Photosynthetic Response to the Low Temperature in Elephant Grass (Pennisetum purpureum) and Zea mays

Photosynthetic CO2 uptake and the quantum efficiency of PSII photochemistry (Fv/Fm) of C4 grasses (Pennisetum purpureum and Zea mays) were studied at 14 and 25 °C. P. purpureum showed superior photosynthetic rates at chilling temperature (14 °C) than Z. mays. Growth at a chilling temperature compared to 25 °C had no significant effect on the light saturated assimilation rate (Asat), the quantum yield (φ), the CO2 saturated rate of CO2 uptake (Amax) and the carboxylation efficiency of P. purpureum but caused more than 78% loss of those occurred in Z. mays. The values of Fv/Fm were significantly reduced only in Z. mays at 14 °C compared to 25 °C and as a result, the photosynthetic apparatus of P. purpureum was more resistant to chilling temperature than of Z. mays.