Agricultural Officer (Rice Agronomy), Crop and Grassland Service, FAO, Rome
World rice production continued to increase during the 1995-2000 period providing the population with more food. The main aspects of rice production, consumption and nutrition are summarized below.
World rice production increased from about 547 million tonnes (Mt) in 1995 to about 610 Mt in 1999 and then decreased to about 594 Mt in 2000. The annual growth rate of world rice production during this period was 1.82 percent per year (Table 1). Traditionally, the world produces less rice than wheat. However, world production of rice in 1999 and 2000 exceeded that of wheat and maize (Fig. 1). If this trend persists, rice will become the worlds most important crop, not only in terms of food but also in terms of production volume.
FIGURE 1 World production of wheat, rice and maize, 1996-2000
Source: FAOSTAT, 2002.
The worlds rice harvested area increased from about 149 million hectares (Mha) in 1995 to about 157 Mha in 1999, decreasing to about 154 Mha in 2000. It revealed a growth rate of about 0.81 percent per year. The growth rate of the harvested area during this period, however, was very much higher than that during 1990-94 (-0.03% per year) and that during 1980-89 (0.18% per year) (FAOSTAT, Jan. 2002). How this growth rate of rice harvested area is to be maintained in the first decade of the 21st century, however, is unclear. Land and water resources for rice production, especially in Asia, must increasingly compete with the demand from the other sectors of the economy, in particular the urban and industrial sectors. In terms of agro-ecological systems, about 57 percent of the worlds rice harvested area in 2000 comes from irrigated ecologies, 27 percent from rainfed lowland, 10 percent from upland, and the remaining harvested areas come from deepwater and tidal wetland ecologies.
World rice yield increased from 3 661 kg/ha in 1995 to 3 888 kg/ha in 1999 and then decreased to 3 859 kg/ha in 2000 (Table 1). The growth rate of world rice yield during this period was only 1 percent per year, which was lower than the population growth rate during the same period. The growth rate of rice yield during 1990-94 (1.03% per year) and 1980-89 (2.34% per year) was higher than that observed during this period. This decline in the growth rate of rice yield is a major concern. This declining trend needs to be reversed if rice production is to meet the demand of the world population in the 21st century.
TABLE 1 World population and rice (paddy) production harvested area and yield, 1995-2000
|
1995 |
1996 |
1997 |
1998 |
1999 |
2000 |
GRREa (%/year) |
Population ('000) |
5661865 |
5741665 |
5821129 |
5900184 |
5978721 |
6056710 |
1.36 |
Production (tonnes) |
547101100 |
568425700 |
577182400 |
578971500 |
610230700 |
594381500 |
1.82 |
Harvested area (ha) |
149437700 |
150252600 |
151395500 |
151601500 |
156938800 |
153999600 |
0.81 |
Yield (kg/ha) |
3661 |
3783 |
3812 |
3819 |
3888 |
3859 |
1 |
a GRRE = Exponential growth rate.
Source: FAOSTAT, 2002.
TABLE 2 Rice production (tonnes) in different continents, 1995-2000
|
1995 |
1996 |
1997 |
1998 |
1999 |
2000 |
GRREa (%/year) |
Asia |
499189400 |
521628600 |
528084500 |
531490200 |
554610100 |
540604900 |
1.7 |
Latin America and Caribbean |
21126500 |
19135560 |
19382170 |
18359270 |
24323880 |
22738570 |
3 |
Africa |
15163660 |
15712670 |
16979190 |
16169030 |
17650450 |
17386980 |
2.85 |
SubSaharan Africa |
10367590 |
10759420 |
11463840 |
11671240 |
11795140 |
11357990 |
2.17 |
North America |
7887000 |
7771000 |
8300000 |
8366000 |
9345000 |
8657810 |
2.98 |
Europe |
2699600 |
3194183 |
3163984 |
3189952 |
3177046 |
3216987 |
2.51 |
Oceania |
1034976 |
983649 |
1272595 |
1396992 |
1124150 |
1776200 |
9.56 |
a GRRE = Exponential growth rate.
Source: FAOSTAT, 2002.
Rice production in different continents
During 1995-2000, the relative contribution from different continents to world rice production remained more or less unchanged. In 2000, about 91 percent of the worlds rice production still came from Asia. Latin America and the Caribbean (in second position) account for 3.8 percent and Africa (third) for 2.9 percent. Rice production in all continents exhibited positive growth rates during this period (Table 2).
In Asia, rice production in 2000 was about 40 Mt more than in 1995. However, the growth rate of rice production in Asia during 1995-2000 was only 1.7 percent per year (Table 2). The low growth rate of rice production was due mainly to the low growth rate of rice yield. The growth rate of rice yield during this period was only 0.91 percent per year (Table 4). The growth rate of rice harvested area in Asia during this period was substantial - 0.78 percent per year (Table 3) - compared to that observed during the earlier periods (FAOSTAT, 2002). The rice harvested area in 2000 was 4.4 Mha more than in 1995.
Of the different continents, the growth of rice production during 1995-2000 was most rapid in Oceania: 9.56 percent per year (Table 2). The impressive increase in production in this continent during this period was due to a combination of a moderate growth rate of harvested area (1.57% per year, Table 3) and a high growth rate of rice yield (7.87% per year, Table 4). The yield increase achieved in Oceania was spectacular, considering the very high yield level in Australia in 1995 (8 200 kg/ha). The high growth rate of rice yield in this continent, however, suggested that sustainable rice production could still be achieved by increasing productivity. Rice production in this continent comes mainly from Australia, where rice is produced in a subtropical dry summer climate. Australian rice yield in 2000 was the worlds highest.
TABLE 3 Rice harvested area (ha) in different continents, 1995-2000
|
1995 |
1996 |
1997 |
1998 |
1999 |
2000 |
GRREa (%/year) |
Asia |
133574500 |
135338300 |
135901900 |
136232600 |
140266000 |
137936500 |
0.78 |
Latin America and Caribbean |
6857702 |
5867254 |
5657597 |
5647630 |
6569263 |
6224439 |
-0.42 |
Africa |
7081731 |
7139490 |
7804346 |
7678536 |
7959226 |
7859142 |
2.4 |
SubSaharan Africa |
6490623 |
6537941 |
7143039 |
7155504 |
7295350 |
7192825 |
2.44 |
North America |
1251700 |
1134700 |
1255700 |
1318000 |
1421300 |
1229850 |
1.83 |
Europe |
545869 |
627595 |
603257 |
575982 |
593028 |
594691 |
0.61 |
Oceania |
126207 |
145267 |
172650 |
148680 |
129976 |
154976 |
1.57 |
a GRRE = Exponential growth rate.
Source: FAOSTAT, 2002.
TABLE 4 Rice yield (kg/ha) in different continents, 1995-2000
|
1995 |
1996 |
1997 |
1998 |
1999 |
2000 |
GRREa (%/year) |
Asia |
3737 |
3854 |
3885 |
3901 |
3954 |
3919 |
0.91 |
Latin America and Caribbean |
3080 |
3261 |
3425 |
3250 |
3702 |
3653 |
3.43 |
Africa |
2141 |
2200 |
2175 |
2105 |
2217 |
2212 |
0.44 |
SubSaharan Africa |
1597 |
1645 |
1604 |
1631 |
1616 |
1579 |
-0.27 |
North America |
6301 |
6848 |
6609 |
6347 |
6575 |
7039 |
1.12 |
Europe |
4945 |
5089 |
5244 |
5538 |
5357 |
5409 |
1.89 |
Oceania |
8200 |
6771 |
7371 |
9396 |
8648 |
11461 |
7.87 |
a GRRE = Exponential growth rate.
Source: FAOSTAT, 2002.
During 1995-2000, rice production in Africa grew at a rate of 2.85 percent per year (Table 2). Much of the increase in rice production, however, comes from the expansion in rice area, which showed a growth rate of 2.44 percent per year (Table 3). Rice yield in Africa grew at a rate of only 0.44 percent per year during this period (Table 4). The expansion of rice area took place mostly in subSaharan Africa, while the yield increase comes mainly from Africa north of the Sahara. The growth rate of rice-harvested area in subSaharan Africa was 2.44 percent per year (Table 3) and that of rice yield was -0.27 percent per year (Table 4). Therefore, there is great potential for increasing rice production in subSaharan Africa through productivity improvement.
Rice production in North America takes place only in the United States of America (California and the Gulf regions) in subtropical or temperate climates. From 1995 to 2000, rice production in North America grew by 2.98 percent per year (Table 2). The increase in harvested area contributed to the increased production. The growth rate of harvested area was 1.83 percent per year (Table 3), while that of rice yield was only 1.12 percent per year (Table 4).
In Latin America and the Caribbean, the growth rate of rice production during 1995-2000 was 3 percent per year (Table 2). The production increase is substantial, considering that the harvested area in the region decreased at a rate of -0.42 percent per year (Table 3). The yield increase of 3.43 percent per year (Table 4) was the main force of the production increase in Latin America and the Caribbean during this period. The high growth rate of rice yield in Latin America and the Caribbean during this period may be partially due to the reduction of upland rice area, especially in Brazil.
Rice production in Europe achieved a decent growth rate of 2.51 percent per year during 1995-2000 (Table 2). The main driving force behind this production increase was the yield increase. During the same period, the growth rate of rice yield was 1.89 percent per year (Table 4), while that of harvested area was only 0.61 percent per year (Table 3).
Rice production in the worlds top producing countries
China, India, Indonesia, Bangladesh, Viet Nam, Thailand and Myanmar were the top seven rice-producing countries in the world. In 2000, they produced a total of about 481 Mt of rice, i.e. about 81 percent of world rice production. Any change in rice production in these countries, therefore, would have an important influence on world rice production.
From 1995 to 2000, the growth in rice production was most rapid in Bangladesh and Viet Nam (Fig. 2). The annual rate of growth of rice production in Bangladesh was over 6 percent, while in Viet Nam it was over 5 percent in the same period.
In India, rice production increased modestly but consistently from 1995 to 1999, and then decreased in 2000; peak production (in 1999) was about 15 percent above the 1995 production level. In contrast, rice production in Myanmar decreased during 1995-98, but then increased sharply in 1999. Peak production in China (1997) and in Thailand (1999) was about 8 to 10 percent above the 1995 figure for these countries. However, rice production in China consistently decreased during 1997-2000 (Fig. 2). In Indonesia, rice production was practically stagnant as of 1995.
The Indian harvested area (HA) was the worlds largest, followed by China, Indonesia, Bangladesh, Thailand, Viet Nam and Myanmar. The harvested area in India, China, Indonesia and Viet Nam showed a declining trend during the latter part of 1995-2000 (Fig. 3). In China and Indonesia, the harvested area in 2000 was about 4 to 5 percent less than in 1995, while in India the harvested area in 1995 was about 2 percent above that in 2000. In Viet Nam the harvested area in 1995 and 2000 was more or less equal. If the declining trend in the harvested area of these four countries continues, it may have a substantially negative effect on world rice production in the first decade of the 21st century. Together, India, China, Indonesia and Viet Nam contributed more than 60 percent of the worlds rice harvested area in 2000.
The rice production increase in the worlds top seven producers during 1995-2000 was, therefore, due mainly to the increase in productivity. In 1995, national rice yield was as follows:
China > Indonesia > Viet Nam > Myanmar > India > Bangladesh > Thailand,
while in 2000 it was:
China > Indonesia > Viet Nam > Bangladesh > Myanamar > India > Thailand.
FIGURE 2 Rice production in the worlds top producing countries, 1995-2000 (1995 = 100%)
In general, rice yield in Bangladesh increased substantially during 1995-2000; the trend in yield increase, however, was not very persistent. To a lesser extent, a similar situation was observed with regards to rice yield in India (Fig. 4). In Indonesia, Myanmar and Thailand, rice yield also fluctuated from year to year, but in general the growth in rice yield was almost stagnant. In China, rice yield showed a steady decline as of 1996; yield in 2000 was about 10 percent less than in 1996. In contrast, rice yield in Viet Nam grew steadily during 1995-99 (Fig. 4).
Together with the above-mentioned trend in harvested area, the trend of yield growth in the worlds top rice producers during 1995-2000, especially in China, indicates the difficult situation of sustainable world rice production in the near future. There is a need for more attention, effort and investment in rice production in order to provide food security.
About 90 percent of the rice produced in any given year is consumed as food, while the remainder is used for other purposes. World rice production during 1997-99 was about 2.5 times that recorded during 1961-63. The rice production increase resulted in more rice being available for consumption, regardless of the continuing increase in population. On average, the energy supply from rice was about 400 to 480 kcal/person/day in the early 1960s, but it increased to about 560 to 580 kcal/person/day in the late 1990s. In 1999, rice was consumed by the population in at least 175 countries and territories (FAOSTAT, 2002). On the basis of rice supply per caput, rice-consuming countries and territories may be grouped as follows:
Very high rice consumption (per caput supply > 200 kg paddy): Myanmar, Lao Peoples Democratic Republic, Viet Nam, Bangladesh, Cambodia and Indonesia (6 countries).
High rice consumption (per caput supply = 100-200 kg paddy): Thailand, Philippines, Sri Lanka, Sierra Leone, Republic of Korea, Nepal, Madagascar, China, Gambia, Malaysia, Guinea-Bissau, Guyana, Maldives, Brunei Darussalam, Suriname, Democratic Peoples Republic of Korea, Côte dIvoire, India, Senegal, China-Macao and Costa Rica (21 countries and territories).
Average rice consumption (per caput supply = 50-100 kg paddy): Mauritania, Solomon Islands, Guinea, Japan, United Arab Emerates, Comoros, Liberia, Mauritius, Kiribati, China-Hong Kong, Peru, Republic of the Fiji Islands, Ecuador, Panama, Kuwait, Vanuatu, Mali, Cape Verde, Saint Vincent and the Grenadines, Cuba, Djibouti, French Polynesia, Dominican Republic, Egypt, Brazil, Saint Kitts and Nevis, Papua New Guinea, Bahamas, Haiti, Saudi Arabia, Iraq (32 countries and territories).
Below average rice consumption (per caput supply = 20-50 kg paddy): 27 countries and territories.
Low rice consumption (per caput supply < 20 kg paddy): 89 countries and territories.
FIGURE 3 Rice harvested area in the worlds top producing countries, 1995-2000 (1995 = 100%)
FIGURE 4 Rice yield in the worlds top producing countries, 1995-2000 (1995 = 100%)
In 1999, rice provided between 680 and 2 049 kcal per caput per day to more than 3 billion people in 26 countries (Table 5). The majority of these countries had a relatively high population growth rate during 1995-99. Moreover, the quantity of rice consumed as food in 22 of these countries rose during the same period (Table 5) - an indication of the continuing increase in demand for rice in these countries in the first decade of the 21st century. In fact, since 2000 rice consumption has exceeded production; it has been forecast that consumption is to surpass production for the period from 2000 to 2002, with the gap being filled using supplies released from stocks (Figure 5).
A rice grain consists of the hull (including awn, lemma and palea) and the rice caryopsis or brown rice. The brown rice is the edible fraction of the rice grain. Dietary fibre, minerals and B vitamins are highest in the bran and lowest in the aleurone layers. Rice endosperm is rich in carbohydrates and contains a fair amount of digestible protein, composed of an amino acid profile which compares favourably with other grains (FAO, 1993). Rice is a good source of the B vitamins, thiamin, riboflavin and niacin, but it contains little to no vitamin C, D or beta-carotene, the precursor of vitamin A. The amino acid profile of rice is high in glutamic and aspartic acids, but low in lysine (Grist, 1986; FAO, 1993). The main antinutritional factors, most of which are concentrated in the bran, are phytate, trypsin inhibitor, oryzacystatin and haemagglutinin-lectin (FAO, 1993). The nutrient composition of rice grains, however, varies depending on the rice variety.
TABLE 5 Total population, rice food, rice supply and rice food energy in countries with a very high to high rate of rice consumption, 1995-99
|
Total population |
Rice food |
Rice supply |
Rice food energy |
||||
1999 ('000) |
GRREa 1995-99 |
1999 (tonnes paddy) |
GRREa 1995-99 |
1999 (kg paddy/caput/year) |
GRREa 1995-99 |
1999 (kcal/caput/day) |
GRREa 1995-99 |
|
Myanmar |
47114 |
1.52 |
14875480 |
1.14 |
315.7 |
-0.37 |
2049.60 |
-0.37 |
Bangladesh |
134584 |
2.15 |
33946310 |
5.45 |
252.2 |
3.24 |
1676.10 |
3.22 |
Viet Nam |
77118 |
1.43 |
19692130 |
2.46 |
255.4 |
1.01 |
1676.00 |
0.11 |
Cambodia |
12766 |
2.88 |
3161290 |
3.21 |
247.6 |
0.31 |
1526.90 |
0.31 |
Indonesia |
209287 |
1.44 |
48330240 |
2.93 |
230.9 |
1.46 |
1525.10 |
1.55 |
Lao PDR |
5156 |
2.42 |
1324599 |
1.39 |
256.9 |
-1.01 |
1516.10 |
-1 |
Korea (Rep. of) |
46403 |
0.8 |
6553750 |
0.36 |
141.2 |
-0.43 |
1020.70 |
-0.4 |
Thailand |
62008 |
1.37 |
9372800 |
-0.13 |
151.2 |
-1.47 |
1004.40 |
-1.47 |
Philippines |
74184 |
2.07 |
11087800 |
2.4 |
149.5 |
0.32 |
974.2 |
0.32 |
Sierra Leone |
4272 |
1.13 |
635384 |
2.14 |
148.7 |
0.99 |
964.1 |
0.99 |
Sri Lanka |
18747 |
0.96 |
2789298 |
2.98 |
148.8 |
2 |
960.5 |
2 |
Madagascar |
15512 |
2.99 |
2115910 |
3.29 |
136.4 |
0.29 |
926.4 |
0.26 |
China |
1271954 |
0.93 |
171909700 |
0.64 |
135.9 |
-0.28 |
913.11 |
-0.28 |
Guinea-Bissau |
1173 |
2.13 |
153492 |
-3.94 |
130.9 |
-5.94 |
871.9 |
-5.94 |
Nepal |
22501 |
2.43 |
3150718 |
4.45 |
140 |
1.97 |
862.6 |
1.96 |
Malaysia |
21791 |
2.15 |
2887612 |
2.09 |
132.5 |
-0.06 |
861.1 |
-0.09 |
Gambia |
1267 |
3.25 |
170429 |
7.85 |
134.5 |
4.46 |
842.8 |
4.46 |
Maldives |
282 |
3.06 |
35505 |
16.19 |
125.9 |
12.74 |
821.4 |
12.74 |
Guyana |
757 |
0.48 |
96862 |
0.52 |
128 |
0.04 |
790.4 |
-0.48 |
Brunei Darassalam |
322 |
2.27 |
38933 |
5.89 |
120.9 |
3.54 |
787.9 |
3.62 |
Korea DPR |
22110 |
0.85 |
2499402 |
1.21 |
113 |
0.36 |
737.1 |
-1.32 |
India |
992686 |
1.72 |
110421100 |
-1.53 |
111.2 |
-3.2 |
735.8 |
-3.2 |
Suriname |
415 |
0.39 |
48443 |
-7.33 |
116.7 |
-7.69 |
726.6 |
-7.56 |
Senegal |
9184 |
2.57 |
979986 |
5.51 |
106.7 |
2.87 |
697.3 |
2.87 |
Côte d'Ivoire |
15685 |
2.18 |
1747836 |
8.26 |
111.4 |
5.94 |
681.1 |
5.9 |
Costa Rica |
3933 |
2.57 |
403832 |
14.82 |
102.7 |
11.95 |
640 |
11.95 |
Source: FAOSTAT, 2002.
FIGURE 5 Global rice production and consumption
Source: Calpe, 2002.
TABLE 6 Per caput rice supply, life expectancy, under-5 mortality rate and percentage of children under 5 suffering from malnutrition in selected countries
|
Per caput rice supply (1997-99 average) a (g/caput/day) |
Life expectancy (1999) b (years) |
% children under 5 who suffered from stunting c |
Myanmar |
577.9 |
61 |
- |
Lao PDR |
470.0 |
54 |
47 (estimated) |
Viet Nam |
464.7 |
68 |
34 |
Cambodia |
448.6 |
54 |
56 |
Bangladesh |
441.2 |
59 |
55 |
Indonesia |
413.6 |
66 |
42 |
Thailand |
285.3 |
69 |
16 (estimated) |
Philippines |
267.4 |
69 |
30 |
Nepal |
262.3 |
58 |
54 |
Korea (Rep. of) |
259.0 |
73 |
- |
Sierra Leone |
258.4 |
39 |
35 (estimated) |
Guinea-Bissau |
258.0 |
45 |
- |
Sri Lanka |
255.3 |
74 |
18 |
Madagascar |
251.5 |
58 |
|
China |
251.0 |
70 |
17 |
Gambia |
246.9 |
48 |
30 |
Malaysia |
245.2 |
72 |
- |
Guyana |
231.8 |
65 |
10 |
India |
207.9 |
63 |
52 (estimated) |
Côte d'Ivoire |
193.1 |
47 |
24 (estimated) |
Suriname |
189.5 |
71 |
- |
Senegal |
186.7 |
53 |
23 |
Guinea |
185.4 |
47 |
29 (estimated) |
Costa Rica |
170.4 |
76 |
6 |
Japan |
165.6 |
80 |
- |
Ecuador |
129.9 |
70 |
34 (estimated) |
Peru |
127.8 |
69 |
26 |
Panama |
125.2 |
74 |
14 |
Liberia |
123.7 |
50 |
- |
Dominican Republic |
116.7 |
71 |
11 |
Brazil |
108.1 |
67 |
11 |
Papua New Guinea |
101.6 |
59 |
43 (estimated) |
a Based on FAOSTAT, 2001.
b Based on UNICEF, 2001.
c Based on UNICEF, 1999.
Life expectancy is an indicator of the health of a population. Data in Table 6, however, do not show any clear relationship between rice consumption and life expectancy. The life expectancy in major rice-consuming countries, such as Viet Nam (68 years), Thailand (69 years), Republic of Korea (73 years) and Sri Lanka (74 years), is quite high, while life expectancy in other major rice-consuming countries, such as Lao Peoples Democratic Republic (54 years), Cambodia (54 years), Sierra Leone (39 years), Guinea-Bissau (44 years) and Gambia (48 years), is quite low. However, the percentage of children under 5 who suffer from stunting is generally high in major rice-consuming countries (Table 6). This suggests the possibility of malnutrition in association with heavy rice consumption.
Efforts to create nutritionally superior cultivars, made by scientists at IRRI (International Rice Research Institute) with the collaboration of the University of Adelaide, have led to the identification of varieties with above average levels of iron and zinc content (Graham et al., 1999).
An entire biosynthetic pathway for beta-carotene was introduced through the use of a technique called agrobacterium-mediated transformation, which resulted in rice grains containing a significant amount of previously non-existent carotenoids, the precursors of vitamin A. The most promising experimental line contained 1.6 µg/g of carotenoid (Ye et al., 2000). In a similar experiment, again using genetic modification, via the utilization of a ferritin gene from Phaseolus vulgaris, the iron content of rice grains was doubled (Lucca et al., 2000). To boost iron absorption iron by humans, a heat-tolerant phytase from Aspergillus fumigatus was engineered into rice (Lucca et al., 2000). In the Philippines one type of fortified rice has successfully undergone consumer acceptability tests. The iron-fortified rice was tested for effectiveness in a clinical trial of 218 school children. After 6 months, the experimental group showed significantly higher mean haemoglobin levels and a significant reduction in the prevalence of anaemia compared to the control (Florentino, 2001).
Calpe, C. 2002. Global rice market situation and outlook. Paper presented at the 20th Session of the International Rice Commission, 23-26 July 2002, Bangkok, Thailand.
FAO. 1993. Rice in Human Nutrition, by B.O. Juliano. 162 pp.
FAOSTAT. 2001. FAO Statistical Databases. Available online at http://apps.fao.org/. Accessed 2 May 2001.
FAOSTAT. 2002. FAO Statistical Databases. Available online at http://apps.fao.org/. Accessed January 2002.
Florentino, R. 2001. Experiences on Rice Fortification in the Philippines. In Proceedings of Conference Forging Effective Strategies to Combat Iron Deficiency, Atlanta, Georgia, 7-9 May 2001.
Graham, R., Senadhira, D., Beebe, S., Iglesias, C. & Monasterio, I. 1999. Breeding for micronutrient density in edible portions of staple food crops: conventional approaches. Field Crops Res., 60: 57-80.
Grist, D.H. 1986. Rice. Singapore, Longman Singapore Publishers. 599 pp. (6th edition)
Lucca, P., Wunn, J., Hurrell, R. & Potrykus, I. 2000. Development of iron-rich rice and improvement of its absorption in humans by genetic engineering. J. of Plant Nutrition, 23: 1983-1988.
UNICEF. 1999. State of the worlds children 1999. United Nations Childrens Fund, New York, Oxford University Press.
UNICEF. 2001. State of the worlds children 2001. United Nations Childrens Fund. Available online at www.unicef.org/sowc01. Accessed 2 May 2001.
Ye, X., Al-Babili, S., Kloti, A., Zhang, J., Lucca, P., Beyer, P. & Potrykus, I. 2000. Engineering the provitamin A (ß Carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science, 287: 303-305.