Genetic control of rooting ability of lodgepole pine cuttings

Abstract

This study evaluates the genetic control of rooting ability ex vitro for 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 calculated, together with variance components and phenotypic and genetic correlations among variables. Years, families within latitude of origin, clones within families within latitudes, and cutting type (type of shoot used as cutting) had statistically significant effects on rooting traits of cuttings. Years and clones within families had significant effects on height increment. Broad-sense heritabilities of clonal means were 0.55 for rooting frequency, 0.66 for root size, 0.56 for height increment, and 0.34 for vitality. To reduce the nongenetic variation when estimating genetic parameters, cuttings should not be taken from different shoot types. Genetic correlations among the variables were generally negligible. Cutting propagation of lodgepole pine seems possible for producing plants for genetic tests. After refinement of the methods it may also be used operationally, but clones that produce few shoots and have low rooting ability might be lost.