The 13C discrindnating val-ues (δ13C) of assindlates of the fimc-tional leaves of Yuanyou l, GERl lbOth their rnaemal and Paeed culh-vars, 2-line hybrid rice N3ls x P40, 3’line hybrid rice Weiyou 64 mp tmdelgreenhouse by pot experiment a1Guangzhu in 1993 were analsed b)mass specbometer MAT25l. The re-sults obtained showd tha alsc of as’sindlates of Yuanyu l and GER-l, thei]rnaemal rice cultivars Gul 630 and L-anwian 8, two line hybrid rice N3lEx P40 and thee line hybrid rice wiiy-ou od were approximately same and aresignificanily fferent from those ofAsrghum and Zea. It demonstraes thatsignifican higher photoSynthehc rate ofYuanou 1, GER-1 can probaby be ex-plained by their higher Calvin-cyclemetabolism efficiency rather than bytheir cthen-fixaion pathway.
