Abstract There are two species of cultivated rice in the world— Oryza sativa L. from Asia and Oryza glaberrima Steud. from Africa. The former was domesticated from the wild progenitor Oryza rufipogon Griff. and the latter from the African wild rice species Oryza barthii A. Shiv. The first known center of rice cultivation in China generated the O. sativa subspecies japonica . The indica subspecies arose from the second center of domestication in the Ganges River plains of India. Variants of domesticated lines and the continuous hybridization between cultivated varieties and the wild progenitor(s) resulted in weedy rice types. Some weedy types resemble the wild ancestor, but the majority of weedy rices today bear close resemblance to cultivated rice. Weedy rice accompanies rice culture and has increased in occurrence with the global shift in rice establishment from transplanting to direct-seeded or dry-drill-seeded rice. Weedy rice ( Oryza spp.) is the most difficult weed to control in rice, causing as much as 90% yield loss or abandonment of severely infested fields. The gene flow continuum between cultivar and weedy rice or wild relative, crop de-domestication, and regionalized adaptation have resulted in a myriad of weedy rice types. The complex lineage of weedy rice has resulted in confusion of weedy rice nomenclature. Two names are generally used for weedy rice— Oryza sativa L. and Oryza sativa f. spontanea . Genomic data show that O. sativa L. applies to weedy rice populations derived from cultivated O. sativa , whereas O. sativa f. spontanea applies only to weedy types that primarily descended from O. rufipogon . Neither of these names applies to African weedy rice, which is of African wild rice or O. glaberrima lineage. Therefore, unless the lineage of the weedy population in question is known, the proper name to use is the generalized name Oryza spp.
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Plant Microfossil Results from Old Kiyyangan Village: Looking for the Introduction and Expansion of Wet-field Rice (Oryza sativa) Cultivation in the Ifugao Rice Terraces, Philippine Cordilleras
Pollen, phytolith, and starch analyses were carried out on 12 samples from two trenches in
Old Kiyyangan Village, Ifugao Province, providing evidence for human activity from ca.
810–750 cal. B.P. Seed phytoliths and endosperm starch of cf. rice (Oryza sativa),
coincident with aquatic Potamogeton pollen and sponge spicule remains, provide
preliminary evidence for wet-field cultivation of rice at the site. The first rice remains
appear ca. 675 cal. B.P. in terrace sediments. There is a marked increase in these remains
after ca. 530–470 cal. B.P., supporting previous studies suggesting late expansion of the
cultivation of wet-field rice in this area. The study represents initial, sediment-derived,
ancient starch evidence for O. sativa, and initial, sediment-derived, ancient phytolith
evidence for this species in the Philippines. KEYWORDS: Philippines, Ifugao Rice Terraces,
rice (Oryza sativa), pollen, phytoliths, starch.
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- Award ID(s):
- 1460665
- PAR ID:
- 10080584
- Date Published:
- Journal Name:
- Asian perspectives
- Volume:
- 57
- Issue:
- 1
- ISSN:
- 0066-8435
- Page Range / eLocation ID:
- 159-176
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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