Relationship between Transpiration and Silica Content of the Rice Panicle under Elevated Atmospheric Carbon Dioxide Concentration

Abstract

Silica is distributed in rice plant by the transpiration stream. However, it is unknown the effects of atmospheric carbon dioxide concentration ([CO2]) on silica deposition in the rice plants. In the present study, we investigated the effects of elevated [CO2] on silica contents of the rice plant and focused on the relationships between transpiration rate and silica content of the panicle and leaves under elevated [CO2] at the flowering stage. The rice seedlings were grown hydroponically in two chambers until the flowering stage. The [CO2] in the chambers was maintained at 350 µmol mol-1 (ambient [CO2]) or 700 µmol mol-1 (elevated [CO2]). Silica contents of the panicle and the flag leaf under elevated [CO2] significantly decreased compared with those under ambient [CO2] when silica was applied to the culture solution. The transpiration rate of the panicle decreased with increasing panicle silica content under ambient [CO2]. No correlations between transpiration rate and silica content of the panicles and leaves were observed under elevated [CO2].