Abstract:Analysis of combining ability plays an important role in assessing the breeding potential of parents and cultivation of hybrids. Five females and four males were used as parents to mate hybrids to analyze the combining ability effect, and the AMMI (additive main effects and multiplicative interaction) model was adopted to depose the interaction effect (same as the SCA, i.e. special combining ability) of parents. The results showed that the IPCA (interaction principal component axis) scores from AMMI model can well present the parents’ potential on the aspect of SCA, and the interaction effect of female and male parents also can be assessed by the inner product of their parents’ IPCA vectors. According to the length and direction of IPCA vectors, these parents may be classed into four groups: (1) the vector length of at least one parent of hybrid approximates the coordinate origin, implying that the heterosis of hybrid mainly depends on the GCA of parents; (2) the direction of two vectors of hybrid is in the vertical position, meaning that the interaction effect of hybrid approximates zero and performance of hybrid also greatly depends on the GCA of parents; (3) the direction of two vectors with the distant length is in the almost opposite position, implying that two parents have an enormous negative interaction effect; (4) the direction of two vectors with the distant length is in almost same position, implying that two parents have an enormous positive interaction effect. Above all, it is very necessary for developing hybrids with strong heterosis to select appropriate parents having distant length and similar direction of vectors representing the SCA score.