2015 Volume 4 Issue 2 Pages 45-51
To find cutting cultivars of Cryptomeria japonica, which are heterozygous for a male-sterility gene (Aa), we crossed a homozygous male-sterile tree (aa) with 10 clones selected from Toyama Prefecture. These clones are resistant to snow damage. Male sterility in this case is controlled by a recessive allele at a single locus and is expressed only in homozygotes. The crossing of a particular cutting cultivar clone, “Zasshunbo” , with a male sterile mother tree, produced 27 F1 male-sterile individuals and 23 F1 fertile individuals. The segregation ratio fitted the expected value of 1:1 according to the chi-square test. These results indicate that “Zasshunbo” was heterozygous for the male-sterility gene. The physical characteristics of “Zasshunbo” , including snow damage, the modulus of elasticity of a tree trunk, tree height, and diameter (DBH) were compared to 5 native cutting cultivars. The growth rate and the modulus of elasticity for “Zasshunbo” were highest among cultivars and its snow damage was lower than or equal to that of the other cultivars. Our results suggest that “Zasshunbo” is a promising breeder for the creation of superior male-sterile C. japonica trees.