Up-regulation of photosynthesis and sucrose-P synthase in rice under elevated carbon dioxide and temperature conditions

Basmati rice (Oryza sativa L.) cultivars viz. PRH-10 (pusa rice hybrid-10) and PS-2 (Pusa Sugandh-2) were grown under two different day/night temperatures (31/24°C, 35/28°C) at ambient (370 µmol/mol) and elevated (550 µmol/ mol) carbon dioxide (CO 2 ) concentration, respectively, to characterize how an increase in CO 2 and temperature affects rice photosynthesis and carbohydrate metabolism. At elevated CO 2 , the photosynthetic rates increased under both the temperature regimes, compared with plants grown at ambient CO 2 . The photosynthetic rate, sucrose-P synthase (SPS) activity and accumulation of soluble sugars and starch were higher in PRH-10 (pusa rice hybrid-10), compared to PS-2 (Pusa Sugandh-2). Elevated temperature decreased the photosynthetic rates both under ambient and elevated CO 2 conditions. The SPS (sucrose-P synthase) activity and the accumulation of soluble sugars and starch were enhanced at elevated CO 2 under both temperature regimes compared with plants grown at ambient CO 2 . The up-regulation of SPS (sucrose-P synthase) under elevated CO 2 and temperature would be beneficial for growth and productivity of rice plants for the future climatic conditions.