摘要：Controlled pollination is an essential element in forest tree breeding. Although the concept is simple, the process requires multiple steps, which must be done correctly to obtain successful crosses. As tree-breeding cooperatives of the Pacific Northwest begin a third cycle of breeding and testing, it is timely to describe this process for the major forest conifer species, Douglas-fir (Pseudotsuga menziesii Mirb. Franco). Stimulation by stem girdling and injection of gibberellic acids 4 and 7 is crucial for early flower induction; it can often begin 2 years after grafting into a seed orchard or breeding orchard. Other stimulation techniques (root pruning, calcium nitrate fertilization) can also be effective. Estimates of 10 seeds per female cone and 2 pollen buds to pollinate a female flower can be used for planning. Pollen dried to 6 to 8 percent can be used immediately or stored for future seasons. Important ingredients of successful crossing include attention to detail, constant vigilance, and exact timing, especially when bagging, harvesting pollen buds, and applying pollen to receptive female flowers
