Weedy rice
Encyclopedia
Weedy rice, also known as red rice, is a species of rice
(Oryza
) that produces far fewer grains per plant than cultivated rice and is therefore considered a pest. The name "weedy rice" is used for all types and variations of rice which show some characteristic features of cultivated rice and grow as weeds in commercial rice fields. Populations of weedy rice are found in many rice-growing regions. Weedy rice is various species and subspecies of rice which can distribute their seeds before harvest. Variations of weedy rice adapt to a wide range of natural conditions.
Weedy rice grains often have a red pericarp, so for this reason in the international literature the term "red rice" is often used. This term, however, is not very relevant, because the rice with a red pericarp are also found in some cultivated varieties, but not in many forms of weedy rice.
In most regions of the rice production, weedy rice is introduced after the transition from transplanting rice to sowing commercial seeds directly in the rice field. It has become very significant since the mid 1980's, especially in Europe
, with the weak semi-dwarf varieties of indica subspecies
. Distribution generally promotes use of commercially purchased seeds containing weed seeds. Weedy rice can be found in 40%-75% of rice fields in Europe, 40% of fields in Brazil
, 55% in Senegal
, 80% in Cuba
and 60% in Costa Rica
.
Because weedy rice and cultivated rice are so closely related, herbicides that would kill red rice would also kill cultivated rice. A genetically modified form of cultivated rice has been developed that will resist a herbicide, but this form of rice has not been approved for human consumption. This genetically modified form of cultivated rice has, however, appeared on the rice market.
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
(Oryza
Oryza
Oryza is a genus of seven to twenty species of grasses in the tribe Oryzeae, within the subfamily Bambusoideae, native to tropical and subtropical regions of Asia, Northern Australia and Africa...
) that produces far fewer grains per plant than cultivated rice and is therefore considered a pest. The name "weedy rice" is used for all types and variations of rice which show some characteristic features of cultivated rice and grow as weeds in commercial rice fields. Populations of weedy rice are found in many rice-growing regions. Weedy rice is various species and subspecies of rice which can distribute their seeds before harvest. Variations of weedy rice adapt to a wide range of natural conditions.
Weedy rice grains often have a red pericarp, so for this reason in the international literature the term "red rice" is often used. This term, however, is not very relevant, because the rice with a red pericarp are also found in some cultivated varieties, but not in many forms of weedy rice.
In most regions of the rice production, weedy rice is introduced after the transition from transplanting rice to sowing commercial seeds directly in the rice field. It has become very significant since the mid 1980's, especially in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, with the weak semi-dwarf varieties of indica subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
. Distribution generally promotes use of commercially purchased seeds containing weed seeds. Weedy rice can be found in 40%-75% of rice fields in Europe, 40% of fields in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, 55% in Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
, 80% in Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
and 60% in Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
.
Because weedy rice and cultivated rice are so closely related, herbicides that would kill red rice would also kill cultivated rice. A genetically modified form of cultivated rice has been developed that will resist a herbicide, but this form of rice has not been approved for human consumption. This genetically modified form of cultivated rice has, however, appeared on the rice market.