Observations on some characters in F2 and F3 of induced inter-subspecific tetraploid rice, with special reference to the sterility and nurnber of spikelet per ear compared with autotetraploid.

Abstract

Four highly fertile tetraploid rice plant were sent to the autlllor in the spring of 1951 from Dr. Luong Dirih Cua. Which were produced by colchicine treatment of the highly sterile inter-subspecific hybrid Sekitori (Japonica) xKonanto (Indica). In the same year 341 F2 plants were reared from these F1 plants in our experimental farm by the ustial transplanting method. Such important practical characters as date of heading, culm height. panicle length, number of ears per plant, number of spikelet per ear, and percentage of sterillity were recorded about all F2 plants. Wide variations were observed among these characters as shown in tables 2-7. 100 F2 piants selected for their larg.e panicle and high fertility were treated in next generation and 360 F3 plants were selected am-ong 82 Iines. Number of spikelet per ear and percentage of sterility were measured about 3-5 ears perplant of the selected F3 plants. These results were compared as in table.s 8, 9, 10 and fig. 1, 2 with those of F2 and autotetraploid plants which were consisted of 30 Iines decended from 5 original stocks discovered by Dr. T. MORlNAGA and E. FUKUSHIMA about 20 years ago. The author discussed briefly from the data obtained that we may be able to hope to use such intersubspecific tetraploid ricefor future breeding materials.