated from multiple species. A divergent array of wild
species was proposed by different workers as the putative ancestor
of O. sativa (Chang 1976b).
workers considered "O. perennis Moench" (an ambiguous
designation of varying applications) as the common progenitor
of both cultigens (Chang 1976b). A large number of scholars had
argued that Asian rice originated in the Indian subcontinent (South
Asia), although A. de Candolle (1884), while conceding that India
was more likely the original home, considered China to have had
an earlier history of rice cultivation
the basis of historical records and the existence of wild rices
in China, Chinese scholars maintained that rice cultivation was
practiced in north China during the mythological Sheng Nung period
(c. 2700 B.C.) and that O. sativa of China evolved from
wild rices (Ting 1961). The finding of rice glume imprints at
Yang-shao site in north China (c. 3200 2500 B.C.) during
the 1920s reinforced the popular belief that China was one of
the centers of its origin (Chinese Academy of Agricultural Sciences
the 1950s, however, rice researchers have generally agreed that
each of the two cultigens originated from a single wild species.
But disputes concerning the immediate ancestor of O. sativa
persist to this day (Chang 1976b, 1985; Oka 1988). A multidisciplinary
analysis of the geographic distribution of the wild species and
their genomic composition in relation to the "Glossopterid
Line" (northern boundary) of the Gondwanaland fragments (Melville
1966) strongly indicated the Gondwanaland origin of the genus
Oryza (Chang 1976a, 1976b, 1985). This postulate of rice
having a common progenitor in the humid zones of the supercontinent
Pangaea before it fractured and drifted apart can also explain
the parallel evolutionary pattern of the two cultigens in Africa
and Asia respectively. It also reconciles the presence of closely
related wild species having the same genome in Australia and in
Central and South America. Thus, the antiquity of the genus dates
back to the early Cretaceous period of more than 130 million years
parallel evolutionary pathway of O. glaberrima in Africa
and of O. sativa in Asia was from perennial wild
Æ annual wild Æ annual cultigen, a pattern
common to other grasses and many crop plants. The parallel pathways
O. longistaminata Æ O. barthii
Æ O. glaberrima.
O. rufipogon Æ O. nivara Æ
scheme can resolve much that has characterized past disputes on
the putative ancestors of the two cultigens. Wild perennial and
annual forms having the same A genome are present in Australia
and in Central and South America, but the lack of incipient agriculture
in Australia and of wetland agronomy in tropical America in prehistoric
times disrupted the final step in producing an annual cultigen.
needs to be pointed out that the putative ancestors, especially
those in tropical Asia, are conceptually wild forms of the distant
past, because centuries of habitat disturbance, natural hybridization,
and dispersal by humans have altered the genetic structure of
the truly wild ancestors. Most of the wild rices found in nature
today are hybrid derivatives of various kinds (Chang 1976b; 1985).
The continuous arrays of variants in natural populations have
impaired definitive studies on the wild progenies (Chang 1976b;
differentiation and diversification of annual wild forms into
the early prototypes of cultigen in South and mainland Southeast
Asia were accelerated by marked climatic changes during the Neothermal
age of about 10,000 to 15,000 years ago. Initial selection and
cultivation could have occurred independently and nearly concurrently
at numerous sites within or bordering a broad belt of primary
genetic diversity that extends from the Ganges plains below the
eastern foothills of Himalaya, through upper Burma, northern Thailand,
Laos, and northern Vietnam, to southwest and southern China.
this belt, geographic dispersal by various agents, particularly
water currents and humans, lent impetus to ecogenetic differentiation
and diversification under human cultivation. In areas inside China
where winter temperatures fell below freezing, the cultivated
forms (cultivars) became true domesticates, depending entirely
on human care for their perpetuation and propagation. In a parallel
manner, the water buffalo was brought from the swamps of the south
into the northern areas and coevolved as another domesticate (Chang
West Africa, O. glaberrima was domesticated from the wild
annual O. barthii (Chevalier 1932); the latter was adapted
primarily to water holes in the savanna and secondarily to the
forest zone (Harlan 1973). The cultigen has its most important
center of diversity in the central Niger delta. Two secondary
centers existed near the Guinean coast (Porteres 1956).
of the wild prototypes preceded domestication. Rice grains were
initially gathered and consumed by prehistoric people of the humid
regions where the perennial plants grew on poorly drained sites.
These people also hunted, fished, and gathered other edible plant
parts as food. Eventually, however, they developed a liking for
the easily cooked and tasty rice and searched for plants that
bore larger panicles and heavier grains.
gathering-and-selection process was more imperative for peoples
who lived in areas where seasonal variations in temperature and
rainfall were more marked. The earlier maturing rices, which also
tend to be drought escaping, would have been selected to suit
the increasingly arid weather of the belt of primary diversity
during the Neothermal period. By contrast, the more primitive
rices of longer maturation, and those, thus, more adapted to vegetative
propagation, would have survived better in the humid regions to
the south (Chang 1976b; 1985). In some areas of tropical Asia,
such as the Jeypore tract of Orissa State (India), the Batticoloa
district (Sri Lanka), and the forested areas of north Thailand,
the gathering of free-shattering grains from wild rice can still
be witnessed today (Chang 1976b; Higham 1989).
of Rice Cultivation
the differentiation of the progenitors of Oryza species
dates back to the early Cretaceous period, the beginning of rice
cultivation was viewed by Western scholars as a relatively recent
event until extensive excavations were made after the 1950s in
China and to a lesser extent in India. Earlier, R. J. Roschevicz
(1931) estimated 2800 B.C. as the beginning of rice cultivation
in China, whereas the dawn of agriculture in India was attributed
to the Harappan civilization, which began about 2500 B.C. (Hutchinson
far, the oldest evidence from India comes from Koldihwa, U.P.,
where rice grains were embedded in earthen potsherds and rice
husks discovered in ancient cow dung. The age of the Chalcolithic
levels was estimated between 6570 and 4530 B.C. (Vishnu-Mittre
1976; Sharma et al. 1980), but the actual age of the rice remains
may be as recent as 1500 B.C. (Chang 1987). Another old grain
sample came from Mohenjodaro of Pakistan and dates from about
2500 B.C. (Andrus and Mohammed 1958). Rice cultivation probably
began in the upper and middle Ganges between 2000 and 1500 B.C.
(Candolle 1884; Watabe 1973). It expanded quickly after irrigation
works spread from Orissa State to the adjoining areas of Andhra
Pradesh and Tamil Nadu in the Iron Age around 300 B.C. (Randhawa
Southeast Asia, recent excavations have yielded a number of rice
remains dating from 3500 B.C. at Ban Chiang (Thailand); 1400 B.C.
at Solana (Philippines); and A.D. 500 at Ban Na Di (Thailand)
and at Ulu Leang (Indonesia). Dates between 4000 and 2000 B.C.
have been reported from North Vietnam (Dao 1985) but have not
yet been authenticated.
various reports have been summarized by T. T. Chang (1988, 1989a).
The widely scattered findings are insufficient to provide a coherent
picture of agricultural development in the region, but rice cultivation
in mainland Southeast Asia undoubtedly preceded that in insular
Southeast Asia (Chang 1988). The paucity of rice-related remains
that were confined to upland sites in northern Thailand could
be attributed to the sharp rise in sea level around the Gulf of
Thailand during the four millennia between 8000 and 4000 B.C.
Floods inundated vast tracts of low-lying land amid which rice
chaffs and shell knives for cutting rice stalks were recently
found at Khok Phanom Di near the Gulf and dated from 6000 to 4000
B.C. (Higham 1989).
the Southeast Asian region, several geographers and ethnobotanists
had earlier postulated that the cultivation of root crops predated
rice culture (Sauer 1952; Spencer 1963; Yen 1977). Yet, this hypothesis
falters in view of the apparently rather recent domestication
(c. 2000 B.C.) of yams in the region (Alexander and Coursey 1969).
In many hilly regions, vegeculture probably preceded dryland rice
cultivation, but not in wetland areas. In the cooler regions,
rice grains were crucial to early cultivators who could store
and consume the harvest during the winter months.
to the 1950s, the belief in the antiquity of rice cultivation
in China was based on mythical writings in which "Emperor
Shen Nung" (c. 2700 B.C.) was supposed to have taught his
people to plant five cereals, with rice among them (Candolle 1884;
Roschevicz 1931; Ting 1949; Chatterjee 1951). This view, however,
was questioned by many non-Chinese botanists and historians because
of the paucity of wild rices in China (or rather the paucity of
information on the wild rices) and the semiarid environment in
north China (Chang 1979b, 1983). Yet in the 1920s, the discovery
of rice glume imprints on broken pottery at the Yang-shao site
in Henan (Honan) by J. G. Andersson and co-workers (Andersson
1934) was important in linking Chinese archaeology with agriculture.
The excavated materials were considered Neolithic in origin and
the precise age was not available, though K. C. Chang later gave
this author an estimated age of between 3200 and 2500 B.C.
diggings in the Yangtze basin after the 1950s yielded many rice
remains that pushed back rice culture in China even further into
antiquity (Chang 1983). The most exciting event was the finding
in 19734 of carbonized rice kernels, rice straw, bone spades,
hoe blades (ssu), and cooking utensils that demonstrated
a well-developed culture supported by rice cultivation at the
He-mu-du (Ho-mu-tu) site in Zhejiang (Chekiang) Province dated
at 5005 B.C. (Chekiang Provincial Cultural Management Commission
and Chekiang Provincial Museum 1976; Hsia 1977).
grains were mostly of the hsien (Indica) type but included
some keng (Sinica or Japonica) and intermediate kernels.
The discovery also indicated the existence of an advanced rice-based
culture in east China that vied in antiquity and sophistication
with the millet-based culture in north China as represented by
the Pan-po site in Shenxi (Shensi). Another site at Luo-jia-jiao
in Zhejiang Province also yielded carbonized rice of both ecogeographic
races of a similar age estimated at 7000 B.P. (Chang 1989a). In
a 1988 excavation at Peng-tou-shan site in Hunan Province, abundant
rice husks on pottery or red burnt clay as well as skeletal remains
of water buffalo were found. The pottery was dated at between
7150 and 6250 B.C. (uncorrected carbon dating). Diggings in neighboring
Hubei (Hupei) Province yielded artifacts of similar age, but the
grain type could not be ascertained (Pei 1989). Excavations in
Shenxi also produced rice glume imprints on red burnt clay dated
between 6000 and 5000 B.C. (Yan 1989).
contrast to all this scholarly effort on the antiquity of rice
cultivation in Asia, our understanding of the matter in West Africa
rests solely on the writing of R. Porteres (1956), who dates it
from 1500 B.C. in the primary Niger center, and from A.D. 1000
to A.D. 1200 in the two Guinean secondary centers.
history also recorded that rice culture was well established in
Honan and Shenxi Provinces of north China during the Chou Dynasty
(1122 to 255 B.C.) by Lungshanoid farmers (Ho 1956; Chang 1968).
During the Eastern Chou Dynasty (255 to 249 B.C.), rice was already
the staple food crop in the middle and lower basins of the Yangtze
River (Ting 1961). Wild rices were amply recorded in historical
accounts; their northern limit of distribution reached 38°
north latitude (Chang 1983).
on the above developments, it appears plausible to place the beginning
of rice cultivation in India, China, and other tropical Asian
countries at nearly 10,000 years ago or even earlier. Since rice
was already cultivated in central and east China at 6000 to 5000
B.C., it would have taken a few millennia for rice to move in
from the belt to the south of these regions. The missing links
in the history of rice culture in China can be attributed to the
dearth of archaeological findings from south China and the relatively
recent age of rice remains in southwest China (1820 B.C. at Bei-yan
in Yunnan) and south China (2000 B.C. at Shih Hsiah in Kwangtung).
These areas represent important regions of ecogenetic differentiation
or routes of dispersal (Chang 1983).
number of scholars have attempted to use etymology as a tool in
tracing the origin and dispersal of rice in Asia. The Chinese
word for rice in the north, tao or dao or dau,
finds its variants in south China and Indochina as kau
(for grain), hao, ho, heu, deu, and khaw (Ting 1961;
Chinese Academy of Agricultural Sciences 1986). Indian scholars
claimed that the word for rice in Western languages had a Dravidian
root and that ris, riz, arroz, rice, oruza, and
arrazz all came from arisi (Pankar and Gowda 1976).
In insular Southeast Asia, the Austronesian terms padi
and paray for rice and bras or beras for
milled rice predominate (Chinese Academy of Agricultural Sciences
1986; Revel 1988).
the other hand, Japanese scholars have also emphasized the spread
of the Chinese words ni or ne (for wild rice) and
nu (for glutinous rice) to Southeast Asia (Yanagita et
al. 1969). N. Revel and co-workers (1988) have provided a comprehensive
compilation of terms related to the rice plant and its parts derived
from the linguistic data of China, Indochina, insular Southeast
Asia, and Madagascar. Yet among the different disciplinary approaches,
linguistic analyses have not been particularly effective in revealing
facts about the dispersal of rice by humans. In part, this is
because the ethnological aspects of human migration in the Southeast
Asian region remain in a state of flux. (For various viewpoints
see Asian Perspectives 1988: 26, no.1.)
Dispersal and Ecogenetic Diversification
early dissemination of rice seeds (grains) could have involved
a variety of agents: flowing water, wind, large animals, birds,
and humans. The latter have undoubtedly been most effective in
directed dispersal: Humans carried rice grains from one place
to another as food, seed, merchandise, and gifts. The continuous
and varied movements of peoples in Asia since prehistoric times
have led to a broad distribution of early O. sativa forms,
which proliferated in ecogenetic diversification after undergoing
the mutation-hybridization-recombination-differentiation cycles
and being subjected to both natural and human selection forces
at the new sites of cultivation. In contrast, O. glaberrima
cultivars exhibit markedly less diversity than their Asian counterparts,
owing to a shorter history of cultivation and narrower dispersal.
The contrast is amplified by other factors as shown in Table II.A.7.1.
dispersal of O. sativa from numerous sites in its primary
belt of diversity involved a combination of early forms of cultivars
and associated wild relatives, often grown in a mixture. Biological
findings and historical records point to five generalized routes
from the Assam-Meghalaya-Burma region. Rice moved: (1) southward
to the southern Bengal Bay area and the southern states of India
and eventually to Sri Lanka; (2) westward to Pakistan and the
west coast of India; (3) eastward to mainland Southeast Asia (Indochina);
(4) southeastward to Malaysia and the Indonesian islands; and
(5) northeastward to southwest China, mainly the Yunnan-Kweichow
area, and further into east, central, and south China. The early
routes of travel most likely followed the major rivers, namely,
Brahmaputra, Ganges, Indus, Mekong, and Yangtze. Routes of sea
travel, which came later, were from Thailand and Vietnam to the
southern coastal areas of China, from Indonesia to the Philippines
and Taiwan, and from China to Japan, as well as from China to
Korea to Japan. These routes are summarized in Map II.A.7.1.
the basis of ancient samples of rice hulls collected from India
and Indochina, covering a span of 10 centuries up to around A.D.
1500, three main groups of cultivars (the Brahmaputra-Gangetic
strain, the Bengal strain, and the Mekong strain) have been proposed
by T. Watabe (1985). The Mekong strain originating in Yunnan was
postulated to have given rise to the Indochina series and the
Yangtze River series of cultivars; the latter consisted mainly
of the keng rices of China. It should be pointed out, however,
that the ecogenetic diversification processes following dispersal
and the cultivators preferences could have added complications
to the varietal distribution pattern of the present, as later
discussions will reveal.
Differentiation and Diversification
the early phase of human cultivation and selection, a number of
morphological and physiological changes began to emerge. Selection
for taller and larger plants resulted in larger leaves, longer
and thicker stems, and longer panicles. Subsequent selection for
more productive plants and for ease in growing and harvesting
led to larger grains. It also resulted in increases in: (1) the
rate of seedling growth; (2) tillering capacity; (3) the number
of leaves per tiller and the rate of leaf development; (4) the
synchronization of tiller development and panicle formation (for
uniform maturation); (5) the number of secondary branches on a
panicle; and (6) panicle weight (a product of spikelet number
and grain weight). Concurrently, there were decreases or losses
of the primitive features, such as: (1) rhizome formation; (2)
pigmentation of plant parts; (3) awn length; (4) shattering of
grains from the panicle; (5) growth duration; (6) intensity of
grain dormancy; (7) response to short day length; (8) sensitivity
to low temperatures; and (9) ability to survive in flood waters.
The frequency of cross pollination also decreased so that the
plants became more inbred and increasingly dependent on the cultivators
for their propagation (by seed) and perpetuation (by short planting
cycles) (Chang 1976b).
rice cultivars were carried up and down along the latitudinal
or altitudinal clines or both, the enormous genetic variability
in the plants was released, and the resulting variants expressed
their new genetic makeup while reacting to changing environmental
factors. The major environmental forces are soil properties, water
supply, solar radiation intensity, day length, and temperature
range, especially the minimum night temperatures. Those plants
that could thrive or survive in a new environment would become
fixed to form an adapted population the beginning of a
new ecostrain while the unadapted plants would perish and
the poorly adapted plants would dwindle in number and be reduced
to a small population in a less adverse ecological niche in the
a process of differentiation and selection was aided by spontaneous
mutations in a population or by chance outcrossing between adjacent
plants or both. The process could independently occur at many
new sites of cultivation and recur when environmental conditions
or cultivation practices changed. Therefore, rich genetic diversity
of a secondary nature could be found in areas of undulating terrain
where the environmental conditions significantly differed within
a small area. The Assam and Madhya Pradesh states and Jeypore
tract of India, the island of Sri Lanka, and Yunnan Province of
China represent such areas of remarkable varietal diversity (Chang
into Ecogeographic Races and Ecotypes
cultivation and intense selection in areas outside the conventional
wetlands of shallow water depth (the paddies) have resulted in
a range of extreme ecotypes: deepwater or floating rices that
can cope with gradually rising waters up to 5 meters (m) deep;
flood-tolerant rices that can survive days of total submergence
under water; and upland or hill rices that are grown under dryland
conditions like corn and sorghum. The varying soil-water-temperature
regimes in the Bengal Bay states of India and in Bangladesh resulted
in four seasonal ecotypes in that area: boro (winter),
aus (summer), transplanted aman (fall, shallow water),
and broadcast aman (fall, deep water). In many double-cropping
areas, two main ecotypes follow the respective cropping season:
dry (or off) and wet (or main) (Chang 1985).
broader terms, the wide dispersal of O. sativa and subsequent
isolation or selection in Asia has led to the formation of three
ecogeographic races that differ in morphological and physiological
characteristics and are partially incompatible in genetic affinity:
Indica race in the tropics and subtropics; javanica race in the
tropics; and sinica (or japonica) race in the temperate zone.
Of the three races, indica is the oldest and the prototype of
the other two races as it retains most of the primitive features:
tallness, weak stems, lateness, dormant grains, and shattering
sinica race became differentiated in China and has been rigorously
selected for tolerance to cool temperatures, high productivity,
and adaptiveness to modern cultivation technology: short plant
stature, nitrogen responsiveness, earliness, stiff stems, and
high grain yield. The javanica race is of more recent origin and
appears intermediate between the other two races in genetic affinity,
meaning it is more cross-fertile with either indica or sinica.
Javanica cultivars are marked by gigas features in plant panicle
and grain characters. They include a wetland group of cultivars
(bulu and gundil of Indonesia) and a dryland group
(hill rices of Southeast Asia).
picture of race-forming processes is yet incomplete (Chang 1985).
Many studies have relied heavily on grain size and shape as empirical
criteria for race classification. Some studies employed crossing
experiments and hybrid fertility ratings. Other workers recently
used isozyme patterns to indicate origin and affinity. Controversies
in past studies stemmed largely from limited samples, oversimplified
empirical tests, and reliance on presently grown cultivars to
retrace the distant past. The latter involved a lack of appreciation
for the relatively short period (approximately 5 to 6 centuries)
that it takes for a predominant grain type to be replaced by another
(Watabe 1973), which was probably affected by the cultivators
preference. Most of the studies have also overlooked the usefulness
of including amylose content and low temperature tolerance in
revealing race identity (Chang 1976b, 1985). It should also be
recognized that early human contacts greatly predated those given
in historical records (Chang 1983), and maximum varietal diversity
often showed up in places outside the area of primary genetic
diversity (Chang 1976b, 1985).
to the expansion in production area and dispersal of the cultivars
to new lands during the last two centuries was the growth of varietal
diversity. In the first half of the twentieth century, before
scientifically bred cultivars appeared in large numbers, the total
number of unimproved varieties grown by Asian farmers probably
exceeded 100,000, though many duplicates of similar or altered
names were included in this tally (Chang 1984 and 1992).
of Asian Rice
records are quite revealing of the spread of Asian rice from South
Asia, Southeast Asia, and China to other regions or countries,
though exact dates may be lacking. In the northward direction,
the Sinica race was introduced from China into the Korean peninsula
before 1030 B.C. (Chen 1989). Rice cultivation in Japan began
in the late Jomon period (about 1000 B.C., [Akazawa 1983]), while
earlier estimates placed the introduction of rice to Japan from
China in the third century B.C. (Ando 1951; Morinaga 1968). Several
routes could have been involved: (1) from the lower Yangtze basin
to Kyushu island, (2) from north China to Honshu Island, or (3)
via Korea to northern Kyushu; hsien (Indica) may have arrived
from China, and the Javanica race traveled from Southeast Asia
(Isao 1976; Lu and Chang 1980). The areas that comprised the former
Soviet Union obtained rice seeds from China, Korea, Japan, and
Persia, and rice was grown around the Caspian Sea beginning in
the early 1770s (Lu and Chang 1980).
the Indian subcontinent and mainland Southeast Asia, the Indica
race spread southward into Sri Lanka (before 543 B.C.), the Malay
Archipelago (date unknown), the Indonesian islands (between 2000
and 1400 B.C.), and central and coastal China south of the Yangtze
River. Hsien or Indica-type grains were found at both He-mu-du
and Luo-jia-jiao sites in east China around 5000 B.C. (Lu and
Chang 1980; Chang 1988). The keng or sinica rices were
likely to have differentiated in the Yunnan-Kweichow region, and
they became fixed in the cooler northern areas (Chang 1976b).
On the other hand, several Chinese scholars maintain that hsien
and keng rices were differentiated from wild rices inside
China (Ting 1961; Yan 1989). The large-scale introduction and
planting of the Champa rices (initially from Vietnam) greatly
altered the varietal composition of hsien rices in south
China and the central Yangtze basin after the eleventh century
(Ho 1956; Chang 1987).
javanica race had its origin on the Asian mainland before it differentiated
into the dryland ecotype (related to the aus type of the Bengal
Bay area and the hill rices of Southeast Asia) and the wetland
ecotype (bulu and gundil) of Indonesia. From Indonesia,
the wetland ecotype spread to the Philippines (mainly in the Ifugao
region at about 1000 B.C.), Taiwan (at 2000 B.C. or later), and
probably Ryukyus and Japan (Chang 1976b, 1988).
Middle East acquired rice from South Asia probably as early as
1000 B.C. Persia loomed large as the principal stepping stone
from tropical Asia toward points west of the Persian Empire. The
Romans learned about rice during the expedition of Alexander the
Great to India (c. 3274 B.C.) but imported rice wine instead
of growing the crop. The introduction of rice into Europe could
have taken different routes: (1) from Persia to Egypt between
the fourth and the first centuries B.C., (2) from Greece or Egypt
to Spain and Sicily in the eighth century A.D., and (3) from Persia
to Spain in the eighth century and later to Italy between the
thirteenth and sixteenth centuries. The Turks brought rice from
Southwest Asia into the Balkan Peninsula, and Italy could also
have served as a stepping stone for rice growing in that region.
Direct imports from various parts of Asia into Europe are also
probable (Lu and Chang 1980).
the spread of rice to Africa, Madagascar received Asian rices
probably as early as 1000 B.C. when the early settlers arrived
in the southwest region. Indonesian settlers who reached the island
after the beginning of the Christian era brought in some Javanica
rices. Madagascar also served as the intermediary for the countries
in East Africa, although direct imports from South Asia would
have been another source. Countries in West Africa obtained Asian
rice through European colonizers between the fifteenth and seventeenth
centuries. Rice was also brought into Congo from Mozambique in
the nineteenth century (Lu and Chang 1980).
Caribbean islands obtained their rices from Europe in the late
fifteenth and early sixteenth centuries. Central and South America
received rice seeds from European countries, particularly Spain,
during the sixteenth through the eighteenth centuries. In addition,
there was much exchange of cultivars among countries of Central,
South, and North America (Lu and Chang 1980).
cultivation in the United States began around 1609 as a trial
planting in Virginia. Other plantings soon followed along the
south Atlantic coast. Rice production was well established in
South Carolina by about 1690. It then spread to the areas comprising
Mississippi and southwest Louisiana, to adjoining areas in Texas,
and to central Arkansas, which are now the main rice-producing
states in the South. California began rice growing in 190912
with the predominant cultivar the sinica type, which can tolerate
cold water at the seedling stage. Rice was introduced into Hawaii
by Chinese immigrants between 1853 and 1862, but it did not thrive
as an agro-industry in competition with sugarcane and pineapple
(Adair, Miller, and Beachell 1962; Lu and Chang 1980).
planting of rice in Australia took place in New South Wales in
1892, although other introductions into the warmer areas of Queensland
and the Northern Territories could have come earlier. Commercial
planting in New South Wales began in 1923 (Grist 1975). The island
of New Guinea began growing rice in the nineteenth century (Bertin
et al. 1971).
dissemination of Asian rice from one place to another doubtless
also took place for serendipitous reasons. Mexico, for example,
received its first lot of rice seed around 1522 in a cargo mixed
with wheat. South Carolinas early plantings of rice around
168594 allegedly used rice salvaged from a wrecked ship
whose last voyage began in Madagascar (Grist 1975; Lu and Chang
addition, the deliberate introduction of rice has produced other
unexpected benefits. This occurred when the Champa rices of central
Vietnam were initially brought to the coastal areas of South China.
In 101112 the Emperor Chen-Tsung of the Sung Dynasty decreed
the shipment of 30,000 bushels of seed from Fukien Province into
the lower Yangtze basin because of the grains early maturing
and drought-escaping characteristics. But its subsequent widespread
use in China paved the way for the double cropping of rice and
the multiple cropping of rice and other crops (Ho 1956; Chang
for African rice (O. glaberrima), its cultivation remains
confined to West Africa under a variety of soil-water regimes:
deep water basins, water holes in the savannas, hydromorphic soils
in the forest zone, and dryland conditions in hilly areas (Porteres
1956; Harlan 1973). In areas favorable for irrigated rice production,
African rice has been rapidly displaced by the Asian introductions,
and in such fields the native cultigen has become a weed in commercial
is interesting to note that the African cultigen has been found
as far afield as Central America, most likely as a result of introduction
during the time of the transatlantic slave trade (Bertin et al.
Practices and Cultural Exchanges
of Cultivation Practices
grains were initially gathered and consumed by prehistoric peoples
in the humid tropics and subtropics from self-propagating wild
stands. Cultivation began when men or, more likely, women, deliberately
dropped rice grains on the soil in low-lying spots near their
homesteads, kept out the weeds and animals, and manipulated the
water supply. The association between rice and human community
was clearly indicated in the exciting excavations at He-mu-du,
Luo-jia-jiao, and Pen-tou-shan in China where rice was a principal
food plant in the developing human settlements there more than
7,000 years ago.
first entered the diet as a supplement to other food plants as
well as to game, fish, and shellfish. As rice cultivation expanded
and became more efficient, it replaced other cereals (millets,
sorghums, Jobs tears, and even wheat), root crops, and forage
plants. The continuous expansion of rice cultivation owed much
to its unique features as a self-supporting semiaquatic plant.
These features include the ability of seed to germinate under
both aerobic and anaerobic conditions and the series of air-conducting
aerenchymatous tissues in the leafsheaths, stems, and roots that
supply air to roots under continuous flooding. Also important
are soil microbes in the root zone that fix nitrogen to feed rice
growth, and the wide adaptability of rice to both wetland and
dryland soil-water regimes. It is for these reasons that rice
is the only subsistence crop whose soil is poorly drained and
needs no nitrogen fertilizer applied. And these factors, in turn,
account for the broad rice-growing belt from the Sino-Russian
border along the Amur River (53°N latitude) to central Argentina
crucial to the expansion and improvement of rice cultivation were
water control, farm implements, draft animals, planting methods,
weed and pest control, manuring, seed selection, postharvest facilities,
and above all, human innovation. A number of significant events
selected from the voluminous historical records on rice are summarized
below to illustrate the concurrent progression in its cultivation
techniques and the socio-politico-economic changes that accompanied
was initially grown as a rain-fed crop in low-lying areas where
rain water could be retained. Such areas were located in marshy,
but flood-free, sites around river bends, as found in Honan and
Shenxi Provinces of north China (Ho 1956), and at larger sites
between small rivers, as represented by the He-mu-du site in east
China (Chang 1968; You 1976). Early community efforts led to irrigation
or drainage projects. The earliest of such activities in the historical
record were flood-control efforts in the Yellow River area under
Emperor Yu at about 2000 B.C. Irrigation works, including dams,
canals, conduits, sluices, and ponds, were in operation during
the Yin period (c. 1400 B.C.).
system of irrigation and drainage projects of various sizes were
set up during the Chou Dynasty. Large-scale irrigation works were
built during the Warring States period (77021 B.C.). By
400 B.C., "rice [tao] men" were appointed to
supervise the planting and water management operations. The famous
Tu-Cheng-Yen Dam was constructed near Chendu in Sichuan (Szechuan)
Province about 250 B.C., which made western Sichuan the new rice
granary of China.
developments during the Tang and Sung dynasties led to extensive
construction of ponds as water reservoirs and of dams in a serial
order to impound fresh water in rivers during high tides. Dykes
were built around lake shores to make use of the rich alluvial
soil (Chou 1986), and the importance of water quality was recognized
farm implements, tools made from stone (spade, hoe, axe, knife,
grinder, pestle, and mortar) preceded those made from wood and
large animal bones (hoe, spade); these were followed by bronze
and iron tools. Bone spades along with wooden handles were found
at the He-mu-du site. Bronze knives and sickles appeared during
Shang and Western Chou. Between 770 and 211 B.C. iron tools appeared
in many forms. The iron plow pulled by oxen was perfected during
the Western Han period. Deep plowing was advocated from the third
century B.C. onward. The spike-tooth harrow (pa) appeared
around the Tang Dynasty (sixth century), and it markedly improved
the puddling of wet soil and facilitated the transplanting process.
This implement later spread to Southeast Asia to become an essential
component in facilitating transplanted rice culture there (Chang
1976a). Other implements, such as the roller and a spiked board,
were also developed to improve further the puddling and leveling
rice grains into a low-lying site was the earliest method of planting
and can still be seen in the Jeypore tract of India and many parts
of Africa. In dry soils, the next development was to break through
the soil with implements, mainly the plow, whereas in wetland
culture, it was to build levees (short dikes or bunds) around
a field in order to impound the water. In the latter case, such
an operation also facilitated land leveling and soil preparation
by puddling the wet soil in repeated rounds.
next giant step came in the transplanting (insertion) of young
rice seedlings into a well-puddled and leveled wet field. Transplanting
requires the raising of seedlings in nursery beds, then pulling
them from those beds, bundling them, and transporting them to
the field where the seedlings are thrust by hand into the softened
wet soil. A well-performed transplanting operation also requires
seed selection, the soaking of seeds prior to their initial sowing,
careful management of the nursery beds, and proper control of
water in the nursery and in the field. The transplanting practice
began in the late Han period (A.D. 23270) and subsequently
spread to neighboring countries in Southeast Asia as a package
comprised of the water buffalo, plow, and the spike-tooth harrow.
is a labor-consuming operation. Depending on the circumstances,
between 12 and close to 50 days of an individuals labor
is required to transplant one hectare of rice land (Barker, Herdt,
and Rose 1985). On the other hand, transplanting provides definite
advantages in terms of a fuller use of the available water, especially
during dry years, better weed control, more uniform maturation
of the plants, higher grain yield under intensive management,
and more efficient use of the land for rice and other crops in
these advantages, however, in South Asia the transplanting method
remains second in popularity to direct seeding (broadcasting or
drilling) due to operational difficulties having to do with farm
implements, water control, and labor supply (Chang 1976a).
of the one-step transplanting method were (1) to interplant an
early maturing variety and a late one in alternating rows in two
steps (once practiced in central China) and (2) to pull two-week-old
seedlings as clumps and set them in a second nursery until they
were about one meter tall. At this point, they were divided into
smaller bunches and once more transplanted into the main field.
This method, called double transplanting, is still practiced in
Indochina in anticipation of quickly rising flood waters and a
long rain season (Grist 1975).
in rice fields have undoubtedly been a serious production constraint
since ancient times. The importance of removing weeds and wild
rice plants was emphasized as early as the Han Dynasty. Widely
practiced methods of controlling unwanted plants in the southern
regions involved burning weeds prior to plowing and pulling them
afterward, complemented by maintaining proper water depth in the
field. Fallowing was mentioned as another means of weed control,
and midseason drainage and tillage has been practiced since Eastern
Chou as an effective means of weed control and of the suppression
of late tiller formation by the rice plant.
tools, mainly of the hoe and harrow types, were developed for
tillage and weed destruction. Otherwise, manual scratching of
the soil surface and removal of weeds by hand were practiced by
weeders who crawled forward among rows of growing rice plants.
Short bamboo tubes tipped with iron claws were placed on the finger
tips to help in the tedious operation. More efficient tools, one
of which was a canoe-shaped wooden frame with a long handle and
rows of spikes beneath it, appeared later (Amano 1979: 403). This
was surpassed only by the rotary weeder of the twentieth century
(Grist 1975: 157).
pests were mentioned in Chinese documents before plant diseases
were recognized. The Odes (c. sixth century B.C.) mentioned
stemborers and the granary moth. During the Sung Dynasty, giant
bamboo combs were used to remove leaf rollers that infest the
upper portions of rice leaves. A mixture of lime and tung oil
was used as an insect spray. Kernel smut, blast disease, and cold
injury during flowering were recognized at the time of the Ming
Dynasty. Seedling rot was mentioned in the Agricultural Manual
of Chen Fu during South Sung (Chinese Academy of Agricultural
relationship between manuring and increased rice yield was observed
and recorded more than two thousand years ago. The use of compost
and plant ash was advocated in writings of the first and third
centuries. Boiling of animal bones in water as a means to extract
phosphorus was practiced in Eastern Han. Growing a green manuring
crop in winter was advised in the third century. The sixth century
agricultural encyclopedia Chi-Min-Yao-Shu (Ku undated)
distinguished between basal and top dressings of manure, preached
the use of human and animal excreta on poor soils, and provided
crop rotation schemes (Chang 1979b).
practices received much attention in China because of the poor
or erratic water supply in many rice areas. Therefore, the labor
inputs on water management in Wushih County of Jiangsu Province
in the 1920s surpassed those of weeding or transplanting by a
factor of two (Amano 1979: 410), whereas in monsoonal Java, the
inputs in water management were insignificant (Barker et al. 1985:
of the cooler weather in north China, irrigation practices were
attuned to suitable weather conditions as early as the Western
Han: Water inlets and outlets were positioned directly opposite
across the field so as to warm the flowing water by sunlight during
the early stages of rice growth. Elsewhere, the inlets and outlets
were repositioned at different intervals in order to cool the
water during hot summer months (Amano 1979: 182). The encyclopedia
Chi-Min-Yao-Shu devoted much space to irrigation
practices: Watering should be attuned to the weather; the fields
should be drained after tillage so as to firm the roots and drained
again before harvesting.
order to supplement the unreliable rainfall, many implements were
developed to irrigate individual fields. The developments began
with the use of urns to carry water from creeks or wells. The
urn or bucket was later fastened to the end of a long pole and
counterbalanced on the other end by a large chunk of stone. The
pole was rested on a stand and could be swung around to facilitate
the filling or pouring. A winch was later used to haul a bucket
from a well (see Amano 1979 for illustrations).
square-pallet chain pump came into use during the Eastern Han;
it was either manually driven by foot pedaling or driven by a
draft animal turning a large wheel and a geared transmission device
(Amano 1979: 205, 240). The chain pump was extensively used in
China until it was replaced by engine-driven water pumps after
the 1930s. The device also spread to Vietnam. During hot and dry
summers, the pumping operation required days and nights of continuous
input. Other implements, such as the water wheel in various forms,
were also used (Amano 1979; Chao 1979).
deepwater rice culture in China never approached the scale found
in tropical Asia, Chinese farmers used floating rafts made of
wooden frames and tied to the shore so as to grow rice in swamps.
Such a practice appeared in Late Han, and the rafts were called
feng (for frames) fields (Amano 1979: 175).
rice cultivars are capable of producing new tillers and panicles
from the stubble after a harvest. Such regrowth from the cut stalks
is called a ratoon crop. Ratooning was practiced in China as early
as the Eastern Tsin period (A.D. 317417), and it is now
an important practice in the southern United States. Ratooning
gives better returns in the temperate zone than in the tropics
because the insects and diseases that persist from crop to crop
pose more serious problems in the tropics.
selection has served as a powerful force in cultivar formation
and domestication. Continued selection by rice farmers in the
field was even more powerful in fixing new forms; they used the
desirable gene-combinations showing up in the plantings to suit
their farmers different needs and fancies. The earliest
mention of human-directed selection in Chinese records during
the first century B.C. was focused on selecting panicles with
more grains and fully developed kernels. Soon, varietal differences
in awn color and length, maturity, grain size and shape, stickiness
of cooked rice, aroma of milled rice, and adaptiveness to dryland
farming were recognized. The trend in selection was largely toward
an earlier maturity, which reduced cold damage and made multiple
cropping more practical in many areas. The encyclopedia Chi-Min-Yao-Shu
advised farmers to grow seeds in a separate plot, rotate the seed
plot site in order to eliminate weedy rice, and select pure and
uniformly colored panicles. The seeds were to be stored above
ground in aerated baskets, not under the ground. Seed selection
by winnowing and floatation in water was advised.
or hill rice was mentioned in writings of the third century B.C.
(Ting 1961). During Eastern Tsin, thirteen varieties were mentioned;
their names indicated differences in pigmentation of awn, stem
and hull, maturity, grain length, and stickiness of cooked rice
(Amano 1979). Varieties with outstanding grain quality frequently
appeared in later records. Indeed, a total of 3,000 varieties
was tallied, and the names were a further indication of the differences
in plant stature and morphology, panicle morphology, response
to manuring, resistance to pests, tolerance to stress factors
(drought, salinity, alkalinity, cool temperatures, and deep water),
and ratooning ability (You 1982). The broad genetic spectrum present
in the rice varieties of China was clearly indicated.
and processing rice is another laborious process. The cutting
instruments evolved from knives to sickles to scythe. Community
efforts were common in irrigated areas, and such neighborly cooperation
can still be seen in China, Indonesia, the Philippines, Thailand,
and other countries. Threshing of grains from the panicles had
been done in a variety of ways: beating the bundle of cut stalks
against a wooden bench or block; trampling by human feet or animal
hoofs; beating with a flail; and, more recently, driving the panicles
through a spiked drum that is a prototype of the modern grain
combine (see Amano 1979: 24854 for the ancient tools).
important postharvest operations are the drying of the grain (mainly
by sun drying), winnowing (by natural breeze or a hand-cranked
fan inside a drum winnower), dehusking (dehulling), and milling
(by pestle and mortar, stone mills, or modern dehulling and milling
machines). Grains and milled rice are stored in sacks or in bulk
inside bins. In Indonesia and other hilly areas, the long-panicled
Javanica rices are tied into bundles prior to storage.
sum up the evolutionary pathway in wetland rice cultivation on
a worldwide scale, cultivation began with broadcasting in rain-fed
and unbunded fields under shifting cultivation. As the growers
settled down, the cultivation sites became permanent fields. Then,
bunds were built to impound the rain water, and the transplanting
method followed. As population pressure on the land continued
to increase, irrigation and transplanting became more imperative
entire range of practices can still be seen in the Jeypore Tract
and the neighboring areas (authors personal observations).
The same process was retraced in Bang Chan (near Bangkok) within
a span of one hundred years. In this case, the interrelationships
among land availability, types of rice culture, population density,
labor inputs, and grain outputs were documented in a fascinating
book entitled Rice and Man by L. M. Hanks (1972).
the twentieth century, further advances in agricultural engineering
and technology have to do with several variations in seeding practices
that have been adopted to replace transplanting. Rice growers
in the southern United States drill seed into a dry soil. The
field is briefly flushed with water and then drained. The seeds
are allowed to germinate, and water is reintroduced when the seedlings
are established. In northern California, pregerminated seeds are
dropped from airplanes into cool water several inches deep. The
locally selected varieties are able to emerge from the harsh environment
(Adair et al. 1973).
many Japanese farmers have turned to drill-plant pregerminated
seed on wet mud. An oxidant is applied to the seed before sowing
so as to obtain a uniform stand of plants. For the transplanted
crop, transplanting machines have been developed not only to facilitate
this process but also to make commercial raising of rice seedlings
inside seed boxes a profitable venture. As labor costs continue
to rise worldwide, direct seeding coupled with chemical weed control
will be the main procedures in the future.
deepwater rice culture, rice seeds are broadcasted on dry soil.
The seeds germinate after the monsoon rains arrive. The crop is
harvested after the rains stop and the flooding water has receded.
dryland rice, seeds are either broadcasted, drilled, or dropped
(dibbled) into shallow holes dug in the ground. Dibbling is also
common in West Africa. Dryland (hill or upland) rice continues
to diminish in area because of low and unstable yield. It has
receded largely into hilly areas in Asia where tribal minorities
and people practicing shifting cultivation grow small patches
and Cultural Exchanges
expansion of rice cultivation in China involved interactions and
exchanges in cultural developments, human migration, and progress
in agricultural technology. Agricultural technology in north China
developed ahead of other regions of China. Areas south of the
Yangtze River, especially south China, were generally regarded
by Chinese scholars of the north as primitive in agricultural
practices. During travel to the far south in the twelfth century,
one of these scholars described the local rain-fed rice culture.
He regarded it as crude in land preparation: Seed was sown by
dibbling, fertilizer was not used, and tillage as a weeding practice
was unknown (Ho 1969).
the picture has been rather different in the middle and lower
Yangtze basins since the Tsin Dynasty (beginning in A.D. 317)
when a mass migration of people from the north to southern areas
took place. The rapid expansion of rice cultivation in east China
was aided by the large-scale production of iron tools used in
clearing forests and the widespread adoption of transplanting.
land ownership, which began in the Sung (beginning in A.D. 960),
followed by reduction of land rent in the eleventh century and
reinforced by double cropping and growth in irrigation works,
stimulated rice production and technology development. As a result,
rice production south of the Yangtze greatly surpassed rice production
in the north, and human population growth followed the same trend
(Ho 1969; Chang 1987). Thus, the flow of rice germ plasm was from
south to north, but much of the cultural and technological developments
diffused in the opposite direction.
Usage and Nutritional Aspects
the rice grain is consumed, the silica-rich husk (hull, chaff)
must be removed. The remaining kernel is the caryopsis or brown
rice. Rice consumers, however, generally prefer to eat milled
rice, which is the product after the bran (embryo and various
layers of seed coat) is removed by milling. Milled rice is, invariably,
the white, starchy endosperm, despite pigments present in the
hull (straw, gold, brown, red, purple or black) and in the seed
coat (red or purple).
rice is another form of milled rice in which the starch is gelatinized
after the grain is precooked by soaking and heating (boiling,
steaming, or dry heating), followed by drying and milling. Milled
rice may also be ground into a powder (flour), which enters the
food industry in the form of cakes, noodles, baked products, pudding,
snack foods, infant formula, fermented items, and other industrial
of milled glutinous rice or overmilled nonglutinous rice produces
rice wine (sake). Vinegar is made from milled and broken
rice and beer from broken rice and malt. Although brown rice,
as well as lightly milled rice retaining a portion of the germ
(embryo), are recommended by health-food enthusiasts, their consumption
remains light. Brown rice is difficult to digest due to its high
fiber content, and it tends to become rancid during extended storage.
Cooking of all categories of rice is done by applying heat (boiling
or steaming) to soaked rice until the kernels are fully gelatinized
and excess water is expelled from the cooked product. Cooked rice
can be lightly fried in oil to make fried rice. People of the
Middle East prefer to fry the rice lightly before boiling. Americans
often add salt and butter or margarine to soaked rice prior to
boiling. The peoples of Southeast Asia eat boiled rice three times
a day, including breakfast, whereas peoples of China, Japan, and
Korea prepare their breakfast by boiling rice with excess water,
resulting in porridge (thick gruel) or congee (thin soup).
kinds of cooked rice are distinguished by cohesiveness or dryness,
tenderness or hardness, whiteness or other colors, flavor or taste,
appearance, and aroma (or its absence). Of these features, cohesiveness
or dryness is the most important varietal characteristic: High
amylose (25 to 30 percent) of the starchy endosperm results in
dry and fluffy kernels; intermediate amylose content (15 to 25
percent) produces tender and slightly cohesive rice; low amylose
content (10 to 15 percent) leads to soft cohesive (aggregated)
rice; and glutinous or waxy endosperm (0.8 to 1.3 percent amylose)
produces highly sticky rice. Amylopectin is the other and
the major fraction of rice starch in the endosperm.
four classes of amylose content and cooked products largely correspond
with the designation of Indica, Javanica, Sinica (Japonica), and
glutinous. Other than amylose content, the cooked rice is affected
by the ricewater ratio, cooking time, and age of rice. Hardness,
flavor, color, aroma, and texture of the cooked rice upon cooling
are also varietal characteristics (Chang 1988; Chang and Li 1991).
preference for cooked rice and other rice products varies greatly
from region to region and is largely a matter of personal preference
based on upbringing. For instance, most residents of Shanghai
prefer the cohesive keng (Sinica) rice, whereas people
in Nanjing about 270 kilometers away in the same province prefer
the drier hsien (Indica) type. Tribal people of Burma,
Laos, Thailand, and Vietnam eat glutinous rice three times a day
a habit unthinkable to the people on the plains. Indians
and Pakistanis pay a higher price for the basmati rices, which
elongate markedly upon cooking and have a strong aroma. People
of South Asia generally prefer slender-shaped rice, but many Sri
Lankans fancy the short, roundish samba rices, which also
have dark red seed coats. Red rice is also prized by tribal people
of Southeast Asia (Eggum et al. 1981; Juliano 1985c) and by numerous
Asians during festivities, but its alleged nutritional advantage
over ordinary rice remains a myth. It appears that the eye appeal
of red or purple rice stems from the symbolic meaning given the
color red throughout Asia, which is "good luck."
pestle and mortar were doubtless the earliest implements used
to mill rice grains. The milling machines of more recent origin
use rollers that progressed from stone to wood to steel and then
to rubber-wrapped steel cylinders. Tubes made of sections of bamboo
were most likely an early cooking utensil, especially for travelers.
A steamer made of clay was unearthed at the He-mu-du site dating
from 5000 B.C., but the ceramic and bronze pots were the main
cooking utensils until ironware came into use. Electric rice cookers
replaced iron or aluminum pots in Japan and other Asian countries
after the 1950s, and today microwave ovens are used to some extent.
is unquestionably a superior source of energy among the cereals.
The protein quality of rice (66 percent) ranks only below that
of oats (68 percent) and surpasses that of whole wheat (53 percent)
and of corn (49 percent). Milling of brown rice into white rice
results in a nearly 50 percent loss of the vitamin B complex and
iron, and washing milled rice prior to cooking further reduces
the water-soluble vitamin content. However, the amino acids, especially
lysine, are less affected by the milling process (Kik 1957; Mickus
and Luh 1980; Juliano 1985a; Juliano and Bechtel 1985).
which is low in sodium and fat and is free of cholesterol, serves
as an aid in treating hypertension. It is also free from allergens
and now widely used in baby foods (James and McCaskill 1983).
Rice starch can also serve as a substitute for glucose in oral
rehydration solution for infants suffering from diarrhea (Juliano
development of beriberi by people whose diets have centered too
closely on rice led to efforts in the 1950s to enrich polished
rice with physiologically active and rinse-free vitamin derivatives.
However, widespread application was hampered by increased cost
and yellowing of the kernels upon cooking (Mickus and Luh 1980).
Certain states in the United States required milled rice to be
sold in an enriched form, but the campaign did not gain acceptance
in the developing countries. After the 1950s, nutritional intakes
of the masses in Asia generally improved and, with dietary diversification,
beriberi receded as a serious threat.
factor in keeping beriberi at bay has been the technique of parboiling
rough rice. This permits the water-soluble vitamins and mineral
salts to spread through the endosperm and the proteinaceous material
to sink into the compact mass of gelatinized starch. The result
is a smaller loss of vitamins, minerals, and amino acids during
the milling of parboiled grains (Mickus and Luh 1980), although
the mechanism has not been fully understood. Parboiled rice is
popular among the low-income people of Bangladesh, India, Nepal,
Pakistan, Sri Lanka, and parts of West Africa and amounts to nearly
one-fifth of the worlds rice consumed (Bhattacharya 1985).
the 1970s, several institutions attempted to improve brown rice
protein content by breeding. Unfortunately, such efforts were
not rewarding because the protein content of a variety is highly
variable and markedly affected by environment and fertilizers,
and protein levels are inversely related to levels of grain yield
(Juliano and Bechtel 1985).
and Improvement in the Twentieth Century
to the end of World War II, statistical information on global
rice production was rather limited in scope. The United States
Department of Agriculture (USDA) compiled agricultural statistics
in the 1930s, and the Food and Agriculture Organization of the
United Nations (FAO) expanded these efforts in the early 1950s
(FAO 1965). In recent years, the World Rice Statistics
published periodically by the International Rice Research Institute
(IRRI) provides comprehensive information on production aspects,
imports and exports, prices, and other useful information concerning
rice (IRRI 1991).
the first half of the twentieth century, production growth stemmed
largely from an increase in wetland rice area and, to a lesser
extent, from expansion of irrigated area and from yields increased
by the use of nitrogen fertilizer. Then, varietal improvement
came in as the vehicle for delivering higher grain yields, especially
in the late 1960s when the "Green Revolution" in rice
began to gather momentum (Chang 1979a).
production in Asian countries steadily increased from 240 million
metric tons during 19646 to 474 million tons in 198990
(IRRI 1991). Among the factors were expansion in rice area and/or
irrigated area; adoption of high-yielding, semidwarf varieties
(HYVs); use of nitrogen fertilizers and other chemicals (insecticides,
herbicides, and fungicides); improved cultural methods; and intensified
land use through multiple cropping (Herdt and Capule 1983; Chang
and Luh 1991).
countries produced about 95 percent of the worlds rice during
the years 191140. After 1945, however, Asias share
dropped to about 92 percent by the 1980s, with production growth
most notable in North and South America (IRRI 1991; information
on changes in grain yield, production, annual growth rates, and
prices in different Asian countries is provided in Chang 1993b;
Chang and Luh 1991; David 1991; and Chang 1979a).
despite the phenomenal rise in crop production and (in view of
rapidly growing populations) the consequent postponement of massive
food shortages in Asia since the middle 1960s, two important problems
remain. One of these is food production per capita, which advanced
only slightly ahead of population growth (WRI 1986). The other
is grain yield, which remained low in adverse rain-fed environments
wetland, dryland, deepwater, and tidal swamps (IRRI 1989).
In fact, an apparent plateau has prevailed for two decades in
irrigated rice (Chang 1983). Moreover, the cost of fertilizers,
other chemicals, labor, and good land continued to rise after
the 1970s, whereas the domestic wholesale prices in real terms
slumped in most tropical Asian nations and have remained below
the 19668 level.
combination of factors brought great concern when adverse weather
struck many rice areas in Asia in 1987 and rice stocks became
very low. Fortunately, weather conditions improved the following
year and rice production rebounded (Chang and Luh 1991; IRRI 1991).
the threat to production remains. In East Asia, five years of
favorable weather ended in 1994 with a greater-than-usual number
of typhoons that brought massive rice shortages to Japan and South
Korea. And in view of the "El Niño" phenomenon,
a higher incidence of aberrant weather can be expected, which
will mean droughts for some and floods for others (Nicholls 1993).
Loss and the Perils of Varietal Uniformity
is a self-fertilizing plant. Around 1920, however, Japanese and
U.S. rice breeders took the lead in using scientific approaches
(hybridization selection and testing) to improve rice varieties.
Elsewhere, pureline selection among farmers varieties was
the main method of breeding.
World War II, many Asian countries started to use hybridization
as the main breeding approach. Through the sponsorship of the
FAO, several countries in South and Southeast Asia joined in the
Indica-Japonica Hybridization Project during the 1950s, exchanging
rice germ plasm and using diverse parents in hybridization.
efforts, however, provided very limited improvement in grain yield
(Parthasarathy 1972), and the first real breakthrough came during
the mid 1950s when Taiwan (first) and mainland China (second)
independently succeeded in using their semidwarf rices in developing
short-statured, nitrogen-responsive and high-yielding semidwarf
varieties (HYVs). These HYVs spread quickly among Chinese rice
farmers (Chang 1961; Huang, Chang, and Chang 1972; Shen 1980).
semidwarf "Taichung Native 1" (TN1) was introduced into
India through the International Rice Research Institute (IRRI)
located in the Philippines. "TNI" and IRRI-bred "IR8"
triggered the "Green Revolution" in tropical rices (Chandler
1968; Huang et al. 1972). Subsequent developments in the dramatic
spread of the HYVs and an associated rise in area grain yield
and production have been documented (Chang 1979a; Dalrymple 1986),
and refinements in breeding approaches and international collaboration
have been described (Brady 1975; Khush 1984; Chang and Li 1991).
the early 1970s, China scored another breakthrough in rice yield
when a series of hybrid rices (F1 hybrids) were developed by the
use of a cytoplasmic pollen-sterile source found in a self-sterile
wild plant ("Wild Abortive") on Hainan Island (Lin and
Yuan 1980). The hybrids brought another yield increment (15 to
30 percent) over the widely grown semidwarfs.
with the rapid and large-scale adoption of the HYVs and with deforestation
and development projects, innumerable farmers traditional
varieties of all three ecogenetic races and their wild relatives
have disappeared from their original habitats an irreversible
process of "genetic erosion." The lowland group of the
javanic race (bulu, gundill) suffered the heaviest losses
on Java and Bali in Indonesia. Sizable plantings of the long-bearded
bulus can now be found only in the Ifugao rice terraces
of the Philippines.
parallel developments, by the early 1990s the widespread planting
of the semidwarf HYVs and hybrid rices in densely planted areas
of Asia amounted to about 72 million hectares. These HYVs share
a common semidwarf gene (sd1) and largely the same cytoplasm (either
from "Cina" in older HYVs or "Wild Abortive"
in the hybrids). This poses a serious threat of production losses
due to a much narrowed genetic base if wide-ranging pest epidemics
should break out, as was the case with hybrid maize in the United
States during 19701 (Chang 1984).
the early 1970s, poorly educated rice farmers in South and Southeast
Asia have planted the same HYV in successive crop seasons and
have staggered plantings across two crops. Such a biologically
unsound practice has led to the emergence of new and more virulent
biotypes of insect pests and disease pathogens that have overcome
the resistance genes in the newly bred and widely grown HYVs.
The result has been heavy crop losses in several tropical countries
in a cyclic pattern (Chang and Li 1991; Chang 1994).
for the rice-growing world, the IRRI has, since its inception,
assembled a huge germ plasm collection of more than 80,000 varieties
and 1,500 wild rices by exchange and field collection. Seeds drawn
from the collection not only have sustained the continuation of
the "Green Revolution" in rice all over the world but
also assure a rich reservoir of genetic material that can reinstate
the broad genetic base in Asian rices that in earlier times kept
pest damage to manageable levels (Chang 1984, 1989b, 1994).
for the Future
the dawn of civilization, rice has served humans as a life-giving
cereal in the humid regions of Asia and, to a lesser extent, in
West Africa. Introduction of rice into Europe and the Americas
has led to its increased use in human diets. In more recent times,
expansion in the rice areas of Asia and Africa has resulted in
rice replacing other dryland cereals (including wheat) and root
crops as the favorite among the food crops, wherever the masses
can afford it. Moreover, a recent overview of food preferences
in Africa, Latin America, and north China (Chang 1987, personal
observation in China) suggests that it is unlikely that rice eaters
will revert to such former staples as coarse grains and root crops.
On the other hand, per capita rice consumption has markedly dropped
in the affluent societies of Japan and Taiwan.
the eastern half of Asia, where 90 to 95 percent of the rice produced
is locally consumed, the grain is the largest source of total
food energy. In the year 2000, about 40 percent of the people
on earth, mostly those in the populous, less-developed countries,
depended on rice as the major energy source. The question, of
course, is whether the rice-producing countries with ongoing technological
developments can keep production levels ahead of population growth.
the preceding section on cultivation practices, it seems obvious
that rice will continue to be a labor-intensive crop on numerous
small farms. Most of the rice farmers in rain-fed areas (nearly
50 percent of the total planted area) will remain subsistence
farmers because of serious ecological and economic constraints
and an inability to benefit from the scientific innovations that
can upgrade land productivity (Chang 1993b). Production increases
will continue to depend on the irrigated areas and the most favorable
rain-fed wetlands, which now occupy a little over 50 percent of
the harvested rice area but produce more than 70 percent of the
crop. The irrigated land area may be expanded somewhat but at
a slower rate and higher cost than earlier. Speaking to this point
is a recent study that indicates that Southeast Asia and South
Asia as well, are rapidly depleting their natural resources (Brookfield
rising costs in labor, chemicals, fuel, and water, the farmers
in irrigated areas will be squeezed between production costs and
market price. The latter, dictated by government pricing policy
in most countries, remains lower than the real rice price (David
1991). Meanwhile, urbanization and industrialization will continue
to deprive the shrinking farming communities of skilled workers,
especially young men. Such changes in rice-farming communities
will have serious and widespread socioeconomic implications.
rice farmers receive an equitable return for their efforts, newly
developed technology will remain experimental in agricultural
stations and colleges. The decision makers in government agencies
and the rice-consuming public need to ensure that a decent living
will result from the tilling of rice lands. Incentives must also
be provided to keep skilled and experienced workers on the farms.
Moreover, support for the agricultural research community must
be sustained because the challenges of providing still more in
productivity-related cultivation innovations for rice are unprecedented
the rice industry faces formidable challenges, there are areas
that promise substantial gains in farm productivity with the existing
technology of irrigated rice culture. A majority of rice farmers
can upgrade their yields if they correctly and efficiently perform
the essential cultivation practices of fertilization, weed and
pest control, and water management.
the research front, rewards can be gained by breaking the yield
ceiling, making pest resistance more durable, and improving the
tolerance to environmental stresses. Biotechnology will serve
as a powerful force in broadening the use of exotic germ plasm
in Oryza and related genera (Chang and Vaughan 1991). We
also need the inspired and concerted teamwork of those various
sectors of society that, during the 1960s and 1970s, made the
"Green Revolution" an unprecedented event in the history
control of human population, especially in the less-developed
nations, is also crucial to the maintenance of an adequate food
supply for all sectors of human society. Scientific breakthroughs
alone will not be able to relieve the overwhelming burden placed
on the limited resources of the earth by uncontrolled population
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