Cone induction in yellow cypress (Chamaecyparisnootkatensis) by gibberellin A3 and the subsequent development of seeds within the induced cones

Abstract

Gibberellin A3 (GA3) induced prolific pollen cones and seed cones in 1- and 3-year-old yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) trees. In the first experiment, the GA3-induced cones developed normally and the viable pollen was allowed to pollinate the GA3-induced seed cones. Embryo development was normal and mature seeds were produced, of which 55% were filled and 93% of all filled seed germinated. In a second experiment 1-year-old potted seedlings grown in cold frames were treated with GA3 in June and July under natural long days (about 18 h of light) or short days (8 h of light). Under the long days, 4 and 5 weeks of GA3 treatment produced the maximum number of pollen cones and seed cones, respectively. Treatment with GA3 under short days induced fewer cones and gave inconsistent results.Thus, induction of cones in yellow cypress by a foliar spray can be accomplished easily and economically in seedlings or in young trees in a seed orchard under natural long days. When compared with cones which develop under natural conditions, GA3-induced cones produced a higher percentage of filled seed with a high germination percentage.