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| Oryza sativa |
Biggest Plant Dictionary | Oryza sativa | Oryza sativa contains two major subspecies: the sticky, short grained japonica or sinica variety, and the non-sticky, long-grained indica variety.
Japonica are usually cultivated in dry fields, in temperate East Asia, upland areas of Southeast Asia and high elevations in South Asia, while indica are mainly lowland rices, grown mostly submerged, throughout tropical Asia. Rice is known to come in a variety of colors, including: white, brown, black, purple, and red.
Japonica are usually cultivated in dry fields, in temperate East Asia, upland areas of Southeast Asia and high elevations in South Asia, while indica are mainly lowland rices, grown mostly submerged, throughout tropical Asia. Rice is known to come in a variety of colors, including: white, brown, black, purple, and red.
A third subspecies, which is broad-grained and thrives under tropical conditions, was identified based on morphology and initially called javanica, but is now known as tropical japonica. Examples of this variety include the medium grain 'Tinawon' and 'Unoy' cultivars, which are grown in the high-elevation rice terraces of the Cordillera Mountains of northern Luzon, Philippines.
Continental East Asia
Rice appears to have been used by the early Neolithic populations of Lijiacun and Yunchanyan. Evidence of possible rice cultivation in China from c. 11,500 BP has been found, however it is still questioned whether the rice was indeed being cultivated, or instead being gathered as wild rice.Bruce Smith, an archaeologist at the Smithsonian Institution in Washington, D.C., who has written on the origins of agriculture, says that evidence has been mounting that the Yangtze was probably the site of the earliest rice cultivation.
Zhao (1998) argues that collection of wild rice in the Late Pleistocene had, by 6400 BC, led to the use of primarily domesticated rice. Morphological studies of rice phytoliths from the Diaotonghuan archaeological site clearly show the transition from the collection of wild rice to the cultivation of domesticated rice. The large number of wild rice phytoliths at the Diaotonghuan level dating from 12,000–11,000 BP indicates that wild rice collection was part of the local means of subsistence. Changes in the morphology of Diaotonghuan phytoliths dating from 10,000–8,000 BP show that rice had by this time been domesticated. Analysis of Chinese rice residues from Pengtoushan, which were carbon 14 dated to 8200–7800 BCE, show that rice had been domesticated by this time.
In 1998, Crawford & Shen reported that the earliest of 14 AMS or radiocarbon dates on rice from at least nine Early to Middle Neolithic sites is no older than 7000 BC, that rice from the Hemudu and Luojiajiao sites indicates that rice domestication likely began before 5000 BC, but that most sites in China from which rice remains have been recovered are younger than 5000 BC.
Rice appears to have been used by the early Neolithic populations of Lijiacun and Yunchanyan. Evidence of possible rice cultivation in China from c. 11,500 BP has been found, however it is still questioned whether the rice was indeed being cultivated, or instead being gathered as wild rice.Bruce Smith, an archaeologist at the Smithsonian Institution in Washington, D.C., who has written on the origins of agriculture, says that evidence has been mounting that the Yangtze was probably the site of the earliest rice cultivation.
Zhao (1998) argues that collection of wild rice in the Late Pleistocene had, by 6400 BC, led to the use of primarily domesticated rice. Morphological studies of rice phytoliths from the Diaotonghuan archaeological site clearly show the transition from the collection of wild rice to the cultivation of domesticated rice. The large number of wild rice phytoliths at the Diaotonghuan level dating from 12,000–11,000 BP indicates that wild rice collection was part of the local means of subsistence. Changes in the morphology of Diaotonghuan phytoliths dating from 10,000–8,000 BP show that rice had by this time been domesticated. Analysis of Chinese rice residues from Pengtoushan, which were carbon 14 dated to 8200–7800 BCE, show that rice had been domesticated by this time.
In 1998, Crawford & Shen reported that the earliest of 14 AMS or radiocarbon dates on rice from at least nine Early to Middle Neolithic sites is no older than 7000 BC, that rice from the Hemudu and Luojiajiao sites indicates that rice domestication likely began before 5000 BC, but that most sites in China from which rice remains have been recovered are younger than 5000 BC.
Red rice is an interfertile, weedy form of cultivated rice (Oryza sativa) that competes aggressively with the crop in the southern U.S., reducing yields and contaminating harvests. Weed strains range from 'crop mimics,' which share many domestication traits with the crop, to strains closely resembling Asian wild Oryza species. Assessments of genetic diversity have indicated that some weed strains are closely related to Asian taxa (including indica rice varieties, which have never been cultivated in the U.S., and the Asian crop progenitor, O. rufipogon), while others show genetic similarity to the tropical japonica varieties cultivated in the southern U.S. This project seeks to examine the population genomic structure of red rice and the roles of foreign weed introduction, genomic introgression and selection in shaping the weed genome. The project will provide a comprehensive view of genome evolution in this weed and will contribute to public databases on Oryza SNP diversity, molecular markers, and linkage disequilibrium.
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