Breeding graft-compatible Douglas-fir rootstocks (Pseudotsuga menziesii (Mirb.) Franco).

Abstract

A study encompassing 24 years was conducted to determine if a breeding program could produce highly graft-compatible rootstocks. Twenty-seven trees of apparent high graft compatibility were selected and crossed to produce 226 control-pollinated families. Seedlings were grown, field planted, and grafted with test scions. Graft unions from field tests were evaluated anatomically for internal symptoms of incompatibility. Average compatibility of progeny from the 226 crosses was 90.6% compared with 65% in native populations. Breeding values were calculated for each parent by the best linear prediction procedure. Average compatibility resulting from crossing among the top 10 parents was estimated by breeding values as 95.4%. Field-test results of progeny from 34 crosses among the 10 most compatible parents showed 96% compatibility. In addition to field-tests for graft compatibility, nursery tests of seedlings from 124 crosses were evaluated for second-year vegetative bud flush and seedling height. It was possible, while maintaining adequately high levels of graft compatibility, to breed both for resistance to spring frost damage and for increased seedling height.

Citation

Copes, D.L. 1999. Breeding graft-compatible Douglas-fir rootstocks (Pseudotsuga menziesii (Mirb.) Franco). Silvae Genetica. 48(3-4): 188-193