Abstract: The effects of calcium and ionophore A23187 on in vitro development of early embryo in rice(Oryza sativa L.)were studied.The main results were as follows:(1) the influence of Ca²⁺ on the in vitro development of 3 to 5 day old embryos was related to the concentration of Ca²⁺ and the age of embryos.Without Ca²⁺ or with the high concentration of Ca²⁺(10^-1 mol/L),the growth of 3 day old embryos was inhibited completely and the development of 4 to 5 day old embryos was affected in certain degree.With 10^-3 mol/L Ca²⁺,3 to 5 day old embryos grew rapidly and the highest frequency of embryogenesis appeared.In the same concentration of Ca²⁺,the older the embryos were,the higher the frequency of embryogenesis and the total induction appeared.(2) A23187 influenced in vitro embryo development and morphosis.With increasing A23187 concentration,the in vitro development of the embryos in rice was inhibited more violently.The younger embryos were,the more obvious inhibition.