Effects of free-air CO2 enrichment on root morphology of rice

In this paper the effects of elevated CO2 and different nitrogen supply on root morphology of rice were examined. The results showed that CO2 enrichment significantly increased root biomass during the whole growth season. CO2 and Nitrogen treat- ments changed root morphology. Root growth showed a positive response to CO2 enrichment, especially in the heading. Root length, number of root tips, total root surface increased at low nitrogen, while root width, number of adventitious roots increased at normal nitrogen. R/S (root/shoot) increased significantly under CO2 enrichment, especially at low nitrogen (P0.001). The ratio of R/S de- creased with increasing growth of rice,owing to faster increase of shoot biomass than the root at later stages.