Estimation of genetic parameters using three generation materials derived from Kumotooshi and Okinoyama sugi parents

Abstract

To clarify the stability of genetic parameters of growth traits of sugi (Cryptomeria japonica D. DON), clonal families of eight individuals of F₁ hybrid between Kumotooshi and Okinoyama sugi and F² families derived from the selfing of each F₁ individual were raised. Measurements of tree heights and root collar diameters at the age of 5 years were analysed by linear and correlation regressions of family means, and by variance analyses of both family means and individual measurements. Eight F₂ families, out of nine, had segregated dwarf plants showing clear growth reduction accompanied by needle anomaly. For tree height, greater heritabilities as 0.4_??_0.6 were estimated by regression analyses. Meanwhile, heritability as little as 0.04 was obtained by variance analyses for heights of all F₂ plants, and it was increased to as much as 0.25 for normal plants. Repeatabilities of tree heights of family means also were increased from 0.47 to 0.82 by excluding the dwarf plants. Similar results also were obtained with the root collar diameters.