Introduction of low temperature germinability into highly palatable cultivars of rice

摘要

In order to breed highly palatable rice cultivars suitable for direct sowing, experiments were conducted to incorporate the genes for low-temperature-germinability (LTG) into highly palatable Japanese cultivars. Examination of 10 Japanese and 10 foreign cultivars for LTG (proportion of the germination rate at 15oC compared to that at 25oC after 7 days of incubation) showed that most of the foreign cultivars which were directly sown in their own countries were extremely useful as donors of LTG. Fivebackcrossed (BC2F2) populations (Koshihikari*3/M202, Hinohikari*3/M202, Koshihikari*3/Italica Livorno, Koshihikari*3/Mutashali and Kinuhikari*3/Mutashali) were developed and selected for LTG. From all populations, lines superior to each recurrent parents were obtained. In particular, from Koshihikari*3/M202 (66 lines), Hinohikari*3/M202 (51 lines) and Koshihikari*3/Mutashali (51 lines), eight, eleven and one line, respectively, were obtained which showed excellent (>81%) LTG. Lines of Hinohikari*3/M202were used as donors of further backcrossing to produce BC3F2 lines (Hinohikari*4/M202, 35 lines). From among these, 5 excellent lines with high LTG were selected. It is concluded that it is possible to breed highly palatable rice cultivars suitable fordirect sowing by introducing LTG derived from foreign cultivars, such as M202, into good eating-quality cultivars.