Net photosynthetic rate and stomatal conductance of rice plants 7 days after submergence and non-submerged plants were measured with an infrared gas analyzer (LI-6400, LI-COR, Lincoln,
NE) around 11:00 am. The conditions in the assimilation chamber were kept as follows: air humidity, 70%; leaf temperature, 35 C; light intensity (PAR), 1200mmol m 2 s 1 , CO2 concentration of 380mmol CO2mol 1. Middle portion (3 cm long) of the fully expanded and not senescent leaf blade was selected for measurement of Pn rate.