To provide physiological basis for thegenetic improvement of hybrid ricewith photoinhibition or photooxidationtolerance, we measured physiologicalindexes related to PS Ⅱ light energyconversion efficiency (Fv/ Fm) and To provide physiological basis for the genetic improvement of hybrid rice with photoinhibition or photooxidationtolerance, we measured physiological indices of related to PSII light energy conversion efficiency (Fv / Fm) and