Education - Rice in the world
Morphology and Distribution 1
(Original figures and data were provided by H. Morishima and M. Akimoto)
Two cultivated species and five wild species belonging to this group show regular chromosome pairing at the meiosis of reciprocal F1 hybrid indicating that they are the relative species having the same AA genome in common. However, various reproductive barriers including hybrid sterility are found among as well as within the species.
O. sativa L. (AA)
A cultivated rice originated in Asia. At present, it is cultivated extensively from the tropical to the temperate zones in the world. Many varieties are differentiated and they are classified into indica and japonica types, the latter is further classified into tropical and temperate types. Extensive improvement has supplied many high yielding varieties widely, but still various native varieties are found in the tropical mountains and the deep-water areas.
O. glaberrima Steud. (AA)
A field of
O. glaberrima.
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A cultivated rice originated in the West Africa. The area of cultivation is limited in the West Africa. Mostly glabrous, ie. hairless, and distinguished by its short and round ligules from O. sativa which has long and pointed ligules. Modern improvement is not much achieved. |
O. rufipogon sensu lato(AA)
O. rufipogon
O. rufipogon and O. sativa
O.rufipogon
O. rufipogon
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A wild ancestor species of O. sativa. Widely grown spontaneously from the tropical and sub-tropical zones in Asia and Oceania. Rich in ecological and geographical variations. Due to the complicated variation of inter- and intra-species there have so far been many confusions in taxonomy and nomenclature. Sometimes, the perennial and out-crossing ecological type adapted to a stable deep water environment is called O. rufipogon sensu strict, while the annual and self-pollinating ecological type adapted to a shallow water environment under severe disturbance is called O. nivara. They have once been called O. perennis complex together with the relative species distributed in the other continents. When co-exist with a cultivated rice, they easily cross spontaneously with each other and their offsprings are often found as weeds in and around paddy fields. |
O. barthii A. Chev. (AA)
O. barthii(Chad)
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A wild ancestor species of O. glaberrima and once called O. breviligulata. This is a seed propagating annual species with long awns, spontaneously growing in a deep-water area in African savanna. It easily crosses spontaneously with O. glaberrima and there are many populations found with continuous variations. |
O. longistaminata Chev. et Roehr. (AA)
O. barthii and O. longistaminata
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Once called O. barthii. This perennial species has a well developed rhizome. Widely distributed in Africa. Has a tendency of self-incompatibility and a high outcrossing rate. Sometimes co-exists with O. barthii but their natural hybrids are scarcely found. |
O. meridionalis Ng (AA)
O. glumaepatula Steud. (AA)
O. glumaepatula
O. glumaepatula in Amazon.
Natural habitat of O. glumaepatula
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Widely distributed in a wet area in Central and South America. Wide variations within species are found from a vegetatively propagating perennial type to a mainly seed-propagating ecotype grown in the area of Amazon river. Sometimes it is included into O. rufipogon due to the occurrence of morphologically resembling types with a perennial type of O. rufipogon. |
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O. sativa complex
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