We studied the relationship between the head-ing sensitivity and the male-sterile sensitivityin photoperiod-sensitive genic male-sterile rice(PGMSR) and conventional rice. Materialsused in this study were 7001S, a late maturingPGMS japonica strain derived from Nongken58S; Akihikari and Youmang-zaojing(YMZJ),two early maturing conventional japonica rice; We studied the relationship between the head-sensitivity and the male-sterile sensitivity in photoperiod-sensitive genic male-sterile rice (PGMSR) and conventional rice. Materialsused in this study were 7001S, a late maturing PGMS japonica strain derived from Nongken 58S; Akihikari and Youmang -zaojing (YMZJ), two early maturing conventional japonica rice;