Abstract: To clarify the genetic mechanism of percentage of stigma exsertion in rice(Oryza sativa L)and improve stigma exsertion rate of a drought tolerant CMS maintainer Huhan 1B．QTL analysis was conducted in a F2 population of 190 plants derived from a cross between Huhan 1B and Ⅱ一32B．Ten QTLs of rice stigma exsertion rate were identified on four chromosomes．Three QTLs of percentage of single exserted stigma(PSES)were mapped on chromosomes 3,7 and 9 with accumulated contribution of 21．4％；Two QTLs of percentage of dual exserted stigma(PDES)were detected on chromosomes 3 and 9 with accumulated contribution of 15．98％ ；Five of percentage of total exserted stigma(PES)were mapped on chromosome 3，4，7，9，including 2QTLs on chromosome 3，whose contribution rates varied from 6．86％ to 9．73％ and
the total contribution rates of the five QTLs was 39.42％．Totally，seven QTLs pairs had significant epistatic effect on the percentage of stigma exsertion rate and accounted for 67．39％ of the phenotypie variation．Most of them were additive×additive epistatic effects，and some of major QTLs were involved in the interactions．The identification of the QTLs markers may be important for improvement of Huhan 1B in stigma exsertion rate．

Key words: rice, drought tolerant hybrid rice, percentage of exserted stigma, QTL analysis