Effects of serial propagation, donor age, and genotype on Chamaecyparis nootkatensis physiology and growth traits

Clonal replicates of Chamaecyparis nootkatensis (D. Don) Spach rooted cuttings (ramets) originating from pruned donor hedges (ortets) were grown for 3 years in a completely randomized common garden in southwestern British Columbia. Ramets were cut when ortets were 3, 7, 11, and 15 years old; selected ramets were also serially propagated for one, two, or three cycles, 4 years apart. Serial propagation and physiological and chronological aging effects of ortets on ramets were evaluated for photosynthetic and gas exchange parameters, rooting, height, biomass, and cold hardiness. Genotypic variation typically exceeded treatment differences. Excepting several genotypes, serial propagation had no significant effect on aging for pruned plants. Some genotypes had crooked or plagiotropic growth. These differences strengthened with ortet age, but serial propagation effects varied with genotype. Rooting success was similar across treatments. Detrimental effects of ortet aging were detected only at age 15. Clonal rooting differences were obscured by age 7; 15-year-old material had the lowest rooting success and smallest individuals. Serially propagated ramets from 15-year-old ortets had smaller shoots. No consistent trends were caused by age or serial propagation for other traits. Serial propagation can successfully mass produce tested elite yellow-cedar planting stock up to age 15.