Genetic variation of root traits of cuttings and their relation to early shoot growth in Cryptomeria japonica

In order to reveal the genetic variation of root traits and their effect on early shoot growth, we investigated the root traits and early shoot growth of cuttings of 193 clones in Cryptomeria japonica. We quantitatively measured seven root traits (root length, root surface area, root volume, average diameter, fine root ratio, root tip density and branch density) and early shoot growth, and assessed their genetic characteristics and relationships between root traits and early shoot growth. The broad-sense heritability of root tip density and branch density was relatively high. There was a strong correlation between traits related to root amount (root length, root surface area and root volume), and these traits also correlated with branch density. Early shoot growth correlated with root length, root surface area, root volume, branch density and fine root ratio. Our results provide a useful genetic basis for root traits and suggest the importance of the root traits as factors influencing shoot growth in C. japonica.