Diminution of photosynthesis in rice (Oryza sativa L.) seedlings under elevated CO2 concentration and increased temperature

The photosynthetic responses to elevated CO2 concentration (EC) at ambient and ambient +4A degrees C temperature were asessed in the second leaf of rice (Oryza sativa L.) seedlings. The duration of different leaf developmental phases, as characterised by changes in photosynthetic pigment contents and photochemical potential, was protracted in the seedlings grown under EC. On the other hand, a temporal shift in the phases of development with an early onset of senescence was observed in the seedlings grown under EC at ambient +4A degrees C temperature. The contents of carotenoids, -carotene, and xanthophyll cycle pigments revealed that EC downregulated the protective mechanism of photosynthetic apparatus against oxidative damages, whereas this mechanism assumed higher significance under EC at ambient +4A degrees C temperature. We observed an enhancement in electron transport activity, photochemical potential, and net photosynthesis in spite of a loss in photostasis of photosynthesis under EC. On the other hand, the loss in photostasis of photosynthesis was exacerbated under EC at ambient +4A degrees C temperature due to the decline in electron transport activity, photochemical potential, and net photosynthesis.