Response of Photosynthesis, Growth, Carbon Isotope Discrimination and Osmotic Tolerance of Rice to Elevated CO_2

摘要

Four rice (Oryza saliva L.) cultivars "IR72", "Tesanai 2", "Guichao 2" and "IIyou 4480" were grown in two plastic house (15 m x 3 m) with 35 μmol/mol and 60 μmol/mol CO_2 concentration which was controlled by computer. As compared with rice at ambient 35 μmol/mol CO_2, the changes in photosynthetic rate at elevated CO_2 showed up-regulation ("IR72" and "Tesanai 2") , stable (unchanged) in "Guichao 2" and down-regulation type ("IIyou 4480"). Growth rate, panicle weight, integrated water use efficiency (WUE) calculated from Δ ~(13)C and the capacity of scavenging DPPH~· (1, 1-diphenyl-2-picrylhydrazyl) free radical were increased at elevated CO_2. An increment in total biomass was observed in three cultivars by elevated CO_2, with the exception of "IIyou 4480" . Ratios of panicle weight/total biomass were altered to different extents in tested cultivars by elevated CO_2. When leaf segments were subjected to PEG osmotic stress, the electrolyte leakage rate from leaves grown at elevated CO_2 was less than that at 35 μmol/mol CO_2. Those in-traspecific variations of rice imply a possibility for selecting cultivars with maximal productivity and high tolerance to stresses adapted to elevated CO_2 in the future.