对１５个常用玉米自交系和１０５个杂交组合穗位叶光合速率的研究表明：①不同杂优类群的玉米自交系光合速率的差别很大，群间差异达显著水平；②群间杂交光合速率高、ＳＣＡ值大，群内杂交光合速率低、ＳＣＡ值小；③穗位叶光合速率的大小与单株籽粒产量无关；④光合速率表型值的大小及光合速率ＧＣＡ的大小，均不能作为杂优类群划分的依据。 The results showed that: (1) The photosynthetic rate of maize inbred lines of different heterotic groups differed greatly, and the differences among the groups reached significant level; (2) The interspecific hybridization Photosynthetic rate was high, SCA value was high, photosynthetic rate of hybrids in the group was low, and SCA value was small; ③The photosynthetic rate of ear position had no relation with grain yield per plant; ④Photosynthetic rate phenotype value and GCA size Can not be used as a basis for the classification of hybrid groups.