Advantages linked to root development enhance rice biomass accumulation under elevated carbon dioxide conditions

Abstract

To explore the effects of an increased CO 2 concentration on the growth and N absorption and utilization of different rice (Oryza sativa L.) cultivars, the Liangyoupeijiu (LY) and Nanjing 9108 (NJ) rice cultivars were grown under ambient CO 2 (400 μmol mol −1) and elevated CO 2 (600 μmol mol −1) combined with high N (2.5 mM) and low N (0.5 mM) treatments. The effects of elevated CO 2 on root morphological and physiological characteristics, N uptake and utilization, and dry matter accumulation and distribution were analyzed. The results showed that the elevated CO 2 levels significantly increased the total biomass of LY under different N levels but only significantly increased the total biomass of NJ under high N. Elevated CO 2 significantly increased the N concentrations in the organs of LY but had no significant effect on the N concentrations in the organs of NJ. As a result, elevated CO 2 significantly increased the N accumulation of LY but decreased the N uptake of NJ under low N. Under elevated CO 2 conditions, the total root length and root surface area of LY increased, and the roots also maintained high activity. The larger roots and higher physiological activity and N accumulation of LY were the important reasons for the high levels of dry matter production in response to elevated CO 2. Improvements in the root morphology and physiological activity of rice in future breeding efforts should enhance the dry matter production of low-response rice.