Rice Cultivation and Cultural Exchanges
The 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).
However, 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.
Private 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.
Culinary Usage and Nutritional Aspects
Before 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).
Parboiled 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 products.
Fermentation 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).
Different 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.
These 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 rice—water 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).
Consumer 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."
The 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.
Rice 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).
Rice, 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 1985b).
The 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.
Another 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 world’s rice consumed (Bhattacharya 1985).
During 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).
Production and Improvement in the Twentieth Century
Prior 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).
During 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).
Rice production in Asian countries steadily increased from 240 million metric tons during 1964—6 to 474 million tons in 1989—90 (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).
Asian countries produced about 95 percent of the world’s rice during the years 1911—40. After 1945, however, Asia’s 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).
But 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 1966—8 level.
This 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).
However, 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).
Germ Plasm Loss and the Perils of Varietal Uniformity
Rice 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.
After 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.
These 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).
Taiwan’s 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).
In 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.
Along 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.
In 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 1970—1 (Chang 1984).
Since 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).
Fortunately 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).
Outlook for the Future
Since 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.
In 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.
From 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 1993).
With 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.
Unless 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 in scope.
Although 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.
On 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 of agriculture.
Lastly, 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 growth.
Te-Tzu Chang (Cambridge.org)