Principles of Plant Genetics and Breeding

Taxonomy
Kingdom Plantae
Subkingdom Tracheobionta
Superdivision Spermatophyta
Division Magnoliophyta
Class Lilliopsida
Subclass Commelinidae
Order Cyperales
Family Poaceae
Genus Oryza L.
Species Oryza sativa L.
Economic importance
Rice accounts for about 20% of the world’s total grain
production, second only to wheat. It is the primary
staple for more than 50% of the world’s population.
An estimated 90% of production and consumption of
rice occurs in Asia where the per capita consumption
is about 45 kg, compared to a world average of about
27 kg and a US average of about 9 kg. World consumption
in 1993/94 was 358.5 million metric tons and has
increased steadily to an estimated 408.8 million tons in
2002/03. Similarly, the area devoted to rice increased
during the same period from 145.2 to 155.1 ha in
1990/2000, with a slight drop thereafter. Production
trends mirror the area cultivated. Rice production in the
USA is dominated by six states – Arkansas, California,
Louisiana, Texas, Mississippi, and Missouri – together
accounting for about 99% of the total US production.
Other minor producers in the USA include Florida,
Tennessee, Illinois, South Carolina, and Kentucky.
Arkansas leads the production in the US, with about
100 cwt of rice produced in 2001 on about 1.61 million
acres (see Appendix 2 for conversion rates for units).
The world’s major producers of rice are China, India,
Indonesia, and Bangladesh, which together account for
29
Breeding rice
more than 70% of the world’s total production. China,
the world’s leading producer regularly accounts for
about 36% of the world’s total production. The expansion
in rice production is attributed largely to the impact
of the Green Revolution, which was implemented in the
1960s and 1970s in Asia and other parts of the tropical
world. Other major producers in Asia include Vietnam,
Thailand, Japan, and Burma, together accounting for
about 12% of the total world production. Outside of
Asia, rice is produced in substantial amounts in countries
including the USA, Italy, Spain, Egypt, Australia,
and countries in the West African region.
Thailand leads the world in rice exports, accounting
for about 25% of the total world exports (about 4 million
metric tons). The USA is the second largest
exporter of rice, exporting about 2.7 million metric
tons. Latin America is the largest market for US rice
export. Other major exporters of rice include Vietnam,
Pakistan, China, Australia, Burma, Italy, India, and
Uruguay.
Origin and history
The origin of rice is not exactly known. Wild species of
rice occur across South and East Asia, including India
and south China. Rice was domesticated in the 5th
millennium bc. The cultivated species of rice Oryza
sativa is believed to have derived from annual progenitors
found in a wide area extending from the Gangetic
Plains, through Burma, northern Thailand, northern
Vietnam, and southern China. Rice trade occurred
between Egypt, India, and China. The Moors are credited
with bringing rice to Spain, from where it was
introduced to Italy (in the 15th century) and subsequently
to Central America. The African cultigen
(O. glaberrima) originated in the Niger River delta of
Mali in West Africa.