Abstract:Contents of IAA, GA1＋4, ABA and iPAs were measured by enzyme-linked irnmunosorbent assay (ELISA) in leaves, panicles and anthers of cytoplasndc male sterile (CMS) rice Zhenshan 97A and its maintainer Zhenshan 97B during panicle development.From stamen and pistil formation to trinucleate pollen stages, IAA content in leaves of CMS line was shown to be lower than that of maintainer line, and the highest level was observed at binucleate pollen stage in maintainer line. So were IAA contents in anthers and panicles. Changes in GAsimilar pattern, i.e. in both lines, the level of GA1＋4 rose at first, then dropped, however,the highest levels were found in leaves as well as in panicles and anthers of maintainer line during uninucleate to trinucleate stages. ABA level in leaves of CMS line were obviously higher than that in maintainer one at early panicle developmental stage, and was at nearly the same level in both lines at griddle stage, then again still higher than that in maintainer line. The levels of ABA in panicles and anthers in CMS line were also higher than those in maintainer line. As to the conteflts of iPAs. in leaves, panicles and anthers, markedly lower level in CMS line than in maintainer line was found at all stages. The ratios of IAA+GA1＋4+iPAs to ABA in leaves, panicles and anthers of CMS line were also lower than those in maintainer one. It is proposed that the changes in contents of these phytohormones in CMS line are abnormal, and IAA, GA1＋4 and iPAs deficiency and ABA accumulation aught be related to the generation of CMS in rice.