Cultivars
Rice seed collection from IRRI
While most rice is bred for crop quality and productivity, there are varieties selected for characteristics such as texture, smell, and firmness. Cultivars exist that are adapted to deep flooding, and these are generally called “floating rice”.
There are four major categories of rice worldwide:
- Indica,
- Japonica,
- Aromatic
- Glutinous.
The different varieties of rice are not considered interchangeable, either in food preparation or agriculture, so as a result, each major variety is a completely separate market from other varieties. It is common for one variety of rice to rise in price while another one drops in price.
The largest collection of rice cultivars is at the International Rice Research Institute in the Philippines, with over 100,000 rice accessions held in the International Rice Genebank.
Rice cultivars are often classified by their grain shapes and texture.
For example, Thai Jasmine rice is long-grain and relatively less sticky, as long-grain rice contains less amylopectin than short-grain cultivars. Chinese restaurants often serve long-grain as plain unseasoned steamed rice though short-grain rice is common as well.
Polished Indian sona masuri rice grains
Japanese mochi rice and Chinese sticky rice are short-grain. Chinese people use sticky rice which is properly known as “glutinous rice” to make zongzi. The Japanese table rice is a sticky, short-grain rice. Japanese sake rice is another kind as well.
Indian rice cultivars include long-grained and aromatic Basmati (grown in the North), long and medium-grained Patna rice and short-grained Sona Masoori (also spelled Sona Masuri).
In the state of Tamil Nadu, the most prized cultivar is ponni which is primarily grown in the delta regions of Kaveri River. Kaveri is also referred to as ponni in the South and the name reflects the geographic region where it is grown.
In the Western Indian state of Maharashtra, a short grain variety called Ambemohar is very popular. This rice has a characteristic fragrance of Mango blossom.
Unpolished long-grain rice grains with bran
Aromatic rices have definite aromas and flavours; the most noted cultivars are Thai fragrant rice, Basmati, Patna rice, Vietnamese fragrant rice, and a hybrid cultivar from America sold under the trade name, Texmati. Both Basmati and Texmati have a mild popcorn-like aroma and flavour. In Indonesia there are also red and black cultivars.
High-yield cultivars of rice suitable for cultivation in Africa and other dry ecosystems called the new rice for Africa (NERICA) cultivars have been developed. It is hoped that their cultivation will improve food security in West Africa.
Draft genomes for the two most common rice cultivars, indica and japonica, were published in April 2002. Rice was chosen as a model organism for the biology of grasses because of its relatively small genome (~430 megabase pairs).
On December 16, 2002, the UN General Assembly declared the year 2004 the International Year of Rice. The declaration was sponsored by more than 40 countries.
Biotechnology
High-yielding varieties
Field of IR8 rice
The High Yielding Varieties are a group of crops created intentionally during the Green Revolution to increase global food production.
Rice, like corn and wheat, was genetically manipulated to increase its yield.
This project enabled labor markets in Asia to shift away from agriculture, and into industrial sectors.
The first “Rice Car”, IR8 was produced in 1966 at the International Rice Research Institute which is based in the Philippines at the University of the Philippines’ Los Baños site. IR8 was created through a cross between an Indonesian variety named “Peta” and a Chinese variety named “Dee Geo Woo Gen.”
Scientists have identified and cloned many genes involved in the gibberellin signaling pathway, including GAI1 (Gibberellin Insensitive) and SLR1 (Slender Rice). Disruption of gibberellin signaling can lead to significantly reduced stem growth leading to a dwarf phenotype.
Photosynthetic investment in the stem is reduced dramatically as the shorter plants are inherently more stable mechanically. Assimilates become redirected to grain production, amplifying in particular the effect of chemical fertilizers on commercial yield. In the presence of nitrogen fertilizers, and intensive crop management, these varieties increase their yield two to three times.
Future potential
As the UN Millennium Development project seeks to spread global economic development to Africa, the “Green Revolution” is cited as the model for economic development.
With the intent of replicating the successful Asian boom in agronomic productivity, groups like the Earth Institute are doing research on African agricultural systems, hoping to increase productivity.
An important way this can happen is the production of “New Rices for Africa” (NERICA). These rices, selected to tolerate the low input and harsh growing conditions of African agriculture are produced by the African Rice Center, and billed as technology “from Africa, for Africa”.
The NERICA have appeared in The New York Times (October 10, 2007) and International Herald Tribune (October 9, 2007), trumpeted as miracle crops that will dramatically increase rice yield in Africa and enable an economic resurgence. Ongoing research in China to develop perennial rice could result in enhanced sustainability and food security.
