摘要：Acommon question but very difficult to answer.
Depending on your defi nition of variety, the answer
could be anything from zero to around 500,000
varieties of Oryza sativa (Asian cultivated rice). In the
technical sense used by taxonomists (biologists who classify
organisms into groups based on evolutionary relationships),
descriptions have been published of 14 varieties, but
most taxonomists now do not accept any of them as valid
taxonomic varieties—so, in this sense, the answer is zero.
Cultivated varieties (abbreviated to “cultivars” to
distinguish from the taxonomists’ concept) are something
different, but even then we count different numbers for
different meanings. Many countries maintain an offi cial
list of recognized varieties released
for cultivation by farmers. In
countries with a legal system for
protecting plant breeders’ rights,
these varieties may have been
subjected to rigorous tests to
demonstrate that they are novel,
distinct from other varieties,
uniform, and stable.
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