MULTIPLE PROPAGATION EFFECTS ON GENETIC ESTIMATES OF ROOTING FOR WESTERN HEMLOCK

Analysis of clonal variation for two rooting traits of western hemlock [Tsuga heterophylla (Raf.) Sarg.] clones indicated that realized genetic gain would be improved by more effective partitioning and reduction of environmental differences associated with clones. Interactions between clones and multiple propagation dates were significant, but clone rank changes between dates were minor. Number of rooted cutting per plot (RC) and number of main roots per cutting (MR) were more highly correlated genetically (1.06) than phenotypically (0.36). Broad-sense heritabilities (H(x)2 = 0.62 and H(x)2 = 0.79 for RC and MR, respectively) and predicted genetic gain from clonal selection were moderately high. Both the percentage of rooted cuttings and root system quality could be rapidly improved by the clonal selection procedures used.