The fertility alteration in photo-senstitive genic male sterile rice(PSGMR)is the integrated resuIt of photo-thermal coi1ditions 5 to 15-20 days prior to the earing stage with the numerical relation presented by a qtiantified grains-producing rate model.Results show that the fertility of the thermo-sensitive PSGMR is controlled largely by temperature over that period and that of the photo-sensitive type by insolation when it is longer than the potimum daylength and otherwise by temperattire. Moreover,the temperature and insolation are inter-supplementary in their impacts on fertility,and below(above)the optimum temperature the sterility has its critical daylength elongated(shortened)with increasing temperatuve,The photo-temperature equivalent can be taken as a tiseftil measure of temperattire aidinsolation influencing the fertility,The general diagrams of the fertility change based on the quantified grains-prodticing rate model and its mechanisms provide a scientific basis for the seed selection,development and reproduction ofsterilitv rice.