Common wild rice, Oryza rufipogon ranges widely in China, which displays a considerable clinal variation. Thus, it’s considered as a unique opportunity to study its geographic variation pattern and adaptive mechanism, and also provides a remarkable material to examine the effects of environmental, physiological and genetic factors.

PhD student ZHOU Wen under the supervision of Professor LIU Guihua from Wuhan Botanical Garden investigated 34 populations in situ in six provinces of China, and combined with transplant experiments to two common gardens, one is beyond its northern range limit (Wuhan, Hubei Province) and the other in the southernmost part of China (Linshui, Hainan Province).

The results showed that seed mass in the field was positively correlated with latitude and longitude, whereas flag-leaf area was negatively correlated with latitude; both effects could be explained as largely a response to temperature. Transplantation revealed that both plasticity and population differentiation contributed to geographical variation. All populations reproduced and overwintered in the southern garden but, in the northern garden, only populations from the northern range were able to reproduce (65%) and survive the winter (58%). Freezing tolerance, the asymmetrical variations between reproduction and photosynthetic growth may the roles in determining species’ distribution limits.

Results entitled “Geographic variation and local adaptation in Oryza rufipogon across its climatic range in China” were published in Journal of Ecology online. This research was supported by the Special Program for S & T Action of Strategic Biotic Resources, the CAS Strategic Priority Research Program, and the China National Science Foundation.

Probability of (a) overwinter survival and (b) reproductive success of 34 populations of Oryza rufipogon transplanted to the northern experimental garden, in relation to their latitude of origin. (Image by ZHOU Wen)