STUDIES ON EFFECTS OF MALE STERILE CYTOPLASM IN RICE(Oryza sastiva L. ind ica and Oryza sativa L. f.spontanea)

Thirty-six combinations were obtained by crossing eight types of homonucleus-al-loplasmic male sterile lines and their relative maintainer lines with four restorer lines,respec-tively,and the difference of male sterile cytolasmc effects with homonucleus background wascompared under split-plot experiment.The results showed :male sterile cytoplasms werefound expressing mostly negative effects on single plant yield and main agronomic charactersof F1, but a very significant difference was retained among the different cytoplasms.It wasfound that the cytoplasmic effect of O. sativa L.ind ica was better than that ofO.sativa L.f.spontanea in the study,it suggested that O. sativa L. ind ica should be priority for selectingsuperior male sterile cytoplasm. The sterile cytoplasmic effect was certainly affected by re-storer lines and the studied characters were significantly controlled by nucleo-cytoplasmic in-teraction. Therefore,selecting and breeding restorer lines with strong combining ability willstill be an important way for developing superior hybrid combination. The possibility and ne-cessity of selecting superior male sterile cytoplasm in breeding of three lines hybrid rice werealso dicussed.