Abstract:To explore the genetic variation and heterosis of growth and shoot traits of F1 progeny of Castanea during young forest stage and lay a theoretical foundation for parent selection and early selection index screening of Castanea, we used the progenies of 9 combinations (interspecific and intraspecific cross between C. mollissima and C. henryi) and their parents as materials to analyze the genetic variation and heterosis of growth and shoot traits in study. Meanwhile, The genetic distance among 7 parents was detected by SSR molecular markers, which was used to analyze the relationship between the heterosis of growth and shoot traits and genetic distance of parents. Results showed that: (1) there was a high genetic variation among growth and shoot traits for F1 progeny of Castanea. The variation range of F value about traits was 5.08-22.03 among combinations, and the variation coefficient within combinations ranged from 6.60% to 27.69%. The general heritability of each trait is above 0.5, except for ground diameter, the inheritance of transfer ability of other traits were all above 100%,which indicated that the traits were greatly influenced by heredity and high genetic stability. The midparent heterosis rate of each trait ranged from -6.01% to 44.40%, and there was a general superparental separation phenomenon of F1 progeny of chestnut hybrids in growth and shoot traits. (2) A total of 115 polymorphic allelic loci were detected from 7 mating parents in 28 SSR markers. The number of allelic loci per SSR markers ranged from 3 to 5, and the average was 4.1. The mean of Shannons index (I) and polymorphism information content (PIC) were 1.25 and 0.674, respectively, which reveal that the genetic diversity were abundant in parents. (3) There was a significant linear relationship between the heterosis of annual branch length, diameter, node spacing and genetic distance of parents, and the genetic distance increased with the increase of heterosis.