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Ser. Meyerianae
O. granulata
O. meyeriana
O. neocaledonica
Ser. Ridleyanae
O. longiglumis
24
24
24
GG
GG
??
South, Southeast Asia
Southeast Asia
New Caledonia
48
HHJJ
O. ridleyi
48
Ser. Schlechterianae
O. schlechteri
48
HHJJ
Indonesia (Irian Jaya), Papua New
Guinea
Southeast Asia
HHKK
Indonesia (Irian Jaya), Papua New
Guinea
Table 1-2. Genera, number of species, distribution,
chromosome number and spikelet structure in the subfamily
Oryzeae (adapted from Chang and Vaughan, 1991).
Genera
No. of
Distribution
Tropical
species
(T)/temperate (t)
Oryza
Leersia
Chikusiochloa
Hygroryza
Porteresia
Zizania
22
17
3
1
1
3
Luziola
11
Zizaniopsis
5
Rhynchoryza
Maltebrunia
1
5
Prosphytochloa
Potamophila
1
1
Pan-tropical
Worldwide
China, Japan
Asia
South Asia
Europe, Asia, N.
America
N. and S.
America
N. and S.
America
S. America
Tropical and S.
Africa
S. Africa
Australia
T
t+T
t
t+T
T
t+T
t+T
t+T
t
T
t
t+T
The need for genetic conservation
Traditional varieties and the wild species of rice are being lost through genetic erosion. Farmers
adopt new varieties, and cease growing the varieties that they have nurtured for generations and
eventually lose these varieties. The wild species are threatened with extinction as their habitats
are destroyed by human disturbance. Future crop improvement needs the genetic variation from
traditional varieties and related wild species to cope with the many biotic and abiotic stresses that
challenge rice production around the world.
The genebank
IRRI has maintained a collection of rice genetic resources since 1962. The collection comprises
more than 107,000 accessions, mostly landrace or breeding materials of O. sativa, O. glaberrima,
and wild species, and representative species from 8 genera in the tribe Oryzeae (Table 1-3).
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