Smith - 2003 - Rice origin, history, technology, and production

Origin, Domestication, ond Diversification
n
Centres of diversity of cultivars S
“ “ “* Sínicas of Japónicas
Indicas
■' Javanicas
------ Distribution of wild relatives
Figure 1.1.3, Extent of wild relatives ond spread of ecogenetic races of 0. sativa in Asia and Oceania. (Adapted
from Cliong, 1985.)
EVOLUTION OF 0. GLABBRRIMA
M ost rice workers find little dissension with the postulate that the African cultigen
O. glaberrima came from the wild annual O. barhtii A. Chev., which, in turn, was
likely to have been derived from the rhizomatous and self-incompatible wild perennial
O, longistaminata Chev. et Roehr. O, harthii was formerly called O. hreviligulata
A. Chev. et Roehr, and the perennial longistaminata as O. barthii sensu Hutch, et
Dalz. Weedy intermediates have been grouped tentatively under O. stapfii Roschev.
The three species have become sufficiently differentiated from each other to warrant
their assignment to different subgenomes o f A, A®, A'’, and A^ respectively (see
Chang, 1964b).
Studies by Porteres (1956) have indicated that the primary area o f diversity for
O, glaberrima is in the swampy basin o f the upper Niger River and two secondary
centers located to die northwest, near tlie Guinean coast
Various studies have shown that cultivars o f O, glaberrima are less diverse than
those in O. sativUi but they also contain both deepwater and dryland strains. Details
appear in Oka and Chang (1964), Bardenas and Chang (1966), Oka and M orishima
(1967), Chang et al., (1977), Harlan (1975, 1977,1989) and Ng et al., (1991).