Effect of applied growth regulators on cone production in Douglas-fir, and relation of endogenous growth regulators to cone production capacity

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Abstract
Extracts of buds and young shoots of a good cone-producing clone of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were tested for cone production effect on seed orchard Douglas-fir trees chosen for their history of poor cone production. Other metabolites, including gibberellin 4/7, arginine, and abscisic acid were also tested. Growth regulator levels in good and poor cone-producing clones of Douglas-fir were compared over the period of bud break and shoot elongation.No evidence was obtained for the presence of growth regulators critical to cone production in purified extracts from ramets of the good cone-producing clone. Applied gibberellin 4/7 increased male and female cone production. Crude extracts of a good cone-producing clone increased male cone bud production. Arginine and abscisic acid had no effect.Bioassays indicated that growth regulator levels in buds and young shoots changed greatly with stage of development but were similar in good and poor cone-producing clones.