GENETIC-CONTROL OF ROOTING ABILITY OF LODGEPOLE PINE CUTTINGS

This study evaluates the genetic control of rooting ability ex vitro f or cuttings of lodgepole pine (Pinus contorta var. latifolia Engelm.). More than 200 clones from 21 full-sib families were studied during 4 yr in the greenhouse. Clonal averages in rooting frequency, root size score, shoot extension during rooting, and vitality score were calcula ted, together with variance components and phenotypic and genetic corr elations among variables. Years, families within latitude of origin, c lones within families within latitudes, and cutting type (type of shoo t used as cutting) had statistically significant effects on rooting tr aits of cuttings. Years and clones within families had significant eff ects on height increment. Broad-sense heritabilities of clonal means w ere 0.55 for rooting frequency, 0.66 for root size, 0.56 for height in crement, and 0.34 for vitality. To reduce the nongenetic variation whe n estimating genetic parameters, cuttings should not be taken from dif ferent shoot types. Genetic correlations among the variables were gene rally negligible. Cutting propagation of lodgepole pine seems possible for producing plants for genetic tests. After refinement of the metho ds it may also be used operationally, but clones that produce few shoo ts and have low rooting ability might be lost.