Preliminary Research on the Heredity of Classificatory Characters in the Hybridization Between Indica and Japonica

In this study, the cross combinations of different type rice were classified by Cheng's index method. The results showed that F, from japonica-indica cross was indicaclinous and their F2 varied consistently, most of them were intermediate types, while those from japonica-javanica cross were japonicaclinous and their F2 were mainly japonicaclinous and japonica, and those from japonica-japonica cross were all japonicaclinous. Analysis of correlation showed that the six classificatory characters of Cheng's index method were closely correlated with each other and the method was suitable for analyzing the classification of F2. For the F2 from japonica-indica cross, the segregation of Phenol Reaction (PhR) character showed double-peak curve, whereas those of the other five showed single-peak curve distributions. The scores of the other five characters were all between their parents and partly dominant except the length of 1st 2nd rachis (LOR) character. The date of heading was very significantly negatively correlated with Cheng's index of the parents and F1, so was the seed-setting rate with Cheng's index of F2.