Prota 1: Cereals and pulses/Cιrιales et lιgumes secs
Compt. Rend. Acad. Sci., sιr. 2, Mec. Phys. Chim. Sci. Univers. Sci. Terre. 159: 561 (1914).
2n = 24
Oryza barthii auct. non A.Chev.
Wild rice, red rice (En). Riz sauvage vivace, riz vivace (Fr).
Origin and geographic distribution
Oryza longistaminata is distributed throughout tropical Africa (including Madagascar) and is also found in South Africa.
The grains of Oryza longistaminata are sometimes eaten and sold on local markets. They serve as famine food, e.g. in Sudan and Ethiopia. Dense stands provide good grazing for cattle. The straw is used for thatching.
Robust perennial grass up to 2.5 m tall, with long, creeping, branched rhizomes; stem (culm) up to 2.5 cm or more in diameter, erect or ascending, with aerial roots from the lower nodes, glabrous. Leaves alternate, simple and entire; leaf sheath spongy, pale green to brownish, smooth, glabrous; ligule (1)1.55.5 cm long, acute, often split down the middle; blade linear, 1045(75) cm Χ 0.51.5(2.5) cm, acuminate, bright to dark green, glabrous, smooth or slightly rough on the lower surface, slightly rough on the upper surface. Inflorescence a terminal panicle 1640 cm Χ 2.58 cm, dense, erect or slightly drooping, with obliquely ascending to almost erect branches. Spikelet asymmetrically elliptical-oblong, 712(15) mm long (awn excluded), deciduous, pale green to brownish, 3-flowered but 2 lowest florets reduced to sterile lemmas ( 2)2.54(4.5) mm long; glumes reduced to a membranous rim; lemma of fertile floret slightly shorter than spikelet, boat-shaped, leathery, hairy, with pink or purplish, rather slender awn (2.5)47.5(8) cm long; palea slightly shorter than lemma and much narrower, acute or tapering into a point; lodicules 2; stamens 6; ovary superior, with 2 plumose blackish stigmas. Fruit an oblong caryopsis (grain) 7.58.5 mm long, glabrous, pale brown, glossy.
Oryza comprises about 20 wild species distributed throughout the tropics and subtropics, and 2 cultivated species, Oryza sativa L. and Oryza glaberrima Steud. Oryza longistaminata is classified in ser. Sativae, together with Oryza sativa, Oryza glaberrima and Oryza barthii A.Chev.
Oryza longistaminata can be distinguished from other wild Oryza spp. by its very long, pointed ligule. Oryza longistaminata is partly self-incompatible and allogamous. Often only few seeds are set and natural reproduction is mainly by its rhizomes.
Oryza longistaminata is found in shallow or deep water in pans, pools, swamps, flood plains and riverbanks, up to 1800 m altitude. It often occurs in pure stands. Oryza longistaminata is a noxious weed in wet-rice cultivation; it suppresses cultivated rice and forms hybrids with it. It may also act as a reservoir for important rice diseases and pests, such as bacterial leaf blight (Xanthomonas oryzae pv. oryzae).
Oryza longistaminata is mostly collected from the wild and only occasionally cultivated. The grains shatter easily, and it is common practice to harvest panicles just before maturity or to shake ripe panicles over a basket or calabash. The long, scabrid awns form a disincentive to touch the panicle.
Genetic resources and breeding
As seed production of Oryza longistaminata is very poor, in situ conservation is recommended. Oryza longistaminata is considered a source of resistance genes to various diseases affecting cultivated Oryza sativa. Resistance to bacterial leaf blight has successfully been transferred. Oryza longistaminata is a host plant of rice yellow mottle virus (RYMV), an important disease of Oryza sativa in Africa, but in general Oryza longistaminata is more tolerant of it, and some accessions are immune. Oryza longistaminata is a potential source of genes for the development of perennial types of Oryza sativa, which would provide a permanent ground cover and reduce erosion.
Oryza longistaminata serves as a famine food during times of shortage, but is also a noxious weed of Oryza sativa. The greatest potential of Oryza longistaminata is probably in Oryza sativa breeding as a source of genes conferring disease resistance and perennial habit.
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Correct citation of this article:
Brink, M., 2006. Oryza longistaminata A.Chev. & Roehr. In: Brink, M. & Belay, G. (Editors). PROTA 1: Cereals and pulses/Cιrιales et lιgumes secs. [CD-Rom]. PROTA, Wageningen, Netherlands.