在玉米杂交育种过程中,如何尽快地选配出综合性状好、杂交优势强的单交种投入生产是育种的中心任务。通常采用顶交法对初选的自交系进行一般配合力测定以淘汰配合力低下的材料,而后用双列杂交法系统地对入选的高世代自交系进行特殊配合力测定以选出优良的单交组合,也有的采用测交结合等方法进行选择。总之,这些方法都必须在测交后才能判断杂交优势的强弱。除此之外,可否根据亲本自交系的外部性状,有预 In the course of maize hybrid breeding, how to allocate single cross-breeding species with good comprehensive characters and strong heterosis as soon as possible is the central task of breeding. Usually the top selection method is used to determine the general combining ability of the primary line of inbred lines to eliminate the low-combining materials, and then the specific combining ability of the selected high-generation inbred lines is systematically selected by the double-line hybridization method to select excellent Of the single cross combination, but also some methods such as combining test selection. In short, these methods must be submitted to measure the hybrid heterosis strength. In addition, depending on the external traits of the parent inbred lines, there is a possibility