This study investigated the effect of silicon (Si) on the photosynthetic gas exchange parameters (net CO 2 assimilation rate [A], stomatal conductance to water vapor [g s ], internal CO 2 concentration [C i ], and transpiration rate [E]) and chlorophyll fluorescence a parameters (maximum quantum quenching [F v /F m and F v ′/F m ′], photochemical [q P ] and nonphotochemical [NPQ] quenching coefficients, and electron transport rate [ETR]) in wheat plants grown in a nutrient solution containing 0 mM (–Si) or 2 mM (+Si) Si and noninoculated or inoculated with Pyricularia oryzae. Blast severity decreased due to higher foliar Si concentration. For the inoculated +Si plants, A, g s , and E were significantly higher in contrast to the inoculated –Si plants. For the inoculated +Si plants, significant differences of F v /F m between the –Si and +Si plants occurred at 48, 96, and 120 h after inoculation (hai) and at 72, 96, and 120 hai for F v ′/F m ′. The F v /F m and F v ′/F m ′, in addition to total chlorophyll concentration (a + b) and the chlorophyll a/b ratio, significantly decreased in the –Si plants compared with the +Si plants. Significant differences between the –Si and +Si inoculated plants occurred for q P , NPQ, and ETR. The supply of Si contributed to decrease blast severity in addition to improving gas exchange performance and causing less dysfunction at the photochemical level.