Distribution and conservation of an endangered wild rice Oryza granulata in China

Nearly Twenty years after the first large-scale field survey on wild rice in China during 1978 1982, we have recently made an extensive survey on Chinese Oryza granulata (Nees et Am. Ex Watt.), including its current distribution, population characteristics and status of endangerment. Because of the change in the division of administrative areas, the number of counties or cities where the wild rice grows has reached up to 30. Oryza granulata grows normally under the coverage of 90% - 210% in the tropical forest with resistance to drought and moderate disturbance. The measurement of aggregation showed that it maintains a colony pattern in the community. Oryza granulata scatters seeds mainly by gravity and animals, causing limited scale of gene flow between local populations and attaining a typical metapopulation structure of the distributional pattern. Our survey revealed that 12.9% of the populations had been extinct, and 83.9% were endangered. The extent of disturbance varied in different areas. Up to date, the majority of the populations grow in the mountainous areas of southwestern Hainan and drainage area of Nanding river, Lancang river Of Yunnan, under the threat of human activity. A total DNA bank was established that consists of 1 109 individuals from 49 populations. In the practice of conservation, difficulties such as lacking immediate utility and scattered distribution impeded the conservation efficient. However, owing to its characteristics of population genetics, sustainable and ex situ conservation strategies are appropriate in some places to salvage this important rice germplasm.