Studies on Japonica Discrimination of Indica-Compatible Japonica Lines by Cheng's Indexes in Rice ( Oryza sativa L.)

In order to discriminate the characteristics of the indica compatible japonica lines (ICJLs) in rice ( Oryza sativa L.) exactly.The japonica characteristics of candidate ICJLs in rice and their F 1 hybrids were identified by Cheng's indexes. The results are as follows: the results of the japonica discrimination ofICJLs by means of Cheng's index are basically correct; and the results in different years and seasons are steady. The F 1 hybrids between the quasi japonica lines and the indica or quasi indica lines mainly belong to indica and quasi indica type.One of 15 candidate ICJLs is grouped into japonica and four candidate ICJls are grouped into quasi japonica lines by Cheng's index. The KClO 3 resistance of seedlings can be used as the good japonica discrimination index of ICJLs. The japonica discrimination of ICJLs identified by the improved Cheng's index is more exact than that by Cheng's index.